1. The Mannich and Vilsmeier reactions with 4(5)-methyl-2-imidazolinone proceed with involvement of the C5(4) carbon atom. 2. The reaction of 4(5)-methyl-5(4)-piperidinomethyl-2-imidazolinone with a mixture of thioacetic acid and acetic anhydride gives 1-acetyl-4-acetylmercaptomethyl-5-methyl-2-imidazolinone. 3. The chlorination of the N1,N3-diacetyl derivatives of the 4(5)-methyl- and 4,5-dimethyl-2-imidazolinones with sulfuryl chloride gives the α-chloro derivatives, which when treated with potassium thioacetate are converted to the corresponding thioacetates.