Total number of alkali insoluble solid sulphonamides obtained by reaction of given amines with Hinsberg's reagent is $\_\_\_\_$.
Aniline, N-Methylaniline, Methanamine, N, N-Dimethylmethanamine, N-Methyl methanamine, Phenylmethanamine, N-propylaniline, N-phenylaniline, N, N-Dimethylaniline, Allyl amine, Isopropyl amine

Hinsberg's reagent (benzenesulfonyl chloride) classifies amines by their reaction products:
Primary amines (RNH₂) form alkali-soluble sulfonamides (soluble in NaOH).
Secondary amines (R₂NH) form alkali-insoluble sulfonamides (precipitate in NaOH).
Tertiary amines (R₃N) do not react.
Analyzing the given amines:
Aniline (primary), Methanamine (primary), Phenylmethanamine (primary), Allyl amine (primary), Isopropyl amine (primary) → alkali-soluble.
N,N-Dimethylmethanamine (tertiary), N,N-Dimethylaniline (tertiary) → no reaction.
N-Methylaniline (secondary), N-Methyl methanamine (secondary), N-Propylaniline (secondary), N-Phenylaniline (secondary) → alkali-insoluble.
Total alkali-insoluble sulfonamides: 4.