Sodium Hydroxide → Benzoic acid, 3-sulfo-, sodium salt (1:1)

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Reaction Conditions

Reaction Steps

The pH of 345 g of mother liquor from Example 1 is adjusted to 4 with about 60 g of sodium hydroxide. 300 ml of this solution are introduced together with 264.5 g of 3-(chlorosulfonyl)benzoic acid (water content: 25.7%) (corresponding to 196.5 g (0.89 mol) of 100% 3-(chlorosulfonyl)benzoic acid). The reaction mixture is heated to 100° C. and stirred for a further 45 minutes at this temperature. The mixture is then allowed to cool over about 1 hour to 40° C. Subsequently it is cooled with an ice bath to <5° C. and stirred for a further 30 minutes at this temperature. The precipitated product is filtered off with suction and washed with 256 g of 5% strength sodium chloride solution, prepared from 13.8 g of sodium chloride and 243.2 g of water and cooled to 5° C., in two portions. The filter cake is dried at 100° C./100 torr (13.16 kPa). 192.6 g of sodium 3-sulfobenzoate are obtained with a purity of 96% and a sodium chloride content of 3.2% (corresponding to 184.9 g (0.83 mol) of 100% sodium 3-sulfobenzoate). The yield is 92.6% of theoretical.

Provenance & Evidence