SU339157A1 - Method of producing thiocyanates a-halocarbonic acid acids - Google Patents

Description

This invention relates to a new process for the preparation of α-halo-carboxylic acid thiocyanates of the general formula

ABOUT

/

R-c

NCS

where R is halogenated methyl, which contains from 1 to 3 halogen atoms.

A method of producing α-halocarboxylic acid thiocyanates by reacting α-halocarboxylic acid chlorohydride with dialkylacipine thiociapate is known. The disadvantage of this method is the need to use hard-to-reach and highly toxic Thiocyanates secondary arsines.

With the aim of eliminating this drawback, as well as simplifying the process, it has been proposed that the α-halocarboxylic acid chloride be reacted with trimethyl- roda-silane.

Trimethylrodansil and interacts with chloro- or bromohydrin monohalide- or polyhaloalkylcarboxylic acids in solutions of aprotic solvents (acetone, dioxane, acetonitrile, etc.) or without them at 20-70 ° С. At the same time, trimethyl halo-silanes and halocarboxylic K1 acids are formed in quantitative yield.

The reaction is conveniently carried out without isolation of trimethyl rodanesilane from the reaction g-mass after its preparation. In this case, a mixture of trimethylchlorosilane and the solvent can be used to re-synthesize trn-methylrodapsylan, which makes it possible to obtain acyl thiocyanates in a closed cycle.

Carrying out the reaction without isolation of the terpaniline-danoplan from the reaction mass after its preparation is very effective in the synthesis of fluorine or perfluoroacylthiocyanates, since in this case, trimethylchlorosilane can be used in the amount of 5-20%.

Example 1. Trichloroacetic Thiocyanate

K1 ACIDS.

A mixture of 10.0 g (0.055 g-mol} trichloroacetyl chloride and 6.6 g (0.05 g-mol) of trimethylrodansilapa is transferred at room temperature for 1 hour. The formed trimethylchlorosilane is distilled off at atmospheric pressure and the residue is fractionated in vacuo. Get 9.5 g (93%) of a colorless liquid, m.p. 68-69 ° C / 10 mm Hg, 1.5660, df 1.5754.

Found,%: C 17.39; C1 52.54; N 6.63; S 15.25.

CsClsNOS.

Under similar conditions, with a yield of 85-95%, compounds 1-3 are listed in the table.

Example 2. A-b rumma thiocyanate: hydrochloric acid.

To a suspension of 5.8 g (0.06 g-mol) of. Total potassium in 30 ml of anhydrous acetone is added dropwise. 4.4 g {0.05 g-mol) of trimethyl-chloroslica with stirring. The mixture was stirred at room temperature for 2 hours, filtered, 10.2 g (0.055 g-mol) of α-bromomal acid chloride was added to the filtrate, after 1 hour the mixture was evaporated in a bath (temperature 75-80 ° C) and the residue Ccioiuyut in a vacuum. 9.3 g (89%) of a colorless liquid are obtained, i.e. 95-96 ° C / 15 mm Hg. Art., nfo 1,5608, df 1,5147.

Similarly, they receive the items 2 and 3 listed in the table.

Trifluoroacetic acid thiocyanate

Example 3. Acids.

To a suspension of 6.8 g (0.07 g-jol) of potassium thiocyanate in 35 ml of anhydrous dioxane 1.1 g (0.01 g-mol) of trimethylchlorosilane are added and then 6.6 g (0.05 g-mol) trifluoroacetyl chloride. The mixture is stirred at room temperature for 2 hours and 4 hours at 50-60 ° C (the trifluoroacetyl chloride evaporated on heating and trapped in a trap and returned: ay into the reaction mass). The mixture is fractionated in an effective column and 6.9 g of liquid (m.p. 72–74 ° C / 756 mm Hg) are separated, which, according to gas-liquid chromatography, contains 81% trifluoroacetic acid thiocyanate (yield 72%) and 19 % dioxane.

The subject matter of the invention 20 1. The procedure for the production of α-halo carboxylic acid thiocyanates using α-halo carboxylic acid chlorohydride, characterized in that, in order to simplify the process, α-halohydrocarboxylic acid chloride is reacted with trimethylrodane-silane with the subsequent separation, followed by separation. 2. A method according to claim 1, characterized in that the process is carried out at a temperature of 20-70 ° C.