DE553039C - Process for the preparation of aminoanthraquinones - Google Patents

Description

The invention relates to a process for the preparation of aminoanthraquinones, in particular 2-AminO "3-chloroanthraquinone.

It has been found that in halogenated aminoanthraquinones, the halogen atoms in the α position contain, the latter can be replaced by hydrogen if the haloaminoanthraquinones in aqueous Suspension in the presence of alkali or alkaline earth metal hydroxides with reducing agents, such as metallic zinc or aluminum, hydrosulfites or reducing sugars. For example, i, s-dichloro-a-aminoanthraquinone with alkali metal hydrosulfite is obtained at elevated temperature 2-amino-3-chloroanthraquinone, according to known Process such as recrystallization from an organic solvent or by precipitation Sulfuric acid, can be purified.

Other aminoanthraquinone derivatives can also be removed by this method of the halogen can be produced from the α-position, for example i-amino-2-bromoanthraquinone from 1-amino-2, 4-dibromoanthraquinone, i-amino-2-chloroanthraquinone from i-amino-2, 4-dichloroanthraquinone, i-amino-2-chloroanthraquinone from i-amino-2-chloro-4-bromoanthraquinone, 1-amino-2-methylanthraquinone from 1 - amino - 2 - methyl-4-bromoanthraquinone, 2,6-diaminoanthine rachinone from 2,6-diamino-i, 5-dichloroanthraquinone.

It is true that there is already a method of replacing halogen atoms in polyhalogenated ones Aminoanthraquinones partially or completely known by hydrogen atoms after looking at polyhalogenated aminoanthraquinones or their derivatives, with the exception of alkali metal alcoholates, act as reducing agents leaves.

The solvent used in this process is essentially pyridine and then reduced with iron filings and glacial acetic acid. With this procedure, it is imperative necessary to make it economical to recover the pyridine. In the present procedure, however, the Exchange of the halogen atoms in the α position for hydrogen atoms in aqueous solution. Another advantage is that the leuco compound is formed immediately. So you can get to the desired one without any additional measures or detours Leuco connection.

The method is explained below using a few exemplary embodiments. All parts are parts by weight.

Example ι

The example describes the preparation of crude i, 3-dichloro-2-aminoanthraquinone from 2-aminoanthraquinone.

40 parts of 2-aminoanthraquinone are suspended in 400 parts of nitrobenzene. In the well-stirred mixture, chlorine is passed in until the formation of dichloro-2-aminoanthraquinone hydrochloride corresponding increase in weight is achieved. The mixture is then boiled for 1 hour, and after leaving it for a few hours at ordinary temperature, the product is filtered off. The hydrochloride obtained is in this way with water hydrolyzed.

The melting point of the crude product is 215 to 218 ^° C. It has a brownish yellow color. '

Example 2

2 parts of dichloro-aminoanthraquinone are suspended in 50 parts of water. 2 parts Sodium hydroxide and 2 parts sodium hydrosulfite are added and the mixture Boiled for 1 hour while stirring. You then send air through the mix and when nothing more precipitates, the product is filtered off.

Example 3

This example describes the purification of crude 2-amino-3-chloroanthraquinone, the following the procedure of Example 2 is obtained.

10 parts of crude 2-amino-3-chloroanthraquinone are dissolved in 100 parts of concentrated sulfuric acid. It is so much water is added slowly to the well stirred solution until the strength of the acid at 80 o / _o lowered. The precipitating sulfate of 2-amino-3-chloranthrachinons is filtered off, washed with 8o ° / ₀ hydrochloric acid and then boiled with water for the purpose of hydrolysis of the sulfate.

The purified product melts at around 310 ° C.

It can be brominated and provides i-bromo ^ -amino ^ -chloranthraquinone, the is a valuable starting material for the production of synthetic dyes.

Example 4

10 parts of 1,3-dichloro-2-aminoanthraquinone are suspended in a solution of 70 parts of caustic alkali in 90 parts of water and then 5 parts of glucose are added. The mixture is stirred at 125 to 130 ^° C. for ι hour. Air is then allowed to enter the warm mixture until no further precipitation occurs. The product is filtered off and washed free of alkali. It consists essentially of 2-amino-3-chloroanthraquinone, which can be further purified according to the method of Example 3.

Example 5

10 parts of i-chloro-aminoanthraquinone are suspended in a solution of 70 parts of potassium hydroxide in 90 parts of water and 5 parts of glucose are added. The mixture is stirred at 125 to 130 ^° C. for about ¹ ₂ hours, then diluted with water and air passed through until the product is completely precipitated. It is filtered off, washed free of alkali and consists essentially of 2-aminoanthraquinone.

Exampleö _g

10 parts of i-bromine ^ -amino ^ -chloranthraquinone are mixed with 400 parts of water and 10 parts of calcium oxide. The mixture is stirred and a temperature of 60 to 70 ⁰ C treated with sodium hydrosulfite 2'Teilen. Stirring is continued, and a further 10 parts of sodium hydrosulfite were added ₂ hours in the course of about 1 ¹ Z. Air is then blown through the mixture until oxidation is complete, whereupon the product is filtered off. The filtrate is washed alkali-free and dried.

It consists essentially of 2-amino-3-chloroanthraquinone.

Example 7

10 parts of i-bromo ^ -amino-s-chloranthraquinone are stirred in a solution of 12 parts of sodium hydroxide in about 68 parts of water. The mixture is heated to the boiling point and 7 parts of finely divided zinc dust are introduced in about ^{1 1} ₂ hours. The oxidation is brought about by blowing in air, the mixture is acidified with hydrochloric acid, filtered, the residue is washed free of acid and then dried. The product consists essentially of 2-amino-3-chloroanthraquinone.

Examples

10 parts of i-amino-2, 4-dichloroanthraquinone, 10 parts of sodium hydrosulfite, 10 parts of caustic soda and 250 parts of water are mixed with one another in the cold. The temperature is ^{increased to 65 °} C. over the course of one hour and held at this temperature for 2 hours. Air is then blown in until all of the anthraquinone derivative has precipitated. It is filtered off, washed and dried. It consists essentially of i-amino-2-chloroanthraquinone.

Example 9

13.2 parts of slaked lime, 10 parts of i-amino- I ₁ 4-dibromoanthraquinone and 150 parts.

Of water are heated together at 50 ⁰ C. At this temperature, 6 parts of sodium hydrosulfite for a time of ¹ /. Hours added. Air is then blown through the mixture. The precipitate, which consists essentially of i-amino-2-bromoanthraquinone, is filtered off, washed and dried.

In general, it should be noted that instead of zinc aluminum and instead of glucose other reducing agents
can find.

Sugar usage

Claims (1)

Claim: Process for the preparation of aminoanthraquinones, in particular 2-amino-3-chloroanthraquinone, characterized in that halogenated aminoanthraquinones which contain halogen in the α-position, in aqueous suspension in the presence of alkali or alkaline earth metal hydroxides with reducing agents such as metallic Zinc or aluminum, hydrosulphites or reducing sugars can be treated.