Yield:-

Reaction Conditions:

Stage #1: naphthalene-1,5-disulfonatewith 4-nitro-2,6-dichloroaniline;sulfuric acid;cis-nitrous acid in 1,2-dimethoxyethane at 0 - 5; for 0.166667 h;
Stage #2: with sodium carbonate;m-acetylamino-N,N-diethylanilne in 1,2-dimethoxyethane at 0 - 40; pH=6 - 8; for 0.5 h;

Steps:

1

240 ml of ethylene glycol dimethyl ether was added 12.60 g of 2,6-chloro-4-nitroaniline and 25.92 g of 1,5_ naphthalene disulfonic acid (mass fraction of 74.41%), slowly dropping at 0-5 ° C 21.48g sulfuric acid solution containing 39.02% (nitric acid) nitrous acid sulfuric acid solution, reaction lOmin, with thin layer chromatography to detect the end of the reaction (raw material has been completed), pumping the diazonium salt solid.A solution of 17.28 g of 1,5-naphthalene disulfonic acid and 14.85 g of N, N-diethyl-3-acetamidoaniline was dissolved in 100 g of ice water to keep the temperature at 0 ° C, The filtrate was concentrated at 55 ° C, 40 ° C with a rotary distillate under reduced pressure, and the filtrate was concentrated at 37 ° C, and the filtrate was concentrated at 37 ° C To the concentrate in the solid content of 90%, the concentrate into the 4 times the volume of ethanol, the alcohol, filtration, drying,sodium 1,5-naphthalene disulfonate, The recovery was 97.0% and the liquid purity was greater than 98% (Figure 1).

References:

CN105152987,2017,B Location in patent:Paragraph 0028; 0029