The kinetics of hydrolysis of trimethylamine- and of triethylaminesulphur
trioxide addition compounds have been studied in water and in aqueous acetone.
Reaction occurs according to the equation,������������� f - + R,N.SO,+H,O-tR,XH+HSO~.The solvolysis reactions
are first-order and are not catalyzed by acids. The halide ions, Cl', Br', and 1', show only a normal salt effect on the
rate of hydrolysis of + - (CH,),N.SO, but in the presence of fluoride ions, the
rate constant for the production + - of acid from (C,H,),N.SO, in water at 95
OC is about one-seventh of that in the absence of fluoride under the same
conditions. It is suggested that the fluorosulphonate
ion is formed rapidly, and that this ion then undergoes slow hydrolysis :�In
the presence of alkali, using water as the solvent, second-order kinetics are
observed, the equation for the reaction being,�������������� + - R,N.SO,+~OH-+R,X+SO~= +H,O. Assuming the reaction with
water is bimolecular, the ratio of the (bimolecular) rate constants at 35 OC, ko~-/k~,o is approximately lo8 for each complex. In aqueous
acetone, at low water concentrations, the hydrolysis reactions of the trialkylaminesulphur trioxide complexes show second-order
kinetics. At 35 OC for the hydrolysis of + - (CH,),N.SO, the ratio of the
second-order rate constant in aqueous acetone to the + - (calculated)
second-order rate constant in water is approximately 550 ; for (C,H,),N.SO, the
same ratio is 6900.
It is considered that hydrolysis occurs in
water and in aqueous acetone via a bi- molecular attack at sulphur.