DD241261A1 - METHOD FOR PRODUCING CATIONIC DYES - Google Patents

Abstract

The invention relates to the preparation of cationic dyes by reacting a 1,3,3-trimethyl-2-methylenindoline with a compound of the formula R-HN-Ar in which R is H and Ar are the radical of an optionally substituted by alkyl or alkoxy aryl group or R and Ar together represent a cyclic radical, and orthoformate in a one-pot reaction in acetic acid at 70 to 80C in the presence of catalytic amounts of mineral acid.

Description

(V)

in which R and Ar have the abovementioned meanings, and ethyl orthoformate in acetic acid at temperatures between 70 and 80 ^° C., characterized in that the reactants are reacted in a one-pot reaction in the molar ratio 1: 1.1: 1.3 in the presence of catalytic amounts of mineral acid become.

Field of application of the invention

The invention relates to a process for the preparation of cationic dyes of the general formula

* ^ a = cH- ^ ^K

anion

CHi

in the X = H, alkyl or alkoxy, R = H

and Ar = the radical of an optionally substituted alkyl or alkoxy substituted aryl group,

or H and Ar together with the nitrogen atom represent a heterocyclic radical.

Characteristic of the known technical solutions

The literature describes a number of processes which involve the preparation of dyes of the formula I by condensation of ω-formylmethylene derivatives of heterocyclic nitrogen bases, especially those of the indoline of the formula

II

with suitable aromatic amines or with hydrogenated heterocyclic nitrogen bases, such as indolines and tetrahydroquinolines, to the content (DE-PS 710750, US-PS 2155459). The dye-forming condensation can in this case

-3- 241 2S1

From the obtained after the condensation reaction mixture, the dye is separated and optionally washed with brine.

The inventive method allows instead of expensive ω-aldehydes of the formula II directly the precursors of these aldehydes, the Methylenindolinbasen the formula

YI

in which X has the abovementioned meaning, to use in the condensation.

In comparison with the known technical solutions, the dyes of the formula I are obtained by the process according to the invention in a process stage and in a one-pot reaction.

The production process according to the invention is thus of higher technical and economic effectiveness.

embodiments

example 1

102 parts of p-anisidine and 130 parts of 1,3,3-trimethyl-2-methylenindoline and 150 parts of orthoformate are dissolved in acetic acid. After addition of 2.2 parts of sulfuric acid conz. the reaction mixture is stirred at 80 ⁰ C for ⁴ h. Subsequently, it is diluted with 2000 parts of water and 130 parts of hydrochloric acid conz. added. It is briefly heated again to 8O ⁰ C. Then allowed to cool to room temperature and stirred for 3 hours. The precipitated dye is filtered off with suction and dried.

There are about 250 parts of the dye of the formula

ci

<3> VII

receive.

Example 2

The reaction mixture, consisting of 172 parts of 1,3,3-trimethyl-2-methylenindoline, 175 parts of trimethylindoline and 198 parts of orthoformate in acetic acid, is added dropwise with 2.2 g of sulfuric acid conz. and then stirred for 4 h at 8O ⁰ C stirred. Thereafter, with 2000 parts of water and 130 parts of hydrochloric acid conz. added and worked up as described in Example 1. There are about 260 parts of the dye of the formula

VIII

receive.

an organic solvent with an acid condensing agent, such as phosphorus oxytrichloride, or else in m water-miscible inorganic and organic acids.

The aldehydes of formula II may also be functionalized by aldehyde derivatives, such as the enamines of the formula ## STR1 ## resulting from the Vilsmeier reaction

anion

"VlflCyf

be replaced.

The use of acid condensing agents as aggressive and corrosive agents requires a high technical effort for safe handling and maintenance of the system. In addition, the emulsion of acidic and corrosive gases is troublesome.

It is furthermore known that the dyes of the formula I are also obtained from 1,3,3-trimethyl-2-methylenindoline, the precursor of the ω-formylmethyleneindoline of the formula II, by reaction with p-substituted aromatic amines and a C _r building block , As CrBaustein, inter alia orthoformate is used.

In this procedure, however, as interfering accompanying dyes, the methine dyes of the formula

Oi ₃

IY

formed, which are known from DE-PS 410487 and DE-PS 539784.

The dyestuffs of the formula I contaminated with the accompanying dyestuffs of the formula IV are suitable for the user nii in this form.

You show u.a. significant reddish nuance.

To obtain the dyes in the pure and clear shade required by the user, extensive purification operations become necessary after dye synthesis. The disadvantages of this manufacturing process result from the high technical complexity associated with achieving the purity required for the user.

Another significant disadvantage is that the formation of the symmetrical methine dyes of formula IV 1,3,3-trimethyl-2-methylenindoline the reaction to the desired dye of formula I is withdrawn.

The yield of dyes of the formula I is therefore low and the process is of low economic effectiveness.

The preparation of the dyes of formula I can also be done according to DD-PS 224606.

This procedure requires several stages:

1. Preparation of dimethylsulfate Dimethylformarnidadduktes

2. dye formation by condensation of the 1,3,3-trimethyl-2-methylenindoline with the dimethyl sulfate-dimethylformamide adduct and an aromatic amine in a time-separated order.

Object of the invention

The aim of the invention is a one-pot process for the synthesis of the dyes of the formula I in a purity required by the user.

Explanation of the essence of the invention

It has surprisingly been found that the dyes of the formula I are obtained in sufficient for the user Reinh when a 1,3,3-trimethyl-2-methylenindoline with a compound of formula

^ Ar ,

in which R and Ar have the abovementioned meanings, and ethyl orthoformate in a molar ratio of 1: 1.1: 1.3 in acetic acid and in Gegenwrt catalytic amounts of mineral acid at 70 to 8O ⁰ C are reacted.

Claims (1)

Invention claim: Process for the preparation of cationic dyes of the general formula anion in the X = H, alkyl or alkoxy, R = H and Ar = the radical of an optionally substituted alkyl or alkoxy substituted aryl group, or R and Ar together with the nitrogen atom represent a heterocyclic radical by reacting a 1,3,3-trimethyl-2-methylene indoline with a compound of the formula (I)