The invention relates to a synthesis method of
protoplasm spray drying acid red R3G, comprising the steps of
dissolution of 2-amino-5-naphthol-7-
sulfonic acid, one-step condensation, diazoniation,
coupling and finally two-step condensation. The 2-amino-5-naphthol-7-
sulfonic acid is dissolved before the one-step condensation through that the 2-amino-5-naphthol-7-
sulfonic acid is added to water and stirred evenly; then pH of the solution is adjusted to 7 through
sodium hydroxide solution of 30 percent and the temperature rises to 60-70 DEG C; after the full
dissolution, the solution is provided with a bush, the temperature is decreased to 25-15 DEG C and the solution is stirred for two hours under the temperature; then precipitated 2-amino-5-naphthol-7-sulfonic acid is filtered and filtering cake is pressed and dried for purpose in one-step condensation; the finished process is after the completion of dye synthesis, the strength of the 2-amino-5-naphthol-7-sulfonic acid is adjusted to the strength of finished product through
glauber salt and spay dried under the temperature of outlet
ranging from 90-110 DEG C and the finished produce can be packed directly at last. Compared with the products of the prior art, the acid red R3G of the invention improves 10 percent of yield, and eliminates waste water with salt generated from salt
precipitation technique, which not only saves raw materials but also shortens production time, improves product economic benefit, eliminate
discharge of waste water and facilitates
environmental protection.