{"id":185084,"date":"2025-01-22T06:00:11","date_gmt":"2025-01-22T06:00:11","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=185084"},"modified":"2025-01-22T06:00:13","modified_gmt":"2025-01-22T06:00:13","slug":"a-compound-with-molecular-formula-c6h10-displays-the-following-ir-and-mass-spectrum","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/01\/22\/a-compound-with-molecular-formula-c6h10-displays-the-following-ir-and-mass-spectrum\/","title":{"rendered":"A compound with molecular formula C6H10 displays the following IR and Mass Spectrum"},"content":{"rendered":"\n<p>A compound with molecular formula C6H10 displays the following IR and Mass Spectrum. a) Calculate the hydrogen deficiency index (HDI) for the compound in the box below HDI = b) Identify and label the functional group for the indicated peaks in the IR spectrum in the box provided. c) Identify and label the indicated peaks in the mass spectrum. Which is the base peak and which is the molecular ion peak [M]+? d) Propose a structure for the compound that is consistent with the IR and MS spectra in the box below.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/01\/image-383-949x1024.png\" alt=\"\" class=\"wp-image-185085\"\/><\/figure>\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>\ue203To determine the structure of a compound with the molecular formula C\u2086H\u2081\u2080, we can analyze its hydrogen deficiency index (HDI), infrared (IR) spectrum, and mass spectrum.\ue204<\/p>\n\n\n\n<p><strong>a) Hydrogen Deficiency Index (HDI):<\/strong><\/p>\n\n\n\n<p>\ue203The HDI indicates the number of degrees of unsaturation (rings and\/or multiple bonds) in a molecule.\ue204 It is calculated using the formula:\ue206<\/p>\n\n\n\n<p>\ue203HDI=2C+2\u2212H2\\text{HDI} = \\frac{2C + 2 &#8211; H}{2}\ue204\ue206<\/p>\n\n\n\n<p>\ue203For C\u2086H\u2081\u2080:\ue204\ue206<\/p>\n\n\n\n<p>\ue203HDI=2(6)+2\u2212102=12+2\u2212102=42=2\\text{HDI} = \\frac{2(6) + 2 &#8211; 10}{2} = \\frac{12 + 2 &#8211; 10}{2} = \\frac{4}{2} = 2\ue204\ue206<\/p>\n\n\n\n<p>\ue203Thus, the compound has an HDI of 2, indicating two degrees of unsaturation, which could be two double bonds, one triple bond, one ring plus one double bond, or two rings.\ue204\ue206<\/p>\n\n\n\n<p><strong>b) IR Spectrum Analysis:<\/strong><\/p>\n\n\n\n<p>\ue203Key absorption peaks in the IR spectrum help identify functional groups:\ue204\ue206<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\ue203<strong>~3000 cm\u207b\u00b9:<\/strong> Indicates C\u2013H stretching.\ue204\ue206<\/li>\n\n\n\n<li>\ue203<strong>~1650 cm\u207b\u00b9:<\/strong> Corresponds to C=C stretching, suggesting the presence of an alkene.\ue204\ue206<\/li>\n\n\n\n<li>\ue203<strong>~1450 cm\u207b\u00b9 and ~1375 cm\u207b\u00b9:<\/strong> Associated with C\u2013H bending vibrations in methyl and methylene groups.\ue204\ue206<\/li>\n<\/ul>\n\n\n\n<p>\ue203These absorptions are consistent with an alkene functional group.\ue204\ue206<\/p>\n\n\n\n<p><strong>c) Mass Spectrum Analysis:<\/strong><\/p>\n\n\n\n<p>\ue203In the mass spectrum:\ue204\ue206<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\ue203<strong>m\/z 82:<\/strong> The molecular ion peak [M]\u207a, confirming the molecular weight of 82 g\/mol.\ue204\ue206<\/li>\n\n\n\n<li>\ue203<strong>m\/z 67:<\/strong> A significant fragment, resulting from the loss of a methyl group (15 mass units) from the molecular ion.\ue204\ue206<\/li>\n\n\n\n<li>\ue203<strong>m\/z 54:<\/strong> Another fragment, indicating further cleavage, possibly from the loss of an ethyl group (28 mass units) from the molecular ion.\ue204\ue206<\/li>\n\n\n\n<li>\ue203<strong>Base peak at m\/z 67:<\/strong> The most intense peak, representing the most stable and abundant fragment ion.\ue204\ue206<\/li>\n<\/ul>\n\n\n\n<p>\ue203These fragmentation patterns are characteristic of cyclohexene, where the loss of alkyl groups leads to stable carbocation fragments.\ue204\ue206<\/p>\n\n\n\n<p><strong>d) Proposed Structure:<\/strong><\/p>\n\n\n\n<p>\ue203Considering the HDI of 2, the presence of a C=C bond (alkene) from the IR spectrum, and the fragmentation pattern in the mass spectrum, the compound is likely <strong>cyclohexene<\/strong>.\ue204\ue206<\/p>\n\n\n\n<p>\ue203Cyclohexene has one ring and one double bond, satisfying the HDI of 2.\ue204 \ue203The IR absorptions align with those expected for cyclohexene \ue200cite\ue202turn0search1\ue201, and the mass spectrum fragmentation pattern matches that of cyclohexene \ue200cite\ue202turn0search0\ue201.\ue204\ue206<\/p>\n\n\n\n<p>\ue203In summary, the compound with molecular formula C\u2086H\u2081\u2080 is identified as cyclohexene, based on the calculated HDI, IR spectral data indicating an alkene, and mass spectral fragmentation patterns consistent with known data for cyclohexene.\ue204<\/p>\n","protected":false},"excerpt":{"rendered":"<p>A compound with molecular formula C6H10 displays the following IR and Mass Spectrum. a) Calculate the hydrogen deficiency index (HDI) for the compound in the box below HDI = b) Identify and label the functional group for the indicated peaks in the IR spectrum in the box provided. c) Identify and label the indicated peaks [&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 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