SU374269A1 - METHOD OF OBTAINING a-ALKOKSI- /? ,? -DIFTORSTYROLOV - Google Patents

Description

one

The invention relates to methods for the preparation of fluorine-containing styrenes used as monomers for the preparation of fluorinated polymers, namely, the synthesis of a-alkoxy; c, / -difluorostyrenes, which are potential monomers and starting materials for the synthesis of other organofluorine compounds of other classes.

The synthesis of p-alkoxy-a, p-difluoro-styrenes by the action of alkali metal alcoholates on s, / 3, / 5-trifluorostyrene is known.

The aim of the invention is to expand the range of fluoromonomers, in particular fluorostyrenes, by producing a-alkoxy-p, difluorostyrene. For this, trifluoroacetophenone is treated with the appropriate aliphatic alcohols in the presence of a catalytic amount of hydrochloric acid, the resulting trifluoroacetophenone semiketals are chlorinated, the resulting α-alkoxy-a-chloro (5: 8), γ-trifluoroethyl benzenes are dehalogenated and the desired products are isolated by known methods.

Chlorinated half-ketals of trifluoroacetophenone are better chlorinated in soft fields, for example, by the action of thionyl chloride. Dehalogenation is carried out by a known method, for example, by the action of zinc or magnesium in the presence of zinc or magnesium chlorides, respectively.

The process is carried out according to the following scheme:

ROHSOCl

-c „n, - ..

CF, -CO-С "Н, - СРз-С (РО) НС1

he

M / MCI,

CC1 (OK) -SbN, GR -

 - C (OR) -C, H5

where R is alkyl, M-Zn, Mg.

Example 1

Synthesis of a-ethoxy- / 5, / -difluorostyrene.

A mixture of 10 g of trifluoroacetophenone, 30 ml of ethanol and 0.1 ml of concentrated hydrochloric acid is boiled for 10, cooled and poured into water. The precipitated precipitate is filtered off, dissolved in ether and the ethereal extract is calcined with magnesium sulphate. The ether is evaporated, and the residue is dissolved in air for 1.5 hours. Obtain 8.2 g (65%) of ethyl polyketal triptoreline, formula CioHiiFi3O2 with T. pl. 63--64 ° C.

Found,%: fluorine 25.68.

Calculated,%: fluorine 25.9.

To a solution containing 8.2 g of ethyl polyketal trifluoroacetophenone in 50 ml of methylene chloride is added 5 ml of pyridine and while cooling to minus 50 ° C and periodically shaking, 6 ml of thionyl chloride is gradually added. The mixture was brought to room temperature and poured into water. The organic layer is separated, dried with magnesium sulfate and distilled. 1.8 g of trifluoroacetophenone and 4.7 g (57%) of a-ethoc were isolated: b-for-chloro-y9, jS, / 3-t, rifluoroethylbenzene with m.p. 08 ° C / 33 mm. Formula CioHioFsCiQ.

Calculated,%:

Found%:

C50,33

C50,80

H4.19

H4.08

F23,88

F23,37

F NMR spectrum (hereinafter, the external standard CFsCOOH): a singlet with a chemical shift of 1.7 ppm

In a flask with a capacity of 100 ml, 4.6 g of a-ethoxy-a-chloro / 3, / 3, / 8-trifluoroethylbenzene, 20 ml of absolute dioxane, 4.5 g of zinc powder and a catalytic amount of zinc chloride are placed. The mixture was boiled for 2 hours, filtered, and the filtrate was poured into water. The organic layer is separated, dried with magnesium sulfate and distilled. 2.0 g (yield 58%) of a-ethoxy-; 3, / -difluoristirol with a boiling point of 63 ° C / 45 mm, formula CioHjoFaO were isolated.

Found,%: F 20.05.

Calculated,%: F 20.56.

F NMR spectrum: two doublets with a chemical shift of 21.0 and 31.0 ppm J 59.5 Hz. The mass spectrum contains the peak of the molecular ion and the expected fragments.

Hmme r 2. Synthesis of α-methoxy-; 5, J8-diphornol, a-methoxy-, u3-difluoro-styrene with a boiling point of 87 ° C / 50 is obtained from a similar sequence of operations from trifluoroacetophenone and methanol.

Nredmet of the invention

The method of obtaining a-alkoxy-UZ-UZ-difluoro-styrenes, characterized by the fact that trifluoroacetophenone is treated with the appropriate aliphatic alcohols in the presence of a catalytic amount of hydrochloric acid, the resulting trifluoroacetophenone semi-ketals are chlorinated with subsequent dehalopody of the resulting a-alkoxy-a-chloro 3- trifluoroethylbenzenes and. Isolation of the target product by known methods.