W. J. Le Noble

The effect of pressure on sterically hindered Menshutkin reactions

Abstract A systematic study is described of the effect of pressure on the rates of the Menshutkin reactions of pyridine and various 2,6-dialkylpyridines with methyl, ethyl, and isopropyl iodide. A general increase of the pressure-induced acceleration of the rates with steric hindrance has been found. The magnitude of the effect does not appear to be solvent dependent, which lends strength to the interpretation advanced by Gonikberg that this effect is primarily due to the interpenetration of interfering groups.

Kinetics of reactions in solutions under pressure. 49. Chlorine kinetic isotope effects in the methylation of pyridine and 2,6-lutidine

Pyridine and 2,6-lutidine were methylated with methyl chloride in bromobenzene solution in sealed glass ampoules at 100.0/sup 0/C. The ionic chloride was isolated, purified, and completely reconverted to methyl chloride. Isotope ratios were determined with an isotope ratio mass spectrometer. It appears that the increase in the transition state is a manifestation of the Hammond postulate--the most hindered and slowest reaction possessing the most product-like transition state. 1 table.

Facile Reduction of Aromatic Nitro Compounds to Anilines With 2-Propanol and Raney Nickel

Abstract 2-Propanol in the presence of Raney nickel rapidly reduces aromatic nitro compounds to give the corresponding anilines. Reduction of the aromatic ring itself can generally be avoided by the judicious choice of the reaction time and temperature. Some substituent effects are noted.

Reactions in solutions under pressure

Abstract The effect of pressure on the equilibrium constant for the process relating the tight and loose ion pairs of sodium naphthalenide in THF has been measured over a range of 600 bars. From the effect, the volume change has been calculated: the loose pairs occupy 15 cm3/mol less space. This reinforces our earlier conclusion that the electrostriction effects accompanying ionic processes in nonpolar solvents are much larger than in polar media, as implied by the Drude—Nernst equation.

Truly constant diameter high‐pressure quartz optical cell

A small design change in a previously published model of an all‐quartz high‐pressure optical cell is described that allows its use without any need for corrections in the abosorbance.

Mechahism of the base promoted fragmentatiom of chloroacetylhydrazide

Abstract Experiments are described supporting the positions that the visible transient intermediate occurring during the fragmentation of chloroacetylhydrazide is the anion of acetyldiazene, and that the concurrent reduction is not a simple recombination reaction.