Chapter 12 Review Sheet

Chapter 12 Review Sheet - A l c o h o l s O-H stretch 3640...

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Chapter 12: Infared Spectra IR is useful for determining functional groups present. Characteristic molecular motions can be seen in the IR spectrum and interpreted to give the identity of functional groups. Most functional groups always exhibit the same IR absorption bands resulting from various stretching modes and don't change from one compound to another, no matter how complex the molecule. Key IR absorptions to look out for on quizzes and exams are Carbonyls from 1680 to 1750 cm -1 and Alcohols from 3400 to 3650 cm -1 . There can be slight variations from these but for the most part they are correct. Remember IR tables will be provided on quizzes and exams so there is no need to memorize the table! Just be familiar with how to use the data to determine the structure. O O Typical Infrared Absorptions Vibration frequency range (cm-1) C a r b o n y l (C=O) stretch 1870 - 1650
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Unformatted text preview: A l c o h o l s O-H stretch 3640 - 3250 C-OH stretch 1160 - 1030 C-OH in-plane bend 1440 - 1260 C-OH wag 700 - 600 A l k a n e s C-H stretch 2980 - 2850 CH 2 wag 1470 - 1450 CH 2 rock 740 - 720 CH 3 wag 1390 - 1370 CH 3 twist 1470 - 1440 A l k e n e s =CH 2 stretch 3040 - 3010 =CH 2 wag 950 - 900 C=C stretch (cis isomer) 1665 - 1635 C=C stretch (trans isomer) 1675 - 1665 A m i n e s N-H stretch 3460 - 3280 NH 2 wag 1650 - 1590 C-N stretch 1190 - 1130 C-N-C scissor 510 - 480 E s t e r s C-O-C asymmetrical stretch 1290 - 1180 O-C-O scissors 645 - 575 N i t r o c o m p o u n d s NO 2 symmetrical stretch 1570 - 1550 NO 2 asymmetrical stretch 1380 - 1360 NO 2 scissors 650 - 600 NO 2 rock 530 - 470 S u l f o n e s SO 2 symmetrical stretch 1170 - 1120 SO 2 asymmetrical stretch 1360 - 1290 SO 2 scissors 610 - 545...
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This note was uploaded on 12/08/2009 for the course CHEM V25 taught by Professor Miller during the Spring '08 term at NYU.

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