Patent GB-646956-A (GB)
Title: Improvements in or relating to the preparation of quaternary ammonium salts of n-phenyl-3, 5-diethyl-2-propyldihydropyridine
Filed: 1948-01-07
Abstract: Quaternary ammonium salts of N-phenyl-3,5-diethyl-2-propyl-dihydropyridine (see Group IV (b)), are used in the vulcanization of such rubbery materials as polymers of butadiene-1,3, isoprene, 2,3-dimethyl butadiene and piperylene and copolymers of these compounds with, e.g. acrylonitrile, styrene, methyl acrylate and methacrylate and isobutylene.  0.1 to 5 per cent based on the rubber composition may be used.ALSO:The quaternary ammonium hydrosulphide or iodide of N-phenyl-3,5-diethyl-2-propyldihydropyridine is obtained by heating the latter with elemental sulphur to produce the hydrosulphide or with molecular iodine or a combination of potassium iodide and potassium iodate in acid medium to produce the iodide.  The hydrosulphide may be converted to other quaternary salts by heating with an acid or with an acid and a salt and need not be isolated but converted in situ as in the formation of the quaternary ammonium iodide by heating the base with sulphur, glacial acetic acid and potassium iodide or the formation of the pyridinium chloride or acetate by heating the base with sulphur and either hydrochloric acid or glacial acetic acid respectively.  The corresponding bromide and fluoride may be obtained by similar methods.  It is also possible to convert quaternary ammonium salts other than the hydrosulphide by similar methods, thus the pyridinium stearate and other salts of carboxylic acids, many of which are specified, and sulphate may be obtained by heating the corresponding acetate with the appropriate acid and the pyridinium benzothiazyl-2-mercaptide is obtained by heating the iodide with sodium benzothiazyl-2-mercaptide and other salts of sulphur compounds containing an acidic thiol group, e.g. dithiocarbamic acids, xanthic acids, mercapto-thiazoles and mercapto-thiazolines may be prepared in a similar fashion.  In examples: (1) the above base, sulphur, glacial acetic acid, potassium iodide and water are refluxed at 95-100 DEG  C. for about 8 hours, filtered and benzene added to the filtrate to give three layers which are separated, the bottom layer and middle after washing with benzene, being made alkaline with sodium hydroxide solution when the quaternary ammonium iodide is precipitated as an oil which crystallizes and is recrystallized from butanol-ether and ethanol-ether mixture; (2) the base, sulphur and concentrated hydrochloric acid are refluxed for seven hours, filtered and the filtrate evaporated at reduced pressure after extraction with carbon tetrachloride to give the pyridinium chloride; (3) the pyridinium acetate is prepared by method (2) using glacial acetic acid in place of hydrochloric acid and chloroform and carbon tetrachloride for extraction purposes; (4) the stearate is obtained by heating the acetate with stearic acid at 110 DEG  C and 30 mm. absolute pressure; (5) the acid sulphate by heating the acetate with concentrated sulphuric acid at about 1 mm. absolute pressure; (6) the pyridinium benzothiazyl-2-mercaptide by adding the iodide of (1) to an aqueous solution of sodium benzothiazyl-2-mercaptide; (7) the hydrosulphide by heating the base and sulphur at 80 DEG  C. for half an hour; and (8) the iodide by reacting the base, iodine and acetic acid first at room temperature and then at boiling point for fifteen minutes when on cooling and neutralization with sodium hydroxide solution the iodide is obtained. N-phenyl-3,5-diethyl-2-propyldihydropyridine, used as starting material, is prepared by adding aniline drop-wise to a mixture of butyraldehyde and dilute acetic acid at 10 DEG  C., refluxing for five hours at 98 DEG  C., cooling and separating the oil layer when butyraldehyde and 2-ethyl hexenal are removed by steam distillation and the oil dried to give a product containing 62 per cent of the base, 23 per cent of compounds soluble in hydrochloric acid and small amounts of N-butylaniline and the reaction product of 2 mols. of aldehyde with 1 mol. aniline.  The base is obtained from the above mixture by treating with cold dilute hydrochloric acid and benzene, the benzene layer being washed free of acid, dried with potassium carbonate and the required base distilled off at reduced pressure.ALSO:Quaternary ammonium salts of N-phenyl-3,5-diethyl-2-propyldihydropyridine (see Group IV (b)), are used in the vulcanization of natural rubber, gutta-percha, balata, reclaimed rubber, polymers of butadiene-1,3, isoprene, 2,3-dimethyl butadiene and piperylene, and copolymers of these monomers with acrylonitrile, styrene, methyl acrylate, methyl methacrylate and isobutylene.  0.1 to 5 per cent based on the rubber composition may be used.  The effect on the physical properties of a typical tyre stock vulcanized in the presence of the pyridinium chloride, acetate, stearate and acid sulphate is illustrated.ALSO:Quaternary ammonium salts of N-phenyl - 3, 5 - diethyl - 2 - propyldihydropyridine, (see Group IV (b)), when mixed with an inert carrier make insecticides, fungicides, mildewcides and weed killers.