Phenolphthalein → Calcium Bromide

Participants

Reaction Conditions

Reaction Steps

After neutralizing 1.743 g (9.53 mmol) of 2-bromomalonic acid in 2.0 ml of water by adding calcium hydroxide in portions in the presence of phenolphthalein indicator, 1.000 g (3.81 mmol) of 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane is added. The reaction mixture is heated at 40°, 45° and finally at 50° C. for a total of 72 hours, then the reaction mixture is heated at 60° C. for 24 hours while portionwise adding 0.85 g (11.47 mmol) of calcium hydroxide under vigorous stirring. Then, the precipitate (the major part of which is calcium hydroxymalonate) is filtered off and washed with 4 to 5 ml of water in 3 portions. The combined filtrate is evaporated under reduced pressure and then 2×35 ml of methylene chloride are distilled off from the evaporation residue to obtain a solid product which is dried at 75° to 85° under reduced pressure. In this way the title product is obtained in a yield of 2.710 g (89.7%) with a calcium bromide content of 31.5% by weight.

Provenance & Evidence