Acetylcholine. 2. The heat of hydrolysis

Thus, we conclude that the rather small differ- ences evidenced in the hydrolysis of acetylcholine and a non-ionic ester such as methyl acetate fit in with what we know about the slow steps and activated complexes in these reactions.SUMMARY 1.The kinetics of hydrolysis of acetylcholine bromide by hydrogen ion and hydroxyl ion have been followed by conventional methods.The bimolecular velocity constants respectively are, in I.mole-l'sec.-l,kH+ = 4-7 x 107 e-1657OIR and kOH-= 1.0 x 109 e-121801XT 2. These data are very similar to those for non- ionic esters, such as methyl acetate.The A factor for k]-s is about 5 times smaller than for such esters, while for kO]OHit is about 20 times larger.These differences find an explanation in the ionic charge of the activated complex.