DE1259895B - Process for the preparation of 2, 4, 5, 7-tetrachlorophenthiazine - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

Number:
File number:
Registration date:
Display day:

C07d

German class: 12 ρ - 4/05

B75831IVd / 12p
March 10, 1964
1st February 1968

The invention relates to a process for the production of 2,4,5,7-tetrachlorophenthiazine (I):
Cl _TT Cl

It is known that 2,4,5,7-tetrachlorophenthiazine can be produced by the action of hydrogen chloride and dinitrogen trioxide in an ethereal solution on phenthiazine ("Reports of the German Chemical Society", Vol. 29, 1896, pp. 1362 to 1368) Action of hydrogen chloride and hydrogen peroxide in alcoholic solution on phenthiazine ("Journal of the Chemical Society", Vol. 97, 1910, pp. 1112 to 1118), by the action of hydrogen chloride on 2,7-dichloro-N-methylphenthiazine-S-oxide ("Journal of the American Chemical Society", Vol. 76, 1954, pp. 5455 to 5459), by the action of hydrogen chloride in glacial acetic acid solution on 2.7 ^: Dinitrophenthiazine-S-oxide ("Reports of the German Chemical Society", Vol. 46, 1913, pp. 2809 to 2820) or by the action of sulfonyl chloride on phenthiazine ("Chemical Abstracts", vol. 56, 1962, column 11 581 h to i). Furthermore is. it is known to produce 2,4,5,7-tetrachlorophenthiazine by reacting 3,3 ', 5,5'-tetrachlorodiphenylamine with sulfur in the presence of iodine. This process has the disadvantage that temperatures of over 200 ^° C. are required for this and that tetrachlorodiphenylamine, which is technically difficult to obtain, must be used as a starting point.

It is also known that phenthiazine can be obtained from diphenylamine and sulfur or sulfur dichloride receives ("Liebigs Annalen der Chemie", vol. 230, 1885, pp. 73 to 136).

However, the known processes for the production of 2,4,5,7-tetrachlorophenthiazine are cumbersome and give inadequate yields. In addition, the process products are usually heavily contaminated.

It has now been found that 2,4,5,7-tetrachlorophenthiazine (I) can be obtained in good purity and good Yields obtained when compounds of the general formula (II)

(Π)

Method of manufacture

of 2,4,5,7-tetrachlorophenthiazine

Applicant:

Aniline & Soda Factory in Baden

Aktiengesellschaft, 6700 Ludwigshafen

Named as inventor:

Dr. Joachim Kranz, 6700 Ludwigshafen

in which R is a hydrogen atom or a nitroso group and in which Xi and X2 are hydrogen atoms or nitro groups, or 2,4,4'-trinitrodiphenylamine, at 0 to 130 ⁰ C, preferably 50 to 100 ° C, with thionyl chloride (SOCl ₂ ) or disulfur dichloride (S2CI2) reacts.

It has also been found that it is advantageous to carry out the reaction in a solvent or diluent undertake, and that the process is particularly economical if you each 5 to 10 moles of the sulfur compounds mentioned with one mole each of the compounds (II) is allowed to react.

Suitable starting compounds (II) are primarily diphenylamine and also N-nitrosodiphenylamine, 4-nitrodiphenylamine, 4,4'-dinitrodiphenylamine, 2,4,4'-trinitrodiphenylamine and mixtures the last three compounds, as they are, for. B. occur on a large scale. The N-nitrosodiphenylamine behaves under the conditions of the process like the unsubstituted diphenylamine.

Suitable solvents and diluents are those with the chlorosulfur compounds do not react noticeably under the process conditions, including chloroform and Carbon disulfide.

It is expedient to proceed in such a way that one of the reactants is initially introduced and at room temperature or at a moderately elevated temperature with the other and the reaction mixture gradually heated even further as the reaction progresses to achieve complete conversion. To When the reaction has ended, the mixture is worked up as usual, e.g. B. with methylene chloride or methanol as a precipitant. The end of the reaction can be recognized, among other things, by the cessation of the evolution of hydrogen chloride.

709 747/543

In contrast to the methods known from the literature cited at the beginning, it allows the claimed synthetic route, the chlorination required to prepare the 2,4,5,7-tetrachlorophenthiazine and ring closure reaction in one process step with a reagent under mild and to make technically simple conditions. Also, with the help of this procedure, it is unexpectedly possible, the nitro and nitroso ίο accruing in technology according to the definition to convert compounds into the valuable 2,4,5,7-tetrachlorophenthiazine.

2,4,5,7-Tetrachlorophenthiazine and its nitrogen-substituted derivatives are valuable intermediates for organic syntheses, e.g. B. for the synthesis of dyes and drugs.

In the following, parts and percentages are units of weight.

For example.

250 parts of thionyl chloride are added at room temperature with 34 parts of diphenylamine while stirring. This forms a dark suspension which heats up ^{to 43 °} C. with the evolution of hydrogen chloride and sulfur dioxide. The mixture is stirred for a further 30 minutes at 70 ^° C., the process product crystallizing out. After cooling, the reaction mixture is diluted with 250 parts of methylene chloride and the 2,4,5,7-tetrachlorophenthiazine obtained is worked up as usual. The yield is 68% of theory, the melting point (from glacial acetic acid) is 234 ° C.

Example 2

35

A solution of 34 parts of diphenylamine and 220 parts of chloroform is added at room temperature while stirring ■ with 250 parts of disulfur dichloride, the mixture is heated for a further 1 hour to the boil, where hydrogen chloride escapes, and then works it up as usual. The yield at 2,4,5,7-tetrachlorophenthiazine is 87% of theory; Melting point 234 to 235 ° C.

Example 3

45

40 parts of N-nitrosodiphenylamine are introduced in portions into 250 parts of disulfur dichloride, the mixture heating up with evolution of hydrogen chloride. After half an hour, the process product is isolated as usual. Yield: 85.2% of theory; Melting point 233 to 234 ⁰ C (from glacial acetic acid).

With the same success, 165 parts of thionyl chloride can be used instead of 250 parts of disulfur dichloride use.

Example 4

On heating, 3 parts of 4,4'-dinitrodiphenylamine with 42 parts of sulfur monochloride for 2 hours at 100 ⁰ C, one obtains a brownish solution from which the 2,4,5,7-Tetrachlorphenthiazin crystallized. Yield: 69% of theory; Melting point 231 to 233 ° C (from glacial acetic acid).

Example 5

If 21.4 parts of 4-nitrodiphenylamine are heated with 95 parts of disulphur dichloride with stirring to 60 ° C., the 2,4,5,7-tetrachlorophenthiazine is obtained in 72% yield after the usual work-up; Melting point 233 to 235 ⁰ C (from carbon tetrachloride).

Examples

A crude mixture of approximately 65% 4-nitrodiphenylamine and 35% 4,4'-dinitro- and 2,4,4'-trinitrodiphenylamine is gradually introduced into 3350 parts of disulfur dichloride, the temperature rising to 116.degree. The thick crystal slurry is then stirred for a further 30 minutes, 1,300 parts of methylene chloride are then added and the 2,4,5,7-tetrachlorophenthiazine formed is isolated as usual. Yield: 84% of theory; Melting point 229 to 231 ^° C. (from N-methylpyrrolidone).

Claims (3)

Patent claims: 1. A process for the production of 2,4,5,7-tetrachlorophenthiazine, characterized in that that one compounds of the general formula (II) in which R is a hydrogen atom or a nitroso group and in which. Xi and X2 hydrogen atoms or nitro groups, or 2,4,4'-trinitrodiphenylamine at 0 to 130 ° C. with thionyl chloride or disulfur dichloride reacts. 2. The method according to claim 1, characterized in that diphenylamine is used as the starting compound (II) used. 3. The method according to claim X, characterized in that a mixture of 4-nitro, 4,4'-dinitro and 2,4,4'-trinitrodiphenylamine is used as the starting material. Considered publications: "Chemisches Zentralblatt", 1962, p. 17 213; Journal of the Chemical Society, Vol. 97, 1910, pp. 1112-1118. 709 747/543 1.68 © Bundesdruckerei Berlin