DE1081022B - Process for the preparation of dye intermediates - Google Patents

Description

Process for the preparation of dye intermediates The invention relates to a process for the preparation of novel heterocyclic dye intermediates of the formula in the-one X for NHZ and the other X for one hydrogen atom and one Z for 2 hydrogen atoms and the other Z for the groups stands, where one Y is NHz and the other Y is a hydrogen atom.

In this process, mixtures of corresponding isomers are always obtained Get connections.

The inventive method for the preparation of dye intermediates takes place by reacting a 2; 3-dichloro-1,4-naphthoquinone with naphthols in the presence of alkaline, acid-binding substances and is characterized in that 8-nitro-2,3-dichloro-1,4-naphthoquinone with a- or ß-naphthol or a dioxynaphthalene in which at least one o-position of each oxy group is unsubstituted, implemented and the nitro group in itself is reduced to the amino group in a known manner. The reduction usually takes place with sodium hydrosulphide or sodium hydrosulphite in an alkaline medium.

The amino compounds thus prepared are obtained in their leuco form. You can then in the usual way by oxidation, for. B. by treatment with air, converted into keto form.

According to the invention, pyridine is preferred as the alkaline acid binder, although other similar organic tertiary amine bases, such as tripropylamine, Dimethylcyclohexylamine, N-methylmorpholine or the lower alkylated pyridines, can be used. The alkaline acid-binding agent preferably acts simultaneously as a diluent for the reaction, which is carried out at 'elevated temperatures, expediently at the boiling point.

In the above reaction, the oxy group of the naphthol compound reacts with a chlorine atom of 8-nitro-2,3-dichloro-1,4-naphthoquinone, with hydrogen chloride is split off. The other chlorine atom reacts with the one in the o-position to the oxy group standing free hydrogen atom, whereby another hydrogen chloride molecule is split off will. If the naphthol contains a second oxy group, this occurs between this second oxy group of naphthol and another molecule of 8-nitro-2,3-dichloro-1,4-naphthoquinone an analogous reaction. Since the directing influence of the nitro group in the 8-nitro-2,3-dichloro-1,4-naphthoquinone is ambiguous, occurs between the two chlorine atoms in the 8-nitro-2,3-dichloro-1,4-naphthoquinone in reacting with the oxy group of naphthol or with the in o-position to the oxy group a certain competition and a mixture of isomeric compounds is always formed.

When using a monooxynaphthalene is one of the obtained isomeric compounds the nitro group in the nitro compound obtained as an intermediate in the cis position to the heterocyclic oxygen atom, while in the other isomeric Connect the nitro group trans to the heterocyclic oxygen atom stands.

If, however, a dioxynaphthalene is used as the reaction component, the possibility of condensation in the cis or trans position occurs with each oxy group, and the following isomeric compounds result; I = cis-cis, II = cis-trans and III = trans-trans. The corresponding amino compounds are then obtained from these nitro compounds by reduction.

The exact amount of each isomer formed during a reaction is not known, but the isomers can optionally be determined by conventional methods separated from their mixtures.

The compounds prepared according to the invention can be used as intermediates serve to produce new vat dyes.

The following examples, in which - unless otherwise stated - all parts are parts by weight illustrate the invention.

Example 1 A charge of 90 parts by volume of pyridine, 5.8 parts by weight of α-naphthol and 10.9 parts by weight of 8-nitro-2,3-dichloro-1,4-naphthoquinone was stirred at reflux temperature for 6 hours. The reaction product was filtered off at room temperature, washed with pyridine and acetone and dried. A mixture of the two isomeric compounds of the formula was obtained obtained, where in each case one X stands for NO 2 and the other X stands for a hydrogen atom.

A charge of 1500 parts by weight of a 20% aqueous sodium hydroxide solution and 6 parts by weight of the above mixture of the two isomeric nitro compounds was heated to 70 ° C., at which temperature 24 parts by weight of sodium hydrosulfite were added and stirring was continued at 70 ° C. for a further half an hour continued. Air was bubbled through the solution while cooling to room temperature. The precipitating amino compounds had the following formula in each of which one X 'stands for NH2 and the other X' stands for a hydrogen atom. They were filtered off, washed neutral and dried. M.p. 303 to 305 ° C; Absorption maximum 500 m # L.

Example 2 A charge of 90 parts by volume of pyridine, 5.8 parts by weight of β-naphthol and 10.9 parts by weight of 8-nitro-2,3-dichloro-1,4-naphthoquinone was reacted as described in Example 1. The reaction product consisted of a mixture of the two isomeric compounds of the formula where in each case one X stands for NO 2 and the other X stands for a hydrogen atom. The mixture was, as described in Example 1, to the corresponding amino compounds of the formula in each of which one X 'stands for N H2 and the other X' for a hydrogen atom, reduced.

Example 3 A charge of 75 parts by volume of pyridine, 3.2 parts by weight of 1,5-dioxynaphthalene and 10.9 parts by weight of 8-nitro-2,3-dichloro-1,4-naphthoquinone was reacted as described in Example 1. The reaction product consisted of a mixture of isomeric compounds of the formula in which in each case one X and one Y stands for NO 2 and the respective other X or Y stands for a hydrogen atom. These compounds were then, as described in Example 1, to give the corresponding amino compounds of the formula in each of which one X 'and one Y' stands for N H2 and the respective other X 'or Y' stands for a hydrogen atom.

Claims (1)

PATENT CLAIM: Process for the preparation of dye intermediates by reacting a 2,3-dichloro-1,4-naphthoquinone with naphthols in the presence of alkaline, acid-binding substances, characterized in that 8-nitro 2,3-dichloro-1,4-naphthoquinone with α- or β-naphthol or a dioxynaphthalene in which at least one o-position of each oxy group is unsubstituted, reacted and the nitro group is reduced to the amino group in a manner known per se. Documents considered: German Patent No. 461650; Chemical Reports, 80, pp. 47-53 (1947). A priority document was displayed when the registration was announced.