Question

1. What is the orientation of acetanilide group on the benzene ring?
2. What can you say about the regioisomers that are formed if the melting point for 4-chloroacetanilide was 160-161˚C?
3. Interpret the IR spectrum peaks of 4-chloroacetanilide

%T 3500 3259.843300.80 3192.04 3126.87 3000 2500 Wavenumbers (cm-1) 2000 1592.66 1500 1662.38 1607.02 1535.15 1485.88 1391.77 1370.35 1312.81 1292.17 1260.42 1179.83 1170.46 11 18.55 1103.44 1090.14 1000 1039.95 1008.99 969.36 839.02 828.37 820.96 749.821 707.87 500

Answer 1

Generally, di-substituted benzene isomers can be identified by IR spectrum. Especially in the finger print region, few peaks are useful to identify the isomers. -C-H wagging frequencies are responsibl for the peaks in 1000 - 700 ant. * For a 1,4-disubstituted benzene, & C-H wagging frequency obsessed at 860-790 um and no ring bending peak observedo For a 1,3-disubstituted benzene, C-H wagging frequency observed at 810-750 un and a ring bending peak at 690 can Therefore the given spectrum is of 4-chloroacetanilide. 3300 cent » -N-H stretch. 1662 cüml =) - -stretch (lowers due to conjugation) 1485 cinta un ? = due to c=c of phenyl ring 1610 ant , 840 cut -C-H wagging.