{"id":12600,"date":"2026-05-21T08:44:03","date_gmt":"2026-05-21T08:44:03","guid":{"rendered":"https:\/\/www.vedprep.com\/exams\/?p=12600"},"modified":"2026-05-21T09:40:31","modified_gmt":"2026-05-21T09:40:31","slug":"wittig-reaction-for-iit-jam","status":"publish","type":"post","link":"https:\/\/www.vedprep.com\/exams\/iit-jam\/wittig-reaction-for-iit-jam\/","title":{"rendered":"Wittig reaction: Proven Tips For IIT JAM 2027"},"content":{"rendered":"<p>The <strong>Wittig reaction<\/strong> is one of those classic topics that you simply cannot skip if you are aiming for a top rank in IIT JAM. It is a brilliant organic reaction used to build alkenes by locking an aldehyde or ketone together with an organophosphorus reagent known as a Wittig reagent.<\/p>\n<h2><strong>Syllabus: Wittig Reaction &#8211; IIT JAM Organic Chemistry Syllabus<\/strong><\/h2>\n<p data-path-to-node=\"2\">If you look at the official <a href=\"https:\/\/jam2026.iitb.ac.in\/files\/syllabus_CY.pdf\" rel=\"nofollow noopener\" target=\"_blank\"><strong>IIT JAM organic chemistry syllabus<\/strong><\/a>, this reaction sits comfortably under the carbonyl compounds subtopic. Interestingly, it is also a staple for higher-level exams like CSIR NET and GATE, which means mastering it now gives you a massive head start for your master&#8217;s degree and beyond.<\/p>\n<p data-path-to-node=\"3\">The exam expects you to know the mechanism of <strong>Wittig reaction<\/strong>, predict the major stereochemical products, and recognize when the reaction hits its limitations. A clear grasp of this topic can easily fetch you secure marks in both Multiple Choice Questions (MCQs) and Numerical Answer Type (NAT) sections.<\/p>\n<p data-path-to-node=\"4\">For a solid deep dive, most of us stick to the trusted classics:<\/p>\n<ul data-path-to-node=\"5\">\n<li>\n<p data-path-to-node=\"5,0,0\"><i data-path-to-node=\"5,0,0\" data-index-in-node=\"0\">Organic Chemistry<\/i> by Paula Yurkanis Bruice<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"5,1,0\"><i data-path-to-node=\"5,1,0\" data-index-in-node=\"0\">Organic Chemistry<\/i> by Jerry March<\/p>\n<\/li>\n<\/ul>\n<p data-path-to-node=\"6\">These books give you great background and structural details, but we know textbook jargon can feel a bit dense when you are on a tight study schedule. That is exactly why we at <a href=\"https:\/\/www.vedprep.com\/online-courses\/iit-jam\"><strong>VedPrep<\/strong> <\/a>like to break these heavy topics down into plain, stress-free concepts.<\/p>\n<h2><strong>Understanding the Wittig Reaction For IIT JAM: Mechanism and Steps<\/strong><\/h2>\n<p data-path-to-node=\"8\">At its core, the <strong>Wittig reaction<\/strong> is like a molecular matchmaking event. You take an aldehyde or a ketone and pair it up with a phosphonium ylide. An ylide is just a fancy name for a molecule that has a negative charge on a carbon right next to a positive charge on a phosphorus atom. Because that carbon carries a negative charge, it acts as a nucleophile, hunting for a positive center.<\/p>\n<p data-path-to-node=\"9\">Here is how the magic happens step-by-step:<\/p>\n<p data-path-to-node=\"10\">First, you need a strong base to steal a proton from a phosphonium salt to create your ylide. Once the ylide is ready, its negatively charged carbon attacks the electrophilic carbonyl carbon of your aldehyde or ketone. This forms a species called a betaine intermediate.<\/p>\n<p data-path-to-node=\"11\">Next, the oxygen and phosphorus atoms under the <strong>Wittig reaction<\/strong>, almost magnetic chemical affinity for each other\u2014bond to form a four-membered ring called an oxaphosfetane. This ring is highly strained and unstable. It quickly collapses, snapping the old bonds to form a brand new carbon-carbon double bond (an alkene) and leaving behind a very stable byproduct: triphenylphosphine oxide (<span class=\"math-inline\" data-math=\"Ph_3PO\" data-index-in-node=\"388\">Ph<sub>3<\/sub>PO<\/span>).<\/p>\n<p data-path-to-node=\"11\">You know exactly where the double bond is going to form, making it an invaluable tool when you are trying to design complex organic frameworks in <strong>Wittig reaction<\/strong>.<\/p>\n<h2><strong>Worked Example: A CSIR NET Style Question<\/strong><\/h2>\n<p data-path-to-node=\"14\">Let&#8217;s look at a practical problem to see how this plays out in an exam scenario to understand the <strong>Wittig reaction<\/strong>. Imagine you are working through a practice paper and run into a question with these specific lab conditions: a 1.0 M solution run for 30 minutes at 20\u00b0C.<\/p>\n<p data-path-to-node=\"15\">The reaction mixes 0.05 mol of benzaldehyde with 0.06 mol of the Wittig reagent, methylenetriphenylphosphorane (<span class=\"math-inline\" data-math=\"Ph_3P=CH_2\" data-index-in-node=\"112\">Ph<sub>3<\/sub>P=CH<sub>2<\/sub><\/span>). Your goal is to find the limiting reactant and calculate the final yield.<\/p>\n<p data-path-to-node=\"16\">First, check out the balanced chemical equation:<\/p>\n<p data-path-to-node=\"16\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-17780 aligncenter\" src=\"https:\/\/www.vedprep.com\/exams\/wp-content\/uploads\/balanced-chemical-equation-300x25.png\" alt=\"balanced chemical equation\" width=\"300\" height=\"25\" srcset=\"https:\/\/www.vedprep.com\/exams\/wp-content\/uploads\/balanced-chemical-equation-300x25.png 300w, https:\/\/www.vedprep.com\/exams\/wp-content\/uploads\/balanced-chemical-equation-768x64.png 768w, https:\/\/www.vedprep.com\/exams\/wp-content\/uploads\/balanced-chemical-equation-800x67.png 800w, https:\/\/www.vedprep.com\/exams\/wp-content\/uploads\/balanced-chemical-equation.png 805w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/p>\n<table style=\"width: 63.1829%;\" data-path-to-node=\"19\">\n<thead>\n<tr>\n<td style=\"width: 63.9053%;\"><strong>Reactant<\/strong><\/td>\n<td style=\"width: 187.574%;\"><strong>Moles<\/strong><\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"width: 63.9053%;\"><span data-path-to-node=\"19,1,0,0\">Benzaldehyde<\/span><\/td>\n<td style=\"width: 187.574%;\"><span data-path-to-node=\"19,1,1,0\">0.05<\/span><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 63.9053%;\"><span data-path-to-node=\"19,2,0,0\">Wittig Reagent<\/span><\/td>\n<td style=\"width: 187.574%;\"><span data-path-to-node=\"19,2,1,0\">0.06<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p data-path-to-node=\"20\">Since you have fewer moles of benzaldehyde, it runs out first, making benzaldehyde the limiting reactant.<\/p>\n<p data-path-to-node=\"21\">Because the reaction scales 1:1, your theoretical yield of styrene (<span class=\"math-inline\" data-math=\"C_6H_5CH=CH_2\" data-index-in-node=\"68\">C<sub>6<\/sub>H<sub>5<\/sub>CH=CH<sub>2<\/sub><\/span>) matches the limiting reactant exactly: 0.05 mol. If you assume a perfect 100% conversion and multiply by the molar mass of styrene, you get a final yield of 5.2 grams.<\/p>\n<h2><strong>Common Misconceptions<\/strong><\/h2>\n<p data-path-to-node=\"23\">When you are prepping for a highly competitive exam like IIT JAM, minor misunderstandings can cost you crucial marks. Let&#8217;s clear up three common traps that catch students off guard:<\/p>\n<ul data-path-to-node=\"24\">\n<li>\n<p data-path-to-node=\"24,0,0\"><b data-path-to-node=\"24,0,0\" data-index-in-node=\"0\">Thinking it is a substitution reaction:<\/b> Because you are swapping an oxygen atom out for a carbon group, it looks like a simple substitution at first glance. But remember, the mechanism relies entirely on addition and elimination steps through that cyclical intermediate. It is an addition-elimination pathway, not a substitution.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"24,1,0\"><b data-path-to-node=\"24,1,0\" data-index-in-node=\"0\">Believing it only works on aldehydes:<\/b> Aldehydes are definitely more reactive because they have less steric crowding and are more electrophilic. However, ketones work perfectly fine too. Don&#8217;t rule out a ketone on your exam paper just because it looks bulkier.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"24,2,0\"><b data-path-to-node=\"24,2,0\" data-index-in-node=\"0\">Assuming you must buy or bottle the ylide beforehand:<\/b> Phosphonium ylides can be quite unstable and sensitive to air and moisture. In a real lab environment, chemists almost always prepare them <i data-path-to-node=\"24,2,0\" data-index-in-node=\"193\">in situ<\/i>\u2014meaning right inside the reaction flask. You start with triphenylphosphine, react it with an alkyl halide, drop in a strong base, and then let it go to town on your carbonyl compound.<\/p>\n<\/li>\n<\/ul>\n<h2><strong>Wittig Reaction For IIT JAM: Applications and Real-World Examples<\/strong><\/h2>\n<p data-path-to-node=\"26\">To make this concept stick, let&#8217;s picture a fictional scenario. Imagine a team of pharmaceutical scientists trying to build a new life-saving heart medication. They have two massive molecular fragments, and they need to join them together with a rigid carbon-carbon double bond at a precise location. If they use a standard acid-catalyzed dehydration, the double bond might migrate all over the place, ruining the batch. Instead, they turn to the <strong>Wittig reaction<\/strong> because it acts like a precise molecular stapler, locking the double bond exactly where the old carbonyl group used to sit.<\/p>\n<p data-path-to-node=\"27\">This kind of reliability makes the reaction a massive deal in the real world:<\/p>\n<ul data-path-to-node=\"28\">\n<li>\n<p data-path-to-node=\"28,0,0\"><b data-path-to-node=\"28,0,0\" data-index-in-node=\"0\">Pharmaceuticals:<\/b> It is used heavily in synthesizing statins, which are widely prescribed cholesterol-lowering drugs.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"28,1,0\"><b data-path-to-node=\"28,1,0\" data-index-in-node=\"0\">Agrochemicals:<\/b> Many complex insecticides and herbicides rely on this reaction to construct their active chemical structures.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"28,2,0\"><b data-path-to-node=\"28,2,0\" data-index-in-node=\"0\">Fragrances &amp; Vitamins:<\/b> The synthesis of retinol (Vitamin A) used in skincare, along with various synthetic musk and terpene fragrances in perfumes, relies on ylide chemistry.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"28,3,0\"><b data-path-to-node=\"28,3,0\" data-index-in-node=\"0\">Material Science:<\/b> It helps build conjugated polymers used in cutting-edge organic electronics and solar cells.<\/p>\n<\/li>\n<\/ul>\n<h2><strong>Wittig Reaction For IIT JAM: Exam Strategy and Study Tips<\/strong><\/h2>\n<p data-path-to-node=\"30\">When you are facing an exam like IIT JAM, you need a strategy that goes beyond just memorizing facts. Here is how you can approach this topic systematically:<\/p>\n<ul data-path-to-node=\"31\">\n<li>\n<p data-path-to-node=\"31,0,0\"><b data-path-to-node=\"31,0,0\" data-index-in-node=\"0\">Master the Stereochemistry:<\/b> This is where examiners love to test you. Unstabilized ylides (where the negative carbon is attached to simple electron-donating alkyl groups) generally give you <i data-path-to-node=\"31,0,0\" data-index-in-node=\"190\">Z<\/i>-alkenes (cis). Stabilized ylides (where the carbon is next to an electron-withdrawing group like a carbonyl or an ester) give you <i data-path-to-node=\"31,0,0\" data-index-in-node=\"322\">E<\/i>-alkenes (trans).<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"31,1,0\"><b data-path-to-node=\"31,1,0\" data-index-in-node=\"0\">Learn the Variations:<\/b> Make sure you look into the Wittig-Horner (Horner-Wadsworth-Emmons) reaction, which uses phosphonate esters to cleanly yield <i data-path-to-node=\"31,1,0\" data-index-in-node=\"147\">E<\/i>-alkenes, and check out the Schlosser modification for turning unstabilized ylides into <i data-path-to-node=\"31,1,0\" data-index-in-node=\"236\">E<\/i>-alkenes.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"31,2,0\"><b data-path-to-node=\"31,2,0\" data-index-in-node=\"0\">Practice Active Solving:<\/b> Do not just read through mechanisms passively. Grab a notebook, cover the answers, and draw out the arrow-pushing mechanisms for old JAM and CSIR NET questions yourself.<\/p>\n<\/li>\n<\/ul>\n<h2><strong>Real-World Lab Application of Wittig Reaction For IIT JAM<\/strong><\/h2>\n<p data-path-to-node=\"34\">When you get into your master&#8217;s program, you will likely run this reaction with your own hands. You will notice how the bright orange or red color of the ylide disappears as it reacts with the carbonyl compound, leaving behind a thick white precipitate of triphenylphosphine oxide. Seeing it happen in a flask makes you appreciate why Georg Wittig won a Nobel Prize for this discovery back in 1979.<\/p>\n<p data-path-to-node=\"35\"><strong>Key Points to Remember: Wittig Reaction For IIT JAM<\/strong><\/p>\n<p data-path-to-node=\"36\">Before you close your books for the day, keep these core takeaways in mind:<\/p>\n<ul data-path-to-node=\"37\">\n<li>\n<p data-path-to-node=\"37,0,0\">The reaction converts aldehydes or ketones into alkenes using a phosphorus ylide.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"37,1,0\">The mechanism passes through a cyclic, four-membered oxaphosfetane transition state.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"37,2,0\">The driving force of the entire reaction is the incredibly strong thermodynamic stability of the phosphorus-oxygen double bond in the <span class=\"math-inline\" data-math=\"Ph_3PO\" data-index-in-node=\"134\">Ph<sub>3<\/sub>PO<\/span>\u00a0byproduct.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"37,3,0\">Your choice of ylide (stabilized vs. unstabilized) dictates whether you end up with an <i data-path-to-node=\"37,3,0\" data-index-in-node=\"87\">E<\/i> or <i data-path-to-node=\"37,3,0\" data-index-in-node=\"92\">Z<\/i> alkene isomer.<\/p>\n<\/li>\n<\/ul>\n<section>\n<h2><strong>Final Thoughts<\/strong><\/h2>\n<p>Preparing for \u00a0the IIT JAM is all about connecting the dots between basic textbook rules and actual exam-day by covering <strong>Wittig reaction<\/strong>. The <strong>Wittig reaction<\/strong> is a prime example of a topic that seems intimidating with its phosphorus chemistry and stereochemical twists, but becomes incredibly manageable once you master the core mechanism and the nature of the ylides. Don&#8217;t let the dense terminology slow you down\u2014break the structures apart, practice your arrow-pushing mechanisms, and focus on predicting the <i data-path-to-node=\"1\" data-index-in-node=\"496\">E<\/i> versus <i data-path-to-node=\"1\" data-index-in-node=\"505\">Z<\/i> outcomes. With a systematic approach and consistent practice, you&#8217;ll be able to confidently secure these marks.<\/p>\n<p>To know more in detail from our faculty, watch our YouTube video:<\/p>\n<p class=\"responsive-video-wrap clr\"><iframe title=\"Reaction Intermediate | Reaction Mechanism | CSIR NET Chemistry |IIT JAM |GATE |VedPrep Chem Academy\" width=\"1200\" height=\"675\" src=\"https:\/\/www.youtube.com\/embed\/TDHOlf9FyFU?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<h2><strong>Frequently Asked Questions<\/strong><\/h2>\n<\/section>\n<style>#sp-ea-17783 .spcollapsing { height: 0; overflow: hidden; transition-property: height;transition-duration: 300ms;}#sp-ea-17783.sp-easy-accordion>.sp-ea-single {margin-bottom: 10px; border: 1px solid #e2e2e2; }#sp-ea-17783.sp-easy-accordion>.sp-ea-single>.ea-header a {color: #444;}#sp-ea-17783.sp-easy-accordion>.sp-ea-single>.sp-collapse>.ea-body {background: #fff; color: #444;}#sp-ea-17783.sp-easy-accordion>.sp-ea-single {background: #eee;}#sp-ea-17783.sp-easy-accordion>.sp-ea-single>.ea-header a .ea-expand-icon { float: left; color: #444;font-size: 16px;}<\/style><div id=\"sp_easy_accordion-1779352477\">\n<div id=\"sp-ea-17783\" class=\"sp-ea-one sp-easy-accordion\" data-ea-active=\"ea-click\" data-ea-mode=\"vertical\" data-preloader=\"\" data-scroll-active-item=\"\" data-offset-to-scroll=\"0\">\n\n<!-- Start accordion card div. -->\n<div class=\"ea-card ea-expand sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177830\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177830\" aria-controls=\"collapse177830\" href=\"#\"  aria-expanded=\"true\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-minus\"><\/i> What is the main purpose of the Wittig reaction?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse collapsed show\" id=\"collapse177830\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177830\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>The primary goal of the Wittig reaction is to convert an aldehyde or a ketone into an alkene. It allows you to introduce a carbon-carbon double bond exactly where the carbonyl oxygen used to be, giving you precise control over the structure of your product.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177831\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177831\" aria-controls=\"collapse177831\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> What exactly is a Wittig reagent?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse177831\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177831\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>A Wittig reagent is a phosphorus ylide (specifically, a phosphonium ylide). It is a neutral molecule that contains a negatively charged carbon atom directly bonded to a positively charged phosphorus atom (<span class=\"math-inline\" data-math=\"Ph_3P^+-C^-\\!R_2 \\leftrightarrow Ph_3P=CR_2\" data-index-in-node=\"205\">Ph<sup>3<\/sup>P<sup>+<\/sup>-C<sup>-<\/sup>R2 \u2194 Ph_3P=CR<sub>2<\/sub><\/span>).<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177832\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177832\" aria-controls=\"collapse177832\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> What drives the Wittig reaction thermodynamically?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse177832\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177832\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>The major driving force behind the reaction is the formation of a remarkably strong phosphorus-oxygen double bond in the byproduct, triphenylphosphine oxide (<span class=\"math-inline\" data-math=\"Ph_3PO\" data-index-in-node=\"158\">Ph<sub>3<\/sub>PO<\/span>). The chemical affinity between phosphorus and oxygen is what pulls the reaction forward to completion.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177833\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177833\" aria-controls=\"collapse177833\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> How do you prepare a Wittig reagent in situ?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse177833\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177833\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>You typically start by reacting triphenylphosphine (<span class=\"math-inline\" data-math=\"Ph_3P\" data-index-in-node=\"52\">Ph<sub>3<\/sub>P<\/span>) with an unhindered alkyl halide via an <span class=\"math-inline\" data-math=\"S_N2\" data-index-in-node=\"98\">S<sub>N<\/sub>2<\/span>\u00a0pathway to form a phosphonium salt. Then, you treat this salt with a strong base (like n-butyllithium, NaH, or <span class=\"math-inline\" data-math=\"NaNH_2\" data-index-in-node=\"214\">NaNH<sub>2<\/sub><\/span>) to pluck a proton off the adjacent carbon, creating the reactive ylide.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177834\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177834\" aria-controls=\"collapse177834\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> What is the difference between a stabilized and an unstabilized ylide?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse177834\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177834\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>An unstabilized ylide features a negatively charged carbon attached to simple, electron-donating alkyl groups, making it highly reactive. A stabilized ylide has an electron-withdrawing group (like a carbonyl, ester, or cyano group) next to the negative carbon, which delocalizes and stabilizes the negative charge.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177835\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177835\" aria-controls=\"collapse177835\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> How does ylide stability affect the stereochemistry of the alkene?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse177835\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177835\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p data-path-to-node=\"13\">As a general rule for your exam papers:<\/p>\n<ul data-path-to-node=\"14\">\n<li>\n<p data-path-to-node=\"14,0,0\"><b data-path-to-node=\"14,0,0\" data-index-in-node=\"0\">Unstabilized ylides<\/b> react under kinetic control to yield mostly <b data-path-to-node=\"14,0,0\" data-index-in-node=\"64\"><i data-path-to-node=\"14,0,0\" data-index-in-node=\"64\">Z<\/i>-alkenes (cis)<\/b>.<\/p>\n<\/li>\n<li>\n<p data-path-to-node=\"14,1,0\"><b data-path-to-node=\"14,1,0\" data-index-in-node=\"0\">Stabilized ylides<\/b> react under thermodynamic control to yield mostly <b data-path-to-node=\"14,1,0\" data-index-in-node=\"68\"><i data-path-to-node=\"14,1,0\" data-index-in-node=\"68\">E<\/i>-alkenes (trans)<\/b>.<\/p>\n<\/li>\n<\/ul>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177836\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177836\" aria-controls=\"collapse177836\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> What is the structure of the intermediate formed in the Wittig reaction?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse177836\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177836\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>The reaction proceeds through a cyclic, four-membered ring intermediate called an <b data-path-to-node=\"16\" data-index-in-node=\"82\">oxaphosfetane<\/b>. While older textbooks mention an acyclic zwitterionic \"betaine\" intermediate forming first, modern computational studies show that the oxaphosfetane is formed directly or rapidly during the process.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177837\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177837\" aria-controls=\"collapse177837\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> Why do aldehydes react faster than ketones in a Wittig reaction?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse177837\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177837\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>Aldehydes are less sterically crowded and have a more electrophilic carbonyl carbon than ketones. This makes it much easier for the nucleophilic ylide carbon to approach and attack them.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177838\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177838\" aria-controls=\"collapse177838\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> Can sterically hindered ketones undergo the Wittig reaction?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse177838\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177838\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>Highly hindered ketones react very slowly or sometimes not at all because the bulky groups block the incoming ylide. In such cases, alternative methods like the Horner-Wadsworth-Emmons reaction or the Peterson olefination are preferred.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-177839\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse177839\" aria-controls=\"collapse177839\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> What is the Horner-Wadsworth-Emmons (HWE) reaction?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse177839\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-177839\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>The HWE reaction is a classic modification of the Wittig reaction that uses phosphonate esters instead of phosphonium salts. It is specifically designed to cleanly produce <b data-path-to-node=\"22\" data-index-in-node=\"172\"><i data-path-to-node=\"22\" data-index-in-node=\"172\">E<\/i>-alkenes<\/b> from aldehydes or ketones using milder bases, and its water-soluble byproduct makes purification much easier.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-1778310\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse1778310\" aria-controls=\"collapse1778310\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> Can the Wittig reaction be classified as a substitution reaction?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse1778310\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-1778310\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>No. Even though it looks like you are substituting an oxygen for a carbon, the mechanism actually involves a cycloaddition followed by a cycloreversion (an addition-elimination sequence). Calling it a substitution is a very common exam trap.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-1778311\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse1778311\" aria-controls=\"collapse1778311\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> What is the Schlosser modification?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse1778311\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-1778311\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>The Schlosser modification is a specific reaction protocol used to force <b data-path-to-node=\"26\" data-index-in-node=\"73\">unstabilized ylides<\/b>\u2014which normally give <i data-path-to-node=\"26\" data-index-in-node=\"113\">Z<\/i>-alkenes\u2014to yield <b data-path-to-node=\"26\" data-index-in-node=\"132\"><i data-path-to-node=\"26\" data-index-in-node=\"132\">E<\/i>-alkenes<\/b>. It involves treating the reaction mixture with an additional equivalent of a strong base at low temperatures to epimerize the intermediate before the ring collapses.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-1778312\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse1778312\" aria-controls=\"collapse1778312\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> Which alkyl halides are best suited for making Wittig reagents?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse1778312\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-1778312\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>Primary and secondary alkyl halides work beautifully because the first step relies on an <span class=\"math-inline\" data-math=\"S_N2\" data-index-in-node=\"89\">S<sub>N<\/sub>2<\/span> displacement by triphenylphosphine. Tertiary alkyl halides fail completely because they are too sterically hindered for <span class=\"math-inline\" data-math=\"S_N2\" data-index-in-node=\"214\">S<sub>N<\/sub>2<\/span>\u00a0attack and undergo elimination instead.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-1778313\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse1778313\" aria-controls=\"collapse1778313\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> What kind of solvent is typically used in a Wittig reaction?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse1778313\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-1778313\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>Because many ylides and strong bases are highly sensitive to moisture and air, the reaction is conducted in anhydrous (dry), aprotic solvents. Common choices include tetrahydrofuran (THF), diethyl ether, dimethyl sulfoxide (DMSO), or dichloromethane (DCM).<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<!-- Start accordion card div. -->\n<div class=\"ea-card  sp-ea-single\">\n\t<!-- Start accordion header. -->\n\t<h3 class=\"ea-header\">\n\t\t<!-- Add anchor tag for header. -->\n\t\t<a class=\"collapsed\" id=\"ea-header-1778314\" role=\"button\" data-sptoggle=\"spcollapse\" data-sptarget=\"#collapse1778314\" aria-controls=\"collapse1778314\" href=\"#\"  aria-expanded=\"false\" tabindex=\"0\">\n\t\t<i aria-hidden=\"true\" role=\"presentation\" class=\"ea-expand-icon eap-icon-ea-expand-plus\"><\/i> Are there any safety hazards associated with the Wittig byproduct?\t\t<\/a> <!-- Close anchor tag for header. -->\n\t<\/h3>\t<!-- Close header tag. -->\n\t<!-- Start collapsible content div. -->\n\t<div class=\"sp-collapse spcollapse \" id=\"collapse1778314\" data-parent=\"#sp-ea-17783\" role=\"region\" aria-labelledby=\"ea-header-1778314\">  <!-- Content div. -->\n\t\t<div class=\"ea-body\">\n\t\t<p>Triphenylphosphine oxide (<span class=\"math-inline\" data-math=\"Ph_3PO\" data-index-in-node=\"26\">Ph<sub>3<\/sub>PO<\/span>) isn't overly hazardous, but it is notoriously annoying to clean up in the lab. It forms a stubborn, white crystalline solid that often requires extensive column chromatography to separate completely from your desired liquid alkene product.<\/p>\n\t\t<\/div> <!-- Close content div. -->\n\t<\/div> <!-- Close collapse div. -->\n<\/div> <!-- Close card div. -->\n<\/div>\n<\/div>\n\n","protected":false},"excerpt":{"rendered":"<p>Wittig Reaction For IIT JAM is a widely used organic reaction that forms alkenes by the condensation of aldehydes or ketones with an organophosphorus reagent called a Wittig reagent. Syllabus: Wittig Reaction &#8211; IIT JAM Organic Chemistry Syllabus This topic belongs to Chapter 2: Organic Chemistry of the CSIR NET \/ NTA syllabus.<\/p>\n","protected":false},"author":11,"featured_media":12599,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":"","rank_math_seo_score":86},"categories":[23],"tags":[2923,2922,7511,7512,7514,7513],"class_list":["post-12600","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-iit-jam","tag-competitive-exams","tag-vedprep","tag-wittig-reaction-for-iit-jam","tag-wittig-reaction-for-iit-jam-notes","tag-wittig-reaction-for-iit-jam-practice","tag-wittig-reaction-for-iit-jam-questions","entry","has-media"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/posts\/12600","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/comments?post=12600"}],"version-history":[{"count":4,"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/posts\/12600\/revisions"}],"predecessor-version":[{"id":17784,"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/posts\/12600\/revisions\/17784"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/media\/12599"}],"wp:attachment":[{"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/media?parent=12600"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/categories?post=12600"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vedprep.com\/exams\/wp-json\/wp\/v2\/tags?post=12600"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}