DE1023771B - Process for the diazotization of aromatic amines which are sparingly soluble in water, the salts of which are easily hydrolyzed in water - Google Patents

Description

GERMAN

KL.12q 10

INTERNAT. KL. C 07 C

PATENT OFFICE

TO M E LDE DAY:

NOTICE
THE REGISTRATION
AND ISSUE OF THE
LEGAL LETTERING:

F 19749 IVh / 12 q MARCH 9, 1956

- February 6, 1958

Aromatic amines are usually diazotized in the presence of excess amounts of mineral acid. As Hantzsch (Reports of the German Chemical Society, 32, p. 1691) has shown, it happens the diazotization of aniline via the undissociated aniline salt. Weaker basic for diazotization Amines, such as polyhaloanilines, will use larger amounts of acid; H. higher acid concentrations needed to suppress the hydrolysis of the salts and the formation of diazoamino compounds or to avoid self-coupling (Stein, reports of the German Chemical Society, 27, p. 2806, and Alt schul, Journal der practical chemistry, 54, p. 508). If the amine is not dissolved by a large excess of acid can be, the diazotization can in some cases, for example in the case of nitrochloroanilines, in mineral acid Perform suspension, provided that the base is finely divided as a paste for application is coming (Fierz-David, Color Chemistry, 1952, P. 238). If the base salts are sparingly soluble, the diazotization is carried out according to the German method Patent 615 744 with very fine distribution of the base salts with emulsifiers effective in an acidic medium, such as monooleylethylenediamine trimethylammonium methyl sulfate, achieved. In this case too, excess mineral acid is used. Dinitraniline and nitrodichloroanilines are not or only very incompletely diazotized in an aqueous medium. These strongly negatively substituted amines can only be used in concentrated sulfuric acid or a mixture of concentrated sulfuric acid and glacial acetic acid, in which the bases are present as undissociated sulfuric acid salts, be diazotized smoothly (Fieser and Fieser, "Textbook of Organic Chemistry", 1954, p. 702).

According to the previously customary known processes, it is possible to use the customary aromatic To diazotize amines in a technically satisfactory manner. Of these, the water-insoluble ones have amines great importance as diazotization components for the ice color technique. A large part of these amines is only marketed in the form of the diazo salts, because their diazotization after that in the dye works common methods is difficult or impossible to carry out. However, diazo salts are only limited shelf life; their manufacture and storage are not without risk. It therefore consists in the Dyeing technology, also with regard to economic reasons, the need for such technically valuable aromatic amines, which so far mainly or exclusively because of the difficult diazotization in the form of their diazo salts are commercially available to have diazotization processes which allow it to be carried out in a simple manner Wise solutions of the diazo compounds to produce a process for diazotizing aromatic compounds Amines ,, which are sparingly soluble in water

Ii '"■ ■',

whose salts are easily hydrolyzed in water

Applicant:

Paint factories Bayer Aktiengesellschaft, Leverkusen-Bayerwerk

Dr. Detlef DeIf s, Opladen, Dr. Erich Lehmann, Burscheid, and Dr. Heinrich Morschel, Leverkusen,

have been named as inventors

provide, for example, do not contain a large excess of mineral acids before further use would have to be neutralized and, as a result of the salts formed, the dyeing process could disturb.

It has now been found that, surprisingly, it is possible to obtain primary aromatic substances which are sparingly soluble in water Amines <© d € * = s © teh € = f> M-mä, s & - ^ Aaaiee, their Easily hydrolyze salts in water by exposure to nitrous acid in a weakly acidic medium to be converted smoothly into their diazonium compounds. An essential precondition for diazotization in a weakly acidic medium is the fine distribution of the bases used. The particle size should expediently below 30 μ, preferably below 10 μ. Simultaneous use is also advantageous a dispersant. Liquid amines can be produced by means of known emulsifying agents that work in an acidic medium are effective to be dispersed in water, while solid bases are dry or moist, if appropriate with the use of a dispersing agent. For the method according to the invention is further characteristic that the selection of a certain pjj range, which for each amine is specific and depends on its constitution or basicity, provides particularly favorable results.

An acidity of the diazotization solution, the one

also result in only partial salt formation of the amines

5Q should be avoided, as this affects the particle size the amines to be diazotized can change in the sense of an enlargement. Likewise is a Pjj range that is above the optimal value, harmful, since under these conditions the formation

709 698/429

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is promoted by diazoamino compounds. To avoid the formation of diazoamino compounds, a constant excess of nitrous acid during the diazotization reaction is advantageous.

According to the present method can be poorly soluble, relatively basic amines, such as ρ - aminoazo compounds, for example 4 - Amino - 2,5 - dimethoxy-4'-nitro-azobenzene, diazotized at _pH 3 to 4 smooth.

Example 4

A mixture of 525 parts by weight of 2-nitro-1-aminobenzene and 975 parts by weight of a dispersing or wetting agent (1) is added with 160 Parts by weight of water are divided in a suitable kneader until the nitroaniline has an average particle size of 8 μ is reached. The kneaded product is ground after drying. In the desired concentration suspended in water, it becomes in one

Other poorly soluble amines, the salts of which are _{diazotized in io p H} 2.9. After 5 minutes it becomes clear

d to W D

Obtained diazonium salt solution with almost quantitative yield.

Example 5

A mixture of 525 parts by weight of 1-aminoanthraquinone, 875 parts by weight of a dispersing or wetting agent (1) and 100 parts by weight of a The dispersant or wetting agent (2) becomes like this in a kneader after adding 280 parts by weight of water

Water hydrolyze readily, will be at p _H values
diazotized, for example for 2-nitroaniline at p _H
And 2.6 to 2.9 for 2-Aminodiphenylsulfon at p _H 1.7
to 2.0. Although so far it has been assumed
that such strongly negatively substituted amines in
strongly mineral acid solution must be diazotized in order to form diazoamino compounds
to avoid, it turns out that surprisingly
in the process of the present application despite
of working in a less strongly acidic medium, the a ° grind for a long time until an average particle size of the formation of diazoamino compounds has practically reached 3 μ. The dried and ground can be avoided. ■ Product is added in the desired concentration

. ·, Ι a p _H 1.8 diazotized. After three hours of diazo

A yield of 83% is achieved, for example, for the duration of the experiment.

A mixture of 300 parts by weight of 2'-nitro-25 From the diazotization residue is as usual ab-2,4'-dimethyl-5-methoxy-4-aminoazobenzene, 600 filtered.

parts by weight of a dispersant or wetting agent (1) Example 6

of the type of a condensation product from naphtha

linsulfonic acid and formalin in the form of its alkali 750 parts by weight of a 20% paste of the through

salt and 100 parts by weight of a dispersing or coupling of diazotized; 4-nitroaniline with 2,5-di-wetting agent (2) of an alkylnaphthalenesulfonemethoxy-1-aminobenzene type and filtration acid salt, e.g. butylnaphthalenesulfonic acid Na-4'-nitro-2,5-dimethoxy-4-aminoazobenzene trium, with the addition of 180 parts by weight with 100 parts by weight of an emulsifier from 50 GeWasser divided in a kneader until a mean part by weight of olein polyglycol ether and 50 weight particle size of the aminoazobenzene derivative of 5 μ 35 parts diglycol mixed well. That reaches through the copper is. After drying, the resulting fine distribution of the aminoazo body is obtained

remains completely intact.

300 parts by weight of this mixture are with

250 parts by weight of water stirred; after addition

nitrite diazotized at a p _H 3.0 to 3.5. The 4 ° of 120 parts by weight of a 50% acetic acid yield of the diazotization is almost 100%. are 85 parts by weight of a 10% nitrite solution

Ground product. For diazotization, the powder is suspended in water in the desired concentration and after adding acetic acid and sodium

Example 2

A mixture of 1050 parts by weight of a 26% paste of 4'-nitro-2,5-dimethoxy-4-aminoazobenzene and 500 parts by weight of a dispersing or wetting agent (1) is mixed in a suitable kneading apparatus divided until a mean particle size of the amino azo compound of 3 μ is reached.

stirred in. The diazotization takes place with repeated stirring at 20 to 30 ° within one half an hour with excellent yield.

Example 7

1510 parts by weight of a 20% paste of the through Coupling of diazotized! 4 - Get nitroaniline with 2,5-dimethoxy-l-ammobenzene and filtration

The resulting paste is diluted with water to the overall 50 nen 4'-nitro-2, placed 5-dimethoxy-l-aminoazobenzene werwünschte concentration and, after addition of the 302 parts by weight of dextrin and 43 Gewichtsvon acetic acid and sodium nitrite at a p _H 2.9 share an emulsifier made from abietic acid polyglycol

ether finely distributed. The homogeneous paste is dried in a vacuum drying cabinet and then marry. A powder is obtained which contains the aminoazo bodies in extremely fine particle sizes contains between 1 and 10 μ.

300 parts by weight of this powder are mixed with 1500 parts by weight of water and, after the dispersing agent or wetting agent (2) is added, 60 parts of 700 parts by weight of a 50% acetic acid are mixed with 210 parts by weight of water in a suitable with 500 parts by weight of a 10 ° / oigen nitrite solution kneader until a mean particle size of the base of 5 μ is achieved. The moist ground product is dried and crushed. the
Diazotization takes place after the mixture 65 has been suspended
in the desired concentration at a p _H 1.7 to
2.2. A diazotization yield of 96.5% is achieved after 30 minutes. From a minor one
Turbidity is removed by filtration as usual. ■ - 70

to 3.5 diazotized. The resulting clear solution has a diazotization yield of almost 100%.

Example 3

A mixture of 500 parts by weight of 2-aminodiphenyl sulfone, 800 parts by weight of a dispersing or wetting agent (1) and 100 parts by weight of one

diazotized at room temperature. The diazotization is complete after approximately 30 minutes. The yield of diazotization is practically quantitative.

Claims (1)

PATENT CLAIM: Process for the diazotization of aromatic amines that are sparingly soluble in water-e4e *. tfi whose salts are easily hydrolyzed in water, characterized in that one primary aromatic amines with a particle size smaller than 30 μ, preferably smaller than 10 μ, if necessary using a dispersing agent, in weakly acidic aqueous suspension with a _pH value greater than 1.5 treated with nitrous acid. Documents considered: German Patent No. 615 744. When the registration was announced, three pages of test reports were laid out. © 70i 898/42 »9.57