{"id":220975,"date":"2025-05-29T05:10:15","date_gmt":"2025-05-29T05:10:15","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=220975"},"modified":"2025-05-29T05:10:17","modified_gmt":"2025-05-29T05:10:17","slug":"for-the-reaction-performed-in-this-experiment-the-ir-spectra-for-the-reactants-and-product-are-shown-below","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/05\/29\/for-the-reaction-performed-in-this-experiment-the-ir-spectra-for-the-reactants-and-product-are-shown-below\/","title":{"rendered":"For the reaction performed in this experiment, the IR spectra for the reactants and product are shown below."},"content":{"rendered":"\n

For the reaction performed in this experiment, the IR spectra for the reactants and product are shown below. For the IR spectra of acetone and the product, identify the important IR signals for each spectrum. Specifically: for the IR spectrum of acetone, identify the signal which indicates the presence of the C=O bond and the signal which represents the CH bond (indicate the hybridization of the carbon). For the IR spectrum of the product, indicate which signal represents the CH bond (hybridization?) and which signal represents the O-H bond.<\/p>\n\n\n\n

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

Key IR Absorptions<\/strong><\/h3>\n\n\n\n

Acetone IR Spectrum:<\/strong><\/h4>\n\n\n\n
    \n
  1. C=O (Carbonyl Stretch):<\/strong>\n
      \n
    • Wavenumber:<\/strong> ~1715 cm\u207b\u00b9<\/li>\n\n\n\n
    • Explanation:<\/strong> This strong, sharp signal corresponds to the stretching vibration of the carbonyl (C=O) bond, a key functional group in ketones like acetone.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
    • C\u2013H Stretch (sp\u00b3 Hybridized):<\/strong>\n
        \n
      • Wavenumber:<\/strong> ~2850\u20132960 cm\u207b\u00b9<\/li>\n\n\n\n
      • Explanation:<\/strong> These medium-intensity signals represent the stretching vibrations of C\u2013H bonds where the carbon is sp\u00b3 hybridized<\/strong> (from the methyl groups in acetone).<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n

        Product IR Spectrum:<\/strong><\/h4>\n\n\n\n

        Assuming the product is an alcohol<\/strong> formed by reduction of acetone:<\/p>\n\n\n\n

          \n
        1. O\u2013H Stretch (Hydroxyl group):<\/strong>\n
            \n
          • Wavenumber:<\/strong> ~3200\u20133600 cm\u207b\u00b9<\/li>\n\n\n\n
          • Explanation:<\/strong> This broad, strong absorption is indicative of hydrogen-bonded O\u2013H stretching from alcohols. Its breadth distinguishes it from other X\u2013H stretches.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
          • C\u2013H Stretch (sp\u00b3 Hybridized):<\/strong>\n
              \n
            • Wavenumber:<\/strong> ~2850\u20132960 cm\u207b\u00b9<\/li>\n\n\n\n
            • Explanation:<\/strong> Similar to acetone, the product contains sp\u00b3 C\u2013H bonds, typically from CH\u2083 or CH\u2082 groups, showing in this same region.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n
              \n\n\n\n

              Explanation <\/strong><\/h3>\n\n\n\n

              Infrared (IR) spectroscopy is a vital analytical technique used to identify functional groups in organic molecules by measuring their vibrational transitions. Each functional group absorbs IR radiation at characteristic frequencies, allowing us to interpret molecular structures based on their IR spectra.<\/p>\n\n\n\n

              In acetone, a simple ketone, the most prominent feature is the carbonyl (C=O) stretch<\/strong> around 1715 cm\u207b\u00b9<\/strong>. This is a strong, sharp absorption due to the polar double bond of the carbonyl group. The high polarity of the C=O bond results in a strong dipole moment change during vibration, making it one of the most diagnostic signals in IR spectroscopy. In addition, acetone\u2019s methyl C\u2013H stretches<\/strong> appear in the region of 2850\u20132960 cm\u207b\u00b9<\/strong>, characteristic of sp\u00b3 hybridized carbon<\/strong> atoms bonded to hydrogen.<\/p>\n\n\n\n

              If acetone is reduced to an alcohol (e.g., 2-propanol), its IR spectrum changes significantly. Most notably, the carbonyl peak at ~1715 cm\u207b\u00b9 disappears, and a new O\u2013H stretch<\/strong> appears between 3200\u20133600 cm\u207b\u00b9<\/strong>. This broad, strong signal is due to hydrogen bonding among hydroxyl groups, which causes the band to broaden significantly compared to non-hydrogen-bonded X\u2013H stretches. The C\u2013H stretches from sp\u00b3 carbons remain visible at 2850\u20132960 cm\u207b\u00b9<\/strong>, indicating the retention of alkyl groups.<\/p>\n\n\n\n

              By comparing these IR spectra, one can confirm the transformation of acetone (a ketone) into an alcohol: the loss of the C=O signal and the appearance of the O\u2013H stretch in the product provide clear evidence of chemical change.<\/p>\n\n\n\n

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

              For the reaction performed in this experiment, the IR spectra for the reactants and product are shown below. For the IR spectra of acetone and the product, identify the important IR signals for each spectrum. Specifically: for the IR spectrum of acetone, identify the signal which indicates the presence of the C=O bond and 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-220975","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/220975","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=220975"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/220975\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=220975"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=220975"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=220975"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}