{"id":189769,"date":"2025-02-10T08:31:04","date_gmt":"2025-02-10T08:31:04","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=189769"},"modified":"2025-02-10T08:31:05","modified_gmt":"2025-02-10T08:31:05","slug":"please-identify-the-number-of-gauche-butane-gb-interactions-in-each-chair-conformation","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/02\/10\/please-identify-the-number-of-gauche-butane-gb-interactions-in-each-chair-conformation\/","title":{"rendered":"Please identify the number of gauche butane (GB) interactions in each chair conformation"},"content":{"rendered":"\n<p>Please identify the number of gauche butane (GB) interactions in each chair conformation. * Me* Me Me H H H H H Gauche Butane -0.9 kcal\/mol Axial methyl (CH3) -1.8 kcal\/mol (2 gauche butane interactions) Me H Me H G.B Me G.B Me H H Me A H Me H G.B H G.B H H G.B<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/02\/image-232.png\" alt=\"\" class=\"wp-image-189770\"\/><\/figure>\n\n\n\n<p><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-6-color\"><strong>The Correct Answer and Explanation is :<\/strong><\/mark><\/p>\n\n\n\n<p>In the chair conformation of substituted cyclohexanes, the number of gauche butane (GB) interactions\u2014steric interactions between adjacent substituents at a 60\u00b0 dihedral angle\u2014depends on the positions of the substituents. Each GB interaction contributes approximately 0.9 kcal\/mol to the molecule&#8217;s strain energy.<\/p>\n\n\n\n<p><strong>Axial Methyl Group (CH\u2083):<\/strong><\/p>\n\n\n\n<p>When a methyl group occupies an axial position on a cyclohexane ring, it can engage in two GB interactions:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>First GB Interaction:<\/strong> The axial CH\u2083 group is at a 60\u00b0 angle to the axial hydrogen on the same carbon, resulting in a GB interaction.<\/li>\n\n\n\n<li><strong>Second GB Interaction:<\/strong> The axial CH\u2083 group is also at a 60\u00b0 angle to the axial hydrogen on the adjacent carbon, leading to another GB interaction.<\/li>\n<\/ol>\n\n\n\n<p>Therefore, a cyclohexane conformation with an axial methyl group experiences two GB interactions, contributing a total of 1.8 kcal\/mol to the strain energy.<\/p>\n\n\n\n<p><strong>Equatorial Methyl Group (CH\u2083):<\/strong><\/p>\n\n\n\n<p>In contrast, when a methyl group is in an equatorial position, it does not engage in any GB interactions because it is not at a 60\u00b0 angle to any adjacent substituent.<\/p>\n\n\n\n<p>Consequently, the conformation with an equatorial methyl group is free from GB interactions, resulting in a more stable structure.<\/p>\n\n\n\n<p><strong>Summary:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Axial Methyl Group:<\/strong> 2 GB interactions (1.8 kcal\/mol strain energy)<\/li>\n\n\n\n<li><strong>Equatorial Methyl Group:<\/strong> 0 GB interactions (no additional strain energy)<\/li>\n<\/ul>\n\n\n\n<p>This analysis underscores the preference for larger substituents to occupy equatorial positions in cyclohexane rings, as this orientation minimizes steric strain and enhances molecular stability.<\/p>\n\n\n\n<p>For a visual explanation of gauche interactions, you might find the following video helpful:<\/p>\n\n\n\n<p>\ue200video\ue202Gauche-butane interaction in cis- and trans-methyldecalins\ue202turn0search5\ue201<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Please identify the number of gauche butane (GB) interactions in each chair conformation. * Me* Me Me H H H H H Gauche Butane -0.9 kcal\/mol Axial methyl (CH3) -1.8 kcal\/mol (2 gauche butane interactions) Me H Me H G.B Me G.B Me H H Me A H Me H G.B H G.B H H [&hellip;]<\/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 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