DD290653A5 - PROCESS FOR THE PREPARATION OF 6-ALKYL / ARYL-4-AMINO-3-THIOXO-1,2,4-TRIAZIN-5 (2H, 4H) -ONEE - Google Patents

Abstract

The invention relates to a novel process for the preparation of * the general formula II by reacting alkyl / arylmagnesium halides with Oxalsaeurediethylester and anschlieszender reaction of the resulting mixture - consisting of alkyl / aryl-2-oxo-carboxylic acid ethyl ester and still existing Oxalsaeurediethylester - with thiocarbohydrazide. These compounds of formula II are starting materials for the production of * which are used as crop protection and pest control agents, for. As the Tertiaer-butyl compound as a herbicide. Formula {2-Oxocarbonsaeureethylester; thiocarbohydrazide; Intermediate; Phytosanitary and pest control products}

Description

Fields of application of the invention

The invention relates to a novel process for the preparation of 6-alkyl / aryl-4-amino-3-thioxo-1,2,4-triazine-5 (2H, 4H) -ones of the general formula II in which R is alkyl and aryl Mean radicals. These compounds of formula II are starting materials for the preparation of 6-alkyl / aryl-4-amino-3-methylthio-1,2,4-triazine-5 (4H) -ones, which are used as crop protection and pesticides, z , As the tertiary-butyl compound.

Characteristic of the known state of the art

So far, there is a process for the synthesis of 6-alkyl / aryl-4-amino-3-thioxo-1,2,4-triazine-5 (2H, 4H) -ones. Reaction of the alkyl / aryl-2-oxo-carboxylic acids with thiocarbohydrazide gives 6-alkyl / aryl-4-amino-3-thioxo-1,2,4-triazine-5 (2H, 4H) -ones of the formula II accessible.

A. Dornow, H. Menzel, P. Marx; Chem. Ber. 97 (1964), 2173

The disadvantage of this method is that only a few representatives of the 6-alkyl / aryl-4-amino-3-thioxo-1,2,4-triazine-5 (2H, 4H) -one are accessible, since the alkyl / aryl -2-oxo-carboxylic acid can be obtained very cumbersome and over many reaction stages.

Object of the invention

The aim of the invention is the preparation of 6-alkyl / aryl-4-amino-3-thioxo-1,2,4-triazine-5 (2 H, 4H) -ones with readily available starting compounds.

Explanation of the essence of the invention

The object of the invention is to develop a process by which the -alkyl / aryl-amino-S-thioxo-1'-triazine-5 (2H, 4H) -one can be easily prepared.

According to the invention, 6-alkyl / aryl-4-amino-3-thioxo-1,2,4-triazine-5 (2H, 4H) -ones of the general formula II in which R is branched and unbranched alkyl (C 1 -C ₄ ) - And aryl radicals, prepared, in a known manner from alkyl / arylmagnesium halides with diethyl oxalate available alkyl / aryl-2-oxo-carboxylic acid ethylen of the general formula I directly in the reaction mixture still containing Oxalsäurediethylester be reacted with Thiocarbohydrazig. The subsequent methylation gives the 6-alkyl / aryl-4-amino-3-methylthio-1,2,4-triazine-5 (4H) -ones of general formula III. The formula scheme illustrates the method according to the invention.

embodiment

n-butyl-magnesium chloride

12 g (0.5 mol) of magnesium turnings are poured over 50 ml of absolute ether and mixed with V20 of a total of 0.5 mol of n-butyl chloride with stirring. To initiate the reaction, a granule of iodine must be added. After the reaction had started, the remainder of the n-butyl chloride, dissolved in 125 ml of ether, was added dropwise with stirring, whereby a gentle boiling of the ether must be ensured. The solution was then heated for a further 30 minutes on the water bath until all magnesium had dissolved.

2-oxo-caproic acid ethyl ester

73 g (0.5 mol) of diethyl oxalate, dissolved in 300 ml of absolute ether were slowly added dropwise with cooling with ice-salt mixture and stirring to 0.5 mol of the diluted with 175 ml of ether n-butyl-magnesium chloride solution. After removing the cold bath, the solution was brought to room temperature. Then 5% hydrochloric acid could be added carefully. After separation of the ethereal phase, this was washed with sodium carbonate solution and then dried over sodium sulfate.

6-n-butyl-4-amino-3-thioxo-1,2,4-triazin-5 (2H, 4H) -one

0.5 mol of thiocarbohydrazide was dissolved in hot water, which had been acidified with a few drops of concentrated hydrochloric acid, and added dropwise with stirring, the dissolved in ethanol mixture of 2-oxo-capronsäureethylester and diethyl oxalate.

After refluxing for 4 hours, the solution was cooled. The product crystallized out. It was filtered off with suction and recrystallized (water / ethanol).

Yield: 50% (based on the n-butyl chloride used). F _p : 130 ^° C.

6-n-butyl-4-amino-3-methylthio-1,2,4-triazin-5 (4H) -one

0.1 mol of 6-n-butyl-4-amino-3-thioxo-1,2,4-triazine-5 (2H, 4H) -one was dissolved in a solution prepared from 2.3 g of sodium and 150 ml of methanol , Then 0.105 mol of methyl iodide were added dropwise with stirring. After stirring for 3 hours and allowing to stand overnight, the solution was poured onto ice. The precipitated product was filtered off and recrystallized from cyclohexane.

Yield: 80%; F _p : 79 ° C

Claims (1)

A process for the preparation of 6-alkyl / aryl-4-amino-3-thioxo-1,2 _/ 4-triazine-5 (2H, 4H) -ones of general formula II from alkyl / aryl-magnesium halides and diethyl oxalate, characterized characterized in that the resulting alkyl / aryl-2-oxo-carboxylic acid ethyl ester of the general formula I, in which R has the same meaning as in formula I, are reacted directly in the reaction mixture still containing oxalic acid with thiocarbohydrazide. For this 1 page formulas