CS242130B1 - Method of 2,3-dimethyl-p-phenylendiamine production from azo-dye-stuffs - Google Patents

Abstract

Process for preparing 2,3-dimethyl p-phenylenediamine azo dyes prepared from 2,3- -dimethyl-1-aminobenzene by hydrogenation cleavage. For mono- or bisazo dyes of formula (I) OBJECTIVE · CH? (Y) n - Ar (N = N- (I)) wherein Ar represents an aromatic hydrocarbon residue with the number of carbons - C ^, Y is COOMe or s0jMe, Me is hydrogen or a cation, n = 1 to 3, m = 1 or 2 and X represents NH, or N = N ____ 7q or mixtures thereof act with hydrogen for pressure of 0.1 to 10 MPa in the presence of hydrogenation catalysts in a water environment preferably at pH 5-8 optionally organic solvents.

Description

The present invention relates to a process for the preparation of 2,3-dimethyl-p-phenylenediamine by reducing azo dyes prepared from 2,3-dimethyl-1-aminobenzene.

Reductive cleavage of azo dyes has hitherto been predominantly applied in determining the constitution of mono-, di- and polyazo dyes. For example, by titrating azo dye solutions with titanium tetrachloride, the number of -N = N-bonds can be quantitatively determined. The principle of azo dye cleavage is used in the production of some important intermediates such as p-aminosalicylic acid. The reducing agents used include, for example, metals in a mineral acidic medium, stannous chloride, dithionite, and other known reducing agents. 2,3-dimethyl-p-phenylenediamine. A disadvantage of the prior art processes for the preparation of 2,3-dimethyl-p-phenylenediamine from aminoazo dyes is the difficulty of separating the multi-component reaction mixtures in which, in addition to the organic constituents, the products of the reducing agents are present.

We have now found a process for the preparation of 2,3-dimethyl-p-phenylenediamine by reducing the azo dyes prepared from the 2,3-dimethyl-1-aminobenzene object of the present invention, which comprises treating the mono- or bisazo dyes of the general formula I (Y) _n Ar (-N = N- (o-X) _B (I)

242 130 where Ar is an aromatic hydrocarbon radical having carbon numbers of from C to C, Y is COOMe or SO4, Me is hydrogen or a cation ^CH and ^CH3 n = 1 to 3, mel or 2, X is N1 · ^ or t or

N = N <O / ~ ^NH2 mixtures thereof with hydrogen under superatmospheric pressure in _# 1 to 10 MPa in the presence of hydrogenation catalysts in the environment of water, preferably at a pH of 5-8 and optionally organic solvents.

The desired dyes are prepared, for example, by aniline sulfoacids or naphthylamine sulfonic acids or arainoarylcarboxylic acids or their salts in a known manner and coupled with a vicinal oxylidine, usually in an aqueous medium. If 2 to 3 solubilizing groups are present in the auxiliary active azo component, diazotization can be carried out by direct introduction of nitrite into acid solutions or suspensions of the azo component. For example, sulfanilic acid, p-aminobenzoic acid, metanilic acid, 1-naphthylamine-6- or 1-naphthylamine-7- or 1-naphthylamine-4-sulphocarboxylic acids, it is preferred to precipitate said acids from alkaline aqueous solutions with mineral acids to fine suspensions and diazotize them directly. Also, the alkaline solutions of said monobasic acids can be mixed with the calculated amount of nitrites and the mixture added to the dilute mineral acids with stirring.

In diazotizations, whether direct or indirect, it is advantageous to maintain low temperatures, as is customary in such operations. Coupling with 2,3-dimethyl-1-aminobenzene can be accomplished by adding the amine or a salt thereof to the reaction mixture after diazotization of the selected active azo component. Alternatively, the reaction mixture obtained by diazotization can be added to the present vic. o-xylidine.

In the case of hydrogenation of bisazo dyes, the dye preparation is analogous, but as the auxiliary active azo component, for example, one of the phenylenediamine sulfo acids or 4,4'-diaminostilbene-2,2''-disulfonic acid or diaminodiphenyldisulfonic acid or salts thereof or some other known bifunctional azokomponenty. Thus, both symmetrical and asymmetric bisazo dyes can be hydrogenated.

According to the present invention can be prepared by 2 _t 3-dimethyl-para-phenylenediamine and a mixture of the azo dyes of formula IY and can be processed as a mixture of the azo dyes prepared by diazotising a mixture of l-naphthylamine-6- and -7-sulphonic acids (Cleve acids) and subsequent coupling 8 2, 3-dimethyl-1-aminobenzene.

It is not decisive for the process according to the invention how and from which azo components the dyes are obtained, whether the isolated dyes, either in the form of a paste or dry matter, or the reaction mixtures resulting from the dye synthesis, are used.

The hydrogenation cleavage and bonding takes place under a hydrogen overflow of 0/1 to 10 MPa; it is possible to work at higher pressures, but it is uneconomic. Catalysts may be any hydrogenation catalyst such as Raney nickel-copper3, cobalt, supported catalysts such as nickel and coal, platinum on diatomaceous earth, palladium on carbon and the like.

In the new process, it is surprising the ease with which the aza bond is uniquely hydrogenated; This fact is probably associated with the application ^ ^ strongly gkumulovaného aterického effect caused by grouping -N = N-O-NH _2, which e occurs in all dyes of the above formula 1 ·

The rate of hydrogenation cleavage and binding of dyes of the formula I and e increases with temperature and is already measurable at 20 ° C.

At 70 ° C at a hydrogen pressure of 20 bar in the presence of Raney nickel, the cleavage of the dye prepared from sulfanilic acid and 2,3-dimethyl-1-aminobenzene takes place within 10 minutes. However, it is advantageous to operate at a pH of about 7, where the corrosion stress of the production equipment is minimized.

In the reaction mixtures after cleavage of the azo dyes, the desired 2,3-dimethyl-p-phenylenediamine and the aminosulfoic acid and the p-phenylenediamine are present. a salt thereof, used as an auxiliary active azo component;

The 2,3-dimethyl-p-phenylenediamine is separated from the aminosulfoic acid and the amine sulfonic acid by a known method. salts thereof, which are preferably

242 130

4 can return to the process. If a separation process is chosen to allow perfect isolation of both products, the state of the art can be achieved in which the only waste is slightly contaminated water.

Hydrogenation cleavage of azo dyes, characterized by formula (I), has some technically significant advantages over prior art reduction processes:

In the process according to the invention, no other components are introduced into the system. The catalyst used is, as a solid phase, mechanically easily separated or returned to the process, and the two-component system can then be relatively easily separated.

The hydrogenation reaction mixtures, containing easily oxidizable 2,3-dimethyl-p-phenylenediamine, are stable to oxidation over a prolonged period in the presence of the catalyst.

The production can be modified so that after the isolation of the components only slightly polluted water leaves the process and the process is transferred to waste-free tetnology.

Example 1

Pour 300 ml of water into a stainless steel autoclave, add 0.1 mol of sodium sulfoaminoazo dye prepared by diazotization of sulfanilic acid followed by coupling with 2,3-dimethyl-1-aminobenzene and 3 g of Raney nickel aqueous paste.

The autoclave was charged with 4 MPa of hydrogen, heated to 70 ° C and held at that temperature for 2 hours.

242 130

In the reaction mixture obtained, 0.0980 mol of 2,3-dimethyl-p-phenylenediamine was determined, in addition to the same amount of sodium sulfanilic acid. This mixture may be resolved by any of the known methods.

Similarly, the potassium or ammonium salt of said sulfoaminoazo dye is hydrogenated.

Example 2

Pour 300 ml of water into a stainless steel autoclave, add 0.1 mol of sodium dye prepared by coupling of diazotized methanilic acid with 2,3-dimethyl-1-aminobenzene and 2 g of palace and on activated carbon. Following an analogous hydrogenation to the example, a reaction mixture containing 0.0983 mol of 2,3-dimethyl-p-phenylenediamine in addition to the sodium methanilic acid salt is obtained.

Example 3

Analogous to Example 1, 0.1 mol of disodium dye salt prepared from diazotized 1-naphthylamine-4,6-disulfonic acid and / or dye is hydrogenated. its sodium salt and 2,3-dimethyl-1-arainobenzene · The reaction mixture contains 0.0981 mol of 2,3-dimethyl-p-phenylenediamine next to the disodium salt of 1-naphthylamine-4,6-disulfonic acid.

Example 4

A mixture of 200 ml of water and 100 ml of 96% ethanol is poured into a stainless steel autoclave, and the components as in Example 1 are added. The hydrogen is gradually charged to the autoclave with the mixture heated to 95 DEG C. so as not to exceed 0.4 MPa. After 5 hours, the contents of the reactor were cooled to 25 ° C and the mixture analyzed. 0.0980 mol of 2,3-dimethyl-p-phenylenediamine was formed.

Example 5

Pour 300 ml of water into a stainless steel autoclave, add 0.1 mol of a mixture of sodium salts of sulfoaminoazo dyes prepared by diazotizing a mixture of 1-naphthylamine-6- and -7-sulfoacids (a mixture of so-called Cléve acids) followed by coupling with 2,3- dimethyl-1-aminobenzene g platinum catalyst (Pt / C). After 2 hours hydrogenation

242,130 at 70 ° C, a reaction mixture is obtained which contains 0.0979 mol of 2,3-dimethyl-p-phenylenediamine in addition to the mixture of sodium salts of Ceve acids.

Example 6

Analogously to Example 1, the triple potassium salt of a dye prepared from 1-naphthylamine-3,6,8-trisulfonic acid and 2,3-dimethyl-1-aminobenzene was hydrogenated. A reaction mixture is formed which comprises 2,3-dimethyl-p-phenylenediamine and 1-naphthylamine-3,6,8-trisulfonic acid tripotassium salt.

Example 7

Analogous to Example 1, 0.05 mol of bisazo dye sodium salt prepared by tetrazotation of 0.05 mol of 4,4'-diaminostilbene-2,2'-disulfonic acid is coupled by hydrogenation followed by coupling with 0.1 mol of 2,3-dimethyl- 1-aminobenzene. A mixture is obtained comprising 0.0982 moles of 2,3-dimethyl-p-phenylenediamine in addition to the disodium salt of 4,4'-diaminostilbene-2,2 ^from disulfonic acid and a small amount of disodium salt of diaminodibenzyldisulfonic acid.

Example 8

Analogously to Example 1, the bisazo dye of the formula is hydrogenated

NaO ^ S

A mixture was obtained which contained 0.0978 mol of 2,3-dimethyl-p-phenylenediamine next to the disodium salt of 1-naphthylamine-4,6-disulfonic acid.

^{Example 9} 242 130

Analogously to Example 1, the azo dye from β, 1 mole of p-aminobenzoic acid and 0.1 mole of 2,3-dimethyl-1-aminobenzene were hydrogenated. The reaction mixture contained 0.0978 mole of 2,3-diraethyl-p-phenylenediamine.

Similarly and with the same result, 5-aminobenzenedicarboxylic acid can be used.

Claims (3)

SUBJECT OF THE INVENTION 1. A process for the production of ethyl-p-phenylenediamine from azo dyes prepared from 2,3-di-ethyl-1-aminobenzene, characterized in that the mono- or bisazo dyes of the formula I are: C 3, ^CH 3 (Y) _n 'Ar ( -ν = ν7ο ^. X) (I) wherein Ar represents an aromatic hydrocarbon radical having a carbon number of 14 Y ^te θθθΜβ or SOgMe, Me is hydrogen or a cation, ^CH 3 ^CH 3 n = l to 3, m = l or 2 and X is NH? Or The N = N, N-O-NH or mixtures thereof are treated with hydrogen at a pressure of 1 to 100 bar in the presence of hydrogenation catalysts in a water environment, preferably at a pH of 5 to 8, optionally in the presence of organic solvents. 2. A process according to claim 1, wherein the bisazo dyes prepared from bifunctional active azo components and 2,3-dimethyl-1-aminobenzene are hydrogenated. 3. A process according to claim 1, wherein the bisazo dyes of the formula IX are hydrogenated CH ₃ CH ₃ CH ₃ CH ₃ (Y) Ar - N = N NH, wherein Ar, n and Y are as defined in point 1 above.