In organic solvents, 1,3-dimethyl-4-(2,4-dichlorobenzoyl)-5-hydroxypyrazole (DTP) converted chlorophyll a and b extracted from rice seedlings (Oryza sativa L. ;Kinmaze') into pheophytin a and b, respectively. On comparing the chlorophyll-converting activity of DTP to those of acetic, glycolic,