Question

Please show me the IR spectra sheets for the following pure compounds and fully annotate them:

a. benzoic acid

b. trans-stilbene

c. 3-aminoacetophenone

Answer 1

a. Benzoic acid

Carboxylic Acids 2500-3500 s, broad O-H stretch

Ar-C(O)-OH 1680-1710 s C=O stretch

Aromatic Compounds 3010-3100 m Ar C-H stretch

1450-1600 m-s ring C=C stretch

b. trans-stilbene

Aromatic Compounds 3010-3100 m Ar C-H stretch

1450-1600 m-s ring C=C stretch

Alkenes 3020-3140 w-m =C-H stretch

1640-1670 vw-m C=C stretch

trans-ArCH=CHAr 960-980 s =C-H bend

c. 3-aminoacetophenone

Ar-C(O)-R 1675-1695 s C=O stretch

Aromatic Compounds 3010-3100 m Ar C-H stretch

1450-1600 m-s ring C=C stretch

m-disubstituted 750-810 s C-H bend  

R-NH2 ~3400 + ~3500 w N-H symmetric
      (two bands) & asym. stretch

1580-1650 w-m N-H bend