1980 Volume 25 Issue 3 Pages 173-178
1-Alkyl-3-(substituted phenyl) dihydrouracils [1-alkyl-3-(4-chlorophenyl) dihydrouracils (ACDU) and 1-methyl-3-(substituted phenyl) dihydrouracils (MSDU)] which were the ring closure compounds of N-alkyl-N-(substituted phenylcarbamoyl), β-alanines and other related amino acid derivatives were examined on their herbicidal activity by pot tests. Activity of the optical isomers of amino acid residues of the compounds was also evaluated. Results obtained were as follows:
(1) In general, activity of ACDU was higher than that of the compounds before ring closure, and these results were consistent with the higher values of the hydrophobicity (log P) of the both compounds. The alkyl moiety with the highest activity among ACDU was iso-propyl group.
(2) Activity of MSDU decreased in the following order: -H≥4-Br≥3-Cl≥3, 4-diCl compounds. But, from the standpoint of a margin of selectivity between wheat and broad-leaved plants, 3, 4-dichlorocompound (DCMD) was the most excellent.
(3) Activity of 3-(3, 4-dichlorophenyl) hydantoin derivatives, N-(N′-methoxymethyl-N′-substituted phenylcarbamoyl) amino acids and substituted benzothiazole derivatives (urea, hydantoin and dihydrouracil types) were generally low.
(4) Within the limits of this experiments (16 compounds), activity of the optical isomers of the amino acid residues of the compounds was higher usually in the following order: D->DL->L- isomers.
