GB2038809A - Chemical compounds - Google Patents

Abstract

Anthraquinone compounds having the formula: <IMAGE> wherein X and Y are each independently a hydrogen atom or a hydroxyl group; and R<1>, R<2> and R<3> are each independently a hydrogen atom or a -CH2Z group in which Z is an organic radical attached through a carbon atom thereof to the -CH2- group, the said carbon atom carrying no hydrogen atoms or a single hydrogen atom, provided that at least one of R<1>, R<2> and R<3> is a -CH2Z group. The compounds are useful as intermediates in the manufacture of anthraquinone dyes.

Description

SPECIFICATION Chemical compounds This invention relates to chemical compounds and more particularly to certain anthraquinone compounds and their manufacture.

According to the present invention there are provided anthraquinone compounds having the general formula:

wherein X and Y are each independently a hydrogen atom or a hydroxyl group; and R1, R2 and R3 are each independently a hydrogen atom or a -CH2Z group in which Z is an organic radical attached through a carbon atom thereof to the -CH2- group, the said carbon atom carrying no hydrogen atoms or a single hydrogen atom, provided that at least one of R1, R2 and R3 is a -CH2Z group.

Examples of the groups represented by Z are secondary and tertiary alkyl, carboxyl, alkoxycarbonyl, alkoxyalkoxycarbonyl and -CONR4R5 in which R4 and R5 each independently represent a hydrogen atom or an alkyl group.

It is preferred that the alkyl groups represented by R4, R5 and Z are lower alkyl groups, and that the alkoxycarbonyl and alkoxyalkoxycarbonyl groups represented by Z are lower alkoxycarbonyl and lower alkoxy lower alkoxycarbonyl groups, respectively.

By "lower alkyl" and "lower alkoxy" we mean alkyl and alkoxy groups respectively which contain from 1 to 4 carbon atoms.

Compounds of formula (I) in which Z represents a secondary or tertiary alkyl group may be prepared by reacting an anthraquinone compound of

formula:, (Il) x c wherein X and Y have the meanings stated above, with an aldehyde of formula Z.CHO, wherein Z is a secondary ortertiary alkyl group, in the presence of sodium dithionite and sodium hydroxide. The aldehyde Z.CHO must be such that it is incapable of undergoing an aldol condensation or which undergoes a retro-aldol condensation under the reaction conditions.

An example of an aldehyde Z.CHO which can be used in the above process of preparation is isobutyraldehyde.

The reaction may be carried out at a temperature from 20 to 1000C, conveniently from 60 - 80"C, for a reaction period from 1 to 24 hours. The reaction product separates out from the aqueous mixture and can be collected, washed with water and dried. Yields are virtually quantitative and the compounds are essentially pure.

Compounds of formula (I) in which Z represents a carboxyl group may be prepared by reacting an anthraquinone compound of formula (II) with glyoxylic acid in the presence of sodium dithionite and sodium hydroxide, under reaction conditions similar to those described above. In this case the reaction product, being a carboxylic acid, remains in solution and is ìsolated by acidifying the reaction mixture, when the product precipitates and can be isolated as described previously.

Compounds of formula (I) in which Z represents an alkoxycarbonyl or alkoxyalkoxycarbonyl group may be prepared from the corresponding compound of formula (I) in which Z represents a carboxyl group by esterification with the appropriate alkanol or alkoxyalkanol. Examples of alkanols and alkoxyalkanols which may be used are methanol, ethanol, methoxyethanol, ethoxyethanol and butoxyethanol. The esterification is carried out by known methods, for example, by heating the carboxylic acid in excess of the esterifying alkanol or alkoxyalkanol under reflux in the presence ofp4oluenesulphonic acid as catalyst.

Compounds of formula (I) in which Z represents a -CONR4R5 group as hereinbefore defined may be prepared from the corresponding compound of formula (I) in which Z represents a carboxyl group by conversion of the latter into its acid chloride, for example, by reaction with thionyl chloride, followed by reaction of the acid chloride with an amine of formula R4R5NH wherein R4 and R5 have the meanings defined above.

These various methods of preparation, which constitute further features of the invention, enable compounds of formula (I) to be made more cheaply and in excellent yield from a-hydroxy substituted anthraquinones than by existing methods.

The anthraquinone compounds of formula (I) are useful as intermediates in the preparation of anthraquinone dyestuffs. Thus, the compounds may be nitrated and reduced using standard methods whereby amino groups may be introduced. These amino derivatives are dyestuffs which may be further reacted to introduce halogen atoms, for example, by reaction with sulphuryl chloride, or the amino groups may be alkylated, for example, by reaction with formaldehyde.

The invention is illustrated by the following Examples in which parts and percentages are by weight.

Example 1 To 20 parts of sodium hydroxide in 200 parts of water are added 24 parts of 1,8-dihydroxyanthraquinone and 30 parts of sodium dithionite. A dark red solution is obtained. 15 Parts of isobutyraldehyde are then added, the reaction mixture is heated at 60-70"C for 5 hours and then cooled to room temperature. The solid which separates is filtered off washed with water and dried to give 34.5 parts of yellow 2,7-diisobutyl-1,8dihydroxyanthraquinone (99% yield), m.p. 140C.

(a) Nitration and reduction of the product gives 4,5-diamino-2,7-di-isobutyl-1,8-di-hydroxyanthraquinone m.p.190 , free from undesirable ss-aminated products. This dyestuff dyes polyester in clear reddish-blue shades with good technical properties.

(b) Chlorination of 4,5-diamino-2,7-di-isobutyl-1,8 dihydroxyanthraquinone with sulphuryl chloride gives the corresponding 3,6-dichloro product m.p. 291", which continuously dyes polyester in bright blue shades with excellent technical properties.

Example 2 The procedure of Example 1 is followed using only 8 parts of isobutyraldehyde to give a mixture of 2-isobutyl and ,'ir-di-isobutyl-l ,8-dihydroxyanthraquinone.

(a) Nitration and reduction of the product using standard methods gives a mixture of mainly 4,5-diamino-2-isobutyl (and 2,7-di-isobutyl)-1 ,8-dihydroxyanthraqu inone m.p. 130" which dye polyester in reddish-blue shades with particularly good build-up.

(b) Partial methylation of blue dyestuff (a) with formaldehyde gives a mixture of N-methylated products which dyes polyester in strong navy-blue shades.

Example 3 The procedure of Example 1 is followed using 1 ,5-dihydroxyanthraquinone in place of the 1,8-isomer. 26 Parts of 2,6-di-isobutyl-1 ,5-dihydroxyanthraquinone, m.p. 188", are obtained.

(a) Nitration and reduction of the product by standard methods gives 4,8-diamino-2,6-di-isobutyl-1,5- dihydroxyanthraquinone, m.p. 286-1 88", which dyes polyester in bright reddish-blue shades.

Claims (6)

1. Anthraquinonecompounds having the formula:

wherein X and Y are each independently a hydrogen atom or a hydroxyl group; and R1, R2 and R3 are each independently a hydrogen atom or a -CH2Z group in which Z is an organic radical attached through a carbon atom thereof to the -CH2- group, the said carbon atom carrying no hydrogen atoms or a single hydrogen atom, provided that at least one of R', R2 and R3 is a -CH2Z group.

2. An anthraquinone compound as claimed in claim 1 an specifically identified herein.

3. A method for the preparation of an anthraquinone compound as defined in claim 1 wherein Z is a secondary or tertiary alkyl group which comprises reacting an anthraquinone compound of the formula:

wherein X and Y have the meanings stated in claim 1, with an aldehyde of formula Z.CHO, wherein Z is a secondary or tertiary alkyl group, in the presence of sodium dithionite and sodium hydroxide.

4. A method as claimed in claim 3 wherein the aldehyde is isobutyraldehyde.

5. A method as claimed in claim 3 conducted substantially as hereinbefore described with reference to any one of the foregoing Examples.

6. An anthraquinone compound whenever prepared by a method claimed in any one of claims 3 to 5.