{"id":235402,"date":"2025-06-15T10:51:47","date_gmt":"2025-06-15T10:51:47","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=235402"},"modified":"2025-06-15T10:51:49","modified_gmt":"2025-06-15T10:51:49","slug":"select-the-best-answer-for-the-indicated-products-of-the-reaction-shown-below","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/15\/select-the-best-answer-for-the-indicated-products-of-the-reaction-shown-below\/","title":{"rendered":"Select the best answer for the indicated products of the reaction shown below."},"content":{"rendered":"\n

Select the best answer for the indicated products of the reaction shown below. a.) b.) HBr Br Kinetic Product Thermodynamic Product Br Kinetic Product Thermodynamic Product Br Br Kinetic Product Thermodynamic Product<\/p>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

The correct answer is a.)<\/strong>.<\/p>\n\n\n\n

Explanation:<\/h3>\n\n\n\n

This reaction is an electrophilic addition of HBr to a conjugated diene, 2,3-dimethyl-1,3-butadiene. Such reactions can yield two different products: a kinetic product and a thermodynamic product, which arise from 1,2-addition and 1,4-addition, respectively.<\/p>\n\n\n\n

Step 1: Protonation and Formation of the Carbocation Intermediate<\/strong><\/p>\n\n\n\n

The reaction begins with the electrophilic attack of a proton (H+) from HBr on one of the double bonds. The proton adds to a terminal carbon (C1 or C4) to form the most stable possible carbocation. In this case, protonation at C1 forms a tertiary allylic carbocation. This intermediate is particularly stable because the positive charge is on a tertiary carbon and is also delocalized across the adjacent double bond through resonance.<\/p>\n\n\n\n

The carbocation intermediate exists as a hybrid of two resonance structures:<\/p>\n\n\n\n

    \n
  1. A\u00a0tertiary carbocation<\/strong>\u00a0(major contributor due to its higher stability)<\/li>\n\n\n\n
  2. A\u00a0primary carbocation<\/strong>\u00a0(minor contributor due to its lower stability)<\/li>\n<\/ol>\n\n\n\n

    The positive charge is shared between carbon-2 (C2) and carbon-4 (C4), but there is a greater concentration of positive charge on the more stable tertiary carbon (C2).<\/p>\n\n\n\n

    Step 2: Nucleophilic Attack and Product Formation<\/strong><\/p>\n\n\n\n

    The bromide ion (Br\u207b) then acts as a nucleophile and can attack either of the positively charged carbons.<\/p>\n\n\n\n

      \n
    • Kinetic Product (1,2-Addition):<\/strong>\u00a0The kinetic product is the one that forms the fastest. The rate of this step is determined by the activation energy. The attack by Br\u207b on C2, the site of the more stable tertiary carbocation and greater positive charge density, has a lower activation energy. This rapid attack leads to the\u00a01,2-addition product<\/strong>. This product, 3-bromo-2,3-dimethyl-1-butene, has a less substituted double bond.<\/li>\n\n\n\n
    • Thermodynamic Product (1,4-Addition):<\/strong>\u00a0The thermodynamic product is the most stable final product. Attack by Br\u207b at C4 leads to the\u00a01,4-addition product<\/strong>. This product, 1-bromo-2,3-dimethyl-2-butene, contains a tetrasubstituted double bond. According to Zaitsev’s rule, more substituted alkenes are more stable. Therefore, the 1,4-adduct is the more stable, or thermodynamic, product.<\/li>\n<\/ul>\n\n\n\n

      In summary, option a.)<\/strong> correctly identifies the faster-forming 1,2-adduct as the kinetic product and the more stable 1,4-adduct as the thermodynamic product.<\/p>\n\n\n\n

      \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

      Select the best answer for the indicated products of the reaction shown below. a.) b.) HBr Br Kinetic Product Thermodynamic Product Br Kinetic Product Thermodynamic Product Br Br Kinetic Product Thermodynamic Product The Correct Answer and Explanation is: The correct answer is a.). Explanation: This reaction is an electrophilic addition of HBr to a conjugated diene, […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-235402","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/235402","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=235402"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/235402\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=235402"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=235402"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=235402"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}