{"id":248810,"date":"2025-07-08T18:36:48","date_gmt":"2025-07-08T18:36:48","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=248810"},"modified":"2025-07-08T18:36:50","modified_gmt":"2025-07-08T18:36:50","slug":"this-ir-spectrum-is-of-which-compound","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/08\/this-ir-spectrum-is-of-which-compound\/","title":{"rendered":"This IR spectrum is of which compound"},"content":{"rendered":"\n

This IR spectrum is of which compound? 100 (A) Transmittance (%) 50 0 4000 (B) OH Et 3000 2000 1500 Wavenumber (cm
) (C) O H 500 (D)<\/p>\n\n\n\n

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

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

The correct answer is (A)<\/strong>.<\/p>\n\n\n\n

This IR spectrum corresponds to compound (A), cinnamyl alcohol, which is (E)-3-phenylprop-2-en-1-ol. Here is a step-by-step analysis of the spectrum to support this conclusion.<\/p>\n\n\n\n

    \n
  1. O-H Stretch:<\/strong>\u00a0The most prominent feature in the diagnostic region is the very broad, strong absorption band centered at approximately 3400 cm\u207b\u00b9. This is a classic signal for the O-H stretching vibration of an alcohol, broadened due to hydrogen bonding. This immediately suggests the presence of an -OH group, making compound (A) a strong candidate while ruling out compounds (B), (C), and (D), which do not contain an alcohol functional group.<\/li>\n\n\n\n
  2. C-H Stretches:<\/strong>\u00a0There are several peaks in the C-H stretching region. The sharp absorptions just above 3000 cm\u207b\u00b9 (around 3020-3080 cm\u207b\u00b9) are characteristic of C-H stretches from sp\u00b2 hybridized carbons, found in both the benzene ring and the alkene. The weaker peaks just below 3000 cm\u207b\u00b9 are from the sp\u00b3 hybridized C-H bonds of the -CH\u2082- group.<\/li>\n\n\n\n
  3. C=C Stretches:<\/strong>\u00a0The spectrum shows a medium-intensity peak around 1650 cm\u207b\u00b9, which corresponds to the C=C double bond stretch of the alkene. Additionally, the sharp peaks in the 1600-1450 cm\u207b\u00b9 range are characteristic of C=C bond stretching within the aromatic (phenyl) ring.<\/li>\n\n\n\n
  4. Fingerprint Region:<\/strong>\n
      \n
    • C-O Stretch:<\/strong>\u00a0A strong absorption is visible around 1050 cm\u207b\u00b9. This falls in the typical range (1000-1250 cm\u207b\u00b9) for a C-O single bond stretch, consistent with a primary alcohol like cinnamyl alcohol.<\/li>\n\n\n\n
    • Alkene C-H Bend:<\/strong>\u00a0Crucially, there is a very strong, sharp peak at approximately 970 cm\u207b\u00b9. This is a highly characteristic out-of-plane C-H bending vibration for a\u00a0trans<\/em>-disubstituted alkene, confirming the stereochemistry shown for compound (A).<\/li>\n\n\n\n
    • Aromatic C-H Bends:<\/strong>\u00a0The presence of a monosubstituted benzene ring is supported by strong absorption bands in the 770-730 cm\u207b\u00b9 and 690-710 cm\u207b\u00b9 range (out-of-plane C-H bending).<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n

      In contrast, the other options are inconsistent with the spectrum. Compound (B) is an aldehyde and would show a very strong C=O stretch around 1700 cm\u207b\u00b9 and characteristic aldehyde C-H stretches around 2720 and 2820 cm\u207b\u00b9, none of which are present. Compounds (C), an ether, and (D), a hydrocarbon, lack the alcohol -OH group necessary to explain the broad peak at 3400 cm\u207b\u00b9. Therefore, the combination of all observed peaks uniquely identifies the compound as cinnamyl alcohol <\/p>\n\n\n\n

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

      This IR spectrum is of which compound? 100 (A) Transmittance (%) 50 0 4000 (B) OH Et 3000 2000 1500 Wavenumber (cm) (C) O H 500 (D) The Correct Answer and Explanation is: The correct answer is (A). This IR spectrum corresponds to compound (A), cinnamyl alcohol, which is (E)-3-phenylprop-2-en-1-ol. Here is a step-by-step analysis of […]<\/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-248810","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/248810","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=248810"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/248810\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=248810"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=248810"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=248810"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}