Various trichloromethyl-1, 3, 5-triazines were synthesized and effects of trichloromethyl-1, 3, 5-triazines on nitrification in the upland soil were investigated. 2-Substituted-4, 6bis(trichloromethyl)-1, 3, 5-triazines were prepared by trimerization or cotrimerization using CC13CN in the presence of Norton-Wakabayashi complex catalyst, e. g. A1Br3-HCI. 2-Amino-4-substituted-6-trichloromethyl-1, 3, 5-triazines were obtained through the haloform type of reactions of trichloromethyl-1, 3, 5-triazines with amines.The PI50 values of highly active trichloromethyl-1, 3, 5-triazines were 4. 5-5. 5. Essentially they have a CC13-group and an amino or alkylamino group in the three substituents of 1, 3, 5-triazine ring. QSAR between pI55 values and log P(S) parameters were investigated by multi-parameter regression analysis. Hydrophobic parameters, log P(S) estimated by semi-empirical calculation, were used for convenience instead of log P(H) determined by HPLC in this QSAR study.The optimum log P(S) was calculated as 2.91, a little more hydrophobic figure compared with the log P value (ca. 2.4) in our previous paper.By the use of this value, it will become possible to design highly active trichloromethyl-1, 3, 5-triazine nitrification inhibitors.

A series of 2-substituted-4-arylamino-6-trichloromethyl-1, 3, 5-triazines is one of the most interesting chemical species for nitrification-inhibitory activity. This type of compounds has conventionally been obtained by the rather laborious processes via following reactions, i. e., hydroxylation of 2-substituted-4, 6-bis(trichloromethyl)-1, 3, 5-triazines to 2-substituted-4hydroxy-6-trichloromethyl-1, 3, 5-triazines, chlorination of the hydroxy-1, 3, 5-triazines to 2substituted-4-chloro-6-trichloromethyl-1, 3, 5-triazines, followed by substitution reaction of the chloro-1, 3, 5-triazines with arylamines. A new method has recently been found which permits the direct nucleophilic replacement of one trichloromethyl group attached to a 1, 3, 5-triazine ring with an arylamino group. The desired replacement reaction of the trichloromethyl by an arylamino group is accomplished in the present of tertiary amines such as triethylamine. By this method, a lot of biologically active 2-substituted-4-arylamino-6-trichloromethyl-1, 3, 5triazines can be synthesized from 2-substituted-4, 6-bis(trichloromethyl)-1, 3, 5-triazines.