Abstract

A series of experiments were performed to evaluate the effect of a catalyst (copper sulphate) on the rate of disulphide bond formation of desmopressin. Parameters that were considered during the evaluation were reaction time, yield, chromatographic peak purity and ease of processing during reaction work up. Experiments were done by using solvent as water, 50%Water : 50%acetonitrile, 50%Water:50%methanol and 50%Water:50%ethanol. A concentration of 1 mg/ml of desmopressin was chosen for the experiments. For each solvent pair, a set of two oxidation reactions was studied at concentrations of 1 mg/ml. One set was done without addition of copper sulphate and in a second one adding catalytic amount of copper sulphate at the start of reaction. It was observed that the use of organic solvents has increased the solubility of desmopressin Bis-SH and therefore the yield obtained increased. The use of catalyst increased the rate of the reaction by 50%. The reaction in 50%Water: 50%acetonitrile at 1mg/ml concentration using copper sulphate is the most effective for formation of disulphide bond. The area of desmopressin is 1.5 times more than the initial area of desmopressin Bis-SH and reaction completed was in 3 hours. Therefore it can be concluded that the use of solvent can be an option for formation of disulphide bridge as it is helping to dissolve the precursor completely and copper sulphate offers an added advantage towards increasing the rate of reaction.

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