SU287672A1 - Method for preparing bromo derivatives of aromatic diamines - Google Patents

Description

 The invention relates to the preparation of bromo derivatives of aromatic diamines, which are the starting materials for the preparation of the corresponding EHS diisocyanates used for the synthesis of

elastic self-extinguishing polyurethanes.

A known method of producing a tribromo derivative of m-phenylenediamine by passing a mixture of bromine vapor with air through an aqueous solution of m-phenylenediamine. However, the disadvantages of this method include the preparation of a dark-colored product due to oxidation of the reaction mass with an excess of bromine, and the imperfection of the technology; The precipitate of bromo-derivatives must be continuously removed as it forms, as it will tar and darken.

The purpose of the invention, which is to improve the technology — and to obtain various high purity bromomatic diamines with close to quantitative yields, is achieved by direct bromination of the original aromatic diam sJiyMeHtapiibiM bromine in a heterogeneous

medium at the interface. Bromine rast: is thrown in a non-polar solvent, for example dichloroethane, ether, and the diamine, for example, in 55% sulfuric acid, and is carried out at a temperature of from -5 to -20 ° C. i 55% sulfuric acid possesses high solvating ability and a high dielectric constant, is able to form salts with || minogroups, understand | Zha, thus their activity, upon dilution with water, forms hydrosulfide | roksoni.

i The initial amine and 55% sulfuric acid are loaded into the reaction vessel and mixed until the amine is completely dissolved. : The resulting solution was cooled from 0 to ~ 5 ° C, and slowly while stirring, added: - A solution of bromine in the Policer solvent. In the resulting heterogeneous medium, conditions are created for directional halogenation into the nucleus of aromatic diamines.

Since the solubility of bromine in di orthoethane or ether is many times higher than its solubility in sulfuric acid, serocl cojib amine is much more logistical than in an aqueous acid solution than in a non-solvent, bromine ions react with an aromatic diamine only at the interface phases, which is also confirmed by complete tarring of the reaction products in a homogeneous medium. The proposed method makes it possible to obtain various bromaromatic diamines from non-deficient raw materials according to a non-lethal technology, which makes it possible to avoid washing and to obtain pure individual products with high values; gokhodami. Example 1. Preparation of 3,5-dif-2, 4-diaminotoluene. A four-necked flask, filled with a stirrer, a thermometer, a dropping funnel and a reflux condenser, is charged with 12.2 g (0.1 g-mol) of M-toluene diamine (mp 98-100 ° C) 250 ml 55% - sulfuric acid (specific weight 1.445 and stir the mass until the dissolution of the di- sine is complete. Then the mixture is cooled from 0 to -5 ° C and with intensive stirring, 1 O, 3 ml (O.2 g-mol) of bromine {beats. weight 3.119 g / cm dissolved in 250 ml of dichloroethane, stirred for another 3 hours at -5 ° C and kept for 12 hours at 20 ° C. After combining the filtered, washed with water, the separated A white crystalline precipitate of 3: 5-dibromo-2,4 diaminotoluene with a precipitate separated from the aqueous filtrate after neutralization with ammonia gives a technical product with a yield of 92.5% of theory, based on the starting M-toluene-1-diamine, m.p. 138-140 ° C. Recrystallization from hexane gives brilliant pearl leaves with a melting point of 140-141 ° C. The product is highly soluble in alcohol, ether, sulfuric acid, difficult to dissolve in hexane, insoluble in water. Calculated,%: S AOR, OO; H 2.86; N 10.10; Br57.20. CvHeN Br Found,%: C 30, 60; H 2.82; N9.99; Br56.31. The solvent after simple cleaning can be used in the following experience. Example 2. Getting 3,5,6 trnbrom-M-phenylenediamine. nepei leiJiHBciKJi and cyt; iic- i, iHKj m -fyyilidaminam in sulfuric acid, cool to -5 oC. 15.4tt ml (0.3 g-mol) of bromine (sp. Weight 3.1 g / cm) dissolved in 30% ml of dichloregan5 is added dropwise to the cooled mixture. Get technical product-white crystalline powder with so pl. 151-153 ° C, the output of 84.5% (on the original diamine). Example 3. Preparation of 3-3 dihpor-4-4-diamino-5, 5-dibromodiphenyl methane. 6 g (0.022 g-mol) of 3,3-dichloro-4-4-diaminodiphenylmethane (mp. 103 ° C) and 2OO ml of 55% sulfuric acid, cooled-; give the resulting suspension from O to and drop by drop from the dropping funnel for 1 hour 2.34 ml (O, O45 g-mol) of bromine (specific weight of 3.1 g / cm) dissolved in 1OO ml of dichloroethane. Then the mass is stirred for more than 4 hours npg from 0 to -5 ° C and 10-12 hours at 20 ° C. The 3,3-dichloro-4,4-diamino5, 5-dibromodiphenylmethyl precipitate is separated, washed with water and added to the bulk of the product, isolated by neutralization of the acidic filtrate with aqueous ammonia. The product yield of 9.49 g (99.3% of the original amine). Recrystallization from benzene gives white shiny needles, mp. 245 ° C. The product is soluble when heated in hexane, insoluble in water, ether, acetone. Calculated,%: C 36.8; H 2.35; N6.59; a 16.7; Br 37.7. QaH.oNgCe Brs Found:%: 35.91; H 2.4 O; N 7, On; halides 55.63. Example 4. Preparation of 3.3 dimethyl-4, 4-dia fino-5.5-dibro.m diphenylmethane. 9.04 g (0.04 g-mol) of 3,3-dimethyl-4,4-diaminodiphenylmethane (mp, 155 C) and 400 ml of 55% sulfuric acid are charged to a liter flask. The resulting suspension is cooled from 0 to -5 ° C, added dropwise from an addition funnel over. hour 4.06 ml (0.08 g-ml) of bromine (sp. weight 3.1 g / cm), pacTBOpSHHOiX) in 1OO ml of dichloroethane, then stirred for 2 hours at a temperature from O ao., and J O-12 hours at 2 ° C.

The output of the product is 97.2% of the theory, with a reaction to the reacted amine.

Crystalline; izash1 from benzene gives slightly yellow ng / sh1 with m.pl, 205 C. Dissolve the product in acetone, when heated in carbon tetrachloride, insoluble in water, ether, hexane, ethanol.

Calculated,% C 46.8; H 4.17; N7.3; Br 41.6.

CisMieNgBrj

Found,%: C 45.97; H 4.26; N7.24; Br 41.28.

Claims (1)

1. A method of producing bromine aromatic diamines by Brsylation of an aromatic diamine solution, characterized in that, in order to increase the yield and increase the purity of the target product, a solution of bromine in a non-pnr and pnrm solvent is used as a brominating agent. solvent aromatic diamine take sulfuric acid and the process is carried out at temperature from minus 5 to plus 20 ° С.