Manufacture of aromatic amino bases

摘要

Oily to resinous, low-melting and soluble polynuclear aromatic amino-bases, the residues of which are directly or indirectly coupled by methylene groups so that the molecular proportion of methylene groups to aromatic amino residues is between 0,5 : 1 and 1 : 1, are prepared (a) by causing a molar proportion of a methylene base of the type of anhydroformaldehyde-aniline or anhydro-p-aminobenzyl alcohol to react with less than a molar proportion of a primary aromatic amine having a free p-position to the amino group in presence of an acid and at a temperature below 120 DEG C. and in presence or absence of a solvent; (b) by causing a molar proportion of a methylene base of the type of anhydroformaldehyde - aniline or anhydro-p-aminobenzyl alcohol to react with 1--2 molar proportions of a primary aromatic amine having a free p-position to the amino group, in presence or absence of a solvent and either in presence of an organic acid or in presence of a few per cent of a strong mineral acid, at a temperature exceeding 20 DEG and below 120 DEG C.; (c) by a modification of (a) and (b) comprising forming in situ a methylene base of the type of anhydroformaldehyde-aniline in presence of requisite amount of aromatic amine by gradual addition of formaldehyde or an agent yielding formaldehyde (hexamethylenetetramine, methylal) to a primary aromatic amine having a free p-position to the amino group, in presence of less than 0,2 molar proportion of a strong mineral acid per mol. of amine, the total quantity of formaldehyde added or provided amounting to not more than 0,8 molar proportions per mol. of aromatic amine and the reaction temperature not exceeding 100 DEG C.; (d) a modification of (a) comprising forming in situ a methylene base of the type of anhydro-p-aminobenzyl alcohol in presence of requisite amount of aromatic amine by condensing formaldehyde or an agent yielding formaldehyde (hexamethylenetetramine, methylal) with 1--2 molar proportions of a primary aromatic amine having a free p-position to the amino group, in aqueous solution and in presence of a quantity of a strong mineral acid amounting to at least 0,2 molar proportions for each molar proportion of amine, and wherein either (1) condensation is conducted at a temperature not exceeding 50 DEG C. and the reaction mixture is then heated to 70--80 DEG C. or allowed to stand for at least 24 hours until substantially no uncondensed amine remains in the reaction mixture, or (2) condensation is conducted from the commencement at a temperature between 50--100 DEG C. As catalytically acting acids used in (a) or (b) mention is made of hydrochloric, sulphuric, formic, acetic and salicylic acids and suitable organic solvents are alcohol or cyclohexanone; aniline, o- and m-toluidine and a -naphthylamine are mentioned as suitable amines. The bases are freely soluble in the usual solvents, particularly alcohol-benzene mixtures; they may be used as an addition to pickling solutions, in the rubber industry or in the manufacture of synthetic resins. In examples (1) 11 mols. aniline are rapidly mixed with 5 mols. of formaldehyde, the temperature rising to 70 DEG C., at which the mixture is maintained while adding a little hydrochloric acid; after an hour the mass is neutralized and distilled to remove free aniline and leave a thick oil; (2) equimolar proportions of o-toluidine and anhydroformaldehyde-aniline are condensed together in alcohol and in presence of glacial acetic acid, the temperature rising to about 35 DEG C.; (3) 2 molar proportions of formaldehyde are gradually added to 3 molar proportions of aniline in presence of a small quantity of hydrochloric acid while stirring, the temperature rising to and being maintained at 70 DEG C.; (4) 5 mols. of aniline hydrochloride are added to 4 mols. of formaldehyde in aqueous solution, the temperature rising to 60 DEG C. and being then further raised to 80 DEG C.; (5) 2 molar proportions of aniline hydrochloride are added to 1,34 molar proportions of formaldehyde and the solution allowed to stand for three days; (6) 2 molar proportions of aniline hydrochloride are mixed with 2 molar proportions of formaldehyde, the temperature rising to 50 DEG C.; 0,6 molar proportions of anilinehydrochloride are then added and the mixture heated on the water bath; (7) 1 mol. of a -naphthylamine hydrochloride is condensed with anhydroformaldehyde-aniline (1,3 molar proportions) in aqueous-alcoholic solution, the mixture being heated under reflux for several hours. British Specifications 274,155, 300,287, [both in Class 2 (iii)], and 342,325 and German Specifications 87934 and 335,984 are referred to. The Specification as open to inspection under Sect. 91 relates to the production of the foregoing polynuclear aromatic amino bases from primary aromatic amines having a free p-position and compounds containing active methylene groups, such as formaldehyde, anhydroformaldehydeaniline, anhydro-p-aminobenzylalcohol, hexamethylenetetramine, methylal, by reacting the methylene compound below 120 DEG C. with the amine in presence of acid and avoiding a considerable excess of amine, the presence of a solvent being optional. This subject-matter does not appear in the Specification as accepted.