SU729191A1 - Method of aromatic amines stabilization - Google Patents

Description

I

This invention relates to an improved method for stabilizing aromatic amines which are used in the manufacture of dyes, pharmaceuticals, rubber antioxidants and photoagents.

It is known that aromatic amines rapidly oxidize and darken on contact with air. The change in the color of amines is due to the formation of compounds having a quinoid structure, azoxy compound, nitro derivatives, azo compounds, and phenazines. The oxidation of amines proceeds particularly intensively in the presence of 5 metals. The loss of amines due to oxidation during storage for a month can reach 4%. Oxidized amines are not suitable for synthesis without purification, which, as is known, is associated with 20 additional loss.

To preserve the light color of amHQB, stabilizers (anti-oxidizing agents for amines) are used.

It is known to use as stabilizers amines inorganic derivatives meta-seam, for example, halides of iron, vanadium, cobalt, nickel, chromium fl. However, it is known that salts of heavy metals: vanadium, iron and cobalt can act catalytically as oxygen transmitters, i. promote oxidation of amines.

It is known to use as stabilizers compounds of boron: boric acid and its ethyl, butyl esters of alkali metal borohydrides. However, alkylborates are not very effective at stabilizing aniline, toluidine, naphtylamine, m-chloroaniline; Sodium borohydride is very poorly soluble in aniline, which explains its low stabilization efficiency.

The use of stabilizers containing in its composition aer molecules, in particular organic serusroschik compounds, such as thiourea and its derivatives 4, is described. the introduction

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sir; containing: cich stabilized; and: t in aromatic and physical amines is extremely undesirable, since they act, although medpelno, as stimulants for the oxidation of amines. Moreover, they are harmful when using stabilized amines, in the production of pi, dyes, etc.

IchZvesten also a method of stabilization of the color of amines in the treatment of the established mass, formed by hydrogenation of the corresponding nitrodegree. I, with its hydrazine derivative 5. This method consists in that. The reduced mass obtained during the production of aromatic aJvn-iHa by catalytic hydrochloric acid of the corresponding nitro compound in the presence of a noble metal as a catalyst is mixed with 0.1 ™ 0.5 weight%,% gdrazin or its derivative, heated for 0.25-2 h with SO-ISO C, most prevalently at 90-1, followed by separation of the semi-amine; In Kaches-guva, catalysts are usually used Platinum-y, palladium and mixtures of these trays on carbon black, and also nickel.

Stabilized samples are kept in transparent glass vessels at a light at a constant temperature in order to follow the color change. Amine coloration is determined visually when COTI is prepared with the Gardner scale or by changing the optical density,

The method is known to be one of the most progressive in terms of the result achieved, but it has a number of disadvantages, the ocHoBtttiMH of which is a relatively small effect of stabilization, limited application, since its use is possible for the stabilization of amino obtained only by the method of catalytic hydrogenation; the complexity of the technological process, which is associated with the necessity of the presence of a thickening catalyst - a noble metal of the USh group, as in the presence of a hydrogenating catalyst, hydrazide hydrate is relatively ineffective.

The aim of the invention is to increase the efficiency of stabilization of aromatic amines and ynpomeiffle processes.

The goal is achieved due to the fact that hydroxylamine derivatives are used as a stabilizer in an amount of 0.1-0.5 wt.% With respect to the original aromatic amine. F3 gsce

1914

In hydroxylamine derivatives, hydroxylsiline chloride or hydroxyl aminus phosphate is used in the form of water, X solutions.

According to the proposed method for stabilizing aromatic amines, freshly distilled aromatic amine with the addition of 0.1-0.5% by weight of a hydroxylamine derivative, such as hydrochloride hydroxylmine chloride or hydroxylamine sulfate, is placed in a glass jar, a black tin plate is lowered into the amine, the lid is blackened and put on the light for snatch. The color change is determined by the change in optical density, which is measured on a photocolorimeter, and compared with data obtained for a control sample without a stabilizer.

The proposed method makes it possible to significantly increase the efficiency of stabilization of aromatic amines, to simplify the technoplogical stabilization process, using HcKjnontm as a catalyst for precious metals. The method is applicable for the stabilization of aromatic amines regardless of the method of their preparation.

EXAMPLE 1 A 100 g of 3-toluidium, 0.48 g of hydroxylamine hydrochloride, is placed in a Claisen glass flask connected to a holochnik, a receiver, a vacuum gauge and a vacuum pump. The contents of the flask are heated and distilled at 82 ° C in vapor and a pressure of 10 mm Hg.

Distilled Z-toluidine, containing 99.67% amine, is placed in a glass jar, dipped in black iron plate, sealed tightly with a lid and set under light for aging.

The control sample 3 of toluidine was distilled without the addition of a stabilizer, a plate of blackened tin would be placed into it and placed in the light for exposure.

The color change is determined by the change in optical density, which is measured on a FEK-M photocolorimeter with a blue filter in a 5 мм mm cuvette relative to air.

When stored for three months, the control sample acquires a dark brown color with a red tint, with an optical density of more than 2, the content of amine in it is 98.7%.

Stabilized 3 toluvdin after three months has a light: yellow color, optical density 0.85, content

amine 09.5%. The change in the optical density of Z-toluidine at chronea and in

The presence of iron is given in the table.

EXAMPLE 2 It is carried out under the conditions of Example 1 with the only difference that for i: stabilization, 4-, anisidine, 4 anisidine color are taken after distillation pale yellow, m.p., 56.6 C, amine content 99.77%. After three months, 4-anisidnn, stabilized, becomes light-beige color, so pl. 56.6 C, the amine content of 99.6%. Three months later, pestabilized 4anizidine has a dark brown color. Example 3. In two glass jars, 1OO g of light is placed each: n-distilled 2-anisidine with Tcr, content of 99.8%. In one Ji3 cans, 0.1 g of hydroxyacid padroxylamine is added, in ..: aloda. of them put on a plate of black tin. The cans are sealed with a lid (not hermetically sealed) and placed in the light at the weaning point. A control sample in a can without a stabilizer after three months of a dark brown color, an optical density greater than 2, Tcr 5.8®C, content of 2-anisidine 98.6 % The stabilized 2-anisidine after three months has a pale yellow color, an optical density of 0.77. Tcr 6 ,, amine content of 99.4%. The method according to the invention allows to increase the shelf life by about 3 times. So, 2-anisidine, stabilized with hydrazine hydrate 5, after 14 days of storage in the absence of a useful plastic, has the same optical density (O, 365-O, 4) as 2-anisidine, stabilized with hydroxylamine hydrochloric acid, has in the presence of an iron plate after 45 days of storage (0.360). EXAMPLE 4 A Klaipen glass flask connected to a direct cooler, a BaKyyNtMeTpoM p vacuum pump, is charged with 1OO g 2-anizdine, 3.57 g 14%. Notes of a solution of hydroxylamine sulfate (0.5 g 10O.th), contains a free sulfuric acid, and 0.85 g of magnesite (for neutralization of free sulfuric acid). The content of xyloids is distilled at 10 11.7 ° C in pressure and a pressure of 10 mm Hg. Distilled 2 anisidine has a Tcr of 6.7 ° C, an amine content of 99.7%, an optical density of 0.315. After three months of exposure to light in the presence of a plate of blackened tin, the color of the 2-anisidipa is fresh, the optical density is 1.0; Tcr 6.6 ° C, amine content 99.4%. of the invention. Form 1. A method for stabilizing aromatic amines by treating with a nitrogen-containing stabilizer gas, characterized in that, in order to increase the efficiency of stabilizing aromatic amines and to increase the process, hydroxylamine derivatives are used as stabilizer in an amount of 0.1-0.5 wt. source aromatic amine. 2. A method according to claim 1, wherein it is used so that hydroxyllamine chloride or hydroxylamine sulfate is used as a hydroxylamine derivative in aqueous solutions. 11 information sources accepted in BHtiMaHiie at the expert 1. US patent K 2512504, cl. 26О-578, published, 20.ОС, 50. 7 2. Patent CAU number 292713fi. cl. 260-578, publ. 01.OZ.60. 3. US patent number 3222310, class. 26O-29.6 away. 07,12.65. 72S1918 Cl. 26О-578, publisher. 12.O5.59. j (prototype) 4. US patent Kv 2886597, 5. US patent N 3359315, class. 26О-575, published. 19,12.67

Claims (2)

Claim 1. The method of stabilization of aromatic amines by treatment with a nitrogen-containing stabilizer is distinguished by the fact that, in order to increase the efficiency of stabilization of aromatic amines and simplify the process, hydroxylamine derivatives in an amount of 0.1.-0.5 wt.% Are used as stabilizer relative to the original aromatic amine. 2. The method according to π. 1, with the fact that as a derivative of hydroxylamine, hydroxylamine chloride or hydroxylsulfate in the form of aqueous solutions are used.