NEW MATERIAL:A pyrimidine expressed by formulaI(R is lower alkyl; R1 and R2 are lower alkyl; R3 is H or lower alkyl; X is S or O).

EXAMPLE: O,O-Dimethyl O-[2-( dimethoxymethyl )-6-methylpyrimidin-4-yl]phosphorothionate.

USE: An insecticide, acaricide and nematocide without the fear of environmental pollution with low toxicity, capable of exhibiting improved effects on rice borers, leafhoppers of the families Delphacidae and Deltocephalidae in paddy fields, diamondback moth or cabbage armyworm damaging vegetables, fruit trees and wood, and injurious insects of stored grains.

PROCESS: A 4-hydroxypyrimidine expressed by formula II is reacted with a halogen compound expressed by formula III in a solvent, e.g. acetone or benzene, at 30W100°C for 1W several hours to give the compound expressed by formulaI.