FTIR -- InfraRed IR 1. Bet vis & microwave 2. Organic chemists use cm cm -1  E of vibration No 2 cmpds give exact sample IR (enantimoers) 2 types of molecular vibration stretching bending 3 vibrations symmetrical asymmetrical scissoring

Stretching Frequencies ( ) C-C C-O C-N cm -1 C=C C=O C=N N=O C C C N C-H O-H N-H imprt areas for prelim exam of spectra fct group region fingerprint complex Imprt for -OH NH C=O strong bands aromatics (benzene ring) strong out-of-plane bending & ring bending

C - H Stretch Alkanes (s) other: near 1375 & 1450 Cycloalkanes (m) other: near 1450 (m) Alkenes above 3000 (s) other: near 1416 (m) ; (w) ; near 850 (s) Alkynes (n,s) stronger-narrower than OH & NH other: (b,s) ; (w,o) Aromatics & (w,o) other: (s) ; (m) Aldehydes (2:s) w / near 1390 other: near 2720 (m)

C to C Alkanes below 500; (w) are of little value best is C-H CH & 2872 CH 2 near 2926 & near 2853 (+ / -10) CH near 1375 & near 1450 Alkenes (m) Alkynes (w)

ALCOHOLS -- PHENOLS Alkenes - Phenols -OH & C-O OH (b,s) ; (m) CO (s) ETHERS Ethers C-O-C similar to C-C-C but more intense (s)

CARBONYL C=O containing Carbonyls (ketones, aldehydes, carboxylic acids, esters, anhydrides, amides) C=O (s) Ketones (m) Aldehydes C-H (2:m) & near 2720 (m) Carboxylic Acids O-H (b,s) C=O near 1766 (s) C-O & O-H near (m) & near (m) Esters C=O (s) higher freq than ketones C-O (2:s)

NITROGEN CONTAINING Amides NH 2 or NH other: near 3520 (m) & near 3400 (m) C=O 1694 & 1650 (s) C-N near 1400 (m) Amine N-H near 3500 (w) & near 3400 (w) other: NH (m) C-N (m) aromatic C-N (s) Nitriles C=N (m)