{"id":232328,"date":"2025-06-11T23:04:58","date_gmt":"2025-06-11T23:04:58","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=232328"},"modified":"2025-06-11T23:05:21","modified_gmt":"2025-06-11T23:05:21","slug":"choose-the-correct-compound-for-the-given-ir-spectrum-3","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/11\/choose-the-correct-compound-for-the-given-ir-spectrum-3\/","title":{"rendered":"Choose the correct compound for the given IR spectrum."},"content":{"rendered":"\n

Choose the correct compound for the given IR spectrum. % Transmittance 100 80 60 40 20 0 4000 3500 3000 2500 2000 A) NH
B) Wavenumber (cm
) 1500 1000<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

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

Expand to view model thoughtschevron_righteditmore_vert<\/p>\n\n\n\n

Correct Answer: A<\/strong><\/p>\n\n\n\n

Explanation:<\/h3>\n\n\n\n

To identify the correct compound, we must analyze the key absorption bands in the provided Infrared (IR) spectrum and match them to the functional groups present in the candidate molecules.<\/p>\n\n\n\n

    \n
  1. Analysis of the IR Spectrum:<\/strong>\n
      \n
    • N-H Stretching Region (3300-3500 cm\u207b\u00b9):<\/strong>\u00a0The most prominent feature in this spectrum is a pair of sharp, medium-intensity peaks (a doublet) located at approximately 3300 cm\u207b\u00b9 and 3400 cm\u207b\u00b9. This two-peak pattern is the characteristic signature of the symmetric and asymmetric N-H stretching vibrations of a\u00a0primary amine (-NH\u2082)<\/strong>. A secondary amine (R\u2082NH) would show a single peak, and a tertiary amine (R\u2083N) would show no peaks in this region.<\/li>\n\n\n\n
    • C-H Stretching Region (2850-3100 cm\u207b\u00b9):<\/strong>\u00a0There are strong, sharp absorption bands just below 3000 cm\u207b\u00b9, specifically in the 2850-2960 cm\u207b\u00b9 range. These are characteristic of C(sp\u00b3)-H stretching vibrations, indicating the presence of a saturated alkyl chain. Importantly, there are no significant peaks\u00a0above<\/em>\u00a03000 cm\u207b\u00b9, which rules out the presence of C(sp\u00b2)-H (alkene or aromatic) or C(sp)-H (alkyne) bonds.<\/li>\n\n\n\n
    • Bending Region (1500-1650 cm\u207b\u00b9):<\/strong>\u00a0A medium-intensity peak is visible at approximately 1600 cm\u207b\u00b9. This corresponds to the N-H bending (scissoring) vibration, which is also characteristic of a primary amine.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
    • Evaluation of the Candidate Compounds:<\/strong>\n
        \n
      • Compound A (Butylamine):<\/strong>\u00a0This molecule has a primary amine group (-NH\u2082) and a butyl group (a saturated alkyl chain).\n
          \n
        • The primary amine group (-NH\u2082) would produce the characteristic N-H stretching doublet around 3300-3400 cm\u207b\u00b9 and the N-H bending peak around 1600 cm\u207b\u00b9.<\/li>\n\n\n\n
        • The butyl group consists entirely of sp\u00b3-hybridized carbons and would produce the C(sp\u00b3)-H stretching peaks just below 3000 cm\u207b\u00b9.<\/li>\n\n\n\n
        • All the major features of the spectrum are perfectly consistent with the structure of butylamine.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
        • Compound B (1-Pentene):<\/strong>\u00a0This molecule is an alkene.\n
            \n
          • It lacks any N-H bonds, so it cannot be responsible for the crucial doublet observed at 3300-3400 cm\u207b\u00b9.<\/li>\n\n\n\n
          • As an alkene, it should exhibit a C(sp\u00b2)-H stretching peak\u00a0above<\/em>\u00a03000 cm\u207b\u00b9, which is absent from the spectrum.<\/li>\n\n\n\n
          • While it would have a C=C stretch around 1640 cm\u207b\u00b9, the overwhelming evidence for a primary amine and the lack of evidence for a vinylic C-H bond definitively rule out 1-pentene.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n

            Conclusion:<\/strong><\/p>\n\n\n\n

            The presence of the two N-H stretching peaks near 3300-3400 cm\u207b\u00b9 is conclusive evidence for a primary amine. The C-H stretching peaks confirm an alkyl structure. Therefore, the spectrum corresponds to Compound A, butylamine<\/strong>.<\/p>\n\n\n\n

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

            Choose the correct compound for the given IR spectrum. % Transmittance 100 80 60 40 20 0 4000 3500 3000 2500 2000 A) NHB) Wavenumber (cm) 1500 1000 The Correct Answer and Explanation is: Expand to view model thoughtschevron_righteditmore_vert Correct Answer: A Explanation: To identify the correct compound, we must analyze the key absorption bands […]<\/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-232328","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/232328","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=232328"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/232328\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=232328"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=232328"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=232328"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}