Phenol → 4-Hydroxybenzenesulfonic acid

Participants

Reaction Steps

478 parts of 20% oleum are added with stirring to 500 parts of melted phenol, with cooling to ensure that the temperature does not exceed 70° C. The mixture is then sulfonated at 105° C. for 1 hour. The phenolsulfonic acid formed is heated slowly at from 150° to 155° C. under reduced pressure of 11 to 13 torr, and this temperature is maintained until 1 g of the condensation product neutralizes 3.8 to 4.0 cm3 of 1-normal sodium hydroxide solution against Congo red. 100 parts of the hydroxyphenyl sulfone-(poly)hydroxyphenyl sulfone monosulfonic acid obtained are melted at 90° C. with 42 parts of water, and 14.4 parts of urea are added. After cooling to 55° C., 38.4 parts of 37% formaldehyde are added dropwise in the course of 2 hours and stirring is continued for about 4 hours until the condensation product gives a clear solution in water.

Provenance & Evidence