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Series of complexes of the types czs-[Pt(am)2 (DMSO)Cl]Cl, m-[PtCl2(am)(DMSO)], and [Pt((am')(DMSO))((am)Cl)]Cl, where am is an alicyclic primary amine, CnH2n.[NH2 ( = 3-8), am' is cyclopropylamine, and DMSO is dimethyl sulfoxide bonded through the sulfur, have been prepared and characterized. The kinetics of the forward and reverse steps of the process, c/s-[PtCl2(DMSO)(am)] + am Í m-[Pt(am)2(DMSO)Cl] + + Cl" (and also the analogous reaction with cyclopropylamine as entering group), have been studied in methanol at 30.0°at constant ionic strength and the equilibrium constants have been determined. The normal two-term rate law is observed but the first-order (nucleophile-independent) path is of little importance. In addition to the expected dependence of rate on the basicity of the leaving group, a very strong cis effect is observed where the least basic amine produces the most reactive substrate. This cis effect is as dependent on basicity as the leaving group effect. It is concluded that the very strong trans effect of S-bonded dimethyl sulfoxide is due to transition-state stabilization that results from the -acceptor properties of the sulfur in this ligand.

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A rapid, accurate and precise method for the determination of phenylpropanolamine hydrochloride in a cough-mixture is described. The method is based on the determination by normal-phase HPLC of benzaldehyde formed after periodate oxidation. The method is applicable to other phenalkanolamine drugs that yield benzaldehyde on periodate oxidation, e.g., ephedrine, and has also been found suitable for other dosage forms, such as syrups, powders, tablets and capsules. The high sensitivity of the method makes it especially useful for individual dosage unit assays.