First-order rate constants for hydration of para substituted styrenes and equilibrium styrene: 1-phenylethanol ratios have been determined, covering a wide range of HC104 molarity. The solvent deuterium isotope effect on hydration also has been extensively investigated. General catalysis has been found for the hydration of p-methoxy-a-methylstyrene in dilute aqueous solution. Based on these results, coupled with earlier ones, the most probable rate-controlling step is simple proton transfer to the ß carbon of the styrene, though rate-controlling rearrangement of a styrene-H30+ complex to -methylbenzyl cation cannot be excluded. A number of other mechanisms, including rearrangement of a styrene-proton complex, are inconsistent with observation. Medium and substituent effects on hydration rate constants and the solvent isotope effects indicate that proton transfer in the activated complex lies between "half-way" and far advanced. This paper deals with the influence of perchloric acid media, deuterioperchloric acid media, and para substituents on the reversible hydration of styrene.1

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Our results support the hypothesis of less nutritional value of hydrolysed versus conventional preterm formulae. Higher renal excretion of essential amino acids may be one of the mechanisms involved. These findings must be confirmed by further studies with larger sample sizes and protein hydrolysates with different degrees of hydrolysis.

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