DE1086708B - Process for the preparation of 2-amino-5-mercapto-1,3,4-thiodiazole - Google Patents

Description

Process for the preparation of 2-amino-5-mercapto-1,3,4-thiodiazole The invention relates to a process for the preparation of 2-amino-5-mercapto-1,3,4-thiodiazole, which is an important intermediate for the production of sulfonamides. This compound, its preparation by the process of the invention is important is simplified, was previously by two to three hours conversion of carbon disulfide with thiosemicarbazide at temperatures of about 1500 C using aqueous Carriers produced.

The yields that can be achieved in this process are proportionate low (on the order of 500/0). This is due to the fact that the 2-amino-5-mercapto-1,3,4-thiodiazole partly in 2,5-dimercapto-1,3,4-thiodiazole converts. During the main conversion between carbon disulfide and thiosemicarbazide Hydrogen sulfide is also formed, which with 2-amino-5-mercapto-1,3,4-thiodiazole reacts and this is converted into 2,5-dimercapto-1,3,4-thiodiazole, which is water-soluble is and is precipitated from its aqueous solutions by acidification with hydrochloric acid.

In U.S. Patent 2,708,670 there is a method of manufacture of thiodiazole compounds described in which at high reaction temperatures Work is carried out in a closed pipe so that the hydrogen sulfide that forms cannot escape and with the 2-amino-5-mercapto-l, 3,4-thiodiazole with formation of 2,5-dimercapto-1,3,4-thiodiazole reacts. When working in the presence of hydrous The aqueous thiosemicarbazide solution obtained in the reaction shows solvents at low reaction temperatures, carbon disulfide is very low compared to carbon disulfide Responsiveness.

Surprisingly, it is obtained even at high temperatures when used of aqueous solvents not the 2-amino-5-mercapto-1,3,4-thiodiazole. According to the USA patent, in the best case one can use a highly contaminated reaction product obtained from which the 2-amino-5-mercapto-1,3,4-thiodiazole desired according to the invention only by further processing can be obtained.

It has now surprisingly been found that the presence of Water has a significant influence on the conversion of 2-amino-5-mercapto-1,3,4-thiodiazole in 2,5-dimercapto-1,3,3-thiodiazole. According to the invention, one works at the process for the preparation of 2-amino-5-mercapto-1,3,4-thiodiazole by reaction of carbon disulfide and thiosemicarbazide in a liquid anhydrous reaction medium, anhydrous benzene, anhydrous diethyl ether, absolute ethyl alcohol or, based on the stoichiometrically required for reaction with the thiosemicarbazide Amount, excess carbon disulfide can be. The reaction temperature is between 130 and 1600 C, the reaction time between 90 and 180 minutes.

Compared to the methods known from the prior art according to the invention, a considerable increase in yield is achieved (yields up to 92%) 0 / o), because it is possible to avoid the formation of secondary reaction products.

The invention is illustrated by the following examples.

Example 1 In a swiveling autoclave, 72 g of thiosemicarbazide, 120 cm3 carbon disulfide and 150 cm3 absolute ethyl alcohol were introduced. Man increases the temperature in the autoclave up to 1400 C and then treats for 2 hours while maintaining this temperature. The mixture is then left in the autoclave cool and remove the hydrogen sulfide formed during the reaction. That 2-Amino-5-mercapto-1,3,4-thiodiazole deposited in large colorless crystals is filtered and dried in the oven at 500 ° C. The raw product is already enough pure. Recrystallized from water, it melts at 2440 ° C. Yield 92 C / o.

Example 2 150 g of thiosemicarbazide, 220 cm3 carbon disulfide and 350 cmS of anhydrous ether introduced. You - raise the temperature in the autoclave up to 1500 C and continue heating for 150 minutes. It is then cooled and the hydrogen sulfide formed during the reaction is discharged and - the obtained 2-amino-5'-inercapto-1,3,4-thiodiazole filtered, with a little ether washed and dried. The crude product obtained has a good degree of purity; the yield is 81%.

Example 3 120 g of thiosemicarbazide, 190 cm3 carbon disulfide and 280 cmS benzene introduced and 150 minutes on a Heated temperature of 1500 C. After cooling, that formed in the reaction Hydrogen sulphide is derived and the 2-amino-5-mercapto-1, which is obtained in yellowish crystals , 3,6-thiodiazole filtered off, washed with a little benzene and dried.

The crude product obtained has a good degree of purity; the yield is 88 0 / o.

Example 4 130 g of thiosemicarbazide are placed in a swiveling 2-1 autoclave and 450 cmS of sulphurous substance were introduced. In this example, the in carbon disulfide present in abundant excess at the same time the task of Reagent and the solvent. The reaction takes place at a temperature carried out at 1500 C for 150 minutes.

After cooling, the hydrogen sulfide formed during the reaction becomes derived and the 2-amino-5-mercapto-1 which crystallizes out in the form of strong, yellowish needles , 3,4-thiodiazole filtered off, washed with alcohol and dried. The accruing The raw product is practically pure; the yield is 90%.

Claims (1)

PATENT CLAIM: Process for the production of 2-amino-5-mercapto-1 , 3'4-tbiodiazole by reacting carbon disulfide and thiosemicarbazide, thereby characterized in that the reaction is carried out in anhydrous benzene, anhydrous diethyl ether, absolute ethyl alcohol or, based on the reaction with the thiosemicarbazide stoichiometrically required amount, excess carbon disulfide at temperatures between 130 and 1600 C for 90 to 180 minutes. ~~~~~~~ Considered Drawn Documents: U.S. Patent No. 2,708,670.