Homework Help is Here – Start Your Trial Now!
Science
Chemistry
Using Figure 21.14 as a guide, identify regions of the IR spectrum in which you would expect to see characteristic functional group absorptions for each of the following compounds: (a) cyclopentanone, (b) methyl acetate, (c) methoxybenzene, (d) acetamide, (e) 1-aminohexane.

Using Figure 21.14 as a guide, identify regions of the IR spectrum in which you would expect to see characteristic functional group absorptions for each of the following compounds: (a) cyclopentanone, (b) methyl acetate, (c) methoxybenzene, (d) acetamide, (e) 1-aminohexane.

Chemistry
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
See similar textbooks
icon
Related questions
icon
Concept explainers
Question

I need help to List the positions of ir absorption peaks of the various functional groups 

FOLLOW-UP ASSIGNMENT Using Figure 21.14 as a guide, identify regions of the IR spectrum in which you would expect to see characteristic functional group absorptions for each of the following compounds: (a) cyclopentanone, (b) methyl acetate, (c) methoxybenzene, (d) acetamide, (e) 1-aminohexane. Where to Begin An efficient approach to interpreting an IR spectrum usually starts with a survey of the 4000-1500 cm-1 functional group region and the creation of an inventory of bond types present in the molecule. This inventory allows you to get a good idea of which functional groups are in the compound and which are not. The functional group region can be subdivided into narrower frequency regions that are characteristic of specific bond types. Table 21.2 lists the positions of characteristic IR absorption peaks of various functional groups. It is fairly accurate for strong (s) and broad (br) peaks. However, because the intensities of IR absorptions can vary a good deal, the use of Table 21.2 has limitations, particu- larly for peaks listed as medium (m) and weak (w) intensity. Useful IR corroborating peaks of the C-H out-of-plane bending vibrations TABLE 21. 2 Characteristic infrared absorption peaks of functional groups Vibration Position (cm-) Intensity“ Alkanes C-H stretch C-H bend 2990-2850 m to s 1480-1430 (CH,), 1395–1340 (CH,) m to w Alkenes 3100-3000 1680–1620 (nonconj.)», 1650–1600 (conj.)b 1000-665 (see Table 21.3 for detail) =C-H stretch C=C stretch w to m =C-H bend Alkynes =C-H stretch C=C stretch 3310-3200 2250-2100 s to w (Continued) 328 Part 5 • Spectrometric Methods TABLE 21.2 (Continued) Vibration Position (cm-) Intensity Aromatic Compounds C-H stretch 3100-3000 m to w C=C stretch 1620-1440 m to w
Transcribed Image Text:FOLLOW-UP ASSIGNMENT Using Figure 21.14 as a guide, identify regions of the IR spectrum in which you would expect to see characteristic functional group absorptions for each of the following compounds: (a) cyclopentanone, (b) methyl acetate, (c) methoxybenzene, (d) acetamide, (e) 1-aminohexane. Where to Begin An efficient approach to interpreting an IR spectrum usually starts with a survey of the 4000-1500 cm-1 functional group region and the creation of an inventory of bond types present in the molecule. This inventory allows you to get a good idea of which functional groups are in the compound and which are not. The functional group region can be subdivided into narrower frequency regions that are characteristic of specific bond types. Table 21.2 lists the positions of characteristic IR absorption peaks of various functional groups. It is fairly accurate for strong (s) and broad (br) peaks. However, because the intensities of IR absorptions can vary a good deal, the use of Table 21.2 has limitations, particu- larly for peaks listed as medium (m) and weak (w) intensity. Useful IR corroborating peaks of the C-H out-of-plane bending vibrations TABLE 21. 2 Characteristic infrared absorption peaks of functional groups Vibration Position (cm-) Intensity“ Alkanes C-H stretch C-H bend 2990-2850 m to s 1480-1430 (CH,), 1395–1340 (CH,) m to w Alkenes 3100-3000 1680–1620 (nonconj.)», 1650–1600 (conj.)b 1000-665 (see Table 21.3 for detail) =C-H stretch C=C stretch w to m =C-H bend Alkynes =C-H stretch C=C stretch 3310-3200 2250-2100 s to w (Continued) 328 Part 5 • Spectrometric Methods TABLE 21.2 (Continued) Vibration Position (cm-) Intensity Aromatic Compounds C-H stretch 3100-3000 m to w C=C stretch 1620-1440 m to w
328 Part 5 • Spectrometric Methods TABLE 21.2 (Continued) Vibration Position (cm-) Intensity Aromatic Compounds C-H stretch C=C stretch C-H bend 3100–3000 m to w 1620-1440 m to w 880–680 (see Table 21.3 for detail) Alcohols O-H stretch C-O stretch 3650-3550 (non H-bonded), 3550–3200 (H-bonded) 1300-1000 s to m, br Ethers C-O stretch 1300-1000 Amines N-H stretch C-N stretch 3550-3250 (1° two peaks), (2° one peak) 1250–1025 (alkyl), 1350–1250 (aromatic) br, m Nitriles C=N stretch 2280–2200 Isocyanates N=C=O stretch 2275-2230 Aldehydes =C-H stretch C=O stretch 2900-2800 and 2800–2700, Fermi doublet 1740–1720 (non-conj.), 1715–1680 (conj.) Ketones C=O stretch 1725–1705 (non-conj.), 1700–1650 (conj.) Esters C=O stretch 1765–1735 (non-conj.), 1730–1715 (conj.) 1260–1230 (acetates), 1210–1160 (all others) C(=O)-O stretch Carboxylic Acids O-H stretch 3200-2500 br, m to w C=O stretch C-O stretch 1725–1700 (non-conj.), 1715–1680 (conj.) 1300–1000 Amides N-H stretch C=O stretch 3500–3150 (1° two peaks), (2° one peak) 1700-1630 N-H bend 1570–1515 (primary), 1640–1550 (secondary) Anhydrides C=O stretch 1850–1800 and 1790–1740 C-O stretch 1300–1000 Acid Chlorides C=O stretch 1815-1770 Imines R,C=N-R stretch 1690-1630 m to s Nitro Compounds NO, stretch 1570-1490 and 1390-1300 Sulfoxides S=O stretch 1070–1030 Sulfonates S=O stretch 1375–1335 and 1195–1165 Phosphine Oxides P=O stretch 1200-1130 Alkyl Halides C-F stretch C-CI stretch 1400-1000 785-540 a. s = strong; m = medium; w = weak; br = broad. b. non-conj. = non-conjugated; conj. = conjugated. E n n
Transcribed Image Text:328 Part 5 • Spectrometric Methods TABLE 21.2 (Continued) Vibration Position (cm-) Intensity Aromatic Compounds C-H stretch C=C stretch C-H bend 3100–3000 m to w 1620-1440 m to w 880–680 (see Table 21.3 for detail) Alcohols O-H stretch C-O stretch 3650-3550 (non H-bonded), 3550–3200 (H-bonded) 1300-1000 s to m, br Ethers C-O stretch 1300-1000 Amines N-H stretch C-N stretch 3550-3250 (1° two peaks), (2° one peak) 1250–1025 (alkyl), 1350–1250 (aromatic) br, m Nitriles C=N stretch 2280–2200 Isocyanates N=C=O stretch 2275-2230 Aldehydes =C-H stretch C=O stretch 2900-2800 and 2800–2700, Fermi doublet 1740–1720 (non-conj.), 1715–1680 (conj.) Ketones C=O stretch 1725–1705 (non-conj.), 1700–1650 (conj.) Esters C=O stretch 1765–1735 (non-conj.), 1730–1715 (conj.) 1260–1230 (acetates), 1210–1160 (all others) C(=O)-O stretch Carboxylic Acids O-H stretch 3200-2500 br, m to w C=O stretch C-O stretch 1725–1700 (non-conj.), 1715–1680 (conj.) 1300–1000 Amides N-H stretch C=O stretch 3500–3150 (1° two peaks), (2° one peak) 1700-1630 N-H bend 1570–1515 (primary), 1640–1550 (secondary) Anhydrides C=O stretch 1850–1800 and 1790–1740 C-O stretch 1300–1000 Acid Chlorides C=O stretch 1815-1770 Imines R,C=N-R stretch 1690-1630 m to s Nitro Compounds NO, stretch 1570-1490 and 1390-1300 Sulfoxides S=O stretch 1070–1030 Sulfonates S=O stretch 1375–1335 and 1195–1165 Phosphine Oxides P=O stretch 1200-1130 Alkyl Halides C-F stretch C-CI stretch 1400-1000 785-540 a. s = strong; m = medium; w = weak; br = broad. b. non-conj. = non-conjugated; conj. = conjugated. E n n
Expert Solution
steps

Step by step

Solved in 4 steps with 3 images

SEE SOLUTIONCheck out a sample Q&A here
Blurred answer
Knowledge Booster
IR Spectroscopy of Organic Molecules
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
Chemistry
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
Chemistry
Chemistry
Chemistry
ISBN:
9781259911156
Author:
Raymond Chang Dr., Jason Overby Professor
Publisher:
McGraw-Hill Education
Principles of Instrumental Analysis
Principles of Instrumental Analysis
Chemistry
ISBN:
9781305577213
Author:
Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:
Cengage Learning
Organic Chemistry
Organic Chemistry
Chemistry
ISBN:
9780078021558
Author:
Janice Gorzynski Smith Dr.
Publisher:
McGraw-Hill Education
Chemistry: Principles and Reactions
Chemistry: Principles and Reactions
Chemistry
ISBN:
9781305079373
Author:
William L. Masterton, Cecile N. Hurley
Publisher:
Cengage Learning
Elementary Principles of Chemical Processes, Bind…
Elementary Principles of Chemical Processes, Bind…
Chemistry
ISBN:
9781118431221
Author:
Richard M. Felder, Ronald W. Rousseau, Lisa G. Bullard
Publisher:
WILEY
SEE MORE TEXTBOOKS