{"id":206879,"date":"2025-04-16T17:39:19","date_gmt":"2025-04-16T17:39:19","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=206879"},"modified":"2025-04-16T17:39:21","modified_gmt":"2025-04-16T17:39:21","slug":"identify-the-least-stable-conformation-of-a-di-substituted-cyclohexane-with-ethyl-groups-at-the-1st-and-2nd-carbons","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/04\/16\/identify-the-least-stable-conformation-of-a-di-substituted-cyclohexane-with-ethyl-groups-at-the-1st-and-2nd-carbons\/","title":{"rendered":"Identify the least stable conformation of a di-substituted cyclohexane with ethyl groups at the 1st and 2nd carbons"},"content":{"rendered":"\n<p>Identify the least stable conformation of a di-substituted cyclohexane with ethyl groups at the 1st and 2nd carbons.<\/p>\n\n\n\n<p>trans-1,2-diethylcyclohexane, with both ethyl groups equatorial<br>trans-1,2-diethylcyclohexane, with both ethyl groups axial<br>cis-1,2-diethylcyclohexane, with one ethyl group axial and one ethyl group equatorial<br>They are the same compound, so they are all equal.<\/p>\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>The <strong>least stable conformation<\/strong> of a di-substituted cyclohexane with ethyl groups at the 1st and 2nd carbons is:<\/p>\n\n\n\n<p><strong>\u25b6\ufe0f trans-1,2-diethylcyclohexane, with both ethyl groups axial<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Explanation (Approx. 300 words):<\/strong><\/h3>\n\n\n\n<p>Cyclohexane rings can adopt chair conformations, where substituents occupy either <strong>axial<\/strong> (pointing up\/down, perpendicular to the ring plane) or <strong>equatorial<\/strong> (pointing outward, roughly parallel to the ring) positions. Stability in substituted cyclohexanes depends on the positions of substituents: <strong>equatorial positions are more favorable<\/strong> due to reduced steric hindrance, especially for bulkier groups like ethyl.<\/p>\n\n\n\n<p>In <strong>1,2-disubstituted cyclohexanes<\/strong>, the relative positions of the two substituents (cis vs. trans) dictate their possible orientations in chair conformations:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>trans-1,2-diethylcyclohexane<\/strong>:<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>In one chair flip, both ethyl groups can be <strong>equatorial<\/strong> \u2013 this is <strong>very stable<\/strong>, as both bulky groups avoid axial crowding.<\/li>\n\n\n\n<li>In the flipped chair, both ethyls become <strong>axial<\/strong> \u2013 this is <strong>very unstable<\/strong>, due to <strong>1,3-diaxial interactions<\/strong>, where axial groups clash with axial hydrogens on the same side of the ring. Since ethyl is a bulky group, these clashes are significant, making this conformation <strong>least stable<\/strong>.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>cis-1,2-diethylcyclohexane<\/strong>:<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>One group must be equatorial and the other axial, regardless of the chair flip. This results in a mixed interaction\u2014<strong>intermediate stability<\/strong>\u2014better than two axial groups but worse than two equatorial.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>The statement <strong>&#8220;They are the same compound&#8221;<\/strong> is incorrect because <strong>cis<\/strong> and <strong>trans<\/strong> isomers are distinct stereoisomers with different physical and chemical properties.<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Conclusion:<\/strong><\/h3>\n\n\n\n<p>Among the conformations listed, the <strong>trans-1,2-diethylcyclohexane with both ethyl groups in axial positions<\/strong> is the <strong>least stable<\/strong> due to the severe steric strain caused by the two bulky groups in axial positions.<\/p>\n\n\n\n<p>\u2705 <strong>Correct answer: trans-1,2-diethylcyclohexane, with both ethyl groups axial<\/strong>.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/04\/image-92.png\" alt=\"\" class=\"wp-image-206880\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>Identify the least stable conformation of a di-substituted cyclohexane with ethyl groups at the 1st and 2nd carbons. trans-1,2-diethylcyclohexane, with both ethyl groups equatorialtrans-1,2-diethylcyclohexane, with both ethyl groups axialcis-1,2-diethylcyclohexane, with one ethyl group axial and one ethyl group equatorialThey are the same compound, so they are all equal. The correct answer and explanation is : [&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 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-206879","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/206879","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=206879"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/206879\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=206879"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=206879"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=206879"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}