* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
4 Example 4
STR12 One equivalent of pivalic acid is added at 0° C. to a mixture of 37.7 g (0.239 mol) of 2-ethoxyethyl carbazinate, 38 g (0.239 mol) of O-n-propyl S-methyl methyliminothiocarbonate and 50 ml of n-propanol. Stirring is continued for 2 hours at room temperature, the mixture is concentrated under a water pump vacuum and the residue subsequently distilled under an oil-pump vacuum. 39 g of a crude distillate whose content of the desired 4-methyl-5-propoxy-2,4-dihydro-3H-1,2,4-triazol-3-one amounts to 80.6% are obtained. Yield: 80.1% of theory.
67.4%
3 Example 3
STR11 Carbon dioxide is passed for 12 hours at 40° C. into a mixture of 37.7 g (0.239 mol) of 2-ethoxyethyl carbazinate, 38 g (0.239 mol) of O-n-propyl S-methyl methylimino-thiocarbonate, 50 ml of n-propanol and 4.5 g of water. Evaporation and distillation in vacuo (oil pump) gives 40 g of crude distillate whose content of the desired 4-methyl-5-propoxy-2,4-dihydro-3H-1,2,4-triazol-3-one amounts to 66.1%. Yield: 67.4% of theory.
With hydrogenchloride; NaOCH3; sodium chloride; sodium methylate; Trimethylacetic acid In methanol; propan-1-ol
4 EXAMPLE 4 STR12
EXAMPLE 4 STR12 A solution of 612 g (6.0 mol) of pivalic acid in 200 ml of n-propanol is added dropwise at 0° C. to a mixture of 630 g (6.0 mol) of ethyl carbazinate, 954 g (6.0 mol) of dipropyl methyliminocarbonate and 600 ml of n-propanol, while cooling with an ice/sodium chloride mixture, and the complete mixture is stirred for 30 minutes at 0° C. to 10° C. 2169 g of a 30% strength solution of sodium methanolate in methanol (12 mol of NaOCH3) are then added, and the reaction mixture is stirred for 3 hours at 50° C. The mixture is then neutralized using concentrated hydrochloric acid, with ice-cooling, and subsequently freed from sodium chloride by filtration with suction, and the filtrate is concentrated. The crude product obtained as residue is purified by distillation in vacuo. 808 g (83% of theory) of 4-methyl-5-propoxy-2,4-dihydro-3H-1,2,4-triazol-3-one are obtained as a waxy product. Melting point: 74° C. (from acetone).
With hydrogenchloride; NaOCH3; sodium methylate; Trimethylacetic acid In methanol; propan-1-ol
5 EXAMPLE 5 STR13
EXAMPLE 5 STR13 A solution of 20.4 g (0.2 mol) of pivalic acid in 10 ml of n-propanol is added dropwise with ice-cooling to a mixture of 104 g (1.0 mol) of ethyl carbazinate, 159 g (1.0 mol) of dipropyl methyliminocarbonate and 200 ml of n-propanol, and the complete mixture is stirred for 30 minutes without cooling. 108 g of a 30% strength solution of sodium methanolate in methanol (0.6 mol of NaOCH3) are then added, and the reaction mixture is stirred for 3 hours at 50° C. and for a further 4 hours at 60° C. to 80° C. The mixture is then neutralized using concentrated hydrochloric acid, with ice-cooling, and subsequently concentrated under reduced pressure. The crude product which remains in the residue is purified by distillation in vacuo. 137 g (82.5% of theory) of 4-methyl-5-propoxy-2,4-dihydro-3H-1,2,4-triazol-3-one are obtained as a waxy product. Melting point: 74° C. (from acetone).
10 Preparation of 5-propoxy-4-methyl-2,4-dihydro-1,2,4-triazol-3-one
Example 10 Preparation of 5-propoxy-4-methyl-2,4-dihydro-1,2,4-triazol-3-one In an autoclave, 10.02 g (44.3 mmol) of methyl N'-dipropoxymethylenehydrazinecarboxylate, 3.94 g of 39% strength solution of methylamine (49.9 mmol) in methanol and 46 g of methanol were initially charged. After 3 hours at 150° C., the solvent was distilled off. The crude substance was taken up in water (20 ml) and extracted repeatedly with methylene chloride. The organic solution was concentrated, giving 6.48 g of 5-propoxy-4-methyl-2,4-dihydro-1,2,4-triazol-3-one with a content of 50%, which corresponds to a yield of 46%.
383 g (71.2%, content 87.6%)
With methylamine In methanol; ethanol; water
9 Preparation of 5-propoxy-4-methyl-2,4-dihydro-1,2,4-triazol-3-one
Example 9 Preparation of 5-propoxy-4-methyl-2,4-dihydro-1,2,4-triazol-3-one 693.6 g (94.4%) of methyl N'-dipropoxymethylenehydrazinecarboxylate (3 mol) were dissolved in 1752 g of methanol and admixed with 564.7 g (6 mol) of methylamine, dissolved in ethanol, and the mixture was heated in an autoclave at 100° C. for 20 hours. The reaction mixture was concentrated under reduced pressure, the residue was taken up in water (880 ml) the mixture was extracted with methylene chloride and the extract was concentrated under reduced pressure. The crystals which precipitated out on cooling were filtered off and dried. This gave 383 g (71.2%, content 87.6%) of 5-propoxy-4-methyl-2,4-dihydro-1,2,4-triazol-3-one in the form of a solid. Melting point: 72.5-73.5° C.
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