{"id":3228,"date":"2011-11-25T14:08:23","date_gmt":"2011-11-25T14:08:23","guid":{"rendered":"https:\/\/www.masterorganicchemistry.com\/?p=3228"},"modified":"2026-04-17T20:51:18","modified_gmt":"2026-04-18T01:51:18","slug":"hydrogenation-alkenes-palladium-on-carbon-pdc","status":"publish","type":"post","link":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/","title":{"rendered":"Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation of Alkenes"},"content":{"rendered":"<p><strong>Catalytic Hydrogenation of Alkenes With Pd\/C (And Friends)<\/strong><\/p>\n<ul>\n<li>Alkenes (and alkynes) will undergo addition of hydrogen (H<sub>2<\/sub>) in the presence of a metal catalyst such as Pd, Pt, Ni, or Rh.<\/li>\n<li>These metals are typically finely divided and adsorbed on the surface of a high surface-area material such as activated carbon (most common) or alumina (Al<sub>2<\/sub>O<sub>3<\/sub>) , hence Pd\/C, Pt\/C, Rh\/Al<sub>2<\/sub>O<sub>3<\/sub> and so on.\u00a0 Since these do not dissolve in solution they are called\u00a0<strong>heterogeneous\u00a0<\/strong>catalysts.<\/li>\n<li>Since addition results in a new C-H bond at the expense of a C-C bond the oxidation state of carbon decreases. These reactions are commonly referred to as <strong>reductions<\/strong>.<\/li>\n<li>Reduction of alkenes and alkynes generally occurs with high selectivity for <em>syn<\/em> addition products (<span style=\"color: #800080;\"><em>See article &#8211; <a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/01\/22\/alkene-addition-regioselectivity-syn-anti\/\">Syn and Anti Addition<\/a><\/em><\/span>)<\/li>\n<li>The mechanism (only covered vaguely) involves transfer of hydrogen to alkene on the metal surface<\/li>\n<li>Alkynes can be hydrogenated selectively over alkenes, which in turn can be hydrogenated selectively over ketones and aldehydes.<\/li>\n<li>Wilkinson&#8217;s catalyst, RhCl(PPh<sub>3<\/sub>)<sub>3<\/sub> is a <strong>homogeneous<\/strong> catalyst often used for selective hydrogenations.<\/li>\n<\/ul>\n<p><img fetchpriority=\"high\" decoding=\"async\" class=\"alignnone wp-image-35640\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2011\/11\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif\" alt=\"summary of catalytic hydrogenation of alkenes with heterogeneous catalysts like pd:c and hydrogen 2\" width=\"640\" height=\"459\" \/><\/a><\/p>\n<p><strong>Table of Contents<\/strong><\/p>\n<ol>\n<li style=\"list-style-type: none;\">\n<ol>\n<li><a href=\"#one\">Catalytic Hydrogenation of Alkenes With Pd, Pt and Other Metals<\/a><\/li>\n<li><a href=\"#two\">Examples of Alkene and Alkyne Hydrogenation<\/a><\/li>\n<li><a href=\"#three\">Hydrogenation is Selective for Syn Addition<\/a><\/li>\n<li><a href=\"#four\">(A Rough Sketch of) A Mechanism for Catalytic Hydrogenation<\/a><\/li>\n<li><a href=\"#five\">Other reactions of Pd\/C and H<sub>2\u00a0<\/sub><\/a><\/li>\n<li><a href=\"#six\">Homogeneous Catalysis using Wilkinsons Catalyst<\/a><\/li>\n<li><a href=\"#seven\">Summary<\/a><\/li>\n<li><a href=\"#notes\">Notes<\/a><\/li>\n<li><a href=\"#quiz\">Quiz Yourself!<\/a><\/li>\n<li><a href=\"#references\">(Advanced) References and Further Reading<\/a><\/li>\n<\/ol>\n<\/li>\n<\/ol>\n<hr \/>\n<h2><a id=\"one\"><\/a>1. Catalytic Hydrogenation of Alkenes With Pd, Pt, and Other Metals<\/h2>\n<p>Alkenes (and alkynes) will undergo addition of hydrogen (H<sub>2<\/sub>) to C-C pi bonds in the presence of a metal catalyst in a reaction known as &#8220;<strong>catalytic <\/strong><strong>hydrogenation<\/strong>&#8220;.<\/p>\n<p><span style=\"color: #993366;\"><em>Discovered in the 1890s by <a href=\"#refone\">Sabatier<\/a>, and now used industrially on massive scale for the hydrogenation of vegetable oils. [<a href=\"#noteone\"><span style=\"color: #ff0000;\">Note 1<\/span><\/a>]\u00a0<\/em><\/span><\/p>\n<p>In this reaction a C-C pi bond (bond dissociation energy [BDE] of about 60 kcal\/mol) and a H-H bond (BDE about 104 kcal\/mol) are broken, and two C-H sigma bonds (BDE about 98 kcal\/mol) are formed, making it <strong>exothermic<\/strong> by about <strong>30 kcal\/mol<\/strong>.<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-35605\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/1-overview-of-catalytic-hydrogenation-of-alkenes-using-palladium-on-carbon-or-platinum-on-carbon.gif\" alt=\"overview of catalytic hydrogenation of alkenes using palladium on carbon or platinum on carbon\" width=\"640\" height=\"416\" \/><\/a><\/p>\n<p><span style=\"color: #993366;\"><em>Since C-H bonds are formed at the expense of C-C bonds, hydrogenation reactions of alkenes and alkynes result in a lowering of the oxidation state of carbon and are often described as &#8220;<strong>reductions<\/strong>&#8220;. See: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2011\/08\/01\/oxidation-and-reduction-in-organic-chemistry\/\">Oxidation and Reduction in Organic Chemistry<\/a>. <\/em><\/span><\/p>\n<p>Despite the significantly greater stability of the products, <strong>no reaction<\/strong> between the alkene and H<sub>2<\/sub> typically occurs in the <strong>absence<\/strong> of the metal.<\/p>\n<p>The metal catalyst is typically palladium (Pd) or platinum (Pt),\u00a0 although other metals with similar properties such as nickel (Ni) and rhodium (Rh) can also be used. These relatively electron-rich &#8220;<a href=\"https:\/\/en.wikipedia.org\/wiki\/Transition_metal\">late<\/a>&#8221; metals react with H<sub>2<\/sub> to form metal-bound hydrides (e.g. H-Pd), which are more reactive towards alkenes than H<sub>2<\/sub> itself. Furthermore, late metals readily adsorb alkenes and other molecules with pi bonds onto their surface.\u00a0 The resulting hydrogenation products, lacking a pi bond, are not bound as strongly to the metal and typically dissociate after hydrogenation, freeing up a site on the metal surface for further reaction.<\/p>\n<p class=\"p1\"><span style=\"color: #993366;\"><em>Think of the surface of Pd\/C as kind of like a singles bar, where hydrogen and alkenes (or other organic compounds) meet, react, and leave together. As a catalyst, \u00a0Pd\/C is a lot like a matchmaker who brings couples together, but never gets married himself.<\/em><\/span><\/p>\n<p>Since the reaction takes place on the metal surface, high surface area is important for reasonable reaction rates. The metal is typically finely divided and adsorbed onto a solid support such as <strong>activated carbon<\/strong> or alumina. [<span style=\"color: #ff0000;\"><a style=\"color: #ff0000;\" href=\"#refthree\">Described here<\/a><\/span>].\u00a0 The result is typically a black powder typically containing 5%-10% metal by weight, e.g. 5% Pd\/C or 10% Pt\/C.<\/p>\n<p><span style=\"color: #993366;\"><em>Since powders do not dissolve in organic solvents, they are referred to as <strong>heterogeneous catalysts<\/strong>.\u00a0<\/em><\/span><\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-35606\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/2-picture-showing-palladium-on-carbon-stanford-metals-high-surface-area.gif\" alt=\"picture showing palladium on carbon stanford metals high surface area\" width=\"560\" height=\"214\" \/><\/a><\/p>\n<p><em><a href=\"https:\/\/www.samaterials.com\/palladium\/1874-palladium-on-carbon-catalyst.html\">Photo credit.<\/a> <span style=\"color: #800080;\">The first time I saw palladium on carbon (Pd\/C) and platinum on carbon (Pt\/C) I was expecting to see something more traditionally shiny and metallic, rather than a fine black powder.\u00a0<\/span><\/em><\/p>\n<p>On small scale, hydrogenation is usually carried out by adding pre-formed, commercially available catalyst (e.g. palladium on carbon, Pd\/C) to a solution of the starting material in an inert atmosphere. After H<sub>2<\/sub> is introduced (often via balloon), it&#8217;s party time. [<a href=\"#notetwo\"><span style=\"color: #ff0000;\">Note 2<\/span><\/a>]<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35619\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/3-hydrogenation-using-balloon-atmosphere-carried-out-on-large-scale-credit-to-org-prep-daily-scaled.jpg\" alt=\"hydrogenation using balloon atmosphere carried out on large scale credit to org prep daily\" width=\"640\" height=\"480\" srcset=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/3-hydrogenation-using-balloon-atmosphere-carried-out-on-large-scale-credit-to-org-prep-daily-scaled.jpg 2048w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/3-hydrogenation-using-balloon-atmosphere-carried-out-on-large-scale-credit-to-org-prep-daily-300x225.jpg 300w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/3-hydrogenation-using-balloon-atmosphere-carried-out-on-large-scale-credit-to-org-prep-daily-1024x768.jpg 1024w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/3-hydrogenation-using-balloon-atmosphere-carried-out-on-large-scale-credit-to-org-prep-daily-768x576.jpg 768w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/3-hydrogenation-using-balloon-atmosphere-carried-out-on-large-scale-credit-to-org-prep-daily-1536x1152.jpg 1536w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/3-hydrogenation-using-balloon-atmosphere-carried-out-on-large-scale-credit-to-org-prep-daily-760x570.jpg 760w\" sizes=\"(max-width: 640px) 100vw, 640px\" \/><\/a><\/p>\n<p><strong>Source: <a href=\"https:\/\/orgprepdaily.wordpress.com\/2014\/05\/22\/a-kilo-scale-hydrogenation\/\">Org Prep Daily\u00a0<\/a><\/strong><\/p>\n<p>Since three phases of matter are involved (gaseous H<sub>2<\/sub>, liquid solvent, solid catalyst), vigorous stirring or shaking is necessary for good reaction rates.<\/p>\n<p><iframe class=\"giphy-embed\" src=\"https:\/\/giphy.com\/embed\/xrCjxhmHZnzqfkEYR0\" width=\"480\" height=\"270\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><a href=\"https:\/\/giphy.com\/gifs\/xrCjxhmHZnzqfkEYR0\">via GIPHY<\/a><\/p>\n<p>Parr shaker apparatus. <strong><a href=\"https:\/\/www.youtube.com\/watch?v=CRuTgYslE8I\">Source<\/a><\/strong>.<\/p>\n<p>When the reaction is complete, the catalyst is separated from the reaction mixture by filtration (<span style=\"color: #ff0000;\"><em>note: care must be taken to avoid exposing dry, hydrogenated catalyst to oxygen &#8211; fires can result.)<\/em><\/span><\/p>\n<h2><a id=\"two\"><\/a>2. Catalytic Hydrogenation of Alkenes: Examples<\/h2>\n<p>Both alkenes and alkynes will readily undergo catalytic hydrogenation. Reactions are generally carried out with a molar excess of hydrogen gas, although it is possible to regulate the number of molar equivalents of H<sub>2<\/sub> by using a gas buret or similar device if desired.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35607\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/4-examples-of-catalytic-hydrogenation-of-alkenes-and-alkynes-with-pd-carbon-and-h2-no-stereochemistry.gif\" alt=\"examples of catalytic hydrogenation of alkenes and alkynes with pd carbon and h2 no stereochemistry\" width=\"640\" height=\"501\" \/><\/a><\/p>\n<p><span style=\"color: #993366;\"><em>(There is a lot of variety in the specific identity of the metal &#8211; for example, one can use palladium (Pd), palladium hydroxide (Pd(OH)<sub>2<\/sub>, platinum (Pt), platinum oxide (PtO<sub>2<\/sub>), rhodium (Rh), nickel (Ni), Raney Nickel, and more. This covers the most common cases but is not exhaustive! For our purposes (introductory organic chemistry) these can be treated as equivalent. For more specific cases see<a href=\"#notethree\"> Note 3<\/a>. )<\/em><\/span><\/p>\n<p>The specific pressure of H<sub>2<\/sub> is not always indicated, but is typically 1-4 atmospheres (atm) of hydrogen (15-60 psi). Difficult hydrogenations may require pressure vessels at up to 100 atm.<\/p>\n<p>For example, the benzene ring is generally inert towards many reagents that add to alkenes, a topic that we explore in more detail in the chapter on aromaticity (<span style=\"color: #800080;\"><em>See article &#8211; <a style=\"color: #800080;\" href=\"https:\/\/www.masterorganicchemistry.com\/2017\/01\/20\/introduction-aromaticity\/\">Introduction to Aromaticity<\/a><\/em><\/span>).<\/p>\n<p>Hydrogenation of the benzene ring is possible, but typically requires higher pressures of hydrogen gas than do normal alkenes.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35608\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/5-benzene-rings-tend-to-require-higher-pressures-of-h2-more-atmospheres-of-hydrogen-gas.gif\" alt=\"benzene rings tend to require higher pressures of h2 more atmospheres of hydrogen gas\" width=\"640\" height=\"371\" \/><\/a><\/p>\n<p>When an alkene is hydrogenated to an alkane, the hybridization at carbon goes from sp<sup>2<\/sup> to sp<sup>3<\/sup>. Be alert for the formation of stereoisomers!<\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"35599\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"35599\"] {\n--wq-question-width: 100%;\n--wq-question-color: #009cff;\n--wq-question-height: auto;\n--wq-font-color: #444;\n}\n\n\t\t\t.wq-quiz-wrapper[data-id=\"35599\"] {\n\t\t\t\t--wq-question-width: 600px;\n\t\t\t}\n\n\t\t\t@media screen and (max-width: 600px) {\n\t\t\t\t.wq-quiz-wrapper[data-id=\"35599\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-35599\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-35599 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"35599\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-dsltq\" data-id=\"dsltq\">\n\n\t\n\t<div class=\"item_top\">\n\t\t<div class=\"title_container\">\n\t\t\t<div class=\"wq_questionTextCtr\">\n\t\t\t\t<h4 class=\"wq-question-title\"><\/h4>\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n\n\t<div class=\"card \">\n\t\t<div class=\"front\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2597-Front.gif\" \/>\n\t\t\n\t\t\n\t\n\t\n\t\t\t<span class=\"top-desc\">Click to Flip<\/span>\n\t<\/div>\n\t\t<div class=\"back\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2597-Reverse.gif\" \/>\n\t\t\n\t\t\n\t\n\t<\/div>\n\t<\/div>\n\n\t\n<\/div>\n<\/div>\n<\/div>\n<!-- \/\/ wp quiz-->\n<\/div><!-- End .wq-quiz-wrapper -->\n<p>Here is another example in this vein:<\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"35600\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"35600\"] {\n--wq-question-width: 100%;\n--wq-question-color: #009cff;\n--wq-question-height: auto;\n--wq-font-color: #444;\n}\n\n\t\t\t.wq-quiz-wrapper[data-id=\"35600\"] {\n\t\t\t\t--wq-question-width: 600px;\n\t\t\t}\n\n\t\t\t@media screen and (max-width: 600px) {\n\t\t\t\t.wq-quiz-wrapper[data-id=\"35600\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-35600\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-35600 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"35600\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-lt7z0\" data-id=\"lt7z0\">\n\n\t\n\t<div class=\"item_top\">\n\t\t<div class=\"title_container\">\n\t\t\t<div class=\"wq_questionTextCtr\">\n\t\t\t\t<h4 class=\"wq-question-title\"><\/h4>\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n\n\t<div class=\"card \">\n\t\t<div class=\"front\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2598-Front.gif\" \/>\n\t\t\n\t\t\n\t\n\t\n\t\t\t<span class=\"top-desc\">Click to Flip<\/span>\n\t<\/div>\n\t\t<div class=\"back\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2598-Reverse.gif\" \/>\n\t\t\n\t\t\n\t\n\t<\/div>\n\t<\/div>\n\n\t\n<\/div>\n<\/div>\n<\/div>\n<!-- \/\/ wp quiz-->\n<\/div><!-- End .wq-quiz-wrapper -->\n<p>There is no simple formula for answering questions which ask you to say whether a reaction results in enantiomers, diastereomers, constitutional isomers, and so on since it is highly dependent on the structure of the starting alkene. My advice is just to apply the pattern of bonds formed\/bonds broken to each reaction and then analyze the relationship between any molecules that form. (<em><span style=\"color: #800080;\">See article: <a style=\"color: #800080;\" href=\"https:\/\/www.masterorganicchemistry.com\/2019\/03\/08\/enantiomers-diastereomers-or-the-same-1-using-models\/\">Enantiomers, Diastereomers, or The Same? Two Methods for Solving Problems<\/a><\/span>)<\/em><\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"35601\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"35601\"] {\n--wq-question-width: 100%;\n--wq-question-color: #009cff;\n--wq-question-height: auto;\n--wq-font-color: #444;\n}\n\n\t\t\t.wq-quiz-wrapper[data-id=\"35601\"] {\n\t\t\t\t--wq-question-width: 600px;\n\t\t\t}\n\n\t\t\t@media screen and (max-width: 600px) {\n\t\t\t\t.wq-quiz-wrapper[data-id=\"35601\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-35601\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-35601 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"35601\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-sf76n\" data-id=\"sf76n\">\n\n\t\n\t<div class=\"item_top\">\n\t\t<div class=\"title_container\">\n\t\t\t<div class=\"wq_questionTextCtr\">\n\t\t\t\t<h4 class=\"wq-question-title\"><\/h4>\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n\n\t<div class=\"card \">\n\t\t<div class=\"front\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2599-Front.gif\" \/>\n\t\t\n\t\t\n\t\n\t\n\t\t\t<span class=\"top-desc\">Click to Flip<\/span>\n\t<\/div>\n\t\t<div class=\"back\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2599-Reverse.gif\" \/>\n\t\t\n\t\t\n\t\n\t<\/div>\n\t<\/div>\n\n\t\n<\/div>\n<\/div>\n<\/div>\n<!-- \/\/ wp quiz-->\n<\/div><!-- End .wq-quiz-wrapper -->\n<h2><a id=\"three\"><\/a>3. Hydrogenation Is Stereoselective for <em>Syn<\/em> Addition<\/h2>\n<p>Hydrogenation is generally a\u00a0<strong>stereoselective\u00a0<\/strong>reaction where the two C-H bonds form on the <strong>same face<\/strong> of the alkene.<\/p>\n<p>This is known as\u00a0<em>syn<\/em> addition (in contrast to <em>anti<\/em> addition where the two new bonds form on opposite faces of the alkene).<\/p>\n<p>For example, the major product in the hydrogenation of 1,2-dimethylcyclohexene is\u00a0<em>cis<\/em>-1,2-dimethylcyclohexane.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35609\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/9-stereochemistry-of-catalytic-hydrogenation-is-syn-addition-regardless-of-catalyst-stereoselective.gif\" alt=\"stereochemistry of catalytic hydrogenation is syn addition regardless of catalyst - stereoselective\" width=\"640\" height=\"388\" \/><\/a><\/p>\n<p>In general, catalytic hydrogenation is highly stereoselective for <em>syn<\/em> addition. [<a href=\"#notefour\"><span style=\"color: #ff0000;\">Note 4<\/span><\/a>]<\/p>\n<p><span style=\"color: #800080;\"><em>In practice, particularly with Pd (and less so with Pt) a significant amount of double bond migration can occur before hydrogenation is completed. <\/em><\/span><em><span style=\"color: #800080;\">A related process is responsible for the formation of trans fats in partial hydrogenation of vegetable oils, for example<\/span>. [<a href=\"#notefive\"><span style=\"color: #ff0000;\">Note 5<\/span><\/a>]<\/em><\/p>\n<p>Deuterium (D<sub>2<\/sub>) can be used in place of hydrogen to give isotopically labelled products (<span style=\"color: #800080;\"><em>recall that deuterium is the heavy isotope of hydrogen<\/em><\/span>). The reaction is otherwise identical in all respects, including a preference for\u00a0<em>syn<\/em> addition.<\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"35602\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"35602\"] {\n--wq-question-width: 100%;\n--wq-question-color: #009cff;\n--wq-question-height: auto;\n--wq-font-color: #444;\n}\n\n\t\t\t.wq-quiz-wrapper[data-id=\"35602\"] {\n\t\t\t\t--wq-question-width: 600px;\n\t\t\t}\n\n\t\t\t@media screen and (max-width: 600px) {\n\t\t\t\t.wq-quiz-wrapper[data-id=\"35602\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-35602\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-35602 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"35602\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-1k2aj\" data-id=\"1k2aj\">\n\n\t\n\t<div class=\"item_top\">\n\t\t<div class=\"title_container\">\n\t\t\t<div class=\"wq_questionTextCtr\">\n\t\t\t\t<h4 class=\"wq-question-title\"><\/h4>\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n\n\t<div class=\"card \">\n\t\t<div class=\"front\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2600-Front.gif\" \/>\n\t\t\n\t\t\n\t\n\t\n\t\t\t<span class=\"top-desc\">Click to Flip<\/span>\n\t<\/div>\n\t\t<div class=\"back\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2600-Reverse.gif\" \/>\n\t\t\n\t\t\n\t\n\t<\/div>\n\t<\/div>\n\n\t\n<\/div>\n<\/div>\n<\/div>\n<!-- \/\/ wp quiz-->\n<\/div><!-- End .wq-quiz-wrapper -->\n<p>See if you can work backwards from the final product to the original alkene starting material:<\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"35603\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"35603\"] {\n--wq-question-width: 100%;\n--wq-question-color: #009cff;\n--wq-question-height: auto;\n--wq-font-color: #444;\n}\n\n\t\t\t.wq-quiz-wrapper[data-id=\"35603\"] {\n\t\t\t\t--wq-question-width: 600px;\n\t\t\t}\n\n\t\t\t@media screen and (max-width: 600px) {\n\t\t\t\t.wq-quiz-wrapper[data-id=\"35603\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-35603\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-35603 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"35603\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-ca1tt\" data-id=\"ca1tt\">\n\n\t\n\t<div class=\"item_top\">\n\t\t<div class=\"title_container\">\n\t\t\t<div class=\"wq_questionTextCtr\">\n\t\t\t\t<h4 class=\"wq-question-title\"><\/h4>\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n\n\t<div class=\"card \">\n\t\t<div class=\"front\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2601-Front.gif\" \/>\n\t\t\n\t\t\n\t\n\t\n\t\t\t<span class=\"top-desc\">Click to Flip<\/span>\n\t<\/div>\n\t\t<div class=\"back\" >\n\t\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-images\/2601-Reverse.gif\" \/>\n\t\t\n\t\t\n\t\n\t<\/div>\n\t<\/div>\n\n\t\n<\/div>\n<\/div>\n<\/div>\n<!-- \/\/ wp quiz-->\n<\/div><!-- End .wq-quiz-wrapper -->\n<p>Be alert that in some molecules, the two faces of the alkene are not equally accessible to reagents. In these cases the less hindered side of the alkene will end up bound to the metal.<\/p>\n<p>For example in the bicyclic molecule below, the top face is more accessible since it is only blocked by a one carbon (CH<sub>2<\/sub>) bridge, whereas bottom approach is blocked by a two-carbon bridge.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35610\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/11-catalytic-hydrogenation-of-alkenes-proceeds-through-hydrogenation-of-the-least-hindered-side-least-hindered-face-of-alkene-will-coordinate-with-alkene.gif\" alt=\"catalytic hydrogenation of alkenes proceeds through hydrogenation of the least hindered side - least hindered face of alkene will coordinate with alkene\" width=\"640\" height=\"320\" \/><\/a><\/p>\n<h2><a id=\"four\"><\/a>4. Catalytic Hydrogenation &#8211; A Rough Mechanism<\/h2>\n<p>The mechanism of catalytic hydrogenation is unusual for us in that it&#8217;s not a typical arrow-pushing mechanism.<\/p>\n<p>It happens on a metal surface and all the specific details of how hydrogenation happens on that metal surface haven&#8217;t been completely worked out.[<a href=\"#notesix\"><span style=\"color: #ff0000;\">Note 6<\/span><\/a>]<\/p>\n<p><span style=\"color: #800080;\"><em>As Wolfgang Pauli said; &#8220;God made the bulk; the surface was invented by the devil&#8221;.\u00a0<\/em><\/span><\/p>\n<p>Furthermore, it involves some mechanisms of transition metals that aren&#8217;t really taught fully in introductory organic chemistry classes.<\/p>\n<p>The first two steps of catalytic hydrogenation involve coordination of the alkene and of H<sub>2<\/sub> to the metal surface.<\/p>\n<ul>\n<li>The starting alkene (or alkyne, or other starting material) is typically adsorbed on the surface of the metal through its pi-bond.<\/li>\n<li>When hydrogen gas (H<sub>2<\/sub>) is introduced to the metal, it is converted into metal hydrides that reside on the surface. (<a href=\"#noteseven\"><span style=\"color: #ff0000;\">Note 7<\/span><\/a> )<\/li>\n<\/ul>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35611\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/13-mechanism-of-heterogeneous-catalysis-of-catalytic-hydrogenation-with-pd-c-and-h2.gif\" alt=\"mechanism of heterogeneous catalysis of catalytic hydrogenation with pd c and h2\" width=\"640\" height=\"358\" \/><\/a><\/p>\n<ul>\n<li>With the hydride and alkene in close proximity, a C-H bond forms and the C-C pi bond breaks, resulting in a metal-carbon bond. (<a href=\"#noteeight\"><span style=\"color: #ff0000;\">Note 8<\/span><\/a>)<\/li>\n<li>Finally, the second carbon-hydrogen bond forms, resulting in an alkane. [<a href=\"#notenine\"><span style=\"color: #ff0000;\">Note 9<\/span><\/a>] Without any pi bond, the molecule dissociates.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35612\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/14-mechanism-for-hydrogenation-with-palladium-on-carbon-migratory-insertion-and-reductive-elimination.gif\" alt=\"mechanism for hydrogenation with palladium on carbon - migratory insertion and reductive elimination\" width=\"640\" height=\"304\" \/><\/a><\/p>\n<p>Note the two atoms of H<sub>2<\/sub> are not introduced at <em>exactly<\/em> the same time!<\/p>\n<h2><a id=\"five\"><\/a>5. Alkenes vs. Alkynes vs. C=O and Other Functional Groups<\/h2>\n<p>Alkynes are even more reactive towards hydrogenation than alkenes, and can typically be reduced to alkenes without affecting the other alkenes in the molecule.<\/p>\n<p><span style=\"color: #800080;\"><em>The best way to do this is generally with Lindlar&#8217;s Catalyst (See article &#8211; <a style=\"color: #800080;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/05\/08\/lindlar-nanh3-partial-reduction-of-alkynes\/\">Lindlar&#8217;s catalyst<\/a>) or with sodium in ammonia, both of which only reduce alkynes.\u00a0<\/em><\/span><\/p>\n<p>It can also be done with Pd, usually something like barium sulfate. BaSO<sub>4<\/sub>.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35613\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/15-alkynes-are-more-reactive-in-catalytic-hydrogenation-than-alkenes-selective-hydrogenation.gif\" alt=\"mechanism for hydrogenation with palladium on carbon - migratory insertion and reductive elimination\" width=\"640\" height=\"329\" \/><\/a><\/p>\n<p>When two or more alkenes are present on the same molecule, it\u00a0<em>can<\/em> be possible to hydrogenate one alkene without reducing the other if care is taken to introduce only one mole of H<sub>2<\/sub>.<\/p>\n<p>It&#8217;s usually the least substituted alkene that is hydrogenated first, because it&#8217;s more accessible to the metal catalyst.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35622\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2011\/11\/16-selective-hydrogenation-of-least-sterically-hindered-alkene-in-catalytic-hydrogenation-of-molecules-iwth-multiple-alkenes.gif\" alt=\"selective hydrogenation of least sterically hindered alkene in catalytic hydrogenation of molecules iwth multiple alkenes\" width=\"640\" height=\"311\" \/><\/a><\/p>\n<p>Ketones and aldehydes are even less reactive toward catalytic hydrogenation than are alkenes or alkynes. It&#8217;s very possible to hydrogenate a double bond without aldehyde or ketone being affected.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35615\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/17-hydrogenation-of-alkenes-can-be-done-selectively-in-the-presence-of-carbonyl-groups-without-reducing-carbonyls.gif\" alt=\"hydrogenation of alkenes can be done selectively in the presence of carbonyl groups without reducing carbonyls\" width=\"640\" height=\"197\" \/><\/a><\/p>\n<p>When pushed, ketones can be converted to alcohols (C-OH) or even alkanes (CH<sub>2<\/sub>) ; this topic usually comes up when we cover the reactions of aromatic compounds.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35616\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/18-carbonyls-adjacent-to-aromatic-rings-can-be-reduced-with-palladium-on-carbon-all-the-way-to-the-alkane.gif\" alt=\"carbonyls adjacent to aromatic rings can be reduced with palladium on carbon all the way to the alkane\" width=\"640\" height=\"256\" \/><\/a><\/p>\n<p>Catalytic hydrogenation can also be used to convert nitro groups and nitriles to amines (<span style=\"color: #800080;\"><em>although to be fair this is typically covered much later in the course!)<\/em><\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35617\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/19-can-use-pd-c-palladium-on-carbon-to-reduce-nitro-groups-to-amines-and-cyano-groups-to-primary-amines.gif\" alt=\"can use pd c palladium on carbon to reduce nitro groups to amines and cyano groups to primary amines\" width=\"640\" height=\"346\" \/><\/a><\/p>\n<h2><a id=\"six\"><\/a>6. Homogeneous Catalysis With Wilkinson&#8217;s Catalyst<\/h2>\n<p>An example of a <strong>homogeneous <\/strong>hydrogenation catalyst is Wilkinson&#8217;s catalyst, RhCl(PPh<sub>3<\/sub>)<sub>3<\/sub> . One advantage of carrying out hydrogenations with Wilkinson&#8217;s catalyst is a lack of the scrambling that can sometimes occur with Pd.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35618\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/09\/20-wilkinsons-catalyst-is-a-homogenous-catalyst-that-can-be-used-for-the-hydrogenation-of-alkenes.gif\" alt=\"can use pd c palladium on carbon to reduce nitro groups to amines and cyano groups to primary amines\" width=\"640\" height=\"345\" \/><\/a><\/p>\n<p>The reactions of transition metal catalysts such as Wilkinson&#8217;s catalyst are generally beyond what we cover in introductory organic chemistry as they involve mechanisms such as oxidative addition, migratory insertion, reductive elimination and others that are not necessarily <em>difficult\u00a0<\/em>to learn, but require a fair amount of background in inorganic chemistry to understand.<\/p>\n<p><span style=\"color: #993366;\"><em>For advanced students: <span style=\"text-decoration: underline;\"><a style=\"color: #993366; text-decoration: underline;\" href=\"https:\/\/whitegroupillinois.wixsite.com\/thewhitegroup\/copy-of-c-h-to-c-o-hydroxylations\">these\u00a0notes<\/a><\/span> from Prof. M.C. White (UIUC) are a truly excellent place to start. <a style=\"color: #993366;\" href=\"https:\/\/b1f7d8a6-f05e-4097-864c-ee111c31fe94.filesusr.com\/ugd\/101d60_1b0e46f3ccad46ef9a945b264f30fa6d.pdf\">Wilkinson&#8217;s Catalyst<\/a><\/em><\/span><\/p>\n<h2><a id=\"seven\"><\/a>7. Summary<\/h2>\n<p>Alkenes (and alkynes) can be converted to alkanes through treatment with H<sub>2<\/sub> and a metal catalyst such as Pd, Pt, Ni, or Rh. For our purposes these catalysts are essentially the same, although there are some subtle differences. The metal is usually adsorbed on a high surface area material (such as activated carbon) and filtered off after use.<\/p>\n<p>This is considered a\u00a0<strong>reduction\u00a0<\/strong>since a new C-H bond is formed at the expense of a C-C bond and the oxidation state of carbon is reduced.<\/p>\n<p>For our purposes the reaction is considered\u00a0<strong>concerted<\/strong> and selective for\u00a0<em>syn<\/em> addition.<\/p>\n<p>Pd\/C can also be used for reduction of nitro groups (NO<sub>2<\/sub>) and even CN and aromatic rings. For difficult reductions higher pressures of H<sub>2<\/sub> and higher temperatures may be used.<\/p>\n<p>An example of a\u00a0<strong>homogeneous\u00a0<\/strong>catalyst for hydrogenation is Wilkinson&#8217;s catalyst, RhCl(PPh<sub>3<\/sub>)<sub>3<\/sub>. This reagent is completely stereospecific.,<\/p>\n<hr \/>\n<h2><strong><a id=\"notes\"><\/a>Notes<\/strong><\/h2>\n<div class=\"related-articles\"><p><strong>Related Articles<\/strong><\/p><ul><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2020\/04\/30\/alkene-stability\/\" class=\"\"><span>Alkene Stability<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/06\/17\/reagent-friday-m-cpba-meta-chloroperoxybenzoic-acid\/\" class=\"\"><span>m-CPBA (meta-chloroperoxybenzoic acid)<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/05\/08\/lindlar-nanh3-partial-reduction-of-alkynes\/\" class=\"\"><span>Partial Reduction of Alkynes With Lindlar\u2019s Catalyst or Na\/NH3 To Obtain Cis or Trans Alkenes<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/08\/19\/reagent-friday-lindlars-catalyst\/\" class=\"\"><span>Reagent Friday: Lindlar\u2019s Catalyst<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2019\/03\/08\/enantiomers-diastereomers-or-the-same-1-using-models\/\" class=\"\"><span>Enantiomers vs Diastereomers vs The Same? Two Methods For Solving Problems<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/05\/23\/whats-a-racemic-mixture\/\" class=\"\"><span>What\u2019s a Racemic Mixture?<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/04\/02\/epoxidation-hydroxylation-cyclopropanation-alkene-mechanism\/\" class=\"\"><span>Alkene Addition Pattern #3: The \u201cConcerted\u201d Pathway<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/03\/28\/hydroboration-of-alkenes-the-mechanism\/\" class=\"\"><span>Hydroboration Oxidation of Alkenes<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2017\/01\/20\/introduction-aromaticity\/\" class=\"\"><span>Introduction To Aromaticity<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2023\/10\/18\/cyclopropanation-of-alkenes\/\" class=\"\"><span>Cyclopropanation of Alkenes<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2010\/07\/02\/stereoselective-stereospecific\/\" class=\"\"><span>Stereoselective and Stereospecific Reactions<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/01\/22\/alkene-addition-regioselectivity-syn-anti\/\" class=\"\"><span>Alkene Addition Reactions: \u201cRegioselectivity\u201d and \u201cStereoselectivity\u201d (Syn\/Anti)<\/span><\/a><\/li><\/ul><\/div>\n<p><strong><a id=\"noteone\"><\/a>Note 1<\/strong>. Unsaturated fats contain double bonds and are commonly found in butter, among many other natural sources. The problem with unsaturated fats is that they slowly react with molecular oxygen. The C-H bonds on the carbons adjacent to the double bond (the &#8220;allylic&#8221; positions) are unusually weak, since removal of H by O2 in homolytic fashion gives a resonance stabilized allylic radical. This then combines with the O-OH radical to give a hydroperoxide, which in the case of butter eventually breaks down to <strong>butyric acid, the smell of rancid butter.<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35675\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/10\/F1-unsaturated-fats-can-undergo-air-oxidation-through-removal-of-allylic-hydrogen-by-molecular-oxygen-to-give-rancid-byproducts-such-as-butyric-acid.gif\" alt=\"unsaturated fats can undergo air oxidation through removal of allylic hydrogen by molecular oxygen to give rancid byproducts such as butyric acid\" width=\"640\" height=\"447\" \/><\/a><\/p>\n<p>Hydrogenation of unsaturated fats gives saturated fats, which are much more resistant to homolytic removal of C-H by oxygen. They have very long shelf lives and do not typically spoil.<\/p>\n<p>The double bonds in naturally occurring saturated fats are <strong>cis<\/strong>. One problem with hydrogenation is that it can result in isomerization of the double bond to\u00a0 give\u00a0<em>trans<\/em> fats, which are very bad.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35678\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/10\/F2-shelf-life-of-unsaturated-fats-is-greatly-improved-through-hydrogenation-which-removes-allylic-C-H-bonds.gif\" alt=\"shelf life of unsaturated fats is greatly improved through hydrogenation which removes allylic C-H bonds\" width=\"640\" height=\"437\" \/><\/a><\/p>\n<p><strong><a id=\"notetwo\"><\/a>Note 2<\/strong>. Some important safety considerations with Pd\/C. Hydrogen gas is generally introduced last. If catalyst must be introduced last, make sure the flask has been completely purged of oxygen.\u00a0Don&#8217;t add finely divided metal catalyst to a flask containing hydrogen and oxygen; fires can result this way.<\/p>\n<p>Raney nickel comes with H<sub>2<\/sub> already adsorbed to the metal surface. In the presence of oxygen, it&#8217;s important to keep the catalyst wet to avoid fires.<\/p>\n<p>Be careful when filtering off the metal catalyst at the end of the reaction; the finely divided nickel still contains adsorbed hydrogen, and sucking a bunch of air through the catalyst bed can result in fires. Note the red glowing catalyst in the video below!<\/p>\n<p><iframe class=\"giphy-embed\" src=\"https:\/\/giphy.com\/embed\/Yf7v2WQnM12J7nNH6T\" width=\"480\" height=\"270\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><a href=\"https:\/\/giphy.com\/gifs\/Yf7v2WQnM12J7nNH6T\">via GIPHY<\/a><\/p>\n<p>This is from filtration of Raney Nickel. Source: <a href=\"https:\/\/www.youtube.com\/watch?v=ukYU0AbPYfo\">Named Reactions In Organic Chemistry Youtube Channel<\/a><\/p>\n<p><strong><a id=\"notethree\"><\/a>Note 3<\/strong>. Which catalyst should you use? For our purposes, Pd\/C is good for pretty much everything, but some textbooks (and instructors) have quirks. For the curious, a good &#8220;which catalyst should you use&#8221; discussion for many different reactions can be found <a href=\"https:\/\/www.sigmaaldrich.com\/deepweb\/assets\/sigmaaldrich\/marketing\/global\/documents\/157\/575\/acta-vol12.pdf\">here<\/a> (page 43).<\/p>\n<p>A useful table of <strong>relative reactivities<\/strong> of various functional groups toward Pd\/C puts acid halides at the top and aromatic rings at the bottom. The table below is adapted from House who in turn adopted it from Rylander.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35676\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/10\/F3-relative-reactivity-of-various-functional-groups-towards-reduction-with-Pd-and-Pt-with-alkynes-at-top-and-benzene-at-bottom.gif\" alt=\"relative reactivity of various functional groups towards reduction with Pd and Pt with alkynes at top and benzene at bottom\" width=\"640\" height=\"1056\" \/><\/a><\/p>\n<p><strong><a id=\"notefour\"><\/a>Note 4<\/strong>. While hydrogenation of alkenes is <strong>usually<\/strong> selective for <em>cis<\/em> addition, this is not always the case. One prominent example of the non-stereospecificty of this reaction can be found in the hydrogenation of the tetrasubstituted alkene below.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-35677\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/10\/F4-example-of-how-hydrogenation-is-not-always-stereospecific-hydrogenation-with-PdC-and-H2-can-give-trans-addition-products.gif\" alt=\"example of how hydrogenation is not always stereospecific - hydrogenation with Pd:C and H2 can give trans addition products\" width=\"640\" height=\"317\" \/><\/a><\/p>\n<p>This lack of\u00a0selectivity for <em>syn<\/em> addition arises from the half-hydrogenated product which has a C-Pd bond. Considerable isomerization can occur when Pd is used. Isomerization can be greatly minimized by using platinum (Pt).<\/p>\n<p><strong><a id=\"notefive\"><\/a>Note 5.<\/strong> Isomerization of half-hydrogenated product can lead to formation of\u00a0<em>anti<\/em> addition products. These isomerizations can be minimized by using platinum.<\/p>\n<p><strong><a id=\"notesix\"><\/a>Note 6<\/strong>. The first rough proposal for catalytic hydrogenation was published in 1934 [<a href=\"https:\/\/doi.org\/10.1039\/TF9343001164\">Ref<\/a>] and this has largely stood the test of time. More modern techniques have been helpful for quantifying mechanism, since Pd can vary widely across vendors depending on what method is used for its preparation.<\/p>\n<p><strong><a id=\"noteseven\"><\/a>Note 7<\/strong>. This step is called, &#8220;oxidative addition&#8221;. The Pd(0) reacts with H\u2013H to form H-Pd-H. Palladium is\u00a0<strong>oxidized<\/strong> from the zero oxidation state to the Pd(II) oxidation state, and hydrogen is\u00a0<strong>reduced<\/strong> from the zero oxidation state to the (-1) oxidation state.<\/p>\n<p><strong><a id=\"noteeight\"><\/a>Note 8<\/strong>. This step, called, &#8220;migratory insertion&#8221;, results in formation of a new C-H bond with breakage of C-C (pi) and formation of a new C-Pd bond.<\/p>\n<p><strong><a id=\"notenine\"><\/a>Note 9<\/strong>. This step is called, &#8220;reductive elimination&#8221;. The C-H bond is formed, and palladium goes from the Pd(II) oxidation state back to Pd(0). It is now ready to re-enter the catalytic cycle.<\/p>\n<p>&nbsp;<\/p>\n<hr \/>\n<h2><strong><a id=\"quiz\"><\/a>Quiz Yourself!<\/strong><\/h2>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0613-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <br \/>\n<\/p>\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0616-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <br \/>\n<\/p>\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0629-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0611-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <br \/>\n<\/p>\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/3125-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <br \/>\n<\/p>\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/3126-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <br \/>\n<\/p>\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/1869-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <br \/>\n<\/p>\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/1946-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n<hr \/>\n<h2><strong><a id=\"references\"><\/a>(Advanced) References and Further Reading<\/strong><\/h2>\n<ul>\n<li>A useful reference for this article has been\u00a0<strong>Hydrogenation Methods\u00a0<\/strong>by Rylander (1985). Available for loan on the Internet Archive, <a href=\"https:\/\/archive.org\/details\/hydrogenationmet0000ryla\">here<\/a>. Aldrichimica Acta has a good summary on which catalyst to use for which reaction. <a href=\"https:\/\/www.sigmaaldrich.com\/deepweb\/assets\/sigmaaldrich\/marketing\/global\/documents\/157\/575\/acta-vol12.pdf\">Page 43<\/a><\/li>\n<li><strong>Modern Synthetic Reactions<\/strong>\u00a0 [<a href=\"https:\/\/archive.org\/details\/modernsyntheticr0000hous\/page\/n3\/mode\/2up\">link<\/a>] by H.O. House has a useful first chapter overview.<\/li>\n<li><a href=\"https:\/\/www.science.org\/content\/blog-post\/not-do---hydrogen-balloons\">How Not To Do It: Hydrogen Balloons<\/a><\/li>\n<\/ul>\n<ol>\n<li><strong><a id=\"refone\"><\/a>The Method of Direct Hydrogenation by Catalysis<\/strong><br \/>\nPaul Sabatier<br \/>\nNobel Lecture, December 11, 1912<br \/>\n<a href=\"https:\/\/www.nobelprize.org\/prizes\/chemistry\/1912\/sabatier\/lecture\/\">https:\/\/www.nobelprize.org\/prizes\/chemistry\/1912\/sabatier\/lecture\/<\/a><br \/>\nThe French chemist Paul Sabatier is considered the \u2018father\u2019 of hydrogenation, and received the Nobel Prize in 1912 for his work. This is his Nobel Lecture, describing the path to discovery and his contributions to chemistry.<br \/>\n<em>&#8220;When a stream of ethylene is directed on to nickel, cobalt or iron, which has been freshly reduced and kept in the region of 300\u00b0C, intense incandescence of the metal with deposition of large quantities of carbon due to breakdown of the ethylene occurs. However, the gas which leaves the apparatus is not hydrogen but consists mainly of ethane.&#8221;<\/em><\/li>\n<li><strong>APPARATUS FOR CATALYTIC REDUCTION<br \/>\n<\/strong>Roger Adams and V. Voorhees<strong><br \/>\n<\/strong><em>Org. Synth.<\/em><strong>\u00a01928,\u00a0<\/strong><em>8<\/em>, 10<strong><br \/>\nDOI:\u00a0<\/strong><a href=\"http:\/\/www.orgsyn.org\/demo.aspx?prep=CV1P0061\">10.15227\/orgsyn.008.0010<\/a><br \/>\nThis describes in detail how to build a reactor for catalytic hydrogenation. Nowadays these can be commercially purchased \u2013 the \u201cParr reactor\u201d is very common.<\/li>\n<li><strong>Exchange reactions of hydrogen on metallic catalysts<\/strong><br \/>\nIur\u00f4 Horiuti and M. Polanyi<br \/>\n<em>Trans. Faraday Soc.<\/em>, <strong>1934<\/strong>, 30, 1164-1172<br \/>\n<strong>DOI: <\/strong><a href=\"https:\/\/doi.org\/10.1039\/TF9343001164\">10.1039\/TF9343001164<\/a><strong><br \/>\n<\/strong>Originally postulated mechanism for catalytic hydrogenation on a metal surface, which has held up pretty well.<\/li>\n<li><strong><a id=\"refthree\"><\/a>PALLADIUM CATALYSTS<br \/>\n<\/strong>Ralph Mozingo<br \/>\n<i>Org. Synth.<\/i>\u00a0<b>1946<\/b>,\u00a0<i>26<\/i>, 77<br \/>\n<strong>DOI: <\/strong><a href=\"https:\/\/www.orgsyn.org\/demo.aspx?prep=CV3P0685\">10.15227\/orgsyn.026.0077<\/a><br \/>\nDetailed procedures of how to prepare palladium on barium sulfate (Pd\/BaSO4), palladium chloride on carbon, and both 5% and 10% palladium on carbon (Pd\/C), from <em>Organic Syntheses<\/em>, a compendium of reliable methods for the preparation of organic compounds.<\/li>\n<li><strong>The Hydrogenation of Cyclohexenes over Platinum Oxide<br \/>\n<\/strong>James-Frederick Sauvage, Robert H. Baker, and Allen S. Hussey<br \/>\n<em>Journal of the American Chemical Society<\/em><strong>\u00a01960,\u00a0<\/strong><em>82<\/em>\u00a0(23), 6090-6095<br \/>\n<strong>DOI:\u00a0<\/strong><a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/ja01508a029\">10.1021\/ja01508a029<\/a><br \/>\nCatalytic hydrogenation usually proceeds with addition of both hydrogen atoms to the same face of the double bond (<em>syn<\/em>\u00a0addition). Adsorption to the catalyst surface normally involves the less sterically hindered face of the double bond, and this is seen in this paper.<\/p>\n<div><\/div>\n<\/li>\n<li>\n<div><strong>The Stereochemistry of the Hydrogenation of Cycloolefins on Supported Palladium Catalysts<\/strong><br \/>\nSamuel Siegel and Gerard V. Smith<\/div>\n<div><cite>Journal of the American Chemical Society<\/cite>\u00a0<strong>1960<\/strong>\u00a0<em>82<\/em>\u00a0(23), 6087-6090<br \/>\n<strong>DOI<\/strong>:\u00a0<a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/ja01508a028\">10.1021\/ja01508a028<\/a><br \/>\nOne side-reaction that occasionally occurs with Pd-C is isomerization of adjacent stereocenters, as seen in this paper.\u00a0 Isomerization is less likely when using platinum as the catalyst.<\/div>\n<\/li>\n<li><strong>The Reaction of Sodium Borohydride with Nickel Acetate in Ethanol Solution\u2013A Highly Selective Nickel Hydrogenation Catalyst<br \/>\n<\/strong>Herbert C. Brown and Charles A. Brown<strong><br \/>\n<\/strong><em>Journal of the American Chemical Society<\/em><strong>\u00a01963,\u00a0<\/strong><em>85<\/em>\u00a0(7), 1005-1006<strong><br \/>\nDOI:\u00a0<\/strong><a href=\"https:\/\/pubs.acs.org\/doi\/abs\/10.1021\/ja00890a041\">10.1021\/ja00890a041<\/a><br \/>\nCatalytic hydrogenations are usually very clean reactions with little byproduct formation, but careful studies reveal that sometimes double bond migration can take place in competition with reduction. In this case, hydrogenation of 1-pentene over \u2018P-2 nickel boride\u2019 (nickel acetate reduced with NaBH<sub>4<\/sub>) is accompanied by some isomerization to both\u00a0<em>E<\/em>\u2013 and\u00a0<em>Z<\/em>-2-pentene.<\/li>\n<li><strong>Low-temperature hydrogenation over borohydride-reduced catalysts. A new convenient procedure for improving the selectivity of reduction<br \/>\n<\/strong>Charles Allan Brown<strong><br \/>\n<\/strong><em>Journal of the American Chemical Society<\/em><strong>\u00a01969,\u00a0<\/strong><em>91<\/em>\u00a0(21), 5901-5902<strong><br \/>\nDOI:\u00a0<\/strong><a href=\"https:\/\/pubs.acs.org\/doi\/abs\/10.1021\/ja01049a050\">10.1021\/ja01049a050<\/a><br \/>\nThis paper demonstrates that 1,2-dimethylcyclohexene can be reduced with a preferential\u00a0<em>syn<\/em>\u00a0addition from the less hindered side over Pt under H<sub>2<\/sub>.<\/li>\n<li><strong>Stereochemical Control of Reductions. 9. Haptophilicity Studies with 1,1-Disubstituted 2-Methyleneacenaphthenes<br \/>\n<\/strong>Hugh W. Thompson and Shaker Y. Rashid<strong><br \/>\n<\/strong><em>The Journal of Organic Chemistry<\/em><strong>\u00a02002,\u00a0<\/strong><em>67<\/em>\u00a0(9), 2813-2825<strong><br \/>\nDOI:\u00a0<\/strong><a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/jo010633b\">10.1021\/jo010633b<\/a><br \/>\nFunctional groups can also exert directing effects in catalytic hydrogenation. The substituent can interact with the catalyst surface and direct hydrogenation towards the same side that is closest to it.<\/li>\n<li><strong>Defining the Qualities of High-Quality Palladium on Carbon Catalysts for Hydrogenolysis<\/strong><br \/>\nConor J. Crawford, Yan Qiao, Yequn Liu, Dongmei Huang, Wenjun Yan, Peter H. Seeberger, Stefan Oscarson, and Shuai Chen<br \/>\n<em>Organic Process Research &amp; Development<\/em> <strong>2021<\/strong> 25 (7), 1573-1578<br \/>\n<strong>DOI<\/strong>: <a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/acs.oprd.0c00536\">10.1021\/acs.oprd.0c00536<\/a><br \/>\nVery in depth study on the active catalyst for hydrogenolysis of O-benzyl groups.<\/li>\n<li><strong>Double bond migration and racemization during the hydrogenation of olefins<\/strong><br \/>\n<em>Journal of Catalysis,<\/em>\u00a0<strong>1963<\/strong>, <em>2 <\/em>(6) 498-505<br \/>\n<strong>DOI: <a href=\"https:\/\/doi.org\/10.1016\/0021-9517(63)90005-8.\">10.1016\/0021-9517(63)90005-8<\/a><br \/>\n<\/strong>From the abstract: <em>&#8220;Double bond migration and racemization during the hydrogenation of several optically active alkenes have been studied. Extensive double bond migration and racemization occur with supported and unsupported palladium catalysts. Most, if not all, of the racemization results from double bond migration. Racemization of the alkenes by other processes was not detected. The rate of double bond migration is reduced markedly by the presence of base.&#8221;<\/em><\/li>\n<\/ol>\n<p>&nbsp;&#8216;,&#8217;Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation of Alkenes<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Catalytic Hydrogenation of Alkenes With Pd\/C (And Friends) Alkenes (and alkynes) will undergo addition of hydrogen (H2) in the presence of a metal catalyst such <\/p>\n","protected":false},"author":1,"featured_media":35640,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1418],"tags":[169,417,292,416,412,266,274],"post_folder":[],"class_list":["post-3228","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-alkene-reactions","tag-alkenes","tag-h2","tag-hydrogenation","tag-pdc","tag-reagent-friday","tag-reduction","tag-stereoselective"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation of Alkenes &#8211; Master Organic Chemistry<\/title>\n<meta name=\"description\" content=\"Palladium on carbon (Pd\/C) is a catalyst for the hydrogenation of various multiple-bonded species with H2 gas. Examples in introductory organic chemistry.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation of Alkenes &#8211; Master Organic Chemistry\" \/>\n<meta property=\"og:description\" content=\"Palladium on carbon (Pd\/C) is a catalyst for the hydrogenation of various multiple-bonded species with H2 gas. Examples in introductory organic chemistry.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/\" \/>\n<meta property=\"og:site_name\" content=\"Master Organic Chemistry\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/Master-Organic-Chemistry-242610599108055\/\" \/>\n<meta property=\"article:published_time\" content=\"2011-11-25T14:08:23+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-04-18T01:51:18+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2011\/11\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif\" \/>\n\t<meta property=\"og:image:width\" content=\"882\" \/>\n\t<meta property=\"og:image:height\" content=\"632\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/gif\" \/>\n<meta name=\"author\" content=\"James Ashenhurst\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"James Ashenhurst\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"22 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/\"},\"author\":{\"name\":\"James Ashenhurst\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#\\\/schema\\\/person\\\/78d83ec7d02b4b7365bade2cedaef80c\"},\"headline\":\"Palladium on Carbon (Pd\\\/C) for Catalytic Hydrogenation of Alkenes\",\"datePublished\":\"2011-11-25T14:08:23+00:00\",\"dateModified\":\"2026-04-18T01:51:18+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/\"},\"wordCount\":3590,\"commentCount\":45,\"publisher\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#organization\"},\"image\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2011\\\/11\\\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif\",\"keywords\":[\"alkenes\",\"H2\",\"hydrogenation\",\"pd\\\/c\",\"reagent friday\",\"reduction\",\"stereoselective\"],\"articleSection\":[\"Alkene Reactions\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/\",\"url\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/\",\"name\":\"Palladium on Carbon (Pd\\\/C) for Catalytic Hydrogenation of Alkenes &#8211; Master Organic Chemistry\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2011\\\/11\\\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif\",\"datePublished\":\"2011-11-25T14:08:23+00:00\",\"dateModified\":\"2026-04-18T01:51:18+00:00\",\"description\":\"Palladium on carbon (Pd\\\/C) is a catalyst for the hydrogenation of various multiple-bonded species with H2 gas. Examples in introductory organic chemistry.\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/#primaryimage\",\"url\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2011\\\/11\\\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif\",\"contentUrl\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2011\\\/11\\\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif\",\"width\":882,\"height\":632,\"caption\":\"summary of catalytic hydrogenation of alkenes with heterogeneous catalysts like pd:c and hydrogen 2\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2011\\\/11\\\/25\\\/hydrogenation-alkenes-palladium-on-carbon-pdc\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Palladium on Carbon (Pd\\\/C) for Catalytic Hydrogenation of Alkenes\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#website\",\"url\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/\",\"name\":\"Master Organic Chemistry\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#organization\",\"name\":\"Master Organic Chemistry\",\"url\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#\\\/schema\\\/logo\\\/image\\\/\",\"url\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2019\\\/04\\\/cutmypic.png\",\"contentUrl\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2019\\\/04\\\/cutmypic.png\",\"width\":225,\"height\":225,\"caption\":\"Master Organic Chemistry\"},\"image\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#\\\/schema\\\/logo\\\/image\\\/\"},\"sameAs\":[\"https:\\\/\\\/www.facebook.com\\\/Master-Organic-Chemistry-242610599108055\\\/\"]},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#\\\/schema\\\/person\\\/78d83ec7d02b4b7365bade2cedaef80c\",\"name\":\"James Ashenhurst\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/f9e9df435875e5e6b0bdff6b8522a7279d5717644b3efa7299da22c837bf9fcf?s=96&d=retro&r=g\",\"url\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/f9e9df435875e5e6b0bdff6b8522a7279d5717644b3efa7299da22c837bf9fcf?s=96&d=retro&r=g\",\"contentUrl\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/f9e9df435875e5e6b0bdff6b8522a7279d5717644b3efa7299da22c837bf9fcf?s=96&d=retro&r=g\",\"caption\":\"James Ashenhurst\"},\"description\":\"Ph.D. 2006, McGill University (James L. Gleason). Postdoctoral Associate, 2008-2010, Massachusetts Institute of Technology (M. Movassaghi). Founder, Master Organic Chemistry, 2010-present.\",\"sameAs\":[\"https:\\\/\\\/www.masterorganicchemistry.com\\\/about\\\/\"],\"url\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/author\\\/james\\\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation of Alkenes &#8211; Master Organic Chemistry","description":"Palladium on carbon (Pd\/C) is a catalyst for the hydrogenation of various multiple-bonded species with H2 gas. Examples in introductory organic chemistry.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/","og_locale":"en_US","og_type":"article","og_title":"Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation of Alkenes &#8211; Master Organic Chemistry","og_description":"Palladium on carbon (Pd\/C) is a catalyst for the hydrogenation of various multiple-bonded species with H2 gas. Examples in introductory organic chemistry.","og_url":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/","og_site_name":"Master Organic Chemistry","article_publisher":"https:\/\/www.facebook.com\/Master-Organic-Chemistry-242610599108055\/","article_published_time":"2011-11-25T14:08:23+00:00","article_modified_time":"2026-04-18T01:51:18+00:00","og_image":[{"width":882,"height":632,"url":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2011\/11\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif","type":"image\/gif"}],"author":"James Ashenhurst","twitter_card":"summary_large_image","twitter_misc":{"Written by":"James Ashenhurst","Est. reading time":"22 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/#article","isPartOf":{"@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/"},"author":{"name":"James Ashenhurst","@id":"https:\/\/www.masterorganicchemistry.com\/#\/schema\/person\/78d83ec7d02b4b7365bade2cedaef80c"},"headline":"Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation of Alkenes","datePublished":"2011-11-25T14:08:23+00:00","dateModified":"2026-04-18T01:51:18+00:00","mainEntityOfPage":{"@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/"},"wordCount":3590,"commentCount":45,"publisher":{"@id":"https:\/\/www.masterorganicchemistry.com\/#organization"},"image":{"@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/#primaryimage"},"thumbnailUrl":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2011\/11\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif","keywords":["alkenes","H2","hydrogenation","pd\/c","reagent friday","reduction","stereoselective"],"articleSection":["Alkene Reactions"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/","url":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/","name":"Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation of Alkenes &#8211; Master Organic Chemistry","isPartOf":{"@id":"https:\/\/www.masterorganicchemistry.com\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/#primaryimage"},"image":{"@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/#primaryimage"},"thumbnailUrl":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2011\/11\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif","datePublished":"2011-11-25T14:08:23+00:00","dateModified":"2026-04-18T01:51:18+00:00","description":"Palladium on carbon (Pd\/C) is a catalyst for the hydrogenation of various multiple-bonded species with H2 gas. Examples in introductory organic chemistry.","breadcrumb":{"@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/#primaryimage","url":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2011\/11\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif","contentUrl":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2011\/11\/0-summary-of-catalytic-hydrogenation-of-alkenes-with-heterogeneous-catalysts-like-pdc-and-hydrogen-2.gif","width":882,"height":632,"caption":"summary of catalytic hydrogenation of alkenes with heterogeneous catalysts like pd:c and hydrogen 2"},{"@type":"BreadcrumbList","@id":"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/hydrogenation-alkenes-palladium-on-carbon-pdc\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.masterorganicchemistry.com\/"},{"@type":"ListItem","position":2,"name":"Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation of Alkenes"}]},{"@type":"WebSite","@id":"https:\/\/www.masterorganicchemistry.com\/#website","url":"https:\/\/www.masterorganicchemistry.com\/","name":"Master Organic Chemistry","description":"","publisher":{"@id":"https:\/\/www.masterorganicchemistry.com\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.masterorganicchemistry.com\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.masterorganicchemistry.com\/#organization","name":"Master Organic Chemistry","url":"https:\/\/www.masterorganicchemistry.com\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.masterorganicchemistry.com\/#\/schema\/logo\/image\/","url":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/04\/cutmypic.png","contentUrl":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/04\/cutmypic.png","width":225,"height":225,"caption":"Master Organic Chemistry"},"image":{"@id":"https:\/\/www.masterorganicchemistry.com\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/Master-Organic-Chemistry-242610599108055\/"]},{"@type":"Person","@id":"https:\/\/www.masterorganicchemistry.com\/#\/schema\/person\/78d83ec7d02b4b7365bade2cedaef80c","name":"James Ashenhurst","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/secure.gravatar.com\/avatar\/f9e9df435875e5e6b0bdff6b8522a7279d5717644b3efa7299da22c837bf9fcf?s=96&d=retro&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/f9e9df435875e5e6b0bdff6b8522a7279d5717644b3efa7299da22c837bf9fcf?s=96&d=retro&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/f9e9df435875e5e6b0bdff6b8522a7279d5717644b3efa7299da22c837bf9fcf?s=96&d=retro&r=g","caption":"James Ashenhurst"},"description":"Ph.D. 2006, McGill University (James L. Gleason). Postdoctoral Associate, 2008-2010, Massachusetts Institute of Technology (M. Movassaghi). Founder, Master Organic Chemistry, 2010-present.","sameAs":["https:\/\/www.masterorganicchemistry.com\/about\/"],"url":"https:\/\/www.masterorganicchemistry.com\/author\/james\/"}]}},"_links":{"self":[{"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/posts\/3228","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/comments?post=3228"}],"version-history":[{"count":0,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/posts\/3228\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/media\/35640"}],"wp:attachment":[{"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/media?parent=3228"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/categories?post=3228"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/tags?post=3228"},{"taxonomy":"post_folder","embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/post_folder?post=3228"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}