{"id":6769,"date":"2012-12-04T08:08:08","date_gmt":"2012-12-04T13:08:08","guid":{"rendered":"https:\/\/www.masterorganicchemistry.com\/?p=6769"},"modified":"2026-05-03T04:24:48","modified_gmt":"2026-05-03T09:24:48","slug":"deciding-sn1sn2e1e2-the-solvent","status":"publish","type":"post","link":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/","title":{"rendered":"Deciding SN1\/SN2\/E1\/E2  &#8211; The Solvent"},"content":{"rendered":"<p><strong>Secondary Alkyl Halides With Strongly Basic Nucleophiles. The &#8220;Ask Your Instructor&#8221; Edition<\/strong><\/p>\n<ul>\n<li>In the previous four articles in this series, we covered\u00a0<strong>how to identify <a href=\"https:\/\/www.masterorganicchemistry.com\/2023\/01\/18\/where-will-substitution-elimination-reactions-occur\/\">where an SN1\/SN2\/E1\/E2 reaction could take place<\/a><\/strong>, and then discussed the various roles of the\u00a0<a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/11\/21\/deciding-sn1sn2e1e2-1-the-substrate\/\"><strong>substrate<\/strong><\/a> (primary, secondary, tertiary), the\u00a0<a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/11\/30\/deciding-sn1sn2e1e2-2-the-nucleophilebase\/\"><strong>nucleophile\/base<\/strong><\/a>, and\u00a0<a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/12\/19\/sn1-vs-e1-temperature-sn2-vs-e2\/\"><strong>temperature<\/strong><\/a>.<\/li>\n<li>We&#8217;ve seen that\u00a0<strong>secondary\u00a0<\/strong>alkyl halides with\u00a0<strong>poorly basic nucleophiles\u00a0<\/strong>(such as RS(-), N3)(-), (-)CN and halides) tend to give\u00a0<strong>SN2 products<\/strong>, particularly in\u00a0<strong>polar aprotic solvents\u00a0<\/strong>such as dimethyl sulfoxide (DMSO),\u00a0<em>N,N-<\/em>dimethylformamide (DMF), acetone, and acetonitrile.<\/li>\n<li>Following the consequences of each of these variables only leaves us with\u00a0<strong>one<\/strong> tricky situation we need to deal with:<br \/>\nWhat about\u00a0<strong>secondary<\/strong> alkyl halides with\u00a0<strong>strongly basic<\/strong> nucleophiles like hydroxide (HO<sup>&#8211;<\/sup> ) and\u00a0alkoxide (RO<sup>&#8211;<\/sup>).<\/li>\n<\/ul>\n<p><img fetchpriority=\"high\" decoding=\"async\" class=\"alignnone wp-image-36090\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/0-with-a-secondary-alkyl-halide-and-strongly-basic-nucleophile-which-pathway-dominates-sn2-or-e2.gif\" alt=\"with a secondary alkyl halide and strongly basic nucleophile which pathway dominates sn2 or e2\" width=\"640\" height=\"205\" \/><\/a><\/p>\n<ul>\n<li>The chemical literature is pretty clear that these reactions result in\u00a0mostly<strong> elimination<\/strong> (E2). Additionally, most <strong>textbooks<\/strong> state that\u00a0<strong>elimination<\/strong> (E2) is favored &#8211; even in polar aprotic solvents, which tend to favor substitution reactions with poorly basic nucleophiles.<\/li>\n<li>However, that doesn&#8217;t mean that this topic is taught consistently among all schools or instructors. There are certainly examples of instructors giving exam questions where the expected answer is that this reaction gives substitution. (S<sub>N<\/sub>2).<\/li>\n<li>For that reason, I strongly suggest\u00a0<strong>asking your instructor<\/strong> their opinion on what happens when a strongly basic nucleophile reacts with a secondary alkyl halide (and whether or not a polar protic or polar aprotic solvent will affect this!)\u00a0 and prepare accordingly.<\/li>\n<\/ul>\n<p><img decoding=\"async\" class=\"alignnone wp-image-36131\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2012\/12\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif\" alt=\"summary-sn2 reactions on secondary alkyl halides with strongly basic nucleophiles give mostly E2\" width=\"640\" height=\"539\" \/><\/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\">The Question Many Instructors Avoid: Secondary Alkyl Halides With A Strongly Basic Nucleophile<\/a><\/li>\n<li><a href=\"#two\">What Do Experiments Say? (E2)<\/a><\/li>\n<li><a href=\"#three\">What Do Textbooks Say? (E2&#8230; mostly)<\/a><\/li>\n<li><a href=\"#four\">Some Potentially Ambiguous Exam Questions<\/a><\/li>\n<li><a href=\"#five\">Bottom Line: Ask Your Instructor<\/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. The Question Many Instructors Avoid: Secondary Alkyl Halides With A Strongly Basic Nucleophile<\/h2>\n<p>You&#8217;re in an exam. You&#8217;re given the following question.<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-36076\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/1-a-test-question-with-secondary-alkyl-halide-without-any-other-cues.gif\" alt=\"a test question with secondary alkyl halide without any other cues\" width=\"640\" height=\"246\" \/><\/a><\/p>\n<p>What do you draw as the answer?<\/p>\n<p>Let&#8217;s start by walking through the process for narrowing down whether a reaction is S<sub>N<\/sub>1\/S<sub>N<\/sub>2\/E1\/E2:<\/p>\n<ul>\n<li><strong>LG <\/strong>&#8211; Identify a good leaving group (Cl)<\/li>\n<li><strong>sp<sup>3<\/sup>\u00a0<\/strong>&#8211; Ensure that it&#8217;s on an sp<sup>3<\/sup>-hybridized carbon (it is)<\/li>\n<li><strong>123<\/strong>&#8211; Identify that carbon as primary, secondary or tertiary (secondary). This doesn&#8217;t rule out anything.<\/li>\n<li><strong>N<\/strong> &#8211; the nucleophile is NaOCH<sub>3<\/sub> (sodium methoxide).\u00a0 It&#8217;s a strong nucleophile due to the negative charge on oxygen, but also a <strong>strong base<\/strong>. (For our purposes,\u00a0 anything equally basic to HO(-) or RO(-) qualifies as a strong base.\u00a0 <strong>That rules out S<sub>N<\/sub>1\/E1<\/strong><\/li>\n<li><strong>T &#8211;\u00a0<\/strong>the temperature is not indicated. If heat were indicated, elimination would be likely.<\/li>\n<\/ul>\n<p>Since S<sub>N<\/sub>1 and E1 have been ruled out, we&#8217;re left with S<sub>N<\/sub>2 and E2 here. We have no further clues.<\/p>\n<p><strong>What&#8217;s the product?\u00a0<\/strong><\/p>\n<ul>\n<li>If the question is, &#8220;what would happen in an actual reaction flask&#8221;, the answer is\u00a0<strong>elimination\u00a0<\/strong>(E2). [<a href=\"#reftwo\">Ref<\/a>] How would you know this? You would have to be told explicitly either by your instructor or by your textbook, because this is an experimental observation, not something that could be predicted from first principles.<\/li>\n<li>If the question is, &#8220;what answer would you give on an exam?&#8221; then I would say, &#8220;<strong>ask your instructor<\/strong>, because the answer to this specific type question is not always taught consistently. It could be S<sub>N<\/sub>2 or E2.&#8221;<\/li>\n<\/ul>\n<p>As far as the way that organic chemistry is taught in North America, there is no greater question I know of that has as much variance as the question of &#8220;secondary alkyl halide with strongly basic nucleophile&#8221;.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36077\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/2-Quiz-of-instructors-on-whether-secondary-alkyl-halide-plus-alkoxide-gives-sn2-or-e2.png\" alt=\"Quiz of instructors on whether secondary alkyl halide plus alkoxide gives sn2 or e2\" width=\"640\" height=\"340\" srcset=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/2-Quiz-of-instructors-on-whether-secondary-alkyl-halide-plus-alkoxide-gives-sn2-or-e2.png 1518w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/2-Quiz-of-instructors-on-whether-secondary-alkyl-halide-plus-alkoxide-gives-sn2-or-e2-300x159.png 300w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/2-Quiz-of-instructors-on-whether-secondary-alkyl-halide-plus-alkoxide-gives-sn2-or-e2-1024x544.png 1024w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/2-Quiz-of-instructors-on-whether-secondary-alkyl-halide-plus-alkoxide-gives-sn2-or-e2-768x408.png 768w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/2-Quiz-of-instructors-on-whether-secondary-alkyl-halide-plus-alkoxide-gives-sn2-or-e2-760x404.png 760w\" sizes=\"(max-width: 640px) 100vw, 640px\" \/><\/a><\/p>\n<p>Small sample size, maybe, but there&#8217;s a lot of variation in the answers.\u00a0 And many instructors just flat-out avoid asking this question.<\/p>\n<p>Welcome to the &#8220;ask your instructor&#8221; edition of the S<sub>N<\/sub>1\/S<sub>N<\/sub>2\/E1\/E2 decision!<\/p>\n<h2><a id=\"two\"><\/a>2. What Do Experiments Say? (E2!)<\/h2>\n<p>When I was just starting grad school, I was trying to do a substitution reaction (S<sub>N<\/sub>2) on a secondary alkyl halide as part of my research project with a fairly basic nucleophile (<span style=\"color: #800080;\"><em>a <a href=\"https:\/\/www.masterorganicchemistry.com\/2016\/02\/05\/gilman-reagents-organocuprates-what-theyre-used-for\/\">Gilman reagent<\/a>, to be precise<\/em><\/span>).<\/p>\n<p>My product was almost exclusively elimination (E2). <strong>Very little of my desired S<sub>N<\/sub>2 product was formed<\/strong>.<\/p>\n<p>When I showed the results to my boss, his reaction was &#8220;yeah, the S<sub>N<\/sub>2 is a pretty crappy reaction on secondary alkyl halides&#8221;.<\/p>\n<p>This initially came as a shock. After all, I&#8217;d spent so much time in sophomore organic chemistry learning the various factors that determined whether a reaction was S<sub>N<\/sub>1\/S<sub>N<\/sub>2\/E1\/E2. <em>Surely they wouldn&#8217;t spend all this time teaching us the S<sub>N<\/sub>2 if it wasn&#8217;t useful in the real world, would they?<\/em><\/p>\n<p>Well&#8230; yes. In the real world, the S<sub>N<\/sub>2 can be a great reaction for primary alkyl halides, but for secondary alkyl halides, it only tends to work well if the nucleophile is poorly basic, like RS(-), N<sub>3<\/sub>(-), (-)CN, and halide ions.\u00a0 <em><span style=\"color: #993366;\">We covered this in the post on nucleophiles &#8211; <a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2012\/11\/30\/deciding-sn1sn2e1e2-2-the-nucleophilebase\/\">see article.<\/a> \u00a0<\/span><\/em><span style=\"color: #000000;\">In addition, a polar aprotic solvent like DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), acetonitrile or acetone will assist the rate of S<sub>N<\/sub>2 reactions.\u00a0<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36078\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/3-sn2-reactions-on-secondary-alkyl-halides-are-good-with-weakly-basic-nucleophiles.gif\" alt=\"sn2 reactions on secondary alkyl halides are good with weakly basic nucleophiles\" width=\"640\" height=\"324\" \/><\/a><\/p>\n<p>However, as soon as the nucleophile becomes strongly basic (such as with alkoxides, hydroxide, and acetylides, or Gilman reagents) elimination (E2) becomes the dominant pathway.<\/p>\n<p>Here is the results of an early study on 2-bromopentane. [<a href=\"#reftwo\"><span style=\"color: #ff0000;\">Ref<\/span><\/a>]<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36079\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/4-example-of-sn2-vs-e2-on-with-alkoxide-on-2-bromopentane-gives-82-per-cent-elimination-products.gif\" alt=\"example of sn2 vs e2 on with alkoxide on 2-bromopentane gives 82 per cent elimination products\" width=\"640\" height=\"334\" \/><\/a><\/p>\n<p>Even at room temperature it&#8217;s 82% alkene (elimination). As the temperature is increased, the proportion of elimination products also increases. (<span style=\"color: #993366;\"><em>See article &#8211; <span style=\"color: #993366;\"><a style=\"color: #993366;\" href=\"https:\/\/www.masterorganicchemistry.com\/2012\/09\/10\/elimination-reactions-are-favored-by-heat\/\">Elimination Reactions Are Favored By Heat<\/a><\/span><\/em><\/span>).<\/p>\n<p>The absolute\u00a0<strong>best<\/strong> <strong>case I could find<\/strong> was isopropyl bromide with sodium ethoxide in ethanol \/ H<sub>2<\/sub>O, which gives a <strong>47% yield<\/strong> of S<sub>N<\/sub>2 product <span style=\"color: #993366;\"><em>(and only 21% in pure ethanol).\u00a0<\/em><\/span><\/p>\n<p><span style=\"color: #993366;\"><span style=\"color: #000000;\">This is as good as it gets!\u00a0<\/span><\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36080\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/5-the-best-case-scenario-for-favoring-sn2-over-e2-using-isopropyl-halides.gif\" alt=\"the best case scenario for favoring sn2 over e2 using isopropyl halides\" width=\"640\" height=\"275\" \/><\/a><\/p>\n<p>Even changing out one of the methyl groups for ethyl (i.e. to make 2-bromobutane) makes the yield drop considerably to the 20% range.<\/p>\n<p>Cyclic alkyl halides aren&#8217;t any better. Cyclohexyl bromide, for example, gives about a 1% yield of SN2 product:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36081\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/6-with-more-hindered-alkyl-halides-like-cyclohexyl-bromide-sn2-is-almost-negligible.gif\" alt=\"with more hindered alkyl halides like cyclohexyl bromide sn2 is almost negligible\" width=\"640\" height=\"275\" \/><\/a><\/p>\n<p>You might think you can improve the yield of S<sub>N<\/sub>2 by using a <strong>polar aprotic solvent<\/strong> like dimethyl sulfoxide (DMSO). But in that case the yield of substitution product drops from 47% (in ethanol\/H<sub>2<\/sub>O)\u00a0 to about 3%.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36082\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/7-using-polar-aprotic-solvent-with-secondary-alkyl-halides-and-alkoxides-actually-gives-more-elimination-products.gif\" alt=\"using polar aprotic solvent with secondary alkyl halides and alkoxides actually gives more elimination products\" width=\"640\" height=\"272\" \/><\/a><\/p>\n<p>The bottom line here is that yes, indeed,\u00a0 <strong>reactions of secondary alkyl halides with hydroxide and alkoxides give predominantly E2 products<\/strong>. [<span style=\"color: #ff0000;\">Note 1<\/span>]<\/p>\n<h2><a id=\"three\"><\/a>3. What Do The Textbooks Say? (E2&#8230; <em>mostly<\/em>)<\/h2>\n<p>Given to the amount of angst that S<sub>N<\/sub>1\/S<sub>N<\/sub>2\/E1\/E2 questions cause students in introductory organic chemistry, one might reasonably expect that the issue of competing SN2\/E2 reactions with secondary alkyl halides would get significant coverage.<\/p>\n<p>From what I see, textbooks do not discuss this issue in any great depth. It gets a sentence, or perhaps a short paragraph.<\/p>\n<p>Here&#8217;s what some of the more popular organic chemistry textbooks have to say on the topic of &#8220;secondary alkyl halide + strongly basic nucleophile&#8221;.<\/p>\n<ul>\n<li><strong>Klein<\/strong> (1st, p. 378) &#8211; <strong>E2<\/strong> (major), S<sub>N<\/sub>2 (minor). &#8220;When the substrate is both a strong nucleophile and a strong base, bimolecular mechanisms will dominate (S<sub>N<\/sub>2 and E2).&#8221;<\/li>\n<li><strong>McMurry<\/strong> (OpenStax): For secondary alkyl halides&#8230; E2 elimination predominates if a strong base is used. \u00a0<a href=\"https:\/\/openstax.org\/books\/organic-chemistry\/pages\/11-12-a-summary-of-reactivity-sn1-sn2-e1-e1cb-and-e2\">Reference<\/a><\/li>\n<li><strong>Clayden\u00a0<\/strong>&#8211; shows a chart where strongly basic, unhindered nucleophiles (e.g. RO(-) ) give E2. Weakly basic nucleophiles (e.g. RS(-) give S<sub>N<\/sub>2).<\/li>\n<li><strong>Solomons<\/strong> (12th) &#8211;\u00a0<strong>E2 major<\/strong>.\u00a0 &#8220;With secondary halides, however, a strong base favors elimination because steric hindrance in the substrate makes substitution more difficult.&#8221;\u00a0 Gives the example of isopropyl bromide with NaOH. 79% E2, 21% S<sub>N<\/sub>2.<\/li>\n<li><strong>Wade<\/strong>\u00a0 (8th, p. 272) &#8211; &#8220;with a strong base, either the S<sub>N<\/sub>2 or E2 reaction are possible&#8221;.\u00a0 Nothing more specific than that.<\/li>\n<li><strong>Streitweiser<\/strong> (4th ed. p. 232) &#8211; gives an example (secondary alkyl halide with alkoxide) that gives an 85:5 ratio of E2 to S<sub>N<\/sub>2.<\/li>\n<\/ul>\n<p>So from this relatively small sample, textbooks <em>generally<\/em> say that secondary + strongly basic nucleophile favors E2, but there is a considerable amount of hedging.<\/p>\n<h2><a id=\"four\"><\/a>4. Clear Up This Question With Your Instructor Ahead of Time<\/h2>\n<p>Instructors want to see that you understand that S<sub>N<\/sub>2 reactions result in\u00a0 <strong>inversion\u00a0<\/strong><strong>of configuration<\/strong>.<\/p>\n<p>For that reason, expect to see examples of S<sub>N<\/sub>2 reactions on secondary alkyl halides containing a chiral center.<\/p>\n<p>Hopefully, they&#8217;ll do this using questions involving a poorly basic nucleophile like RS(-), N<sub>3<\/sub>(-), (-)CN or a halide.<\/p>\n<p>But they might not!\u00a0 Be prepared for a situation where the use hydroxide or an alkoxide to demonstrate this point:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-45784\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2012\/12\/8-from-roberts-stewart-caserio-organic-chemistry-methane-to-macromolecules.gif\" alt=\"from-roberts-stewart-caserio-organic-chemistry-methane-to-macromolecules\" width=\"580\" height=\"401\" \/><\/a><\/p>\n<p><span style=\"color: #800080;\"><em>This is from &#8220;<a href=\"https:\/\/archive.org\/details\/ost-chemistry-organic_chemistry\">Organic Chemistry<\/a>&#8221; by John D. Roberts et. al., 1971. I love John Roberts (the father of NMR), but question the choice of nucleophile to demonstrate S<sub>N<\/sub>2 here.\u00a0<\/em><\/span><\/p>\n<p>Despite the fact that the literature is pretty unambiguous that E2 is dominant, and textbooks are generally on the side of E2, <strong>sometimes instructors don&#8217;t explicitly tell you whether or not E2 or S<sub>N<\/sub>2 is favored for cases with a secondary alkyl halide and a strongly basic nucleophile<\/strong>.<\/p>\n<p>That means you might have to guess the product on your own.<\/p>\n<p>You should ask your instructor <strong>ahead of time<\/strong> whether or not reactions like the ones below give predominantly E2 or S<sub>N<\/sub>2 products.<\/p>\n<p>Here&#8217;s the first example. Substitution or elimination?<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36084\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/9-is-the-product-sn2-or-e2.gif\" alt=\"is the product sn2 or e2\" width=\"640\" height=\"383\" \/><\/a><\/p>\n<p>The bulky base (<em>t<\/em>-butoxide) tends to only give S<sub>N<\/sub>2 with methyl halides, but you should get a definitive answer from your instructor on the expected product with ethoxide.\u00a0 <span style=\"color: #800080;\"><em>(The answer key gave both answers as elimination).\u00a0<\/em><\/span><\/p>\n<p>Another example. Substitution or elimination as major product?<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36085\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/10-is-the-product-sn2-or-e2.gif\" alt=\"-is the product sn2 or e2\" width=\"640\" height=\"327\" \/><\/a><\/p>\n<p>In this case the stereochemistry of the leaving group is specified, and the solvent is polar aprotic (acetone). If you weren&#8217;t told ahead of time that these reactions favor elimination, there&#8217;s a good case to be made that this could be S<sub>N<\/sub>2. <span style=\"color: #800080;\"><em>(The answer key said E2).<\/em><\/span> <strong>Check this with your instructor!\u00a0<\/strong><\/p>\n<p>Below is another example where the stereochemistry is specified. Is this substitution or elimination?<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36086\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/11-is-the-product-sn2-or-e2.gif\" alt=\"is the product sn2 or e2\" width=\"640\" height=\"319\" \/><\/a><\/p>\n<p>In this case the answer key also said elimination.<\/p>\n<h2><a id=\"five\"><\/a>5. Summary: All I Can Really Say Is, &#8220;Ask Your Instructor&#8221;.<\/h2>\n<p>At some point before your big midterm on substitution vs elimination reactions, you should try to pin down your instructor on this question.<\/p>\n<p>&#8220;Is S<sub>N<\/sub>2 <strong>ever<\/strong> the major product with a strongly basic nucleophile like hydroxide or alkoxide?&#8221;.<\/p>\n<p>A simple, one-sentence question. Feel free to use any of the examples in this section to make your point.<\/p>\n<p>That way, at least you&#8217;ll be told\u00a0<strong>explicitly\u00a0<\/strong>what to expect.<\/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\/2012\/12\/19\/deciding-sn1sn2e1e2-4-the-temperature\/\" class=\"\"><span>Deciding SN1\/SN2\/E1\/E2 (4) \u2013 The Temperature<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2023\/01\/18\/where-will-substitution-elimination-reactions-occur\/\" class=\"\"><span>Identifying Where Substitution and Elimination Reactions Happen<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/04\/27\/polar-protic-polar-aprotic-nonpolar-all-about-solvents\/\" class=\"\"><span>Polar Protic? Polar Aprotic? Nonpolar? All About Solvents<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/11\/21\/deciding-sn1sn2e1e2-1-the-substrate\/\" class=\"\"><span>Deciding SN1\/SN2\/E1\/E2 (1) \u2013 The Substrate<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/11\/30\/deciding-sn1sn2e1e2-2-the-nucleophilebase\/\" class=\"\"><span>Deciding SN1\/SN2\/E1\/E2 (2) \u2013 The Nucleophile\/Base<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/06\/18\/what-makes-a-good-nucleophile\/\" class=\"\"><span>What Makes A Good Nucleophile?<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/04\/12\/what-makes-a-good-leaving-group\/\" class=\"\"><span>What makes a good leaving group?<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/07\/18\/steric-hindrance-is-like-a-fat-goalie\/\" class=\"\"><span>Steric Hindrance is Like a Fat Goalie<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/organic-chemistry-practice-problems\/sn1-sn2-e1-e2-practice-problems\/\" class=\"\"><span>SN1 SN2 E1 E2 Practice Problems<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2013\/01\/18\/wrapup-the-quick-n-dirty-guide-to-sn1sn2e1e2\/\" class=\"\"><span>Wrapup: The Quick N\u2019 Dirty Guide To SN1\/SN2\/E1\/E2<\/span><\/a><\/li><\/ul><\/div>\n<p>In previous versions of this article, I have said that secondary alkyl halides with strongly basic nucleophiles tend to give S<sub>N<\/sub>2 products with polar aprotic solvents. After doing a deep dive into the old chemical literature, I find that there is really zero evidence for this view. Therefore, I am now advising that the major products of these reactions should be E2 in all circumstances. For not having fixed this earlier, I apologize.<\/p>\n<p><strong><a id=\"noteone\"><\/a>Note 1. <\/strong>One example that does work for the formation of ethers on secondary alkyl halides, but kind of a special case, is <a href=\"https:\/\/www.sciencedirect.com\/science\/article\/abs\/pii\/S0040402001972503\">here<\/a>.<\/p>\n<p>It works because\u00a0 RO(-) is the conjugate base of phenol (pK<sub>a<\/sub> = 10) which is roughly as acidic as a thiol. So elimination isn&#8217;t as much of a concern as it would be with the more basic hydroxide and alkoxide ions.<\/p>\n<p><strong>Note 2.\u00a0<\/strong>Table of results from a 1948 study by Ingold et. al. The results are not presented in a way that is easy to digest, but the key value is top left, where isopropyl bromide at 45\u00b0C in 60% EtOH\/40% H<sub>2<\/sub>O gives a mixture that is 53% alkene (olefin) and presumably 47% substitution product. All other results with isopropyl halides are worse.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-36088\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/F1-SN2-vs-E2-Ingold-1948.png\" alt=\"SN2 vs E2 Ingold 1948\" width=\"640\" height=\"280\" srcset=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/F1-SN2-vs-E2-Ingold-1948.png 1790w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/F1-SN2-vs-E2-Ingold-1948-300x131.png 300w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/F1-SN2-vs-E2-Ingold-1948-1024x447.png 1024w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/F1-SN2-vs-E2-Ingold-1948-768x336.png 768w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/F1-SN2-vs-E2-Ingold-1948-1536x671.png 1536w, https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/04\/F1-SN2-vs-E2-Ingold-1948-760x332.png 760w\" sizes=\"(max-width: 640px) 100vw, 640px\" \/><\/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\/3329-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\/3330-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\/3331-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\/3334-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\/3336-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<ol>\n<li><strong>Mechanism of elimination reactions. Part VII. Solvent effects on rates and product-proportions in uni- and bi-molecular substitution and elimination reactions of alkyl halides and sulphonium salts in hydroxylic solvents<br \/>\n<\/strong>K. A. Cooper, M. L. Dhar, E. D. Hughes, C. K. Ingold, B. J. MacNulty and L. I. Woolf<br \/>\n<em>J. Chem. Soc. <\/em><strong>1948<\/strong>, 2043-2049<br \/>\n<strong>DOI: <\/strong><a href=\"https:\/\/doi.org\/10.1039\/JR9480002043\">10.1039\/JR9480002043<\/a><br \/>\nFor the reaction of isopropyl bromide with hydroxide ion in ethanol at 55\u00b0C, the reaction gives 29% SN2 products and 71% E2 products (see table V).\u00a0 (The amount of SN2 can be increased to 46% by adding 40% H2O by volume).<\/li>\n<li><strong><a id=\"reftwo\"><\/a>Mechanism of elimination reactions. Part X. Kinetics of olefin elimination from isopropyl, sec.-butyl, 2-n-amyl, and 3-n-amyl bromides in acidic and alkaline alcoholic media<br \/>\n<\/strong>M. L. Dhar, E. D. Hughes and C. K. Ingold<br \/>\n<em>J. Chem. Soc.\u00a0<\/em><strong>1948<\/strong>, 2058-2065<br \/>\n<strong>DOI: <\/strong><a href=\"https:\/\/doi.org\/10.1039\/JR9480002058\">10.1039\/JR9480002058<\/a><br \/>\nThis article studies the SN2\/E2 ratios of various secondary alkyl halides such as 2-bromobutane and 2-bromopentane and finds that they almost exclusively (&gt;80%) give E2 products.<\/li>\n<li><strong>The Reaction of Primary and Secondary Alkylaryl and Alkyl Sulfonates with Potassium t-Butoxide in Dimethyl Sulfoxide<br \/>\n<\/strong>Carl H. Snyder and Aida R. Soto<br \/>\n<em>The Journal of Organic Chemistry<\/em> <strong>1964<\/strong> 29 (3), 742-745<br \/>\n<strong>DOI<\/strong>: <a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/jo01026a055\">10.1021\/jo01026a055<\/a><br \/>\nStudy on SN2\/E2 ratios in primary and secondary alkyl sulfonates. In this article the authors state that essentially no SN2 products are isolated from the reaction of secondary alkyl sulfonates (e.g. ROTs) with KOtBu in dimethyl sulfoxide.<\/li>\n<li><strong>Hydroxide-Promoted Elimination Reactions: Alkyl Halides as Substrates\u2020<br \/>\n<\/strong>Manfred Schlosser, Claudio Tarchini<br \/>\n<em>Helvetica Chim. Acta. <\/em><strong>1977<\/strong>, <em>60<\/em>, 3060-3068<br \/>\n<strong>DOI: <\/strong><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/hlca.19770600858\">10.1002\/hlca.19770600858<\/a>.<br \/>\nSecondary alkyl halides are shown as giving almost exclusively elimination products here.<\/li>\n<li><strong>Solvation of ions. XIV. Protic-dipolar aprotic solvent effects on rates of bimolecular reactions. Solvent activity coefficients of reactants and transition states at 25\u00b0.<br \/>\n<\/strong>R. Alexander, E. C. F. Ko, A. J. Parker, and T. J. Broxton<br \/>\n<em>Journal of the American Chemical Society<\/em> <strong>1968<\/strong> 90 (19), 5049-5069<br \/>\n<strong>DOI:<\/strong> <a href=\"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/ja01021a002\">10.1021\/ja01021a002<\/a><br \/>\nRates of 78 SN2 and E2 reactions for primary and secondary alkyl halides in various solvents. In this article the yield of the SN2 reaction of isopropyl bromide with NaOCH<sub>3<\/sub> in DMSO is given as 3% as measured by vapor phase chromatography (97% elimination).<\/li>\n<li><strong>How Alkyl Halide Structure Affects E2 and SN2 Reaction Barriers: E2 Reactions Are as Sensitive as SN2 Reactions<br \/>\n<\/strong>Paul R. Rablen, Brett D. McLarney, Brandon J. Karlow, and Jean E. Schneider<br \/>\n<em>The Journal of Organic Chemistry<\/em> <strong>2014<\/strong> 79 (3), 867-879<br \/>\n<strong>DOI:<\/strong> <a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/jo4026644\">10.1021\/jo4026644<\/a><br \/>\nA more recent article about competition between SN2 and E2 reactions.<\/li>\n<li>https:\/\/www.sciencedirect.com\/science\/article\/abs\/pii\/S0040402001972503<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>Secondary Alkyl Halides With Strongly Basic Nucleophiles. The &#8220;Ask Your Instructor&#8221; Edition In the previous four articles in this series, we covered\u00a0how to identify where <\/p>\n","protected":false},"author":1,"featured_media":36131,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1417],"tags":[472,473,201,244,630,629,502,271,686,279],"post_folder":[],"class_list":["post-6769","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-sn1sn2e1e2","tag-e1","tag-e2","tag-elimination","tag-nucleophilicity","tag-polar-aprotic","tag-polar-protic","tag-sn1","tag-sn2","tag-solvents","tag-substitution"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Deciding SN1\/SN2\/E1\/E2 - The Solvent &#8211; Master Organic Chemistry<\/title>\n<meta name=\"description\" content=\"With a secondary alkyl halide and a poorly basic but strong nucleophile in a polar aprotic solvent, expect SN2. If the nucleophile is a strong base, expect E2, regardless of solvent.\" \/>\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\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Deciding SN1\/SN2\/E1\/E2 - The Solvent &#8211; Master Organic Chemistry\" \/>\n<meta property=\"og:description\" content=\"With a secondary alkyl halide and a poorly basic but strong nucleophile in a polar aprotic solvent, expect SN2. If the nucleophile is a strong base, expect E2, regardless of solvent.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/\" \/>\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=\"2012-12-04T13:08:08+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-05-03T09:24:48+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2012\/12\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif\" \/>\n\t<meta property=\"og:image:width\" content=\"884\" \/>\n\t<meta property=\"og:image:height\" content=\"744\" \/>\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=\"15 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/\"},\"author\":{\"name\":\"James Ashenhurst\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#\\\/schema\\\/person\\\/78d83ec7d02b4b7365bade2cedaef80c\"},\"headline\":\"Deciding SN1\\\/SN2\\\/E1\\\/E2 &#8211; The Solvent\",\"datePublished\":\"2012-12-04T13:08:08+00:00\",\"dateModified\":\"2026-05-03T09:24:48+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/\"},\"wordCount\":2458,\"commentCount\":54,\"publisher\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#organization\"},\"image\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2012\\\/12\\\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif\",\"keywords\":[\"e1\",\"e2\",\"elimination\",\"nucleophilicity\",\"polar aprotic\",\"polar protic\",\"sn1\",\"SN2\",\"solvents\",\"substitution\"],\"articleSection\":[\"SN1\\\/SN2\\\/E1\\\/E2 Decision\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/\",\"url\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/\",\"name\":\"Deciding SN1\\\/SN2\\\/E1\\\/E2 - The Solvent &#8211; Master Organic Chemistry\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2012\\\/12\\\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif\",\"datePublished\":\"2012-12-04T13:08:08+00:00\",\"dateModified\":\"2026-05-03T09:24:48+00:00\",\"description\":\"With a secondary alkyl halide and a poorly basic but strong nucleophile in a polar aprotic solvent, expect SN2. If the nucleophile is a strong base, expect E2, regardless of solvent.\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/#primaryimage\",\"url\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2012\\\/12\\\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif\",\"contentUrl\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/wp-content\\\/uploads\\\/2012\\\/12\\\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif\",\"width\":884,\"height\":744,\"caption\":\"summary-sn2 reactions on secondary alkyl halides with strongly basic nucleophiles give mostly E2\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/2012\\\/12\\\/04\\\/deciding-sn1sn2e1e2-the-solvent\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/www.masterorganicchemistry.com\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Deciding SN1\\\/SN2\\\/E1\\\/E2 &#8211; The Solvent\"}]},{\"@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":"Deciding SN1\/SN2\/E1\/E2 - The Solvent &#8211; Master Organic Chemistry","description":"With a secondary alkyl halide and a poorly basic but strong nucleophile in a polar aprotic solvent, expect SN2. If the nucleophile is a strong base, expect E2, regardless of solvent.","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\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/","og_locale":"en_US","og_type":"article","og_title":"Deciding SN1\/SN2\/E1\/E2 - The Solvent &#8211; Master Organic Chemistry","og_description":"With a secondary alkyl halide and a poorly basic but strong nucleophile in a polar aprotic solvent, expect SN2. If the nucleophile is a strong base, expect E2, regardless of solvent.","og_url":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/","og_site_name":"Master Organic Chemistry","article_publisher":"https:\/\/www.facebook.com\/Master-Organic-Chemistry-242610599108055\/","article_published_time":"2012-12-04T13:08:08+00:00","article_modified_time":"2026-05-03T09:24:48+00:00","og_image":[{"width":884,"height":744,"url":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2012\/12\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif","type":"image\/gif"}],"author":"James Ashenhurst","twitter_card":"summary_large_image","twitter_misc":{"Written by":"James Ashenhurst","Est. reading time":"15 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/#article","isPartOf":{"@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/"},"author":{"name":"James Ashenhurst","@id":"https:\/\/www.masterorganicchemistry.com\/#\/schema\/person\/78d83ec7d02b4b7365bade2cedaef80c"},"headline":"Deciding SN1\/SN2\/E1\/E2 &#8211; The Solvent","datePublished":"2012-12-04T13:08:08+00:00","dateModified":"2026-05-03T09:24:48+00:00","mainEntityOfPage":{"@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/"},"wordCount":2458,"commentCount":54,"publisher":{"@id":"https:\/\/www.masterorganicchemistry.com\/#organization"},"image":{"@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/#primaryimage"},"thumbnailUrl":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2012\/12\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif","keywords":["e1","e2","elimination","nucleophilicity","polar aprotic","polar protic","sn1","SN2","solvents","substitution"],"articleSection":["SN1\/SN2\/E1\/E2 Decision"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/","url":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/","name":"Deciding SN1\/SN2\/E1\/E2 - The Solvent &#8211; Master Organic Chemistry","isPartOf":{"@id":"https:\/\/www.masterorganicchemistry.com\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/#primaryimage"},"image":{"@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/#primaryimage"},"thumbnailUrl":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2012\/12\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif","datePublished":"2012-12-04T13:08:08+00:00","dateModified":"2026-05-03T09:24:48+00:00","description":"With a secondary alkyl halide and a poorly basic but strong nucleophile in a polar aprotic solvent, expect SN2. If the nucleophile is a strong base, expect E2, regardless of solvent.","breadcrumb":{"@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/#primaryimage","url":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2012\/12\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif","contentUrl":"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2012\/12\/0-summary-sn2-reactions-on-secondary-alkyl-halides-with-strongly-basic-nucleophiles-give-mostly-E2.gif","width":884,"height":744,"caption":"summary-sn2 reactions on secondary alkyl halides with strongly basic nucleophiles give mostly E2"},{"@type":"BreadcrumbList","@id":"https:\/\/www.masterorganicchemistry.com\/2012\/12\/04\/deciding-sn1sn2e1e2-the-solvent\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.masterorganicchemistry.com\/"},{"@type":"ListItem","position":2,"name":"Deciding SN1\/SN2\/E1\/E2 &#8211; The Solvent"}]},{"@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\/6769","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=6769"}],"version-history":[{"count":0,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/posts\/6769\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/media\/36131"}],"wp:attachment":[{"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/media?parent=6769"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/categories?post=6769"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/tags?post=6769"},{"taxonomy":"post_folder","embeddable":true,"href":"https:\/\/www.masterorganicchemistry.com\/wp-json\/wp\/v2\/post_folder?post=6769"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}