Patent GB-562761-A (GB)
Title: Manufacture of new colouring matters
IPC: C09B23/04
Filed: 1942-07-13
Abstract: Meso - substituted tetra - aryldipyrromono - methanes of formula <FORM:0562761/IV/1> (where R1 and R11 are aryl radicals, e.g. of the benzene or naphthalene series, substituted or not and the same or different, and R111 is H or a non-reactive substituent, e.g. aryl, alkyl, or acylamino) are obtained by reacting two molecular proportions of a 2 : 4-diarylpyrroles with one molecular proportion of a homocyclic aromatic aldehyde XCHO.  2 : 4-Diarylpyrroles specified are 2 : 4-diphenylpyrrole, 2-phenyl-4-(p - methoxyphenyl) - pyrrole, 2 - (p - methoxyphenyl)-4-phenylpyrrole, 2-(m-hydroxyphenyl)-4-phenylpyrrole, 2-(o-chlorophenyl) - 4 - phenylpyrrole, 2 - (p - acetylaminophenyl) - 4 - phenylpyrrole, 2 - a - naphthyl - 4 - phenylpyrrole, 2 - phenyl - 4 - b  - naphthylpyrrole, 2 : 3 : 4 - triphenylpyrrole, 3-benzoylamino-2 : 4 - diphenylpyrrole, 3 - acetylamino - 2 : 4 - diphenylpyrrole, 3 - benzoylamino - 2 : 4 - di - p - tolylpyrrole, and 3 - acetoacetylamino - 2 : 4 - diphenylpyrrole, and sulphonic acids obtained by sulphonation of the above compounds.  Aldehydes specified are benzaldehyde, 4-dimethylaminobenzaldehyde, 4-diethylaminobenzaldehyde, 2-chlorobenzaldehyde, 4 - chlorobenzaldehyde, benzaldehyde - 2 - sulphonic acid, benzaldehyde - 4 - sulphonic acid, 4 - methoxybenzaldehyde, 2 - hydroxy - 5 - formyl - 3 - methylbenzoic acid, 4 - (ethyl - b  - chlorethylamino) - benzaldehyde, and 4 - formyl - N - methyldiphenylamine, and their simple functional derivatives, e.g. oximes and anils. Symmetrical and unsymmetrical compounds may be obtained.  The reactants may be heated together in a mutual solvent, preferably in presence of an acidic condensing agent, e.g. HCl, KHSO4, H2SO4, or HClO4.  The compounds may be oxidized into the corresponding meso-substituted tetra-aryldipyrromonomethines by passing a stream of air through a solution and/or suspension of the compounds in a suitable liquid, e.g. ethanol, or by using oxidizing agents, e.g. hydrogen peroxide, ferric chloride, lead peroxide, or potassium dichromate. Water-soluble derivatives of the methines may be obtained by forming the sulphamates, quaternary ammonium salts, sulphonic acids (e.g. by sulphonating with fuming sulphuric acid or with chlorosulphonic acid), or sulphonates.  One or both of the reactants used in preparing the methanes may contain one or more water-solubilising groups, e.g. sulphonic acid groups.  In example 1, 2 : 4-diphenylpyrrole and 4-dimethylaminobenzaldehyde dissolved in ethanol are refluxed and then aqueous HCl added.  The methane is obtained by adding aqueous NaOH to an ethanol solution of the hydrochloride thus obtained.  The corresponding methine is obtained by boiling the ethanol solution of the methane with anhydrous ferric chloride, and rendering alkaline.  In examples 2 to 6, methanes and methines are similarly obtained from 2 : 4-diphenylpyrrole and p-diethylaminobenzaldehyde, from 2 : 4-diphenylpyrrole and 2-hydroxy-3-methyl-5-formylbenzoic acid, from 2 : 4-diphenylpyrrole and benzaldehyde, from 2-phenyl-4-(o-chlorophenyl)-pyrrole and sodium benzaldehyde - o - sulphonate, and from 2 - (p - methoxyphenyl)-4-phenylpyrrole and 4-formyl-N-methyldiphenylamine.  2 - Hydroxy - 5 - formyl - 3 - methylbenzoic acid is prepared by reacting 2-hydroxy-5-chloromethyl-3-methylbenzoic acid with hexamethylenetetramine.  4 - (Ethyl - b  - chloroethylamino) - benzaldehyde is prepared from N-methylformanilide and N-ethyl : N-b -chloroethylaniline.  4 - Formyl - N - methyldiphenylamine is prepared from N-methylformanilide and N-methyldiphenylamine. Specification 5533/13, [Class 2 (iii)], 554,102, 556,156, 562,754 and 562,759 are referred to.  The Provisional Specification refers also to compounds of the general formula in which R111 is an alkylamino or a benzylideneamino radical, and also to unsymmetrical compounds obtained by using one molecular proportion of each of two different 2 : 4-diarylpyrroles.