Reaction of 2-methyl-1 (2H)-isoquinolone (I) with formaldehyde and conc. hydrochloric acid was carried out and it was found that the product differed according to reaction conditions. The products obtained and their structure identified were 4-hydroxymethyl-2-methyl-1 (2H)-isoquinolone (II), 4, 4'-methylene-bis [2-methyl-1 (2H)-isoquinolone] (III), and 4-chloromethyl-2-methyl-1 (2H)-isoquinolone (IV).
