O-Cresolphthalein (CAS: 596-27-0)

production methodprocess

1. By phthalic anhydride and adjacent toluene condensation. Mix benzene anhydride and o-cresol heating melt, anhydrous zinc chloride in 110 ℃, and in 110-115 ℃ stirring reaction 12-18 h, going into the steam out of the remaining o-cresol. Dissolve the coarse product sodium hydroxide solution, filtration. The filtrate with dilute hydrochloric acid neutralization, white crystal is the finished product.
2. Mix adjacent armour of phenol with phthalic anhydride, under stirring slowly heated to melt rapidly after adding fresh anhydrous zinc chloride, heating to 105 ~ 110 ℃, heat preservation, 5 ~ 6 h, carries on the condensation reaction:After the reaction, add a small amount of water, stir to dissolve precipitation, and then added to dilute hydrochloric acid, after being precipitated completely, filtration, precipitation with a small amount of distilled water several times, will add dilute hydrochloric acid after precipitation pulverization, filtration. To the crystallization of the filtered adding 10% sodium hydroxide solution, stirring and heating to dissolve, later, to join the cold distilled water, cooling crystallization, filtration, crystallization water washing to qualified. Washing liquid and filtrate to merge, and join the hydrochloric acid concentration, the cooling crystallization, filtration, washed to qualified, merged into the crystallization and dry for a quick a phenolphthalein.