A convenient, rapid, efficient and environmentally benign route has been developed for the synthesis of N-alkyl-2-butyl-5-chloro-1H-imidazole-4-carbaldehydes 3(a-g) using PEG-600 as solvent as well as phase transfer catalyst, where the reaction of 2-butyl-5-chloro-1H-imidazole-4-carbaldehyde (1) was done with alkylating agents 2 using PEG-600 as solvent.