DE738496C - Process for the preparation of quaternary heterocyclic compounds of the thiazole and selenazole series which contain a vinyl group in the 2-position which is substituted by an organic mercapto group - Google Patents

Description

Process for the preparation of quaternary heterocyclic compounds of the thiazole and selenazole series which contain a vinyl group in the 2-position which is substituted by an organic mercapto group Intermediate compounds have become known for the preparation of symmetrical and asymmetrical carbocyanine dyes (British patent 412 3o9, German patent 6371z3) representing alkyl mercapto compounds. One of these compounds has the following structural formula: It can be prepared by the known process from the iodine methylate of 2-methylbenzthiazole and ethylisothioacetanilide in the presence of acetic anhydride. However, this compound and similar products are always contaminated with symmetrical carbocyanine dyes in varying amounts because they are formed with those used as starting materials. quaternary compounds, for example the iodine methylate of 2-methylbenzthiazole, react.

In contrast, the present process produces such alkyl mercapto compounds free of contaminating dyes. In addition, it has the advantage that not only alkyl nercapto compounds but also corresponding aralkyl and aryl mercapto compounds of the same type are accessible for the first time. According to the invention, compounds of the general formula in which your - optionally substituted - phenylene or naphthylene radical, Q is sulfur or selenium, 1Z and R 'j e is a monovalent hydrocarbon radical, for example alkyl or aryl, X is an acid radical and X' is halogen, condensed with a mercaptan.

It is carried out in the presence of an acid-binding agent. Strength tertiary organic bases are useful for this, especially those whose dissociation constant is noticeably higher than that of pyridine. Trialliylamine and \ T-All; ylpiperidine are given as examples. Suitable solvents in this case are Alcohol or pvridine used. Heat accelerates condensation.

The chlorovinyl compounds are particularly suitable for the process. The quaternary chlorine compounds obtainable from this can then be mixed with death salts converted into the corresponding iodine compounds. Suitable mercaptans are for example the aliphatic M: ercaptans, such as butyl mercaptans, or the aromatic "mercaptans, such as phenyl- or naphthyllylcaptans.

Example i 2- (2-Benzyl nercaptopropenyl) -d, 5-naphthothiazole iodoethylate 6 g (1 mol) 2- (chloropropenyl) -, B-naphthothiazole chloroethylate and 2.3 g (1 mol) benzyl mercaptan are absolute in 10 ccm. Ethyl alcohol introduced, which 1.87 g (1 mol) of triethylamine. contains. The mixture is refluxed for 15 minutes, then cooled and decomposed with 150 cc of diethyl ether to precipitate the compound. The precipitate is collected on a filter and washed with more ether. The crude product is dissolved in 5 cc of hot methyl alcohol and an excess of sodium iodide dissolved in warm methyl alcohol is added to the hot solution. The iodide then precipitates, which is filtered off and recovered in a crude yield of 210%. After double recrystallization from ethyl alcohol, dull yellow crystals with a melting point of 178 to 1790 are obtained.

Example 2 2- (2-Benzylmercaptostyryl) -4,5-naphthiothiazole chloroethylate The 2- (2-chlorostyryl) -ß-naphthothiazole-cliloräthylat, which is obtained from 6.6g (1 mol) of 3-ethyl-2 - benzoylmethylene - ß - naphthotmazoline with phosphorus oxychloride in dry. Contains benzene, is dissolved in 2o cc of ethyl alcohol. 2.5 g (i mol) of benzyl mercaptan and 2 g (i mol) of triethylamine are added to the solution and the solution is then refluxed for 10 minutes. The mixture is then cooled to 0 °, the reaction product precipitating out. It is collected on a filter, washed with 20 cc acetone and air dried. The yield is 5.2 g (61% of theory). After two recrystallization from methyl alcohol, yellow crystals are obtained which melt at 193 to 1% 6% with decomposition.

Example 3 5-Cl11or-2- (2-phenylmercaptobuteiiv1) -benzselenazoleethyl iodide The 5-chloro-2- (2-chlorobutenyl) benzoselenazole chloroethylate, which is obtained from 4.,; g (1 mol ) of 5-chloro-3-ethyl-2-propionylmethylene bezoselenazoline is obtained by reaction with phosphoro-xychloride in dry benzene, we add to 10 cc of absolute ethyl alcohol. The mixture is mixed with 1.2 g (1 mol) of thiophenol and 1.5 g (1 mol) of triethylamine are added, the mixture is heated for 5 minutes, cooled under reflux to 0 "and the reaction product is precipitated by adding 100 cc of diethyl ether. The supernatant liquid is decanted and the precipitate is dissolved in 10 ecm of ethyl alcohol Cooling the solution, mixed with an excess of sodium iodide in methyl alcohol, to 0 °, the iodide precipitates. It is collected on a filter, washed with 10 cc of water and 30 cc of acetone and dried in the air. The yield is 2.0. 9 g, corresponding to 36% of theory After two recrystallization from methyl alcohol, brown crystals are obtained which melt at 195 ° to 197 ° with decomposition.

Example q. 2- (2-Phenylmercaptopropenyl) benzthiazolethyl iodide 4.4 g '(1 mol) of 2-acetylmethylene-3-ethylbenzothiazoline are suspended in 5o cc of dry benzene. Then 4.5 g (1.5 times) of phosphorus oxychloride are added. After the mixture has been stirred for about 10 minutes, the chlorovinyl compound separates out as a precipitate. It is filtered off and dissolved in 15 cc of absolute methyl alcohol. 1.6 g (1 mol) of thiophenol and 2 g of triethylamine are added to the solution, the mixture is heated under reflux for 5 minutes, cooled and mixed with 100 cc of diethyl ether to precipitate the product. The liquid portion is poured off and the precipitate is dissolved in 10 cc of methyl alcohol. An excess of sodium iodide in methyl alcohol is then added to the solution. The iodide is obtained on cooling the solution; it is washed once on the filter with water (25 ccm) and acetone (25 ccm) and air-dried. The yield is 3.1 g (35 % of theory). After two recrystallizations from methyl alcohol, brown-yellow crystals are obtained which melt at igi to z93 ° with decomposition.

Similarly, 2- (2-phenylmercaptobutenyl) benzothiazole iodophenylate from 2- (2-chlorobutenyl) benzothiazole chlorophenylate.

Claims (1)

PATENT CLAIM: Process for the preparation of quaternary heterocyclic compounds of the thiazole and selenazole series which contain a vinyl group in the 2-position which is substituted by an organic mercapto group, characterized in that compounds of the general formula where D is an optionally substituted phenylene or naphthylene radical, Q is sulfur or selenium, R and R 'are each a monovalent, organic hydrocarbon radical, for example alkyl or aryl, X is an acid radical and X' is halogen, with a mercaptan in the presence of a tertiary, organic base, the dissociation constant of which is considerably greater than that of pyridine, and can optionally be reacted in a solvent and with heating.