METHOD FOR PREPARING 3,4'-DIAMINO-4-R-BENZOPHENONES Russian patent published in 2008 - IPC C07C213/02 C07C215/68 

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of 3,4'-diamino-4-R-benzophenones of the general formula: wherein R means Cl, Br, F, -CH₃, -OCH₃,

that are used as intermediate product in synthesis of azo dyes useful for staining protein fibers and possessing the unique indices of thermal stability. Method involves steps for nitration reaction of substituted benzophenones with potassium nitrate in concentrated H₂SO₄, nucleophilic replacing halogen (wherein R means Cl) in interaction with O- and N-nucleophilic compounds in dimethylsulfoxide (DMSO) medium in the presence of K₂CO₃ and reduction of 3,4'-dinitro-4-R-benzophenones. The nitration reaction of synthesized benzophenones is carried out at temperature 20^oC for 5 h in the mole ratio 4'-nitro-4-R-benzophenone : KNO₃ = 1.0:1.15. Nucleophilic replacing halogen is carried out at temperature 40-60^oC for 1-5 h in the mole ratio substrate : nucleophilic compound = 1.0:1.05, and reduction of dinitrobenzophenones is carried out with SnCl₂ x 2H₂O in 18% HCl medium, in the mole ratio 3,4'-dinitro-4-R-benzophenone : SnCl₂ x 2H₂O = 1:6, at temperature 20^oC for 0.15 h. Invention provides decreasing cost of synthesis, reducing time and temperature in carrying out the process, enhancing purity and yield of end products.

EFFECT: improved method of synthesis.

4 tbl, 4 ex