Synthesis and Bleaching Activity of 1-Ethyl-and 1 -Propy 1-5-Substituted Imidazoles
Abstract Twenty-eight 1-ethyl-and 1-propyl-5 -substituted imidazoles were synthesized an d their bleaching activity was evaluated by using the lettuce seedling test. 5-Phenyl-1-propylim idazole (1) caused distinct chlorosis, while none of the c ompounds with various alkenyl groups at the 5-position o the imidazole ring show ed this bleaching activity. Introduction of a bromo, chloro, fluoro, methyl or trifluoromethyl groupa t the 4-position on the benzene ring of compound 1 increased the activity in comparison with that of compound 1. 5-[4-(3-Chlorobenzyl-oxy)phenyl]-l-ethylimidazole (15) an d l-ethyl-5-[4-(3-methylbenzyloxy)phenyl]imidazole (21), analogs with a large substituent at the 4 -position on the benzene ring, also caused pronounced chlorosis in the lettuce seedlings. Both compounds 1 and 15 a t 30 ppm decreased total c arotenoid content in the lettuce seedlings to less than 40% of that in the control, and the reduction of total carotenoid content correlated well with treatment dose.