Acta Phys. -Chim. Sin. ›› 1991, Vol. 7 ›› Issue (01): 92-96.doi: 10.3866/PKU.WHXB19910115

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Specific Salt Effects on the Determination of Catalytic Constants of Hydrolysis

Zhang Ben-Li; Tan Chang-E; Gao Zhen-Heng   

  1. Department of Chemistry, Nankai University, Tianjin
  • Received:1988-12-31 Revised:1990-07-06 Published:1991-02-15
  • Contact: Tan Chang-E

Abstract: In order to investigate the influences of specific salt effect of added electrolyte on the classic buffer experiments for distinguishing general and specific acid or base catalysis, the rate constants of the hydrolysis of benzaldehyde di-ter-butyl acetal, triethyl orthobenzoate and N-p-methoxybenzyli-denepyrrolidinium ion in acetate buffers were measured under various conditions. It is found that, for a given reaction, the presence or absence of specific effect of an added salt depends mainly on the ionic stregth and solvent of the buffer solution. In buffers of low ionic strength, e.g. 0.1 mol·L~(-1), using water or mixed solvents containing a small fraction of organic constituent, specific salt effect can be eliminated or considerably reduced and the classic diagnostic buffer experiments can be satisfactory.

Key words: Acid-base catalysis, Catalytic constants, Specific salt effect, Hydrolysis reaction