GB498126A - Manufacture of n:n-dialkyl-dipyrazolanthronyls - Google Patents

Abstract

N : N1-dialkyl-2 : 21-dipyrazolanthronyls are manufactured by treating a 2 : 21-dipyrazolanthronyl simultaneously or successively with two alkylating agents, one providing an alkyl residue containing an alkoxy group and the other a branched alkyl residue containing no alkoxy group, or by treating an N-monoisoalkyl-2 : 21-dipyrazolanthronyl, containing no alkoxy group in the isoalkyl residue, with an alkoxyalkylating agent, or by treating an N-monoalkoxyalkyl-2 : 21-dipyrazolanthronyl, e.g. N-mono-methoxymethyl-, methoxyethyl-, ethoxyethyl- or butoxyethyl-2 : 21-dipyrazolanthronyl, with an alkylating agent providing a branched alkyl residue containing no alkoxy group. The products may be treated with a halogenating agent. Suitable isoalkylating agents are isoalcohols, e.g. isopropyl, isobutyl or isoamyl alcohol, esters thereof, e.g. the hydrogen halide esters, such as isopropyl chloride or the isobutyl or isoamyl halides, the sulphuric esters and especially the arylsulphonic acid esters, also esters of polyhydric isoalcohols containing halogen, e.g. the p-toluenesulphonic acid ester of a : a 1-dichlorhydrin. The reaction may be effected at high temperature, e.g. 120-200 DEG C., in an open vessel or under pressure, if desired in the presence of a solvent or diluent, e.g. nitrobenzene, chlorobenzene, 1 : 2 : 4-trichlorobenzene, amyl alcohol, naphthalene or anisole. When using an isoalcohol still containing a free hydroxyl group it is preferable to alkylate in the presence of an acid, e.g. sulphuric acid, whilst with an ester it is preferable to use an alkali salt of the 2 : 21-dipyrazolanthronyl. The products may be purified by crystallization, by conversion into their salts with strong acids or by treatment with oxidizing agents, e.g. alkali hypochlorite solution, and may be converted into their leuco-derivatives, e.g. leuco-sulphuric acid esters. They are dye stuffs or intermediates therefor, and may be used, if desired in admixture with N : N1-dimethyl-, diethyl-, dimethoxyethyl or diethoxyethyl-2 : 21-dipyrazolanthronyls, for dyeing or printing vegetable fibres, e.g. cotton, for dyeing artificial silk, e.g. acetate artificial silk, or for colouring lacquers and plastic masses. In an example, the dipotassium salt of 2 : 21-dipyrazolanthronyl is heated in chlorobenzene in the presence of potassium carbonate with p-toluenesulphonic acid methoxyethyl and isopropyl esters, in either order or simultaneously. The methoxyethyl ester may be replaced by b -bromethyl methyl ether. The product dyes cotton red shades. Similar dyestuffs are obtained if the methoxyethyl ester is replaced by the ethoxyethyl ester and/or the isopropyl ester by the sec. butyl ester.