{"id":26392,"date":"2025-06-19T13:33:40","date_gmt":"2025-06-19T13:33:40","guid":{"rendered":"https:\/\/gaviki.com\/blog\/?p=26392"},"modified":"2025-06-19T13:33:44","modified_gmt":"2025-06-19T13:33:44","slug":"examine-the-ir-spectrum-of-aspirin","status":"publish","type":"post","link":"https:\/\/gaviki.com\/blog\/examine-the-ir-spectrum-of-aspirin\/","title":{"rendered":"Examine the IR spectrum of aspirin."},"content":{"rendered":"\n<p>Examine the IR spectrum of aspirin. What structural features of aspirin are represented by the peaks at 1693 and 1754 rcm? Salicylic Acid; Acetyl- Infrared Spectrum M L 0.2 2400 2200 2000 1800 1600 1200 1200 1000 800 Wavenumbers (cm-1) 13. Why are those peaks away from the expected 1710 rcm? Give an explanation for each case?<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"693\" src=\"https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/image-63.png\" alt=\"\" class=\"wp-image-26393\" srcset=\"https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/image-63.png 1024w, https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/image-63-300x203.png 300w, https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/image-63-768x520.png 768w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-green-cyan-color\">The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n<p><strong>Question 12:<\/strong><\/p>\n\n\n\n<p>The peaks at <strong>1693 cm\u207b\u00b9<\/strong> and <strong>1754 cm\u207b\u00b9<\/strong> in the IR spectrum of aspirin correspond to the carbonyl (C=O) stretching vibrations of two distinct functional groups in the molecule. The <strong>1693 cm\u207b\u00b9<\/strong> peak represents the <em>ester<\/em> carbonyl group formed when the hydroxyl of salicylic acid reacts with acetic anhydride, yielding the acetylated form of aspirin. The <strong>1754 cm\u207b\u00b9<\/strong> peak corresponds to the <em>carboxylic acid<\/em> carbonyl group that remains from the original salicylic acid structure.<\/p>\n\n\n\n<p><strong>Question 13:<\/strong><\/p>\n\n\n\n<p>These observed C=O stretching frequencies deviate from the expected value of <strong>1710 cm\u207b\u00b9<\/strong>, and this can be explained by the surrounding electronic environments and intermolecular interactions.<\/p>\n\n\n\n<p>The <strong>1693 cm\u207b\u00b9<\/strong> ester peak appears at a lower wavenumber because of <em>conjugation<\/em> with the adjacent aromatic ring. This conjugation spreads electron density across the system, decreasing the bond order of the carbonyl group, which in turn reduces the force constant for vibration. A weaker C=O bond requires less energy to stretch, so the vibration is shifted to a lower wavenumber.<\/p>\n\n\n\n<p>On the other hand, the <strong>1754 cm\u207b\u00b9<\/strong> carboxylic acid peak appears at a higher wavenumber due to limited conjugation and the impact of <em>intramolecular hydrogen bonding<\/em>. In aspirin, the hydroxyl group of the carboxylic acid may form a hydrogen bond with a nearby electronegative oxygen, stabilizing the electron distribution and stiffening the carbonyl bond. This reinforcement leads to a stronger C=O stretching vibration that occurs at a higher energy, causing the peak to shift upward.<\/p>\n\n\n\n<p>These two shifts provide insight into the chemical structure of aspirin and the nature of its interactions, confirming that both an ester and a carboxylic acid group are retained in the molecule. The precise positioning of these bands helps distinguish aspirin from its precursors and related compounds.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"722\" height=\"1024\" src=\"https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/learnexams-banner10-112.jpeg\" alt=\"\" class=\"wp-image-26394\" srcset=\"https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/learnexams-banner10-112.jpeg 722w, https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/learnexams-banner10-112-212x300.jpeg 212w\" sizes=\"auto, (max-width: 722px) 100vw, 722px\" \/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>Examine the IR spectrum of aspirin. What structural features of aspirin are represented by the peaks at 1693 and 1754 rcm? Salicylic Acid; Acetyl- Infrared Spectrum M L 0.2 2400 2200 2000 1800 1600 1200 1200 1000 800 Wavenumbers (cm-1) 13. Why are those peaks away from the expected 1710 rcm? Give an explanation for [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-26392","post","type-post","status-publish","format-standard","hentry","category-quiz-questions"],"_links":{"self":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/26392","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/comments?post=26392"}],"version-history":[{"count":1,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/26392\/revisions"}],"predecessor-version":[{"id":26395,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/26392\/revisions\/26395"}],"wp:attachment":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/media?parent=26392"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/categories?post=26392"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/tags?post=26392"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}