[SH-].[Na+].S([O-])([O-])(=O)=S.[Na+].[Na+].[CH3:10][O:11][C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][C:13]=1[N+:18](=[N:20][C:21]1[CH:26]=[CH:25][CH:24]=[CH:23][C:22]=1OC)[O-:19].[CH3:29]S(C)=O>>[CH3:29][O:19][N:18]([C:13]1[CH:14]=[CH:15][CH:16]=[CH:17][C:12]=1[O:11][CH3:10])[NH:20][C:21]1[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=185 Parts of an aqueous solution of 36 percent technical sodium hydrosulphide, containing 1 percent sodium thiosulphate, were added to a mixture comprising 51.6 parts of 2,2'-dimethoxy azoxybenzene in 100 parts dimethyl sulfoxide at 60° within one hour. Subsequently, the temperature of the reaction mixture was raised to 75° C and maintained at 70° C-75° C for 2 1/2 hours. The pH of the reaction mixture was maintained between 9.5 and 10.0. After this period the starting material was shown to be entirely reduced. Then the reaction mixture was cooled down to 0° C, the separated product was filtered off and washed with water until alkali-free. After drying below 70° C, 43.0 parts of high quality 2,2'-dimethoxyhydrazobenzene of a melting point of 100° C to 102° C were obtained, this repesenting a yield of 88 percent of the theory.
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