Phenylbutazone Salt
By reacting together p- chlorophenoxyacetic acid, beta - diethylaminoethylamine and 4-n- butyl-3,5-diketo-1,2-diphenyl- pyrazolidine in the medium of a non- polar solvent at the temperature of 107 to 148 DEG C, the molecular compound of these three reactants is obtained in a single reaction, the said compound having the Formula 1 <IMAGE> The molecular compound is isolated from the reaction medium and purified by crystallisation from an organic water-miscible polar solvent containing not less than two moles of water per mole of the molecular compound. The molecular compound produced by the process according to the invention has antiphlogistic and antirheumatic properties.