Patent GB-431141-A (GB)
Title: Improvements in or relating to the production of compounds containing a methine or apolymethine chain
IPC: C09B23/02
Filed: 1933-12-23
Abstract: Compounds containing a methine or a polymethine chain are prepared by reacting an organic compound of the formula COOR-CH2-(CX=CH)n-COOR (wherein n stands for O or 1, R for hydrogen or an alkyl residue and X for H or a monovalent substituent) with a quaternary salt of a heterocyclic nitrogen compound containing as a reactive group an alkyl-, aralkyl- or aryl-thioether or selenoether, an aminovinyl an arylaminovinyl, an acetaminovinyl or an acetarylaminovinyl group. The process may be modified by using a mixture of the heterocyclic nitrogen base and an alkyl salt and effecting formation of the quaternary salt simultaneously with the main condensation reaction. Starting materials comprise on the one hand malonic and glutaconic acids and their ethyl esters and aconitic acid; and on the other hand cyclammonium salts having in a - or g -position methylmercapto groups or compounds derived by treating N-alkyl-a -or g -thiones with alkyl salts, or the corresponding seleno bodies (selenoether derivatives are prepared by treating an a - or g - chloro derivative of the nitrogenous base with alcoholic selenourea followed by alkylation of the selenomercaptan so obtained), or the reaction products of cyclammonium salts having reactive methyl groups with formamidines. Many of the dyes are stated to be of use for modifying the sensitivity of an emulsion and some find use as textile dyes.  An acid binding agent such as pyridine is preferably present.  In examples, (1) 1-methylmercaptobenthiazole is heated with methyl-p-toluenesulphonate, malonic acid and pyridine are added and condensation effected to give 2.2<1>-dimethyl-thiocyanine-p-toluenesulphonate; precipitation of this salt with potassium bromide yields the corresponding bromide; from the alkylmercapto derivative of the appropriate heterocyclic compounds the following dyes are similarly prepared :--2.2<1>-dimethyl - 3.3<1> - di - methylmercapto - 1.1<1> - thio - 2.4 - diazolocyamine iodide (the starting material, 1.3-dimethylmercapto - thio - a .b  - diazole is prepared by treating isoperthiocyanic acid with sodium hydroxide and methyl sulphate), 2.2<1> - dimethyl - 4.4<1> - dimethylmercapto - thio - 2.3 - diazolocyanine iodide (the starting material 1.4 - dimethylmercapto - b .b <1> - thiodiazole is made by methylation in alkali of the corresponding mercapto body), 3.3<1> - or 1.1<1> - dimethyl - 2.2<1> - dimethylmercaptopyrimidocyanine perchlorate, 1.1<1> - or 3.3<1> - dimethyl-4.4<1> - quinazocyanine iodide, 1.1<1> - diethylpseudocyanine iodide, 2.2<1> - dimethyloxacyanine iodide, 2.2<1> - dimethyl - 3.4 : 3<1>.4<1>-benzbenzthiocyanine - p - toluenesulphonate, 1.1<1>-dimethylpseudocyanine iodide, 3 . 4 : 3<1>.4<1> - tetramethylthiazolocyanine iodide (the starting material, 2 - methylmercapto - 4 - methylthiazole is prepared by treating 2 - chloro - 4 - methylthiazole with alcoholic thiourea followed by alkylation in alkali), and 2.2<1>-diethylthiocyanine iodide: (2) 1 - w - acetanilidovinylbenzthiazole is condensed with diethyl malonate in pyridine (the product has sensitizing properties): (3) 1-methylmercaptobenzthiazole is heated with ethyl-p-toluenesulphonate, glutaconic acid and pyridine added with further heating and the solution poured into potassium iodide solution to give 2.2<1> - diethylthiocarbocyanine iodide; from the methylmercapto derivatives of the appropriate heterocyclic base there are obtained by a similar or analogous procedure 2.2<1> - dimethyl - 3.4.3<1>.4<1> - benzbenzthiocarbocyanine p - toluenesulphonare, 2.2<1> - dimethyloxacarbocyanine iodide, 1.1<1>-dimethyl - 2.2<1> - carbocyanine bromide and iodide, 2.2<1> - dimethylthiocarbocyanine bromide and iodide: (4) 1 - methylquinoline - 2 - thione is heated with ethyl - p - toluenesulphonate, glutaconic acid and pyridine added and after further heating the dye is precipitated as the bromide.  A sample has been furnished under Sect. 2(5) of 2.2<1>.8 - trimethylthiocarbocyanine iodide prepared by heating 1 - methylmercaptobenthiazole with methyl-p-toluenesulphonate, adding b - methylglutaconic acid and pyridine and after heating pouring the mixture into potassium iodide solution.