CS260485B1 - Process for preparing alkylthioalkanols - Google Patents

Abstract

The method for producing alkylthioalkanols of the general formula I RS(CH2)„OH (I) where R denotes methyl, ethyl and n denotes 2 or 3, from the sodium salt of alkanethiol and omega,-haloalkanol consists in that the sodium salt of alkanethiol, prepared in one step from the thiouronium salt of the general formula II [RSC(NH2)=NH]2'SO4 (II) where R has the above-mentioned meaning, is treated with sodium alcoholate with 1 to 2 carbon atoms in a methanol or ethanol environment at 45 to 60 "C, after 2 h, omega-chloroalkanol is added and the reaction mixture is boiled for 2 to 4 h, after which the separated insoluble components are filtered off with suction, the solvents are evaporated and the product of the general formula I is obtained by distillation.

Description

The invention relates to a process for the preparation of alkylthioalkanols of the general formula ¹¹

RS (Cl 12) _n O 11 (I) wherein R represents methyl or ethyl n represents 2 or 3.

These compounds are used as intermediates in the production of biologically active substances (N. Negwer in Organisch-Chemische Arzneimittel und ihre Synonyms, Akademie Verlag, Berlin 1978) or plant protection products (R. Wergler / Ed / Chemie der Pflanzenschutz- und Schadlingsbekampfungsmittel, Springer Verlag, Berlin, 1977).

According to the prior art, the compounds of the formula I are prepared in a number of ways, of which only the most important ones are mentioned. The first utilizes the reaction of an alkali metal salt of alkanethiol with the corresponding ω-haloalkanol in an environment of various organic solvents (J. Org. Chem. 24, 1301 (1959); J. Org. Chem. 26, 1463 (1961); J. Polym. Sci A 2, 1185 (1964)). The disadvantage of this process is a particularly complex technical device for working with highly toxic volatile, alkanethiols associated with the preparation of the sodium salt. The second process utilizing the reaction of oxirane with the corresponding alkanethiol can only be used in the production of alkylthioethanol (U.S. Pat. Nos. 2,776,997, 3,213,149). The disadvantage of this method is the difficult handling of toxic alkanethiol and oxirane together with the need to work in pressure vessels. U.S. Pat. No. 2,806,884 discloses a process in which the compounds of formula I are obtained by reacting an alkyl chloride with a sodium salt of ω-hydroxyalkanthiol. Due to the high toxicity, flammability, and difficult handling (for example, the methyl chloride is 21 ° C), this process is not advantageous in terms of technology and occupational safety. Other analogous procedures are protected, for example, by Ger. Offen 2,108,902; Japan. Kakai 72, 34, 217.

The process according to the invention follows in a positive sense the prior art. The present invention is based on the reaction of an alkanethiol sodium salt prepared in situ from the known (see Org. Synth. Coli. Vol II, 411 (1943)) isothiouroinium salt of formula II

Claims (1)

A process for the preparation of an alkylthioalkanol of the formula I RS (CH 2) _n OH (I) wherein R is methyl, ethyl and n or 2 or 3, from sodium alkanethiol and ω-haloalkanol, characterized in that the alkali metal sodium salt is prepared in situ from a thiouronium salt of formula II wherein R is as defined above, by the action of sodium alcoholate in an alcoholic environment with a ω-haloalcohol. In this embodiment, a thiouronium salt of formula II is introduced at room temperature into a solution of the methanolate in methanol or ethanolate in ethanol at room temperature. After stirring at 45-60 ° C for 2 hours, ω-chloroalkanol is added. While stirring, the mixture is heated to boiling for 2 to 4 hours. The reaction mixture was then cooled, the insoluble material was filtered off with suction and the solvents were removed by rotary evaporation. The desired product of formula I is obtained from the distillation residue by distillation under reduced pressure in high yield. An advantage of the process according to the invention is the simple work with non-volatile compounds. Since the necessary alkanethiols are obtained in the form of a salt, this process does not require complex technical equipment. It further improves work environment hygiene and occupational safety, making it fully compliant. The invention is illustrated by several specific examples, which are illustrative only and in no way limit the scope of the invention. He did 7.4 g of sodium were dissolved in 100 ml of ethanol, 23.1 g of a salt of formula II wherein R is ethyl were added to the solution, and the mixture was stirred at 50 ° C for 2 hours. To the solution was added 15.2 g of 2-chloroethanol and the reaction mixture was heated to reflux for 3 hours. After cooling, the crystalline fraction was filtered off, the filtrate was evaporated, and after distillation of the crude residue, 12.7 g (80%) of 2-ethylthioethanol of the formula I where R = ethyl and n = 2, bp 79-81 ° C were obtained. Torr. Example 2 In the same manner as in Example 1, 13.2 g of 3-methylthiopropanol (82%) was obtained from 21.0 g of a salt of formula II (where R = CH3), 7.4 g of sodium, 100 ml of ethanol and 17.9 g of 3-chloropropanol. %), i. 92-94 ° C / 20 Torr, of formula I, wherein R is CH 3 and n = 3. OF THE INVENTION (RSC (NH 2) = NH 12 SO 4 (II)) wherein R is as defined above by treatment with 1 to 2 carbon atoms of sodium alcoholate in methanol or ethanol at 45 to 60 ° C, after 2 h add ω-chloroalkanol and reaction the mixture is boiled for 2 to 4 hours, after which the insoluble matter which has precipitated is filtered off with suction, the solvents are evaporated off and the product of the general formula I is distilled off.