CS229082B1 - Method of preparing 3-alkylthio-5,k-dimethylcyclonexenones/1/ - Google Patents

Description

The invention relates to a process for preparing substances of structural formula I

HqC

CH,

H, C

Ί c

ch ₂

C-SR (I) wherein R is methyl or ethyl. Said compounds serve as an important semi-product used for the preparation of pentametincyemine dyes (brit. Pat. 595 784, 595 785) used for sensitizing the silver silver emulsion in the cyan layer color photograph (jap. Pat. 78 142 223).

The only known process for the preparation of the ethyl derivative of the compound of the above formula I is described in British Pat. U.S. Pat. 595 783. Dry hydrogen chloride was added to dimedone (5,5-dimethylcyclohexane-3-dione) in excess ethyl mercaptan under cooling and allowed to stand for 36 hours until the reaction was complete. The product is isolated by pouring the reaction mixture into soda solution, shaking with ether and distillation after drying. A large excess of ethylmercapten escapes into the atmosphere.

It has now been found that the methyl or ethyl derivative of the above formula (I) can be prepared by a much more preferred process without the use of toxic and strongly odorous mercaptans.

The preparation is also based on dimedone. Its tosylation with p-toluenesulfochloride in aqueous sodium hydroxide gives the tosyl derivative of formula II, which is converted to the condensation product of formula III by boiling with thiourea in alcohol. This is then boiled in an aqueous sodium hydroxide medium and subsequently alkylated with a solution of the mercapto compound of formula IV with dimethyl sulfate or diethyl sulfate to give the desired derivatives of the compound of formula I above.

^H 3 ^Cl / ^{CH 3}

H, CH ₂ CH ₂ ² III h ₂ p-toluenesulfochloride (aqueous NaOH)

H

H, C

CH, _CH3 thiomočqvina ^ (ethanol)

NH

I>

C.C-S-C, NH, hydrolysis (aqueous NaOH)

H, C, C;

O ^ (III)

ch ₃ ^H 3 ^C / ^CH: CHo 1 alkylation H, CH 1 1 ' 1 C — SH (R ₂ SO ₄ ) 1 1 and

Sat ₃ H (IV)

H (I) r

Prepared flights are isolated from the reaction mixture by shaking into a suitable solvent such as benzene and purified by distillation under reduced pressure.

The preparation of the fly according to the process of the invention does not require the use of strongly odorous, toxic and commonly unavailable mercaptans, and in addition, a crystalline methyl derivative not previously described is produced in the literature.

The example below describes the principle of the process found and describes all variants of the synthesis route used.

Exemplary embodiment

To a flask equipped with an efficient vibrating stirrer was charged 250 parts by volume of 1056 aqueous sodium hydroxide solution, 5 parts by volume of Slovesol O (wetting agent) were added, and 70 parts by weight were added. dimedon and vibrates to dissolve. Now 105 parts by wt. p-toluenesulfochloride 99.6% e is effectively stirred with a vibrating stirrer. After 10 minutes, the reaction mixture is heated to 50 ° C and simultaneously alkalinized with a total of 120 parts by volume of a 10% sodium hydroxide solution such that the reaction is still alkaline to phenolphthalein. The reaction mixture was then stirred without heating and after the temperature had dropped to 40 ° C, the reaction mixture was cooled by dropping the ice to 10 ° C, whereupon the dimedone tosylderivative of formula II precipitated. After aspiration, washing with cold water and air-drying, 120 parts by weight are obtained. mp 48-50 ° C, which melts at 51-52 ° C after recrystallization from ethanol.

118 parts by weight 150 parts by volume of ethanol are poured in the flask, 40 parts by weight of tosyldimedone are produced. the thioureas and the mixture were refluxed for 3 minutes. Already after boiling for 10 minutes, a crystalline condensation product precipitates. After boiling for an additional 1 hour, the mixture is cooled, the crystals are filtered off at 10 ° C and washed with 100 parts by volume of ice-cold ethanol. After drying in air, 120 parts by weight are obtained. 159 DEG-181 DEG C. (decomposition).

185 parts by weight of the product of formula (III) is poured in a flask of 180 parts by volume of 40% sodium hydroxide and 450 parts by volume of water. The mixture was refluxed for 1 hour, then cooled to 50 ° C and 120 parts by volume of dimethyl sulfate was added dropwise over 10 minutes with rapid stirring. After stirring for 1 hour, the product was shaken with benzene. The benzene shake is dried with kieselguhr and distilled under vacuum. The product passes from about 133 Pa to about 136 Pa. 63 parts by weight are obtained. product of formula I wherein R is methyl, as a yellowish oil which solidified on seeding and PEK had a melting point 37 38 ⁰ EŽ

Using 130 parts by volume of diethyl sulphate instead of dimethyl sulphate, 71 parts by weight are obtained after distillation in the same manner. The product of formula (I) wherein R is ethyl is a yellowish oil which boils at a boiling point of 169-172 ° C at a pressure of about 3 Pa.

Claims (1)

SUBJECT OF THE INVENTION A process for the preparation of 3-alkylthio-5,5-dimethylcyclohexenones of formula (I) S. C — SR S 'O H wherein R is methyl or ethyl by treating dimedone, characterized in that the dimedone is tosylated with p-toluenesulfochloride in aqueous sodium hydroxide solution, the resulting tosyldimedone is treated by boiling in ethanol or methanol with thiourea, the resulting condensation product is saponified by boiling in aqueous solution sodium or potassium, without isolation, is alkylated by the addition of dimethyl sulfate or diethyl sulfate, and the product is isolated.