{"id":6890,"date":"2013-01-22T14:51:08","date_gmt":"2013-01-22T19:51:08","guid":{"rendered":"https:\/\/www.masterorganicchemistry.com\/?p=6890"},"modified":"2025-12-12T03:26:32","modified_gmt":"2025-12-12T09:26:32","slug":"alkene-addition-regioselectivity-syn-anti","status":"publish","type":"post","link":"https:\/\/www.masterorganicchemistry.com\/2013\/01\/22\/alkene-addition-regioselectivity-syn-anti\/","title":{"rendered":"Alkene Addition Reactions: &#8220;Regioselectivity&#8221; and &#8220;Stereoselectivity&#8221; (Syn\/Anti)"},"content":{"rendered":"<p><strong>Alkene Addition Reactions: Regioselectivity and Stereoselectivity<\/strong><\/p>\n<ul>\n<li>Almost all reactions of alkenes we will learn about can be classified as <strong>addition reactions\u00a0<\/strong><\/li>\n<li>In an alkene addition reaction, a <strong>C-C pi bond breaks<\/strong>, and <strong>two<\/strong> new <strong>single bonds to carbon<\/strong>\u00a0are <strong>formed<\/strong><\/li>\n<li>Depending on the structure of the alkene and the bonds formed\/broken in the reaction, a mixture of <strong>constitutional isomers\u00a0<\/strong>may be formed. In alkene addition reactions, these are often called &#8220;<strong>regioisomers&#8221;<\/strong>.<\/li>\n<li>When formation of one regioisomer is favored this is called &#8220;<strong>regioselectivity<\/strong>&#8220;. The most common example of regioselectivity is &#8220;<strong>Markovnikov<\/strong>&#8221; selectivity observed in addition of H-X to alkenes, where the C-H bond forms on the &#8220;least substituted&#8221; carbon (<span style=\"color: #993366;\"><em>fewest carbons directly attached<\/em><\/span>) and the C-X bond forms on the &#8220;most substituted&#8221; carbon (<span style=\"color: #993366;\"><em>most carbons directly attached<\/em><\/span>). The opposite of &#8220;Markovnikov&#8221; regioselectivity is &#8220;<strong>anti-Markovnikov<\/strong>&#8221; regioselectivity, which is observed in two cases (<span style=\"color: #993366;\"><em><a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/03\/28\/hydroboration-of-alkenes-the-mechanism\/\">hydroboration<\/a> and<a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/04\/12\/addition-hbr-alkenes-roor-peroxides-free-radical\/\"> free-radical addition of HBr<\/a><\/em>)<\/span>.<\/li>\n<li>The\u00a0<strong>stereoselectivity\u00a0<\/strong>of alkene addition reactions is also very important!\u00a0 The pi bond of an alkene is flat, and therefore has two <strong>faces\u00a0<\/strong>where addition can occur. When the two new bonds to carbon are formed on the <strong>same<\/strong> <strong>face<\/strong>, this is called, &#8220;<strong><em>syn<\/em>&#8221; addition<\/strong>. When the two new bonds to carbon are formed on <strong>opposite faces,<\/strong> this is called, &#8220;<em><strong>anti<\/strong><\/em>&#8221; <strong>addition<\/strong>.<\/li>\n<li>The stereochemistry of the addition reaction is highly dependent on the\u00a0<strong>mechanism\u00a0<\/strong>of the reaction.\u00a0 Some reactions are selective for <em>syn<\/em> addition, some reactions are selective for <em>anti<\/em> addition, and some reactions provide a mixture of <em>syn<\/em> and <em>anti<\/em> addition (&#8220;unselective&#8221;).<\/li>\n<li>When learning a new alkene addition reaction, there are three key pieces of information you will need to successfully draw the products: 1) the bonds that form\/break, 2) the regioselectivity, and 3) the stereoselectivity<\/li>\n<li>When drawing out the products of an alkene addition reaction, don&#8217;t forget to draw out the addition products from\u00a0<strong>both\u00a0<\/strong>the &#8220;top&#8221; and &#8220;bottom&#8221; faces. Depending on the structure of the alkene, and the nature of the reaction, this can lead to formation of constitutional isomers, enantiomers, diastereomers, or even identical products.<\/li>\n<li>Determining how the products of an alkene addition reaction are related is a <strong>very common type of exam problem!<\/strong><br \/>\n<img fetchpriority=\"high\" decoding=\"async\" class=\"alignnone wp-image-36065\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2013\/01\/0-summary-of-alkene-addition-reactions-regioselectivity-and-stereoselectivity-syn-anti-addition-2.gif\" alt=\"summary of alkene addition reactions - regioselectivity and stereoselectivity syn anti addition 2\" width=\"800\" height=\"861\" \/><\/a><\/li>\n<\/ul>\n<p><strong>Table of Contents<\/strong><\/p>\n<ol>\n<li style=\"list-style-type: none;\">\n<ol>\n<li><a href=\"#one\">Alkene Reactions Follow A Few Key Patterns<\/a><\/li>\n<li><a href=\"#two\">Alkene Addition Reactions<\/a><\/li>\n<li><a href=\"#three\">Regioisomers in Alkene Addition Reactions: Markovnikov vs. anti-Markovnikov Regioselectivity<\/a><\/li>\n<li><a href=\"#four\">Syn and Anti Addition To Alkenes<\/a><\/li>\n<li><a href=\"#five\">Stereoselectivity in Alkene Addition Reactions<\/a><\/li>\n<li><a href=\"#six\">Draw Out The Product Of Addition To Each Face Of The Alkene, Then Determine Relationships<\/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. Alkene Reactions Follow A Few Key Patterns<\/h2>\n<p>In the articles that follow in this chapter, we are going to cover the main reactions of alkenes. In this article, I want to try to help you recognize the key pattern of bonds that form and break (&#8220;addition&#8221;) and some of the terms we use to describe the sub-patterns of &#8220;<strong>regioselectivity<\/strong>&#8221; (Markovnikov vs. anti-Markovnikov) and &#8220;<strong>stereoselectivity<\/strong>&#8221; (<em>syn<\/em> vs <em>anti<\/em>).<\/p>\n<p>If you take a sneak peek at the Reaction Map of alkenes at the end of this chapter, you would be forgiven for thinking there are an intimidating number of alkene reactions to learn &#8211; over 20, depending on how you count.\u00a0 <em>[<span style=\"color: #800080;\">See article &#8211; <a style=\"color: #800080;\" href=\"https:\/\/www.masterorganicchemistry.com\/2014\/01\/21\/synthesis-reactions-of-alkenes\/\">Reactions of Alkenes<\/a><\/span><\/em><span style=\"color: #800080;\">]<\/span><\/p>\n<p>However, it&#8217;s actually a lot easier than it seems, because these reactions follow predictable <strong>patterns.\u00a0<\/strong>And there aren&#8217;t 20 patterns &#8211; there&#8217;s more like <strong>three<\/strong> major patterns (<span style=\"color: #993366;\"><em>with two very minor patterns<\/em><\/span>).<\/p>\n<p>In each of these reactions the specific identity of the\u00a0<strong>bonds<\/strong> that form on the two carbons of the alkene may change, but they will still obey the key patterns.<\/p>\n<h2><a id=\"two\"><\/a>2. Alkene Addition Reactions<\/h2>\n<p>Almost all reactions of alkenes we will learn can be classified as &#8220;<strong>addition&#8221;\u00a0<\/strong>reactions [<a href=\"#noteone\"><span style=\"color: #ff0000;\">Note 1<\/span><\/a> ]<\/p>\n<p>In an <strong>addition<\/strong> reaction, the C-C pi bond is broken, and two new single bonds to carbon are formed.<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-36028\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/1-general-pattern-for-addition-reactions-break-c-c-pi-and-form-c-x-and-c-y-always-break-c-c-pi-bond.gif\" alt=\"general pattern for addition reactions break c c pi and form c x and c y always break c c pi bond\" width=\"640\" height=\"298\" \/><\/a><\/p>\n<p>The reactions below are specific examples of alkene addition reactions. At this point you don&#8217;t need to know how they work or anything else about them. We&#8217;ll cover them in detail in subsequent articles!<\/p>\n<p>Just observe the pattern of bonds that <strong>form<\/strong> and <strong>break<\/strong>. We break a C-C pi bond (about 60 kcal\/mol) and form two new single bonds to carbon.<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-36029\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/2-specific-examples-of-alkene-addition-reactions-include-hydrogenation-halogenation-HX-addition.gif\" alt=\"specific examples of alkene addition reactions include hydrogenation halogenation HX addition\" width=\"640\" height=\"532\" \/><\/a><\/p>\n<p>If you&#8217;ve previously covered <strong>elimination<\/strong> reactions, the pattern above might look somewhat similar. In an elimination reaction, a new pi bond is formed, and two single bonds to carbon are broken.<\/p>\n<p>In other words, addition is the exact opposite of elimination. <a href=\"\" class=\"custom-tooltip\" data-image=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-1-elimination-reaction-pattern.gif\" data-link=\"\" data-title=\"\" data-text=\"\">hover for image <\/a> or click this <a href=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-1-elimination-reaction-pattern.gif\">link<\/a>.<\/p>\n<p>Going forward, make sure you can see the &#8220;hidden&#8221; (<span style=\"color: #993366;\"><em>or &#8220;implicit&#8221;<\/em><\/span>) hydrogens because they will often not be drawn out. <strong>You&#8217;ll be expected to be able to &#8220;see&#8221; that a new C-H bond formed here even if it isn&#8217;t drawn out explicitly.<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36030\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/3-be-able-to-recognize-hidden-hydrogens-on-alkenes-for-the-purposes-of-recognizing-reactions.gif\" alt=\"be able to recognize hidden hydrogens on alkenes for the purposes of recognizing reactions\" width=\"640\" height=\"318\" \/><\/a><\/p>\n<h2><a id=\"three\"><\/a>3. Regioisomers in Alkene Addition Reactions, and The Three Patterns Of Regioselectivity<\/h2>\n<p>Some addition reactions involve forming two <strong>identical<\/strong> single bonds to carbon, and others involve forming two\u00a0<strong>different<\/strong> bonds to carbon.<\/p>\n<p>If the two new single bonds to carbon are <strong>identical<\/strong>, then an addition reaction will form only <strong>one<\/strong> constitutional isomer.<\/p>\n<p>In hydrogenation, for example, two new C-H bonds are formed and a C-C pi bond is broken. There is only one way of ordering the new C-H bonds, so only one constitutional isomer (regioisomer) can form. <span style=\"color: #800080;\"><em>There <strong>can<\/strong> certainly be a mixture of <strong>stereoisomers <\/strong>(see below) which have the same connectivity, but have different arrangement of atoms in space. More on that in a bit.\u00a0<\/em><\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36031\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/4-if-the-same-groups-are-added-there-is-no-possibiity-of-forming-regioisomers.gif\" alt=\"if the same groups are added there is no possibiity of forming regioisomers\" width=\"640\" height=\"482\" \/><\/a><\/p>\n<p>If the alkene addition reaction forms <strong>two<\/strong>\u00a0<strong>different<\/strong> bonds to carbon, then there are\u00a0<strong>two different ways\u00a0<\/strong>of ordering them.<\/p>\n<p>This will only result in formation of a single constitutional isomer if the alkene is completely symmetrical, such as cyclohexene.<\/p>\n<p><a href=\"\" class=\"custom-tooltip\" data-image=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-2-addition-of-HX-to-symmetrical-alkenes.gif\" data-link=\"\" data-title=\"\" data-text=\"\">hover to see it, <\/a> or click this <a href=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-2-addition-of-HX-to-symmetrical-alkenes.gif\">link<\/a>.<\/p>\n<p>If the alkene is not symmetrical &#8211; the vast majority of cases! &#8211;\u00a0 a mixture of constitutional isomers are formed. <span style=\"color: #800080;\"><em>We&#8217;ll discuss the possibility for stereoisomers below.<\/em><\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36032\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/5-if-two-different-groups-are-added-then-regioselectivity-is-possible.gif\" alt=\"if two different groups are added then regioselectivity is possible\" width=\"640\" height=\"415\" \/><\/a><\/p>\n<p>If this pattern were\u00a0<strong>random<\/strong>, then we&#8217;d get a 1:1 mixture of products (constitutional isomers) &#8211; in other words, a reaction completely lacking in\u00a0<strong>regioselectivity<\/strong>.<\/p>\n<p>As it turns out, the reactions we are going to learn all have <strong>predictable<\/strong> patterns of regioselectivity and knowing the pattern will allow us to predict in advance which constitutional isomer will be formed as the major product.<\/p>\n<p>The classic regioselectivity pattern is known as &#8220;<strong>Markovnikov<\/strong>&#8221; regioselectivity and was first observed back in 1870 by Victor Markovnikov in the addition of H\u2013X to alkenes, where a new C-H and C-X bond is formed. [<span style=\"color: #800080;\"><em>See <a style=\"color: #800080;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/02\/08\/markovnikovs-rule-1\/\">Hydrohalogenation of Alkenes and Markovnikov&#8217;s Rule<\/a><\/em><\/span>] <span style=\"color: #993366;\"><em>(note that X here is a halogen, such as Cl, Br or I).\u00a0<\/em><\/span><\/p>\n<p>These reactions tend to happen in a way such that the C\u2013X bond forms to the alkene carbon bearing the most <strong>carbon<\/strong> substituents (the &#8220;most substituted&#8221; carbon) and the <strong>C-H<\/strong> bond forms to the carbon bearing the most <strong>hydrogens<\/strong> (&#8220;less substituted&#8221; carbon).<\/p>\n<p>We&#8217;ll commonly use the term &#8220;Markovnikov-selective&#8221; to refer to this pattern of\u00a0<strong>regioselectivity<\/strong>.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36033\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/6-alkene-forms-constitutional-isomers-with-hbr-giving-2-bromopropane-and-1-bromopropane.gif\" alt=\"alkene forms constitutional isomers with hbr giving 2 bromopropane and 1 bromopropane\" width=\"640\" height=\"422\" \/><\/a><\/p>\n<p>Markovnikov in 1870 had no idea <em>why<\/em> these reactions had the selectivity that they did.<\/p>\n<p>We now know that the reaction proceeds through a <strong>carbocation<\/strong> intermediate. Since carbocations are unstable reaction intermediates with less than a full octet of valence electrons,\u00a0 the reaction will favor the reaction pathway that passes through the <strong>most stable carbocation <\/strong><strong>intermediate<\/strong>, which is generally the carbon which is bonded to the<strong> greater number of carbon substituents<\/strong>. [<em><span style=\"color: #800080;\">See article: <a style=\"color: #800080;\" href=\"https:\/\/www.masterorganicchemistry.com\/2011\/03\/11\/3-factors-that-stabilize-carbocations\/\">Carbocation Stability<\/a><\/span>] .\u00a0<\/em>This results in the observed product!<\/p>\n<p>To see the mechanism, <a href=\"\" class=\"custom-tooltip\" data-image=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-3-mechanism-of-hydrohalogenation-of-alkenes-first-step-is-protonation-of-alkene-to-give-carbocation.gif\" data-link=\"\" data-title=\"\" data-text=\"\">hover here<\/a> or click this <a href=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-3-mechanism-of-hydrohalogenation-of-alkenes-first-step-is-protonation-of-alkene-to-give-carbocation.gif\">link<\/a>.<\/p>\n<p><span style=\"color: #993366;\"><i>Looking ahead a bit, we can apply the same rationale to reactions that pass through positively charged 3-membered ring intermediates such as bromonium ions. (See article &#8211; <a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/03\/15\/alkene-bromination-mechanism\/\">Halogenation of Alkenes<\/a>). Attack of the nucleophile on these intermediates always occurs to the carbon best able to support positive charge, which can be thought of as another expression of &#8220;Markovnikov&#8221; selectivity.\u00a0 <a href=\"\" class=\"custom-tooltip\" data-image=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-4-mechanism-of-halohydrin-formation.gif\" data-link=\"\" data-title=\"\" data-text=\"\">hover to see <\/a> or click this <a href=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-4-mechanism-of-halohydrin-formation.gif\">link<\/a>. <\/i><\/span><\/p>\n<p>If both sides of the alkene are attached to the same number of carbons, then the carbocation intermediates will be of roughly equal stability, and Markovnikov regioselectivity will not manifest itself.<\/p>\n<p>A few reactions (hydroboration and free-radical addition) show the <strong>opposite<\/strong> pattern of regioselectivity, where the<strong> C-H<\/strong> bond ends up being bonded to the <strong>less substituted<\/strong> carbon and <strong>C-X<\/strong> to the <strong>more substituted<\/strong> carbon.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36034\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/7-a-second-pattern-of-alkene-addition-reaction-is-anti-markovnikov-selectivity.gif\" alt=\"a second pattern of alkene addition reaction is anti markovnikov selectivity\" width=\"640\" height=\"361\" \/><\/a><\/p>\n<p>This is somewhat unimaginatively called &#8220;anti-Markovnikov&#8221; regioselectivity.<span style=\"color: #800080;\"><em> For more details, see <a style=\"color: #800080;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/03\/28\/hydroboration-of-alkenes-the-mechanism\/\">Hydroboration-Oxidation<\/a>, and <a style=\"color: #800080;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/04\/12\/addition-hbr-alkenes-roor-peroxides-free-radical\/\">Free-Radical Addition of HBr To Alkenes<\/a>.\u00a0<\/em><\/span><\/p>\n<p>To sum up, every single one of the 20+ addition reactions you will learn can be grouped into one of these three patterns of regioselectivity:<\/p>\n<ul>\n<li>None, or not applicable (N\/A)<\/li>\n<li>Markovnikov selective<\/li>\n<li>anti-Markovnikov selective<\/li>\n<\/ul>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36035\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/8-summary-of-the-3-patterns-of-alkene-regioselectivity-Markovnikov-anti-Markovnikov.gif\" alt=\"summary of the 3 patterns of alkene regioselectivity - Markovnikov anti Markovnikov\" width=\"640\" height=\"223\" \/><\/a><\/p>\n<h2><a id=\"four\"><\/a>4. <em>Syn<\/em> and <em>Anti<\/em> Addition To Alkenes<\/h2>\n<p>The pi bond of an alkene is <strong>flat<\/strong>\u00a0 (planar). The two sides of an alkene are called its <strong>faces<\/strong>.<\/p>\n<p>When an alkene undergoes an addition reaction, the two new single bonds\u00a0can either form on the <strong>same<\/strong> face of the alkene, or they can form on <strong>opposite<\/strong> faces.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36036\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/9-syn-and-anti-addition-in-alkene-reactions.gif\" alt=\"syn and anti addition in alkene reactions\" width=\"640\" height=\"509\" \/><\/a><\/p>\n<p>When the two bonds form on the same face of the alkene, we call this <em><strong>syn<\/strong><\/em> addition. When they form to opposite faces of the alkene, we call this <em><strong>anti<\/strong><\/em> addition.<\/p>\n<p>Back in the chapter on conformations, we used the terms <em>syn<\/em> and <em>anti<\/em> in Newman projections to refer to the orientation of two groups on adjacent carbons of a carbon-carbon single bond that can rotate freely. (<span style=\"color: #993366;\"><em>See article: <span style=\"color: #993366;\"><a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2020\/05\/29\/newman-projection-of-butane-and-gauche-conformation\/\">Newman Projection of Butane<\/a><\/span><\/em><\/span>).\u00a0 When they have a dihedral angle of 0\u00b0 they are said to be <em><strong>syn<\/strong><\/em>. When they have a dihedral angle of 180\u00b0 they are <em><strong>anti<\/strong><\/em>. [<a href=\"#notetwo\"><span style=\"color: #ff0000;\">Note 2<\/span><\/a>]<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36037\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/10-definition-of-dihedral-angle.gif\" alt=\"definition of dihedral angle\" width=\"640\" height=\"404\" \/><\/a><\/p>\n<p>Note that <em>syn<\/em> addition and <em>anti<\/em> addition refers to the <strong>relative<\/strong> <strong>orientation<\/strong> of the groups <strong>immediately after addition has occurred<\/strong>.<\/p>\n<p>Any subsequent bond rotation about the C-C bond will not change a\u00a0<em>syn<\/em> addition product into an\u00a0<em>anti<\/em> addition product (or vice versa).<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36038\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/11-syn-addition-and-anti-addition-products-can-undergo-rotation.gif\" alt=\"syn addition and anti addition products can undergo rotation\" width=\"640\" height=\"505\" \/><\/a><\/p>\n<p>It is tempting to refer to these orientations as &#8220;cis&#8221; and &#8220;trans&#8221;, and in some cases the cis and trans products are actually the products. [<span style=\"color: #800080;\"><em>Note: some of the older chemical literature also uses &#8220;cis&#8221; and &#8220;trans&#8221; to refer to syn and anti addition.<\/em><\/span>]<\/p>\n<p><a href=\"\" class=\"custom-tooltip\" data-image=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-5-syn-and-anti-vs-cis-and-trans-cyclohexadiol.gif\" data-link=\"\" data-title=\"\" data-text=\"\"> hover to see an example, <\/a> or click this <a href=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/Supp-5-syn-and-anti-vs-cis-and-trans-cyclohexadiol.gif\">link<\/a>.<\/p>\n<p>However, <em>cis<\/em> and\u00a0<em>trans<\/em> should really only be used in situations where the two groups are locked in place and cannot undergo bond rotation (i.e. geometric isomers).\u00a0 Try to avoid using &#8220;cis&#8221; and &#8220;trans&#8221; addition for products that can undergo subsequent bond rotation.<\/p>\n<h2><a id=\"five\"><\/a>5. The Three Categories of Stereoselectivity In Alkene Addition Reactions<\/h2>\n<p>The stereoselectivity of alkene addition reactions falls into <strong>three<\/strong> categories.<\/p>\n<ul>\n<li>Reactions that give exclusively <em>syn<\/em> addition products<\/li>\n<li>Reactions that give exclusively <em>anti<\/em> addition products<\/li>\n<li>Reactions that give a roughly equal mixture of <em>syn<\/em> and\u00a0<em>anti<\/em> addition products.<\/li>\n<\/ul>\n<p><span style=\"color: #993366;\"><em>Whether or not a given reaction gives exclusively syn, anti, or syn+anti products is a piece of information that had to be determined experimentally in each case. You will be told which reaction belongs in which category when we cover each one.\u00a0<\/em><\/span><\/p>\n<p>Since you will be expected to draw the products of alkene addition reaction products, knowing which category each reaction falls into is extremely important!<\/p>\n<p>Here&#8217;s an example of a reaction that is stereoselective for <em>syn<\/em> addition products. No products of <em>anti <\/em>addition are formed.<\/p>\n<p>[<span style=\"color: #993366;\"><em>See article: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2012\/05\/23\/whats-a-racemic-mixture\/\">What&#8217;s A Racemic Mixture?<\/a><\/em><\/span>]<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36039\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/12-some-reactions-are-selective-for-syn-addition-products.gif\" alt=\"some reactions are selective for syn addition products\" width=\"640\" height=\"219\" \/><\/a><\/p>\n<p>On the other hand, halogenation of alkenes is stereoselective for <em>anti<\/em> addition products. No <em>syn<\/em> addition products are formed. [<span style=\"color: #ff0000;\"><a style=\"color: #ff0000;\" href=\"#notethree\">Note 3<\/a><\/span>].<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36040\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/13-some-reactions-give-exclusively-anti-addition-products.gif\" alt=\"some reactions give exclusively anti addition products\" width=\"640\" height=\"227\" \/><\/a><\/p>\n<p>Addition of HX to alkenes is <strong>not<\/strong> stereoselective, and gives a roughly equal mixture of <em>syn<\/em> and <em>anti<\/em> addition products.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36041\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/14-some-reactions-give-a-mixture-of-syn-and-anti-addition-products.gif\" alt=\"-some reactions give a mixture of syn and anti addition products\" width=\"640\" height=\"269\" \/><\/a><\/p>\n<p>By combining the three patterns of regioselectivity with the three patterns of stereoselectivity, we can build a little 2 \u00d7 3 table with all the possibilities.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36042\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/15-3-patterns-of-alkene-regioselectivity-and-stereoselectivity.gif\" alt=\"3 patterns of alkene regioselectivity and stereoselectivity\" width=\"640\" height=\"212\" \/><\/a><\/p>\n<p>As it turns out, not every one of these possibilities is represented by reactions we will learn.<\/p>\n<p>To skip ahead to the end of the chapter, there will really be <strong>three<\/strong> key alkene addition patterns to look out for:<\/p>\n<ul>\n<li>Reactions that go through <strong>carbocation<\/strong> intermediates, which tend to be <strong>Markovnikov<\/strong>-selective reactions that give a mix of <strong><em>syn +<\/em>\u00a0<em>anti<\/em><\/strong> stereochemistry. (<span style=\"color: #993366;\"><em>See article: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/02\/22\/addition-pattern-1-the-carbocation-pathway\/\">Alkene Addition Pattern #1: The Carbocation Pathway<\/a><\/em><\/span>).<\/li>\n<li>Reactions that go through a <strong>3-membered ring intermediate<\/strong>, which tend to be <strong>Markovnikov<\/strong> selective <span style=\"color: #993366;\"><em>(when possible)\u00a0<\/em><span style=\"color: #000000;\">and give <strong><em>anti<\/em><\/strong> addition products. (<span style=\"color: #993366;\"><em>See article: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/03\/20\/alkene-addition-pattern-2-the-three-membered-ring-pathway\/\">Alkene Addition Pattern #2: The 3-Membered Ring Pathway<\/a><\/em><\/span>).\u00a0<\/span><\/span><\/li>\n<li>Reactions that go through a more or less <strong>concerted<\/strong> pathway, which mostly have <strong>no<\/strong> regioselectivity (except for hydroboration, which is anti-Markovnikov) and give\u00a0<strong><em>syn<\/em><\/strong> addition products. (<span style=\"color: #993366;\"><em>See article: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/04\/02\/epoxidation-hydroxylation-cyclopropanation-alkene-mechanism\/\">Alkene Addition Pattern #3 : The &#8220;Concerted Pathway&#8221;<\/a><\/em><\/span>).<\/li>\n<\/ul>\n<p>Condensing the reactions of alkenes down into these 3 key buckets will simplify things a lot.<\/p>\n<h2><a id=\"six\"><\/a>6. Determining Relationships Between Products In Alkene Addition Reactions<\/h2>\n<p>Once you have the pattern of bonds that form and break, the regioselectivity, and the stereoselectivity, there&#8217;s just one more piece of the puzzle left to address.<\/p>\n<p>Remember that alkenes are <strong>flat<\/strong>, and in the vast majority of cases, addition can occur with equal likelihood to either face of the alkene.<\/p>\n<p>Depending on the structure of the alkene, this can result in products that are\u00a0<strong>stereoisomers <\/strong>(enantiomers or diastereomers).<\/p>\n<p>You will need to practice drawing the product obtained for addition to\u00a0<strong>each face<\/strong>, and then compare\u00a0those two products to determine how they are related.<\/p>\n<p>Remember &#8220;enantiomers, diastereomers, or the same?&#8221; questions from your chapter on stereochemistry?<\/p>\n<p>Well, we&#8217;re going to do this again, in the context of alkene addition reactions. (<span style=\"color: #993366;\"><em>See artic<span style=\"color: #993366;\">le: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2019\/03\/08\/enantiomers-diastereomers-or-the-same-1-using-models\/\">Enantiomers, Diastereomers or The Same &#8211; Two Methods For Solving Problems<\/a><\/span><\/em><\/span>).<\/p>\n<p><span style=\"color: #993366;\"><span style=\"color: #000000;\">Trust me when I say that this is a <strong>very common type of exam question! <\/strong><\/span><\/span><\/p>\n<p><span style=\"color: #993366;\"><em>This is what makes organic chemistry &#8220;special&#8221; &#8211; concepts from previous chapters (like stereochemistry!) keep recurring and are integrated into the new material.\u00a0<\/em><\/span><\/p>\n<p>Let me show you what I mean using addition of H-Br to alkenes as an example.<\/p>\n<ul>\n<li>In this reaction, a C-C pi bond breaks, and a C-H and C-Br bond forms.<\/li>\n<li>The reaction has Markovnikov regioselectivity (C-Br forms on most substituted carbon)<\/li>\n<li>The reaction gives a mixture of\u00a0<em>syn<\/em> and <em>anti<\/em> addition products.<\/li>\n<\/ul>\n<p>Now let&#8217;s explore the products that form when different alkenes undergo addition.<\/p>\n<p>In the addition of H-Br to 1-methylcyclohexene, we can draw the products that are formed when addition happens to the top and bottom face.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36053\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/03\/16-drawing-the-products-of-addition-of-HBr-to-methylcyclohexene-to-get-identical-products.gif\" alt=\"drawing the products of addition of HBr to methylcyclohexene to get identical products\" width=\"640\" height=\"526\" \/><\/a><\/p>\n<p>In this case addition to the top face and the bottom face results in the <strong>same product<\/strong> (note the absence of any chiral center).<\/p>\n<p>Now let&#8217;s try it on 1-butene.<\/p>\n<p>In this case, applying the pattern to both faces gives 2-bromobutane. However, note the formation of a <strong>new chiral center<\/strong>. These two products are enantiomers of each other, and since they are formed in equal amounts, they constitute a\u00a0<strong>racemic mixture<\/strong>. (<span style=\"color: #993366;\"><em>See article: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2012\/05\/23\/whats-a-racemic-mixture\/\">What&#8217;s A Racemic Mixture?<\/a><\/em><\/span>).<\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"36054\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"36054\"] {\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=\"36054\"] {\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=\"36054\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-36054\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-36054 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"36054\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-wcazs\" data-id=\"wcazs\">\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\/2667-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\/2667-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>If the starting material has a pre-existing chiral center, look out for the possibility of forming <strong>diastereomers<\/strong>.<\/p>\n<div class=\"wq-quiz-wrapper\" data-id=\"36055\"><style type=\"text\/css\" id=\"wq-flip-custom-css\">.wq-quiz-wrapper[data-id=\"36055\"] {\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=\"36055\"] {\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=\"36055\"] .wq_singleQuestionWrapper { width:100% !important; height:auto !important; }\n\t\t\t}\n\t\t<\/style><!-- wp quiz -->\n<div id=\"wp-quiz-36055\" class=\"wq_quizCtr single flip_quiz wq-quiz wq-quiz-36055 wq-quiz-flip wq-layout-single wq-skin-traditional wq-should-show-correct-answer\" data-quiz-id=\"36055\">\n<div class=\"wq-questions wq_questionsCtr\">\n\t<div class=\"wq-question wq_singleQuestionWrapper wq-question-x8qaq\" data-id=\"x8qaq\">\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\/2668-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\/2668-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>Is there a simple trick for knowing immediately if a given reaction will give you enantiomers, diastereomers, constitutional isomers or even just the same molecule?<\/p>\n<p>There is no simple trick. Just practice.<\/p>\n<p>However, there&#8217;s good news. If you have already answered a lot of &#8220;enantiomers, diastereomers, or the same&#8221; type questions, then you&#8217;re <strong>already most of the way toward solving these types of problems.<\/strong><\/p>\n<p>The key thing here is just <strong>applying the pattern\u00a0<\/strong>for each alkene addition reaction (bonds formed\/broken, regioselectivity, stereoselectivity) to each of the two alkene faces, and then comparing the two products.<\/p>\n<h2><strong><a id=\"seven\"><\/a>7. Summary<\/strong><\/h2>\n<p>Lots of concepts covered here, but this lays the groundwork for everything we&#8217;ll discuss later in this chapter on alkene addition reactions.<\/p>\n<ul>\n<li>Every alkene addition reaction involves breaking a C-C pi bond and forming two new bonds to carbon<\/li>\n<li>There are three key classes of\u00a0<strong>regioselectivity<\/strong> in alkene addition reactions: Markovnikov, anti-Markovnikov, and &#8220;none&#8221; (where the two bonds are identical).<\/li>\n<li>There are three key classes of\u00a0<strong>stereoselectivity <\/strong>in alkene addition reactions: <em>syn <\/em>addition, <em>anti<\/em> addition, and <em>syn + anti <\/em>addition (&#8220;unselective&#8221;).<\/li>\n<li>With the pattern of bonds formed\/broken, regioselectivity, and stereoselectivity in hand you should be able to draw the pattern of any alkene addition reaction.<\/li>\n<li>Just remember that alkenes are flat and addition can occur to either face of the alkene. Practice drawing out the products that are formed when addition happens to\u00a0<strong>each of the two faces<\/strong>.<\/li>\n<li>Then compare these two products to determine whether they are enantiomers, diastereomers, or the same<\/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\/2010\/07\/02\/stereoselective-stereospecific\/\" class=\"\"><span>Stereoselective and Stereospecific Reactions<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/02\/08\/markovnikovs-rule-1\/\" class=\"\"><span>Hydrohalogenation of Alkenes and Markovnikov\u2019s Rule<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/02\/22\/addition-pattern-1-the-carbocation-pathway\/\" class=\"\"><span>Addition Pattern #1: The \u201cCarbocation Pathway\u201d<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/03\/20\/alkene-addition-pattern-2-the-three-membered-ring-pathway\/\" class=\"\"><span>Alkene Addition Pattern #2: The \u201cThree-Membered Ring\u201d Pathway<\/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\/04\/12\/addition-hbr-alkenes-roor-peroxides-free-radical\/\" class=\"\"><span>A Fourth Alkene Addition Pattern \u2013 Free Radical Addition<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/04\/23\/alkene-reactions-ozonolysis\/\" class=\"\"><span>Alkene Reactions: Ozonolysis<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2014\/01\/21\/synthesis-reactions-of-alkenes\/\" class=\"\"><span>Synthesis (4) \u2013 Alkene Reaction Map, Including Alkyl Halide Reactions<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/09\/12\/two-types-of-elimination-reactions\/\" class=\"\"><span>Two Elimination Reaction Patterns<\/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\/2018\/09\/10\/types-of-isomers\/\" class=\"\"><span>Types of Isomers: Constitutional Isomers, Stereoisomers, Enantiomers, and Diastereomers<\/span><\/a><\/li><\/ul><\/div>\n<p><strong><a id=\"noteone\"><\/a>Note 1<\/strong>. One reaction of alkenes that doesn&#8217;t fit into this pattern of addition reactions is oxidative cleavage (e.g. ozonolysis). In this reaction, both the C-C sigma bond and the C-C pi bond are broken, and two new bonds between each carbon and oxygen are formed. (<span style=\"color: #993366;\"><em>See article: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/04\/23\/alkene-reactions-ozonolysis\/\">Ozonolysis of Alkenes<\/a><\/em><\/span>).<\/p>\n<p><strong><a id=\"notetwo\"><\/a>Note 2.\u00a0<\/strong>Technically, any two substituents with a dihedral angle between +30\u00b0 and -30\u00b0 are &#8220;<em>syn<\/em>&#8221; and any two substituents with a dihedral angle between +150 and -150\u00b0 are &#8220;<em>anti<\/em>&#8220;.<\/p>\n<p><strong><a id=\"notethree\"><\/a>Note 3.\u00a0<\/strong>In cases where a very stable carbocation can be formed (such as on a benzylic carbon),\u00a0 the 3-membered halonium ion can open to give a free carbocation, and <em>anti<\/em> stereoselectivity can be lost. <span style=\"color: #993366;\"><em>See article: <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2013\/03\/15\/alkene-bromination-mechanism\/\">Halogenation of Alkenes.<\/a>\u00a0<\/em><\/span><\/p>\n<p><strong>Note 4. <\/strong>Original definitions of <em>syn<\/em> and\u00a0<em>anti<\/em> according to <a href=\"https:\/\/link.springer.com\/article\/10.1007\/BF02158433\">Klyne and Prelog<\/a>.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-20710\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2020\/05\/F2-syn-and-anti-periplanar-and-clinal-klyne-prelog-diagram.gif\" alt=\"syn-and-anti-periplanar-and-clinal-klyne-prelog-diagram\" width=\"640\" height=\"782\" \/><\/a><\/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\/3580-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\/3176-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\/3177-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\/3178-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\/3191-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\/3190-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\/3189-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>[references]<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Alkene Addition Reactions: Regioselectivity and Stereoselectivity Almost all reactions of alkenes we will learn about can be classified as addition reactions\u00a0 In an alkene addition <\/p>\n","protected":false},"author":1,"featured_media":36065,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1418],"tags":[294,169,14855,906,201,374,887,482,895,14892],"post_folder":[],"class_list":["post-6890","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-alkene-reactions","tag-addition","tag-alkenes","tag-anti-addition","tag-anti-markovnikov","tag-elimination","tag-hbr","tag-markovnikov","tag-regioselectivity","tag-stereoselectivity","tag-syn-addition"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Alkene Addition Reactions: &quot;Regioselectivity&quot; and &quot;Stereoselectivity&quot; 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