Phenol → 4-Hydroxybenzenesulfonic acid

Participants

Reaction Conditions

Reaction Steps

To a three-neck flask, fitted with a mechanical stirrer, thermometer, and condenser were added 94 g phenol and 98 g concentrated sulfuric acid and the mixture was stirred and heated at 100° C. for two hours under nitrogen atmosphere to form phenolsulfonic acid. To this reaction mixture were added 193 g water and 37 g calcium hydroxide and this mixture was stirred and heated at 95° C. for two hours. The reaction mixture was filtered to remove precipitated calcium sulfate to yield a 39.4% aqueous solution of the phenolsulfonic acid calcium salt. A portion of this salt solution (98 g containing 38.6 g salt), 70 g 4,4'-dihydroxydiphenylsulfone, 38.5 g of 37% aqueous formaldehyde, and 7.4 g calcium hydroxide were reacted for 15 hours at 97° C. under nitrogen atmosphere to form the substantially sulfonic acid-free, water-soluble sulfonated 4,4'-dihydroxydiphenylsulfone-formaldehyde calcium salt. This calcium salt product was diluted to 30% solids using 106 g water and the pH was adjusted to 7.6 with 3.5 g calcium hydroxide.

Provenance & Evidence