DE1295549B - Process for the preparation of C1 to C3 alkyl rhodanides - Google Patents

Description

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The production of low molecular weight alkyl tubular high-pressure reaction vessel promoted rhodanides by converting alkyl halides with a pressure of about 211 kg / cm ² and a Temmit inorganic rhodanides is known. So far, a temperature of around 155 ° C has been maintained. However, the more reactive alkyl methyl chloride is used in such an amount of bromide or iodide and brought in an organ that an excess of 2 niches by weight of solvent at an elevated temperature works out percent over the reaction with the ammo ( see J. Chem. Soc. [London], 1948, p. 1848). niumrhodanid stoichiometric amount required only in cases where the alkyl group results. The length of the reaction vessel and that of an activating radical such as phenyl or the throughput of the reactants are connected to naphthyl, the reaction could also be coordinated so that under the preferred temperature and pressure conditions with the cheaper alkyl chlorides, a reaction can be carried out. From the USA. Patent 1963 100 setting time of about 8 minutes is achieved. A process has become known in which a reaction mixture is steam distilled in higher alkyl chloride, namely lauryl chloride, and gives a yield of about 95% methyl-20% alcohol as the activating solvent 15 rhodanide, based on the amount of am- or in the case of finely dispersed distribution, it can also be reacted in water with monium rhodanide, with a purity of more than inorganic rhodanides. 99%. The alkylrhodanides are suitable, inter alia. This process, which can only be carried out in a rudimentary manner, cannot be transferred to low molecular weight, gaseous or cyanates, thiocarbamates, disulfides, low-boiling liquid alkyl chlorides as intermediates for the synthesis of isothiosiches. ao substances and other organic compounds.

The invention relates to a method of manufacturing the invention is explained below with reference to

Development of C ₁ - to C ₄ -Alkylrhodaniden described by um- examples.

setting of an alkyl halide with an alkali In Examples 1 to 5, there was the

rhodanide, in which the corresponding implementation of the continuous process used alkyl chlorides with an aqueous ammonium, Na 25 reaction vessel from a pressure tube made of stainless trium or potassium rhodanide solution at a pressure steel with a length of about 60 m and about 10.5 up to 246 kg / cm ² and a temperature 6.35 mm inside diameter, which converts a reaction zone of about 90 to 160 ° C. had a volume of about 1800 ml.

Surprisingly, it turned out. . , ..

that no activating solvents, such as Example 1

Alcohol or acetone, are required, but that methyl chloride and a 35 weight percent aqueous

Water can be used as a solvent. membered ammonium thiocyanate were kontinuier-this way be bypassed the difficulties of ELIMINATION Hch under a pressure of 211 kg / cm ² and at a supply of waste products, the organic encryption at temperature of about 155 ⁰ C in a tubular application solvent, the inorganic 35 Reaction vessel introduced. The throughput of the niche chlorides poorly dissolve, arise. Methyl chloride and ammonium thiocyanate solution

It has proven advantageous to _{adjust the C 1} bis in such a way that a methyl chloride over C ₄ alkyl chlorides is in a slight excess of about 10 percent by weight and about 2 to 10 percent by weight, based on the decomposition time of gave about 8 minutes. The appropriate Alkalirhodanid to use. Steam distillation was then purified for the reaction product held by the process according to the invention. The yield of ammonium rhodanide is preferred, although even purified methyl rhodanide was 91.5% of the theory that sodium and potassium rhodanide can be used, based on the ammonium used. Usually the concentration of the rhodanide is, and the product showed a purity of 99% in the case of gas chromato-aqueous alkali metal rhodanide in the range of about 20 45 graphic analysis. up to 50 percent by weight. . .

The reaction temperature can be in a range Example 2

be varied from about 90 and 160 ° C, with methyl chloride and a 35 weight percent aqueous

Temperatures between 100 ⁰ C and in particular membered ammonium thiocyanate were kontinuierzwischen about 135 and 160 ° C are preferred. Hch examples 50 under a pressure of about 211 kg / cm ² and at play is at a pressure of about 176 kg / cm ² at a temperature of about 115 ° C in a rohrförmi- and a temperature of about 100 ⁰ C an environmental Total reaction vessel introduced. The throughput time of 40 minutes is required to achieve a quantity of the methyl chloride and the ammonium-98% yield, while with the same rhodanide solution was set so that a pressure and a temperature of 155 ° C resulted in a methyl chloride excess of about 2 Weight percent setting time of only 8 to 9 minutes is necessary. In the continuous process and a reaction time of about 25 minutes, a pressure of about is given. The yield of purified methylrhodanide up to 246 kg / cm ² , advantageously of about 70, was 89.4% of theory, based on the amount of up to 211 kg / cm ² and preferably from about 141 to about 141 to put ammonium rhodanide. kg / cm ^{2 was} applied. 60

The implementation can also be carried out in an autoclave

be done wisely, advantageously a pressure of methyl chloride and an aqueous, 35 weight percent

of about 10.5 kg / cm ² is used, since the ammonium thiocyanate solution has not been a constant, it is necessary to keep the alkyl chloride in liquid additive under and at ^{a pressure of 70 kg / cm 2.} 65 at a temperature of about 95 ° C in a tubular

In the preferred embodiment of the invention, reaction vessel is introduced. The throughput becomes an aqueous solution with about 35 percent by weight of methyl chloride and ammonium thiocyanate Ammonium rhodanide by pumping into a solution was adjusted so that a methyl

An excess of chloride of about 2 percent by weight and a reaction time of about 47 minutes resulted. The yield of raw methyl thiocyanate was 98% of theory, based on the ammonium thiocyanate used.

Example 4

Methyl chloride and a 35 weight percent aqueous ammonium thiocyanate solution were continuously ^{introduced into a tubular reaction vessel under a pressure of about 35 kg / cm 2} and at a temperature of about 95 ° C. The throughput of methyl chloride and ammonium thiocyanate solution were adjusted so that a methyl chloride excess of about 10 percent by weight and a reaction time of about 45 minutes were achieved. The yield of crude methyl thiocyanate was 95.5% of theory, based on the ammonium thiocyanate used.

Example 5

n-butyl chloride and an aqueous ammonium thiocyanate solution 35gewichtsprozentige were continuously introduced under a pressure of about 211 kg / cm ² and at a temperature of about 13O ⁰ C in a tubular reaction vessel. The throughput rate of n-butyl chloride and ammonium rawdanide solution was adjusted to an excess of n-butyl chloride of about 2 percent by weight. The pure n-butyl rhodanide was separated off from the reaction mixture by distillation. The yield was 33% of theory, based on the n-butyl chloride used.

Example 6

A 50 weight percent aqueous solution of ammonium thiocyanate was placed in an autoclave. The solution was heated with vigorous stirring to 9O ⁰ C. Then methyl chloride was injected in an amount which was 10% above the stoichiometrically required amount, the pressure increasing to about 10.5 to 12.7 kg / cm ² . After a conversion time of about an hour, the end of it. was indicated by a pressure drop to about atmospheric pressure, the reaction vessel was vented. After steam distillation, the contents gave a 95% yield of pure methyl rhodanide, based on the ammonium rhodanide used.

Example 7

A 30gewichtsprozentige aqueous Natriumrohdanidlösung was placed in an autoclave, and the solution was heated with vigorous stirring at ⁰ C HO. Then methyl chloride was injected in an amount which was 10% above the stoichiometrically required amount, the pressure being regulated to 12 to 12.7 kg / cm ² by heating. After 30 minutes the overpressure dropped rapidly to about atmospheric pressure. The autoclave was vented. After steam distillation and drying by azeotropic distillation, its contents gave dry methyl rhodanide of 99% purity in a 79% yield, based on the sodium rhodanide used.

Example 8

A 30 weight percent aqueous solution of potassium rhodanide was placed in an autoclave, and the solution was heated to 100 ° C. with vigorous stirring. Then methyl chloride was injected in an amount which was 10% above the stoichiometrically required amount, the pressure being regulated to 12 to 12.7 kg / cm ² by heating. After 30 minutes the overpressure dropped rapidly to about atmospheric pressure. The autoclave was vented. After steam distillation and drying by azeotropic distillation, its contents gave dry methyl rhodanide of 98% purity in an 82% yield, based on the potassium rhodanide used.

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Claims (1)

Claim: Process for the preparation of C ₁ - to C ₄ -alkyl rhodanides by reacting an alkyl halide with an alkali metal rhodanide, characterized in that corresponding alkyl chlorides are mixed with an aqueous ammonium, sodium or potassium rhodanide solution at a pressure of about 10.5 to 246 kg / cm ² and a temperature of about 90 to 160 ° C.