Reactions of diethyl~inc with isopropanol and water were studied by means of infrared absorption and gas evolution. The former method was found to be more reliable. Ethylzinc isopropoxide, formed from diethylzinc and isopropanol, was shown to be stable in the presence of excess isopropanol. The reaction of diethylzinc with water was found to proceed in a twostep manner, the product of the first being ethylzinc hydroxide. The decomposition of ethylzinc hydroxide was found to be first order with respect to itself and independent of diethylzinc.The reaction of zinc alkyls with compounds containing active hydrogens has been used in the past for qualitative and quantitative estimation of active hydrogen concentrations (1, 2). Generallj-, such procedures have been carried out with an excess of metal alkyl and little attention has been paid to the zinc-containing reaction products. Haurowitz noted that in 111any cases reaction of zinc alkjils with organic coinpouilds containing active hydrogens is not complete. Specifically in the case of benzyl alcohol only 60% of the expected ethane is evolved. Tolkatschev (3) and RIenard and Aston (4) In the studies reported herein, we have: (1) shown that ethylzinc isopropoxide formed from diethylzinc and isopropanol is stable in the presence of excess isopropanol in heptane solution; (2) shown that ethylzinc hydroxide is formed as an intermediate in the reaction of diethylzinc and water in ether solution; and (3) worked out the kinetics of the disappearance of ethylzinc hydroxide in the presence of various concentrations of diethylzinc in dimethoxyethane (glyn~e) solution. Two methods were used to study this latter reaction, namely, measurements of (1) the change in infrared absorption intensity a t 2.9 p (hydroxyl) and (2) ethane gas evolution as a function of time. However, these two methods give rate curves which are quite different. Since a lag in the evolution of ethane appeared to be the reason for this discrepancy, the kinetic a~lalj~sis was based on the infrared results. The initial portions of the gas evolution rate curves were nevertheless useful in obtaining an indication of the activation energy of the process. 'Presented at

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A general study of the UV light‐induced grafting of vinyl monomers upon potato starch is reported. A large variety of monomers with hydrophilic and hydrophobic properties and of initiators of free radicals was used. The best conditions of the grafting reaction were determined and several parameters were investigated: temperature, oxygen, initiator concentration, additives. Percentage of grafting‐time conversion curves, percentage of homopolymer, rate of grafting were obtained. For a given monomer, the most efficient photoinitiator can be selected.

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