A carboxyl group is present in 6-chlorohexanoic acid having IR peak between 1690 -1760 Cm-1 whereas in 4-methoxypentanoyl chloride , a carbonyl group is present as oyl chloride as having peak between 1715 -1745 Cm-1.
Now, in 4-methoxypentanoyl chloride , the peaks are (1 H, m) , (2 H, t ), (2 H , q ) whereas in 6-chlorohexanoic acid , the peaks are (2 H, m), (2 H, m ), (2 H , t )
