The mechanism of the aluminium bromide catalyzed isomerization of n‐propyl bromide

Abstract

n-Propyl bromide is readily isomerized to isopropyl bromide in carbon disulphide solution under the influence of aluminium bromide at -20". The reaction may be followed by infrared spectroscopy or by gas-liquid chromatography. Rate data can be accommodated only by using two kinetic equations, obtaining at high and low molar intake ratios of the reactants, respectively.No incorporation of deuterium takes place when carrying out the reaction in the presence of deuterium bromide, indicating that the isomerization does not involve reversible dehydrobromination.Runs with 2-deuterated n-propyl bromide show a significant isotope effect, a hydrogen atom shifting about 3.4 times more rapidly than a deuterium atom.These and other results obtained may be interpreted in terms of reversible (partial) ionization, followed by a 1.2-hydrogen shift.