{"id":207162,"date":"2025-04-18T16:29:44","date_gmt":"2025-04-18T16:29:44","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=207162"},"modified":"2025-04-18T16:29:46","modified_gmt":"2025-04-18T16:29:46","slug":"we-used-the-bromine-in-dcm-method-to-test-for-unsaturation","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/04\/18\/we-used-the-bromine-in-dcm-method-to-test-for-unsaturation\/","title":{"rendered":"We used the Bromine in DCM method to test for Unsaturation"},"content":{"rendered":"\n

We used the Bromine in DCM method to test for Unsaturation. We also took an IR spectrum of the compound. However, neither method could really give a direct answer for the number of CEC bonds present. What methods could we use to discern this information?<\/p>\n\n\n\n

The correct answer and explanation is :<\/strong><\/mark><\/p>\n\n\n\n

To determine the number of C\u2261C (alkyne) bonds<\/strong> in a compound, \u00b9H NMR (Proton Nuclear Magnetic Resonance)<\/strong> and \u00b9\u00b3C NMR (Carbon-13 Nuclear Magnetic Resonance)<\/strong> spectroscopy are the most reliable techniques.<\/p>\n\n\n\n

\n\n\n\n

Correct Answer:<\/h3>\n\n\n\n

Use \u00b9H NMR and \u00b9\u00b3C NMR spectroscopy to determine the number of C\u2261C bonds present.<\/strong><\/p>\n\n\n\n

\n\n\n\n

Explanation (\u2248300 words):<\/h3>\n\n\n\n

While the Bromine in DCM test<\/strong> and IR spectroscopy<\/strong> can indicate the presence of unsaturation, such as C=C or C\u2261C bonds, they do not quantify<\/strong> the number of unsaturated sites. The bromine test detects unsaturation via decolorization, but it cannot differentiate between alkene and alkyne or determine how many unsaturations are present. Similarly, the IR spectrum can show a characteristic C\u2261C stretch (~2100\u20132260 cm\u207b\u00b9)<\/strong> or a C\u2013H stretch (~3300 cm\u207b\u00b9)<\/strong> for terminal alkynes, but again, it doesn\u2019t provide a count of C\u2261C bonds\u2014just their presence.<\/p>\n\n\n\n

To determine the number<\/strong> of C\u2261C bonds, \u00b9H and \u00b9\u00b3C NMR<\/strong> spectroscopy are far more powerful. In \u00b9H NMR, a terminal alkyne proton<\/strong> typically appears as a singlet between 1.8\u20133.1 ppm<\/strong>, and its presence indicates a terminal (vs. internal) triple bond. More importantly, \u00b9\u00b3C NMR will show distinct signals for sp-hybridized carbon atoms<\/strong> involved in C\u2261C bonds, generally appearing in the 65\u201390 ppm<\/strong> range. By counting the number of such signals (considering symmetry), you can estimate the number of C\u2261C bonds.<\/p>\n\n\n\n

Additionally, advanced NMR techniques like DEPT (Distortionless Enhancement by Polarization Transfer)<\/strong> or 2D NMR (e.g., HSQC, HMBC)<\/strong> can help assign carbon types and confirm the structure.<\/p>\n\n\n\n

For unambiguous structure determination, mass spectrometry (MS)<\/strong> and elemental analysis<\/strong> may also assist in deducing the degree of unsaturation (Double Bond Equivalents, DBE), which includes all \u03c0-bonds and rings.<\/p>\n\n\n\n

Thus, combining \u00b9H and \u00b9\u00b3C NMR<\/strong> is the most effective way to discern both the presence and number of C\u2261C bonds<\/strong> in a compound.<\/p>\n\n\n\n

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

We used the Bromine in DCM method to test for Unsaturation. We also took an IR spectrum of the compound. However, neither method could really give a direct answer for the number of CEC bonds present. What methods could we use to discern this information? The correct answer and explanation is : To determine the […]<\/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-207162","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/207162","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=207162"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/207162\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=207162"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=207162"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=207162"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}