{"id":1691,"date":"2011-07-01T09:11:19","date_gmt":"2011-07-01T14:11:19","guid":{"rendered":"https:\/\/www.masterorganicchemistry.com\/?p=1691"},"modified":"2026-04-18T06:11:22","modified_gmt":"2026-04-18T11:11:22","slug":"reagent-friday-oso4-osmium-tetroxide","status":"publish","type":"post","link":"https:\/\/www.masterorganicchemistry.com\/2011\/07\/01\/reagent-friday-oso4-osmium-tetroxide\/","title":{"rendered":"OsO4 (Osmium Tetroxide) for Dihydroxylation of Alkenes"},"content":{"rendered":"<p><strong>Osmium tetroxide, OsO<sub>4<\/sub><\/strong><\/p>\n<ul>\n<li>Osmium tetroxide (OsO<sub>4<\/sub>) is a useful reagent for the\u00a0<strong>dihydroxylation\u00a0<\/strong>of alkenes<\/li>\n<li>The products of these reactions are 1,2-diols (&#8220;vicinal&#8221; diols), where the two C-O bonds are formed on the same face of the alkene via a concerted mechanism.<\/li>\n<li>Dihydroxylation of alkenes with OsO<sub>4<\/sub> is functionally equivalent to dihydroxylation with cold, basic KMnO<sub>4<\/sub>.<\/li>\n<li>OsO4 does not dihydroxylate alkynes!<\/li>\n<li>The vicinal diols can subsequently be cleaved with NaIO<sub>4<\/sub> providing products that are eqivalent to those obtained through ozonolysis.<\/li>\n<\/ul>\n<p><img fetchpriority=\"high\" decoding=\"async\" class=\"alignnone wp-image-34221\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2011\/07\/0-summary-of-osmium-tetroxide-oso4-for-the-dihydroxylation-of-alkenes.gif\" alt=\"summary of osmium tetroxide oso4 for the dihydroxylation of alkenes\" width=\"640\" height=\"530\" \/><\/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\">Osmium Tetroxide, OsO4 And The Dihydroxylation of Alkenes<\/a><\/li>\n<li><a href=\"#two\">The Mechanism for Dihydroxylation of Alkenes With OsO<sub>4<\/sub><\/a><\/li>\n<li><a href=\"#three\">Predicting the Stereochemistry of Dihydroxylation Products<\/a><\/li>\n<li><a href=\"#four\">OsO4 vs KMnO4 As A Reagent for Dihydroxylation<\/a><\/li>\n<li><a href=\"#five\">Catalytic OsO4 Using Stoichiometric Oxidant<\/a><\/li>\n<li><a href=\"#six\">Reactions of 1,2-Diols &#8211; Oxidative Cleavage With NaIO4\u00a0<\/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. Osmium Tetroxide, OsO4 And The Dihydroxylation of Alkenes<\/h2>\n<p>Osmium tetroxide (OsO<sub>4<\/sub>) is a very useful reagent for the dihydroxylation of alkenes [<span style=\"color: #ff0000;\">Note 1<\/span>] . In this reaction,<\/p>\n<ul>\n<li>A C-C (pi) bond is broken<\/li>\n<li>Two C-O bonds form on adjacent carbons<\/li>\n<li>The two new C-O bonds are delivered\u00a0<strong><em>syn<\/em><\/strong> , which is to say, on the <strong>same face<\/strong> of the alkene.<\/li>\n<\/ul>\n<p>For example, the reaction of cyclohexene with OsO<sub>4<\/sub> gives <strong>exclusively<\/strong> <em>cis<\/em>-cyclohexan-1,2-diol, with <em>none<\/em>\u00a0of the <em>trans<\/em> diol formed.<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-34203\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/1-osmium-tetroxide-oso4-is-a-very-effective-reagent-for-dihydroxylation-of-alkenes-syn-addition.gif\" alt=\"osmium tetroxide oso4 is a very effective reagent for dihydroxylation of alkenes syn addition\" width=\"640\" height=\"488\" \/><\/a><\/p>\n<p>Since we are breaking a C-C bond and forming two C-O bonds, this is an example of an oxidation reaction (<span style=\"color: #993366;\"><em>See article: <a 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>Two alkenes that differ only in their configuration (e.g. the stereoisomers <em>cis<\/em>&#8211; and\u00a0<em>trans<\/em>&#8211; pent-2-ene) will result in products that are themselves stereoisomers.<\/p>\n<p>This fits the definition of a\u00a0<strong>stereospecific\u00a0<\/strong>reaction, as per <a href=\"https:\/\/goldbook.iupac.org\/terms\/view\/S05994\">IUPAC<\/a>. (<a href=\"https:\/\/www.masterorganicchemistry.com\/2010\/07\/02\/stereoselective-stereospecific\/\"><em>See article &#8211; Stereoselective and Stereospecific Reactions<\/em><\/a>)<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-35633\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/10\/2-the-reaction-of-oso4-with-alkenes-qualifies-as-a-stereospecific-reaction-resulting-in-diastereomeric-products.gif\" alt=\"the reaction of oso4 with alkenes qualifies as a stereospecific reaction resulting in diastereomeric products\" width=\"640\" height=\"479\" \/><\/a><\/p>\n<p><span style=\"color: #993366;\"><em>Chiral molecules with exactly opposite (R,S) designations are enantiomers. Chiral molecules that share the configuration at at least one chiral center and differ at the configuration of another chiral center will be diastereomers. For more, see article: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2018\/09\/10\/types-of-isomers\/\">Types of Isomers<\/a>)<\/em><\/span><\/p>\n<p>Note that in each case the two new C-OH bonds form on the\u00a0<strong>same\u00a0<\/strong>face of the alkene.<\/p>\n<h2><a id=\"two\"><\/a>2. The Mechanism for Dihydroxylation of Alkenes With OsO<sub>4<\/sub><\/h2>\n<p>The mechanism of alkene dihydroxylation is a <strong>concerted<\/strong> cycloaddition reaction where the C-C pi bond combines with two Os=O bonds to give a five-membered ring structure known as an osmate ester.<span style=\"color: #993366;\"><em> (Note that in the osmate ester the Os is in the +6 oxidation state as opposed to the +8 oxidation state found in OsO<sub>4<\/sub>)<\/em><\/span><\/p>\n<p>This concerted mechanism nicely accounts for the <em>cis\u00a0<\/em>stereochemistry observed in the dihydroxlyation of cyclohexene.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-34205\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/3-mechanism-for-dihydroxylation-of-alkenes-with-oso4-is-a-concerted-cycloaddition-explains-syn-addition.gif\" alt=\"mechanism for dihydroxylation of alkenes with oso4 is a concerted cycloaddition explains syn addition\" width=\"640\" height=\"426\" \/><\/a><\/p>\n<p>Osmate esters are fairly stable products and can be isolated. [<a href=\"#notetwo\"><span style=\"color: #ff0000;\">Note 2<\/span><\/a>] However, since we are generally much more interested in the diol, a reagent such as potassium bisulfite (KHSO<sub>3<\/sub>) or sodium bisulfite (NaHSO<sub>3<\/sub>) is commonly used to break the Os-O bonds and liberate the diol.<\/p>\n<p>Just a heads-up &#8211; in introductory courses, this second reagent may or may not be included. It purpose is just to get rid of the osmium.<\/p>\n<p>(<span style=\"color: #993366;\"><em>It is much more common nowadays to use catalytic OsO<sub>4<\/sub> and a stoichiometric amount of an oxidant such as N-methylmorpholine N-oxide (NMO) or H<sub>2<\/sub>O<sub>2<\/sub> to regenerate OsO<sub>4<\/sub> from the Os(VI) species. In these cases, KHSO<sub>3<\/sub> is not needed. See section below.<\/em><\/span>)<\/p>\n<p>As a fairly electron-poor reagent, reactions with OsO<sub>4<\/sub> increase in rate as the alkene becomes more electron-rich.<\/p>\n<p>For practical purposes, this means that<\/p>\n<ul>\n<li>reaction rates generally <strong>increase<\/strong> with <strong>increasing<\/strong> substitution on the alkene ( tetrasubstituted (fastest) &gt; trisubstituted &gt; disubstituted &gt; monosubstituted (slowest)<\/li>\n<li>reaction rates generally decrease if the alkene is attached to electron-withdrawing groups such as carbonyls<\/li>\n<\/ul>\n<p>It&#8217;s possible to selectively dihydroxylate an electron-rich alkene in the presence of other alkenes. For a few examples, see <a href=\"#notethree\"><span style=\"color: #ff0000;\">Note 3 <\/span><\/a>below.<\/p>\n<h2><a id=\"three\"><\/a>3. Predicting The Stereochemistry Of Dihydroxylation Products<\/h2>\n<p><em>cis<\/em>&#8211; and\u00a0<em>trans-\u00a0<\/em>alkenes can be each be prepared from alkynes, depending on the reagent(s) used for reduction.<\/p>\n<ul>\n<li>Alkynes treated with sodium (Na) in ammonia (NH<sub>3<\/sub>) gives<strong>\u00a0<em>trans<\/em>-alkenes.<\/strong> (<span style=\"color: #993366;\"><em>See article &#8211; <a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/05\/08\/lindlar-nanh3-partial-reduction-of-alkynes\/\">Partial Reduction of Alkynes Using Na\/NH<sub>3<\/sub><\/a><\/em><\/span>)<\/li>\n<li>Alkynes treated with Lindlar&#8217;s catalyst (<span style=\"color: #993366;\"><em>palladium made less active through the addition of lead and quinoline<\/em><\/span>) in the presence of hydrogen gives\u00a0<strong><em>cis<\/em>-alkenes<\/strong> (<span style=\"color: #993366;\"><em>See article &#8211;\u00a0 <a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/08\/19\/reagent-friday-lindlars-catalyst\/\">Lindlar&#8217;s Catalyst<\/a><\/em><\/span>)<\/li>\n<\/ul>\n<p>Why is this important right now?<\/p>\n<p>Well, since <em>cis<\/em>&#8211; and\u00a0<em>trans<\/em>&#8211; alkenes give dihydroxylation products that are stereoisomers of each other, dihydroxylation reactions provide great fodder for exam questions that challenge your understanding of stereochemistry.<\/p>\n<p>See if you can answer this classic quiz question:<\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"34781\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"34781\"] {\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=\"34781\"] {\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=\"34781\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-34781\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-34781 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"34781\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-t99j9\" data-id=\"t99j9\">\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\/2463-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\/2463-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><span style=\"color: #993366;\"><em>For a refresher on solving these kinds of stereochemistry problems, see article &#8211; <a href=\"https:\/\/www.masterorganicchemistry.com\/2019\/03\/08\/enantiomers-diastereomers-or-the-same-1-using-models\/\">Enantiomers, Diastereomers or the Same<\/a>?<\/em><\/span><\/p>\n<p>Just as important as determining the stereochemistry of products is being able to\u00a0<strong>work backwards\u00a0<\/strong>from the products of dihydroxylation to the starting <strong>alkenes<\/strong>.<\/p>\n<p>This is more challenging with linear (as opposed to cyclic) products, since it will require that you successfully perform a bond rotation.<\/p>\n<p>See if you can work backwards from this diol to the starting alkene:<\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"34782\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"34782\"] {\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=\"34782\"] {\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=\"34782\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-34782\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-34782 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"34782\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-gpchb\" data-id=\"gpchb\">\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\/2464-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\/2464-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 a similar example:<\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"34783\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"34783\"] {\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=\"34783\"] {\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=\"34783\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-34783\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-34783 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"34783\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-nwx24\" data-id=\"nwx24\">\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\/2465-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\/2465-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=\"four\"><\/a>4. OsO<sub>4<\/sub> versus KMnO<sub>4<\/sub> As A Reagent for Dihydroxylation<\/h2>\n<p>A reagent similar to OsO<sub>4<\/sub> that is also capable of performing dihydroxylation is potassium permanganate, KMnO<sub>4<\/sub>.<\/p>\n<p>Treatment of alkenes with cold, alkaline KMnO<sub>4<\/sub> will also result in vicinal diols.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-34206\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/7-comparing-the-dihydroxylation-of-alkenes-using-KMno4-vs-OsO4-both-are-syn-additions.gif\" alt=\"comparing the dihydroxylation of alkenes using KMno4 vs OsO4 both are syn additions\" width=\"640\" height=\"535\" \/><\/a><\/p>\n<p>Like the reaction with OsO<sub>4<\/sub>, this also proceeds through a cyclic, concerted transition state that results in a cyclic metal species (this time called a &#8220;manganate ester&#8221;).<\/p>\n<p>The key difference here is that unless\u00a0 the manganate ester will react further to give the products of <strong>oxidative cleavage<\/strong> unless hydroxide ion HO(-) is present to hydrolyze the Mn-O bonds and liberate the vicinal diol. This is not generally a problem with OsO<sub>4<\/sub>.<\/p>\n<p>This is also why the temperature is kept low for KMnO<sub>4<\/sub> oxidations.<\/p>\n<p><span style=\"color: #993366;\"><em>Yields with KMnO<sub>4<\/sub> tend to be lower and KMnO<sub>4<\/sub> is also much less tolerant of sensitive functional groups like alcohols and aldehydes.\u00a0<\/em><\/span><\/p>\n<p><span style=\"color: #993366;\"><em>Dihydroxylations with KMnO4 are often used with a phase transfer catalyst.\u00a0<\/em><\/span><\/p>\n<h2><a id=\"five\"><\/a>5. Catalytic OsO4 Using Stoichiometric Oxidant<\/h2>\n<p>It&#8217;s one thing to write a reaction down on a sheet of paper that uses a stoichiometric amount of osmium tetroxide.<\/p>\n<p>It&#8217;s another thing entirely to carry it out in the lab.<\/p>\n<p>For one thing, OsO<sub>4<\/sub> is <em>expensive<\/em> &#8211; <a href=\"https:\/\/www.sigmaaldrich.com\/US\/en\/substance\/osmiumtetroxide2542320816120\">$332\/g<\/a> last time I checked, slightly cheaper if you buy in bulk.<span style=\"color: #ff0000;\"><em> The other thing is that it is a highly toxic liquid with a low vapor pressure that should be treated with extreme care.<\/em><\/span><\/p>\n<p><span style=\"color: #993366;\"><em>Particularly noteworthy is its potential to cause blindness &#8211; a<\/em><em><span style=\"color: #993366;\">l<\/span>l that <a href=\"https:\/\/en.wikipedia.org\/wiki\/Retinol\">retinol<\/a> in your cornea is full of juicy double bonds that OsO<sub>4<\/sub> would love to hydroxylate.\u00a0<\/em><\/span><\/p>\n<p>The report on the first synthesis of cortisol from 1952\u00a0 (see <a href=\"#notethree\"><span style=\"color: #ff0000;\">Note 3<\/span>\u00a0<\/a>below) has a reaction that used 68.48 g of OsO<sub>4<\/sub> . That clocks in at, let&#8217;s see&#8230;\u00a0 $<strong>22,768<\/strong> worth of OsO<sub>4<\/sub> at today&#8217;s prices.<\/p>\n<p>Surely there must be a better way? Thankfully, yes.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-34207\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/8-the-upjohn-process-is-catalytic-dihydroxylation-of-alkenes-using-OsO4-and-stoichiometric-nmo-as-stoichiometric-reoxidant.gif\" alt=\"the upjohn process is catalytic dihydroxylation of alkenes using OsO4 and stoichiometric nmo as stoichiometric reoxidant\" width=\"640\" height=\"429\" \/><\/a><\/p>\n<p>The <strong>Upjohn<\/strong> process uses a catalytic amount of OsO<sub>4<\/sub> (usually about 1-2 mol% ) in the presence of a stoichiometric amount of oxidant that converts the Os(VI) product back to OsO<sub>4<\/sub>. The oxidant of choice is generally <em>N<\/em>-methylmorpholine N-oxide (NMO) although various other oxidants can be used.<\/p>\n<p><span style=\"color: #993366;\"><em>[The original paper is <a href=\"https:\/\/orgsyn.org\/demo.aspx?prep=cv6p0342\">here<\/a>\u00a0 &#8211; Org Synth. 1978, 58, 43 &#8211; and has helpful tables that compare oxidants and also its performance to KMnO<sub>4<\/sub>]<\/em><\/span><\/p>\n<p>Yields are generally high and the reaction is mild. Furthermore there&#8217;s no need to add KHSO<sub>3<\/sub> since the osmate ester is cleaved under these conditions.<\/p>\n<p>It&#8217;s even possible to perform a hydroxylation on an alkene without affecting an alkyne, as OsO<sub>4<\/sub> does not react with alkynes.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-34208\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/9-alkynes-are-unreactive-with-oso4-and-alkenes-will-undergo-selective-oxidation.gif\" alt=\"alkynes are unreactive with oso4 and alkenes will undergo selective oxidation\" width=\"640\" height=\"208\" \/><\/a><\/p>\n<p><span style=\"color: #993366;\"><em>An enantioselective version of dihydroxylation known as the Sharpless asymmetric dihydroxylation has been developed. It also uses catalytic osmium (potassium osmate)\u00a0 in the presence of a stoichiometric amount of oxidant. For more details see [<a href=\"#notefour\"><span style=\"color: #ff0000;\">Note 4<\/span><\/a>].\u00a0\u00a0<\/em><\/span><\/p>\n<h2><a id=\"six\"><\/a>6. Reactions of Vicinal Diols &#8211; Cleavage with NaIO4<\/h2>\n<p>vicinal diols can undergo <strong>oxidative cleavage<\/strong> with various reagents to break a C-C bond and form two new C-O (pi) bonds.<\/p>\n<p>The most commonly used reagents for these purposes are sodium periodate (NaIO<sub>4<\/sub>) and lead tetraacetate Pb(OAc)<sub>4<\/sub>, although earlier we also touched on the fact that this is a prominent side reaction when performing dihydroxylations with KMnO4.<\/p>\n<p>Sequentially treating a double bond with OsO<sub>4<\/sub> to give a diol followed by oxidative cleavage with NaIO<sub>4<\/sub> or Pb(OAc)<sub>4<\/sub> gives the functional equivalent of ozonolysis (reductive workup).<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-34209\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/10-treatment-of-alkenes-with-OsO4-followed-by-NaIO4-is-the-functional-equivalent-of-ozonolysis-lemieux-johnson.gif\" alt=\"-treatment of alkenes with OsO4 followed by NaIO4 is the functional equivalent of ozonolysis - lemieux johnson\" width=\"640\" height=\"570\" \/><\/a><\/p>\n<p><span style=\"color: #993366;\"><em>(Later in Org 2, you will learn that diols will react with aldehydes and ketones to form acetals &#8211; See article: <a href=\"https:\/\/www.masterorganicchemistry.com\/2010\/05\/28\/acetals-hemiacetals-hydrates\/\">Hydrates, Hemiacetals, and Acetals<\/a>)<\/em><\/span><\/p>\n<h2><a id=\"seven\"><\/a>7. Summary<\/h2>\n<p>Let&#8217;s summarize the key points we&#8217;ve covered about OsO4.<\/p>\n<ul>\n<li>OsO<sub>4<\/sub> will convert alkenes into vicinal diols (1,2-diols) via a concerted\u00a0<em>syn<\/em> addition<\/li>\n<li>A reducing agent such as KHSO<sub>3<\/sub> is often added to liberate the diol from the osmate ester.<\/li>\n<li>The diols can undergo oxidative cleavage using a reagent such as NaIO<sub>4<\/sub> or Pb(OAc)<sub>4<\/sub> to give aldehydes\/ketones.<\/li>\n<li>Using the oxidant N-methylmorpholine N-oxide (NMO) allows for the\u00a0<em>catalytic\u00a0<\/em>use of osmium.<\/li>\n<li>In the presence of multiple alkenes, OsO<sub>4<\/sub> will react with the most electron-rich alkene.<\/li>\n<li>A related reagent is cold, basic KMnO<sub>4<\/sub> that will also make vicinal syn diols. With KMnO<sub>4<\/sub>, however, there is an increased risk of the resulting diol undergoing oxidative cleavage.<\/li>\n<\/ul>\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\/2011\/08\/19\/reagent-friday-lindlars-catalyst\/\" class=\"\"><span>Reagent Friday: Lindlar\u2019s Catalyst<\/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\/2018\/09\/10\/types-of-isomers\/\" class=\"\"><span>Types of Isomers: Constitutional Isomers, Stereoisomers, Enantiomers, and Diastereomers<\/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\/2010\/05\/28\/acetals-hemiacetals-hydrates\/\" class=\"\"><span>Hydrates, Hemiacetals, and Acetals<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/03\/02\/where-memorization-helps-in-o-chem\/\" class=\"\"><span>Dihydroxylation of Alkenes to give 1,2-diols (MOC Membership) (vicinal diols)<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/organic-chemistry-practice-problems\/alkene-reactions-practice-problems\/\" class=\"\"><span>Alkene Reactions Practice Problems<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/11\/25\/palladium-on-carbon-pdc\/\" class=\"\"><span>Palladium on Carbon (Pd\/C) for Catalytic Hydrogenation<\/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>. OsO<sub>4<\/sub> is prepared through burning metallic osmium in an atmosphere of pure oxygen. From Brauer&#8217;s <a href=\"http:\/\/www.sciencemadness.org\/library\/books\/brauer_ocr.pdf\">Handbook of Preparative Inorganic Chemistry<\/a> (Academic Press, 1963, New York). (page 1603)<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-34227\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/F1-preparation-of-OsO4-from-H-L-Grube-Preparative-Inorganic-Chemistry.png\" alt=\"preparation of OsO4 from H L Grube Preparative Inorganic Chemistry\" width=\"640\" height=\"822\" srcset=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/F1-preparation-of-OsO4-from-H-L-Grube-Preparative-Inorganic-Chemistry.png 1056w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/F1-preparation-of-OsO4-from-H-L-Grube-Preparative-Inorganic-Chemistry-234x300.png 234w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/F1-preparation-of-OsO4-from-H-L-Grube-Preparative-Inorganic-Chemistry-797x1024.png 797w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/F1-preparation-of-OsO4-from-H-L-Grube-Preparative-Inorganic-Chemistry-768x986.png 768w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/F1-preparation-of-OsO4-from-H-L-Grube-Preparative-Inorganic-Chemistry-592x760.png 592w\" sizes=\"(max-width: 640px) 100vw, 640px\" \/><\/a><\/p>\n<p>&#8220;Pure OsO<sub>4<\/sub> is best prepared by a dry method. Osmium powder is heated in a boat placed in a glass or quartz tube through which a\u00a0 stream of dry oxygen is passed. The metal burns to OsO<sub>4<\/sub>, which deposits beyond the heated zone of the tube or, better, in a bulb fused to the tube and cooled in ice. The deposit consists of white shiny crystals, though at first it may be a liquid (occasionally pale yellow in color), which forms a crystalline solid on cooling.&#8221;<\/p>\n<p><strong><a id=\"notetwo\"><\/a>Note 2. <\/strong>Many crystal structures of osmate esters are known. <a href=\"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/ja00829a081\">Here<\/a> is an example of an osmium ester with adenosine. [<a href=\"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/ja00829a081\">Ref<\/a> &#8211;\u00a0<em>J. Am. Chem. Soc.\u00a0<\/em><strong>1974<\/strong>,\u00a0<em>96<\/em>, 7152]<\/p>\n<p><strong><a id=\"notethree\"><\/a>Note 3.\u00a0<\/strong>What if a molecule contains multiple alkenes? Which alkene will OsO<sub>4<\/sub> react with?<\/p>\n<p>OsO<sub>4<\/sub> will react with the <strong>most electron-rich alkene<\/strong> (i.e. generally the one attached to the most carbon substituents).<\/p>\n<p>For example in\u00a0this classic synthesis of cortisone from 1952, note that OsO<sub>4<\/sub> preferentially attacks the isolated alkene and doesn&#8217;t touch the electron-poor diene that is conjugated to the C=O.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-34228\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/F2-dihydroxylation-reaction-in-woodwards-synthesis-of-cortisone-using-68-grams-of-OsO4-selectivity-for-most-electron-rich-alkene.gif\" alt=\"dihydroxylation reaction in woodwards synthesis of cortisone using 68 grams of OsO4 - selectivity for most electron rich alkene\" width=\"640\" height=\"315\" \/><\/a><\/p>\n<p>Woodward and his team employed 68.5 g of OsO4 on 61.5 g of substrate. At current market prices this one reaction would cost [checks Aldrich] $23,105 in today&#8217;s dollars.\u00a0 Thankfully, using so much OsO4 has been made completely unnecessary by using the co-oxidant N-methylmorpholine N-oxide (<strong>NMO<\/strong>).<\/p>\n<p>OsO4 can be made to be even more reactive and even react with very electron-poor alkenes through adding pyridine, which coordinates to osmium and renders it more electron-rich.\u00a0 [<a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/anie.199213451\">Ref<\/a>]<\/p>\n<p><strong><a id=\"notefour\"><\/a>Note 4. <\/strong>The dihydroxylation reaction has been made even more useful through the work of Prof. K. Barry Sharpless&#8217; research group at Scripps. Using <em>chiral\u00a0<\/em>amines to coordinate to osmium and a stoichiometric oxidant, Prof. K. Barry Sharpless&#8217; group at Scripps successfully developed a useful catalytic enantioselective dihydroxylation reaction.<\/p>\n<p>The Sharpless asymmetric dihydroxylation (Sharpless AD) is effective for a wide range of alkenes. For convenience, the oxidant, osmium salt, and chiral ligand are all sold as kits known as &#8220;AD-mix \u03b1&#8221; and &#8220;AD-mix \u03b2&#8221;. Using the mnemonic below, one can choose which of the two reagent kits to use in order to get the desired chiral diol.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-34229\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2023\/02\/F3-Mnemonic-for-sharpless-asymmetric-dihydroxylation-reaction-alpha-and-beta-AD-mix.gif\" alt=\"Mnemonic for sharpless asymmetric dihydroxylation reaction alpha and beta AD mix\" width=\"640\" height=\"437\" \/><\/a><\/p>\n<p>For far more detail see this handout from <a href=\"https:\/\/hwpi.harvard.edu\/files\/myers\/files\/23-sharpless_asymmetric_dihydroxylation_reaction.pdf\">Prof. Andrew Myers&#8217; Chem 115 course at Harvard<\/a> or consult Sharpless&#8217; Nobel lecture.<\/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\/0627-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\/0620-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\/2242-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\/1630-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\/1631-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<p>For examples of reactions employing OsO<sub>4<\/sub>, see:<\/p>\n<ul>\n<li>Osmium Tetroxide, OsO4. <a href=\"https:\/\/books.google.com\/books\/about\/Encyclopedia_of_Reagents_for_Organic_Syn.html?id=oOTrzAEACAAJ\">Encyclopedia of Reagents for Organic Syntheses<\/a>, vol. 6 (N-Sin). Leo Paquette, ed. Wiley.<\/li>\n<li>Carey &amp; Sundberg. <a href=\"https:\/\/www.google.com\/books\/edition\/Advanced_Organic_Chemistry\/2ahCAAAAQBAJ?hl=en&amp;gbpv=1&amp;dq=carey+and+sundberg+4th+edition&amp;printsec=frontcover\">Advanced Organic Chemistry. B: Reactions &amp; Synthesis<\/a>. Chapter 12, Oxidations.\u00a0 4th Ed. Kluwer.<\/li>\n<li>For examples of the Sharpless asymmetric dihydroxylation and leading references, see the handouts by Prof. Andrew G. Myers for Chemistry 115, Harvard University. <a href=\"https:\/\/hwpi.harvard.edu\/files\/myers\/files\/23-sharpless_asymmetric_dihydroxylation_reaction.pdf\"><strong>Link<\/strong><\/a>.<\/li>\n<\/ul>\n<ol>\n<li><strong>On Two Metals, Found In The Black Powder Remaining After The Solution of Patina<\/strong><br \/>\nSmithson Tennant<br \/>\n<em>Philosophical Transactions of the Royal Society,<\/em> <strong>1804<\/strong>, 411<br \/>\n<a href=\"https:\/\/www.jstor.org\/stable\/107152\"><strong>LINK<\/strong><\/a>: (JStor)<br \/>\nThe first description of what was to become known as OsO<sub>4<\/sub> was made in 1804, where Smithson Tennant observed that the oxide of osmium &#8220;stains the skin of a dark color, which cannot be effaced&#8221;. In this remarkable paper he also gives names to what came to be called iridium and osmium.<\/li>\n<li>\n<p class=\"citation__title\"><strong>Zur Kenntnis des Osmiums<br \/>\n<\/strong>Makowka, O.<br \/>\n<em>Chem. Ber.<\/em>\u00a0<strong>1908<\/strong>, \u00a041, 943<br \/>\n<strong>DOI: <a href=\"https:\/\/chemistry-europe.onlinelibrary.wiley.com\/doi\/10.1002\/cber.190804101182\">10.1002\/cber.190804101182<\/a><br \/>\n<\/strong>Believed to be the first application of OsO4 for dihydroxylation of alkenes, from 1908.<\/p>\n<\/li>\n<li><strong>Osmium and Its Compounds<br \/>\n<\/strong>W. P. Griffith<br \/>\n<em><i><strong>Q. Rev. Chem. Soc.<\/strong><\/i>, 1965,<strong>19<\/strong>, 254-273<br \/>\n<\/em><strong>DOI: <a class=\"text--small\" title=\"Link to landing page via DOI\" href=\"https:\/\/doi.org\/10.1039\/QR9651900254\">10.1039\/QR9651900254<\/a><\/strong><br \/>\nOverview of osmium and some of its reactions. A similar review (from the Johnson-Mathey site) is found <a href=\"https:\/\/technology.matthey.com\/article\/18\/3\/94-96\/\">here<\/a>.<\/li>\n<li>\n<div class=\"title\"><strong>CATALYTIC\u00a0<span class=\"chemname\"><span class=\"hotspot\">OSMIUM TETROXIDE<\/span><\/span>\u00a0OXIDATION OF OLEFINS:\u00a0<span class=\"chemname\"><span class=\"hotspot\"><i>cis<\/i>-1,2-CYCLOHEXANEDIOL<\/span><\/span><\/strong><\/div>\n<div class=\"drawing\">V. VanRheenen, D. Y. Cha, and W. M. Hartley<br \/>\n<em><i>Org. Synth.<\/i>\u00a0<b>1978<\/b>,\u00a0<i>58<\/i>, 43<br \/>\n<\/em><strong>DOI: <a href=\"http:\/\/10.15227\/orgsyn.058.0043\">orgsyn.058.0043<\/a><\/strong><br \/>\nThe &#8220;Upjohn method&#8221; for dihydroxylation of alkenes using catalytic OsO4 and stoichiometric NMO (N-methyl morpholine N-oxide) in Organic Syntheses.<\/div>\n<\/li>\n<li><strong>The Total Synthesis of Steroids<\/strong>\n<div>R. B. Woodward, Franz Sondheimer, David Taub, Karl Heusler, and W. M. McLamore<\/div>\n<div><cite>Journal of the American Chemical Society<\/cite>\u00a0<strong>1952<\/strong>\u00a0<em>74<\/em> (17), 4223-4251<br \/>\n<strong>DOI<\/strong>: <a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/ja01137a001\">10.1021\/ja01137a001<\/a><br \/>\nOne step of this paper involves hydroxylation of 61.5 g of substrate with 68.5 g of OsO4.<\/div>\n<\/li>\n<li><strong>Nobel Lecture<\/strong><br \/>\nK. Barry Sharpless<br \/>\n<strong><a href=\"https:\/\/www.nobelprize.org\/uploads\/2018\/06\/sharpless-lecture.pdf\">LINK<\/a><\/strong><br \/>\nProf. Barry Sharpless won the 2001 Nobel Prize in chemistry for the development of asymmetric catalysis. His 2001 Nobel Lecture describes the path toward making asymmetric dihydoxylation a useful process (starts on page 11).<\/li>\n<li><strong>Osmium tetraoxide cis hydroxylation of unsaturated substrates<\/strong><br \/>\nMartin Schroeder<br \/>\n<cite>Chemical Reviews<\/cite>\u00a0<strong>1980<\/strong>\u00a0<em>80<\/em>\u00a0(2), 187-213<br \/>\n<strong>DOI<\/strong>: <a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/cr60324a003\">10.1021\/cr60324a003<\/a><br \/>\nComprehensive review on the dihydroxylation of alkenes with OsO4 up to 1980.<\/li>\n<li>\n<p class=\"article_header-title\"><strong><span class=\"hlFld-Title\">Experimental and Theoretical Kinetic Isotope Effects for Asymmetric Dihydroxylation. Evidence Supporting a Rate-Limiting \u201c(3 + 2)\u201d Cycloaddition<br \/>\n<\/span><\/strong>Albert J. DelMonte, Jan Haller, K. N. Houk, K. Barry Sharpless, Daniel A. Singleton, Thomas Strassner, and Allen A. Thomas<br \/>\n<cite>Journal of the American Chemical Society<\/cite>\u00a0<strong>1997<\/strong>\u00a0<em>119<\/em>\u00a0(41), 9907-9908<br \/>\n<strong><span class=\"hlFld-Title\">DOI: <\/span><\/strong><a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/ja971650e\"><span class=\"hlFld-Title\">10.1021\/ja971650e<\/span><\/a><br \/>\nStudy on the mechanism of the dihydroxylation of alkenes that supports a [3+2] versus a [2+2] mechanism.<\/p>\n<\/li>\n<\/ol>\n<p>&#8216;,&#8217;OsO4 (Osmium Tetroxide) for Dihydroxylation of Alkenes<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Osmium tetroxide, OsO4 Osmium tetroxide (OsO4) is a useful reagent for the\u00a0dihydroxylation\u00a0of alkenes The products of these reactions are 1,2-diols (&#8220;vicinal&#8221; diols), where the two <\/p>\n","protected":false},"author":1,"featured_media":34221,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1418],"tags":[169,466,564,563,251,412,264,265,565],"post_folder":[],"class_list":["post-1691","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-alkene-reactions","tag-alkenes","tag-diols","tag-osmium-tetroxide","tag-oso4","tag-oxidation","tag-reagent-friday","tag-reagent-guide-2","tag-reagents","tag-syn-diols"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>OsO4 (Osmium Tetroxide) for Dihydroxylation of Alkenes &#8211; Master Organic Chemistry<\/title>\n<meta name=\"description\" content=\"OsO4 (Osmium tetroxide) is a reagent most commonly used for the formation of syn 1,2-diols (vicinal diols) from alkenes. Examples + mechanism below.\" \/>\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\/07\/01\/reagent-friday-oso4-osmium-tetroxide\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"OsO4 (Osmium Tetroxide) for Dihydroxylation of Alkenes &#8211; Master Organic Chemistry\" \/>\n<meta property=\"og:description\" content=\"OsO4 (Osmium tetroxide) is a reagent most commonly used for the formation of syn 1,2-diols (vicinal diols) from alkenes. 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