{"id":182509,"date":"2025-01-14T07:27:00","date_gmt":"2025-01-14T07:27:00","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=182509"},"modified":"2025-01-14T07:27:02","modified_gmt":"2025-01-14T07:27:02","slug":"which-isomer-of-1-bromo-3-isopropylcyclohexane-reacts-faster-when-refluxed-with-potassium-tert-butoxide","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/01\/14\/which-isomer-of-1-bromo-3-isopropylcyclohexane-reacts-faster-when-refluxed-with-potassium-tert-butoxide\/","title":{"rendered":"Which isomer of 1-bromo-3-isopropylcyclohexane reacts faster when refluxed with potassium tert-butoxide"},"content":{"rendered":"\n

Which isomer of 1-bromo-3-isopropylcyclohexane reacts faster when refluxed with potassium tert-butoxide, the cis isomer or the trans isomer? Draw the structure of the expected product from the faster-reacting compound.<\/p>\n\n\n\n

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

The cis-isomer<\/strong> of 1-bromo-3-isopropylcyclohexane will react faster with potassium tert-butoxide when refluxed. This reaction involves a Williamson ether synthesis<\/strong> mechanism, where the tert-butoxide ion (a strong base) will deprotonate the isopropyl group (if necessary) or participate in an SN2 substitution<\/strong> reaction.<\/p>\n\n\n\n

Explanation:<\/h3>\n\n\n\n
    \n
  1. Steric hindrance and accessibility<\/strong>: The two isomers (cis and trans) of 1-bromo-3-isopropylcyclohexane differ in the relative orientation of the substituents attached to the cyclohexane ring. In the cis-isomer<\/strong>, the bromine atom at position 1 and the isopropyl group at position 3 are on the same side of the ring. This configuration makes the carbon attached to the bromine (C1) in a more axial position<\/strong>, which is less sterically hindered for an SN2 substitution. Additionally, the isopropyl group is positioned in a more equatorial<\/strong> orientation, reducing any steric strain that would hinder the approach of the nucleophile (tert-butoxide).<\/li>\n\n\n\n
  2. Trans-isomer<\/strong>: In the trans-isomer<\/strong>, the bromine and isopropyl groups are on opposite sides of the ring, making the C1 position more likely to adopt an equatorial<\/strong> position, but it creates steric interference for the nucleophile in the axial position. As the reaction proceeds, the cis-isomer’s axial position for the leaving group allows for better nucleophilic attack compared to the more hindered trans-isomer.<\/li>\n\n\n\n
  3. Reaction mechanism<\/strong>: The tert-butoxide ion, being bulky, prefers to attack the more accessible (axial) carbon in the cis-isomer. The reaction proceeds with an SN2 mechanism<\/strong> (since tert-butoxide is a strong nucleophile), with the nucleophile attacking the electrophilic carbon and the leaving group (Br) departing in a single step.<\/li>\n<\/ol>\n\n\n\n

    Expected product:<\/h3>\n\n\n\n

    The product formed is an ether<\/strong> with the nucleophile (tert-butoxide) replacing the bromine atom. The expected structure from the faster-reacting cis-isomer would be 3-isopropyl-1-(tert-butoxy)cyclohexane<\/strong>.<\/p>\n\n\n\n

    Structure of the expected product:<\/h4>\n\n\n\n
          CH3\n       |\nCH3-CH2-C-O-CH2-C6H11\n       |\n      CH3<\/code><\/pre>\n\n\n\n
    This reaction illustrates how steric factors<\/strong> influence the rate of nucleophilic substitution, with the cis-isomer being more reactive due to its favorable geometry for the SN2 mechanism.<\/p>\n","protected":false},"excerpt":{"rendered":"
    Which isomer of 1-bromo-3-isopropylcyclohexane reacts faster when refluxed with potassium tert-butoxide, the cis isomer or the trans isomer? Draw the structure of the expected product from the faster-reacting compound. The Correct Answer and Explanation is : The cis-isomer of 1-bromo-3-isopropylcyclohexane will react faster with potassium tert-butoxide when refluxed. This reaction involves a Williamson ether synthesis […]<\/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-182509","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/182509","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=182509"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/182509\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=182509"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=182509"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=182509"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}