Yehezkiel Gotshal’s research while affiliated with Hebrew University of Jerusalem and other places

The kinetics of the thermal decomposition of 4-substituted 2-nitrophenyl azides in solvents of widely differing dielectric constants, as well as in the molten or solid neat materials, have been investigated. The decomposition yields the corresponding benzofuroxans and follows first-order kinetics. The rate coefficients are remarkably independent of the nature of the reaction medium. The mechanism of the reaction is discussed.

The reaction between azide ions and 2,4‐dinitrochlorobenzene was found to be of first order in each of the reactants. The reaction is slower in more polar media, and is completely inhibited by acid. The place of azide ions in the nucleophilicity order of aromatic substituting agents is assigned.

Viscose rayon and oxycellulose containing a high concentration of carboxyl groups have been esterified at the carboxyl group using ethylene oxide. This reagent was chosen to minimize changes in accessibility caused by the esterification reaction. Measurements were made of the carboxyl contents, of the capacities of the samples to absorb water, and of their capacities to absorb the cation and anion from solutions of cetyltrimethylammonium bromide. These last measurements were made to test the hypothesis advanced by Sexsmith and White (1) that absorption of ion pairs from the surfactant solution was a clustering process dependent on the presence of exchanged cations which served as nuclei. The marked decrease in ion-pair absorption found after esterification was in agreement with this hypothesis.Some other properties of the esterified oxycellulose samples are also discussed.

Thesis (doctoral)--Hebrew University, 1961.