{"id":249899,"date":"2025-07-10T06:34:04","date_gmt":"2025-07-10T06:34:04","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=249899"},"modified":"2025-07-10T06:34:06","modified_gmt":"2025-07-10T06:34:06","slug":"predict-the-major-product-of-the-reaction-sequence","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/10\/predict-the-major-product-of-the-reaction-sequence\/","title":{"rendered":"Predict the major product of the reaction sequence.\u00a0"},"content":{"rendered":"\n


Predict the major product of the reaction sequence. 1.<\/p>\n\n\n\n

    \n

  1. No Reaction<\/li>\n<\/ol>\n\n\n\n
    \"\"<\/figure>\n\n\n\n

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

    The correct answer is No Reaction<\/strong>.<\/p>\n\n\n\n

    Here is a detailed explanation of why no reaction occurs:<\/p>\n\n\n\n

    The reaction conditions given, 1. NaOH, Br\u2082 and 2. H\u2083O\u207a, are characteristic of the haloform reaction. The haloform reaction is a specific chemical reaction where a haloform (CHX\u2083, where X is a halogen) is produced by the exhaustive halogenation of a methyl ketone (a ketone with a R-CO-CH\u2083 structure) in the presence of a base. The reaction also works for secondary alcohols that can be oxidized to methyl ketones under the reaction conditions.<\/p>\n\n\n\n

    The mechanism of the haloform reaction involves several steps:<\/p>\n\n\n\n

      \n
    1. Enolate formation:<\/strong>\u00a0The base (hydroxide ion, OH\u207b) removes an acidic alpha-hydrogen (a hydrogen on the carbon adjacent to the carbonyl group) to form an enolate ion.<\/li>\n\n\n\n
    2. Alpha-halogenation:<\/strong>\u00a0The enolate then attacks the halogen (Br\u2082), adding a bromine atom to the alpha-carbon.<\/li>\n\n\n\n
    3. Cleavage:<\/strong>\u00a0This process repeats until all three alpha-hydrogens of the methyl group are replaced by bromine atoms. The resulting trihalomethyl ketone is then attacked by hydroxide at the carbonyl carbon. This leads to the cleavage of the C-C bond, releasing a carboxylate anion and a tribromomethanide anion (CBr\u2083\u207b).<\/li>\n\n\n\n
    4. Protonation:<\/strong>\u00a0The CBr\u2083\u207b anion is a strong enough base to deprotonate the carboxylic acid formed in the previous step. The final acidic workup (H\u2083O\u207a) protonates the carboxylate salt to yield the final carboxylic acid product.<\/li>\n<\/ol>\n\n\n\n

      Let’s examine the starting material: 2,2-dimethyl-1-phenylpropan-1-one. The carbonyl group is attached to a phenyl group on one side and a tert-butyl group on the other. For the haloform reaction to occur, there must be at least one hydrogen atom on the alpha-carbon.<\/p>\n\n\n\n

      In this molecule, the carbon atom alpha to the carbonyl group within the alkyl (tert-butyl) chain is a quaternary carbon. This means it is bonded to four other carbon atoms and has no alpha-hydrogens<\/strong>. Because there are no acidic alpha-hydrogens, the hydroxide base cannot deprotonate the molecule to form an enolate. Since the formation of an enolate is the essential first step of the haloform reaction, the reaction cannot proceed.<\/p>\n\n\n\n

      Other possible reactions, like electrophilic aromatic substitution on the phenyl ring, are not favored under these basic conditions and without a proper catalyst. Therefore, the starting material does not react, and it is recovered unchanged after the workup.<\/p>\n\n\n\n

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

      Predict the major product of the reaction sequence. 1. The Correct Answer and Explanation is: The correct answer is No Reaction. Here is a detailed explanation of why no reaction occurs: The reaction conditions given, 1. NaOH, Br\u2082 and 2. H\u2083O\u207a, are characteristic of the haloform reaction. The haloform reaction is a specific chemical reaction where […]<\/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-249899","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/249899","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=249899"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/249899\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=249899"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=249899"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=249899"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}