No abstract

Tetrakis (triphenyl phosphine) platinum (0), in association with a suitable organic halogen coinpound, is an active initiator of free-radical polymerization which does not give rise to inhibition at high halide concentrations. We report here a study of the polymerization of methyl methacrylate initiated by Pt(PPh3)4+CC14. Although showing kinetic features which are generally similar to those of other systems incorporating zero-valent metal derivatives, this initiator is unusual in several respects. The activation energy for initiation is low (11.2 kcal mole-') so that initiation may be usefully effected over a wide range of temperatures, extending from 80°C to below room temperature. The frequency factor for initiation is abnormally low ; an explanation based on steric obstructions encountered in the formation of a transition state involving monomer or solvent, is advanced. Further, initiation is relatively inefficient, a comparatively small portion of the platinum derivative reacting by a radical-producing route.

No abstract

Acyloxy derivatives of silicon were prepared by the interchange reaction between carboxylic acids (including various grades of palmitic acid) and tetraethoxysilane, and by the interchange reaction between palmitic acid and technical ethyl silicate (silica content 40%) or technical isopropyl silicate (silica content 38%). In most of the reactions, sodium methoxide was used as catalyst. Some physical properties of the reaction products were determined, and the materials made from palmitic acid were evaluated as water‐repellent coatings on cotton cloth.

As a means of comparing the reactivities of methylene groups in organic compounds& substances have been condensed, under comparable conditions, with aromatic aldehydes in solution in organic solvents. Benzene is the most satisfactory solvent.