{"id":212673,"date":"2025-05-07T15:42:58","date_gmt":"2025-05-07T15:42:58","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=212673"},"modified":"2025-05-07T15:43:01","modified_gmt":"2025-05-07T15:43:01","slug":"draw-the-major-organic-product-of-the-following-friedel-crafts-alkylation","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/05\/07\/draw-the-major-organic-product-of-the-following-friedel-crafts-alkylation\/","title":{"rendered":"Draw the major organic product of the following Friedel-Crafts alkylation."},"content":{"rendered":"\n

Draw the major organic product of the following Friedel-Crafts alkylation.<\/mark><\/strong> (An excess of benzene is present.) The drawn product would require the formation of a rather unstable primary carbocation intermediate. The aluminum chloride polarizes the alkyl halide’s chlorine-carbon bond. Consider the possibility of a rearrangement reaction.<\/p>\n\n\n\n

The Correct Answer And EXplanation is<\/mark><\/strong><\/p>\n\n\n\n

To address this Friedel\u2013Crafts alkylation problem, let’s walk through the full process carefully, especially focusing on the carbocation rearrangement<\/strong>, which is a crucial feature in such reactions.<\/p>\n\n\n\n

\n\n\n\n

Reaction Setup:<\/strong><\/h3>\n\n\n\n

A Friedel\u2013Crafts alkylation typically involves:<\/p>\n\n\n\n

    \n
  • Aromatic compound:<\/strong> Benzene (C\u2086H\u2086), in excess here.<\/li>\n\n\n\n
  • Alkyl halide:<\/strong> Let’s assume the alkyl halide is 1-chlorobutane (CH\u2083CH\u2082CH\u2082CH\u2082Cl)<\/strong>.<\/li>\n\n\n\n
  • Lewis acid catalyst:<\/strong> AlCl\u2083<\/strong>, which facilitates the formation of a carbocation from the alkyl halide.<\/li>\n<\/ul>\n\n\n\n
    \n\n\n\n

    Step-by-Step Reaction Mechanism:<\/strong><\/h3>\n\n\n\n
      \n
    1. Activation of Alkyl Halide:<\/strong><\/li>\n<\/ol>\n\n\n\n
        \n
      • Aluminum chloride (AlCl\u2083), a strong Lewis acid, coordinates with the chlorine atom in the alkyl halide.<\/li>\n\n\n\n
      • This polarization weakens the C\u2013Cl bond, promoting cleavage and carbocation formation<\/strong>.<\/li>\n<\/ul>\n\n\n\n
          \n
        1. Carbocation Formation:<\/strong><\/li>\n<\/ol>\n\n\n\n
            \n
          • Initially, a 1\u00b0 (primary) carbocation<\/strong> would form: CH\u2083CH\u2082CH\u2082CH\u2082\u207a.<\/li>\n\n\n\n
          • But this 1\u00b0 carbocation is highly unstable.<\/li>\n\n\n\n
          • Rearrangement occurs<\/strong>: a hydride shift<\/strong> from the adjacent carbon occurs (specifically, from the \u03b2-carbon, forming a more stable carbocation).<\/li>\n<\/ul>\n\n\n\n
              \n
            1. Carbocation Rearrangement:<\/strong><\/li>\n<\/ol>\n\n\n\n
                \n
              • A 1,2-hydride shift<\/strong> from carbon 2 to carbon 1 converts the primary carbocation into a more stable 2\u00b0 (secondary) carbocation<\/strong>: CH\u2083CH\u207aCH\u2082CH\u2083 (sec-butyl cation<\/strong>).<\/li>\n<\/ul>\n\n\n\n
                  \n
                1. Electrophilic Aromatic Substitution:<\/strong><\/li>\n<\/ol>\n\n\n\n
                    \n
                  • The benzene ring acts as a nucleophile and attacks the more stable secondary carbocation<\/strong>.<\/li>\n\n\n\n
                  • This leads to the formation of sec-butylbenzene<\/strong> as the major product.<\/li>\n<\/ul>\n\n\n\n
                    \n\n\n\n

                    Final Answer:<\/strong><\/h3>\n\n\n\n

                    The major product is sec-butylbenzene<\/strong> (C\u2086H\u2085CH(CH\u2083)CH\u2082CH\u2083).<\/p>\n\n\n\n

                    \n\n\n\n

                    Explanation Summary (300+ words):<\/strong><\/h3>\n\n\n\n

                    The Friedel\u2013Crafts alkylation is a classic electrophilic aromatic substitution (EAS) reaction that installs an alkyl group onto an aromatic ring, such as benzene. This reaction requires a Lewis acid catalyst (commonly AlCl\u2083) and an alkyl halide. In this case, we are working with 1-chlorobutane as the alkyl halide.<\/p>\n\n\n\n

                    When AlCl\u2083 reacts with the alkyl halide, it polarizes the C\u2013Cl bond, making the carbon more electrophilic. This facilitates the cleavage of the bond, leading to the formation of a carbocation. The initial carbocation formed from 1-chlorobutane would be a primary (1\u00b0) carbocation, which is highly unstable and unlikely to exist for long. As a result, a rearrangement occurs almost immediately to form a more stable intermediate.<\/p>\n\n\n\n

                    The rearrangement in this scenario is a 1,2-hydride shift<\/strong>, where a hydrogen atom with its bonding electrons moves from the \u03b2-carbon to the carbocation center. This stabilizes the carbocation by moving the positive charge to a secondary (2\u00b0) carbon\u2014one that is bonded to two other carbon atoms\u2014which is more stable than a primary (1\u00b0) one. This intermediate is known as the sec-butyl cation<\/strong>.<\/p>\n\n\n\n

                    The benzene ring then reacts with this carbocation in a typical electrophilic substitution mechanism. The \u03c0 electrons of benzene attack the carbocation, forming a new C\u2013C bond. Subsequent loss of a proton restores aromaticity, resulting in the final product: sec-butylbenzene<\/strong>.<\/p>\n\n\n\n

                    Thus, although a primary carbocation would be expected from the alkyl halide, the reaction proceeds through a carbocation rearrangement, leading to a more stable carbocation and a different substitution product. This explains why sec-butylbenzene<\/strong> is the correct major product, not n-butylbenzene.<\/p>\n","protected":false},"excerpt":{"rendered":"

                    Draw the major organic product of the following Friedel-Crafts alkylation. (An excess of benzene is present.) The drawn product would require the formation of a rather unstable primary carbocation intermediate. The aluminum chloride polarizes the alkyl halide’s chlorine-carbon bond. Consider the possibility of a rearrangement reaction. The Correct Answer And EXplanation is To address this […]<\/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-212673","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/212673","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=212673"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/212673\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=212673"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=212673"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=212673"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}