A mixture of methylamine (1° amine) and dimethylamine (2° amine) can be separated with the help of C6H5SO2Cl and KOH (Hinsberg's method).
Methylamine will form N-methylbenzenesulphonamide which is soluble in KOH. Dimethylamine will form N,N dimcthylbenzene sulphonamide which is insoluble in KOH.