Phenyl salicylate reacts considerably faster than phenyl o-methoxybenzoate in acetonitrile solutions of «-butylamine. The nature of this anchimeric assistance by the o-hydroxyl group was investigated because of the relevance of intramolecular catalysis in aprotic media to the mechanism of enzyme action. The reactions have the following properties: (1) the aminolyses of the two esters are both second order in amine; (2) triethylenediamine, an unhindered tertiary amine, catalyzes both reactions; (3) «-butylamine hydrochloride inhibits slightly the rate of aminolysis of phenyl salicylate, whereas the hydrochloride salt catalyzes the aminolysis of phenyl omethoxybenzoate; (4) there is no spectrophotometric evidence for ion or ion-pair formation between amine and phenyl salicylate. These results are consistent with an intermolecular general base-intramolecular general acid mechanism for the reaction of phenyl salicylate with «-butylamine in acetonitrile.Phenyl salicylate (A) reacts considerably faster with «-butylamine in acetonitrile than does phenyl omethoxybenzoate (B). This anchimeric assistance by the o-hydroxyl group was of great interest to us because of the relevance of catalysis in aprotic media to the mechanism of enzyme action.1-4 For example, the catalytic site of crystalline chymotrypsin contains a carboxyl group buried among hydrophobic side chains.5 Unfortunately, nothing is really known about the mechanism and efficiency of intramolecular catalytic processes in aprotic solvents. Snell and coworkers1 2 345are the only ones who have determined the kinetics of an intramolecular catalyzed ester reaction in a nonhydroxylic medium. They found that the rate of aminolysis of methyl salicylate in dioxane is greater than that of phenyl p-hydroxybenzoate, but they did not specify the mechanism of the catalysis. The results of our experiments with phenyl salicylate lead to more detailed conclusions about the role of the hydroxyl group.cnnn"ttmnr.w- Experimental SectionMaterials. Phenyl salicylate (Eastman) was crystallized twice from hexane • and dried under reduced pressure. «-Butylamine (Fisher) was distilled over calcium hydride using a 10-in. vacuumjacketed Vigreux column. Acetonitrile (Eastman Spectro) was boiled under reflux over anhydrous sodium carbonate for 2 hr and distilled then and stored under nitrogen. «-Butylamine hydrochloride was crystallized from methanol-ethyl acetate. Triethylenediamine (Houdry) was purified by crystallization in heptane followed by sublimation. N-«-Butylsalicylamide was prepared by boiling under reflux for 18 hr a mixture of 15 ml of methyl salicylate and 25 ml of «-butylamine. The product, after work-up from aqueous acid, was distilled twice, bp 135-150°(0.15-0.20 mm).Phenyl o-Methoxybenzoate. o-Methoxybenzoyl chloride (1.7 g, 0.010 mole) and phenol (1.0 g, 0.011 mole) were added to about 60 ml of dry pyridine that had been cooled in an ice bath. After(1)

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Br-C(l)-C(2) 109.0 0.5 C(l)-C(2) 1.509 0.010 C(l)-C(2)-C(3) 120.3 0.7 C(2)-C(3) 1.474 0.011 C(l)-C(2)-N 112.5 0.7 C(2)-N 1.291 0.010 N-C(2)-C(3) 127.2 0.6 N-O 1.409 0.008 C(2)-N-D 113.5 0.7 C(3)-C(4) 1.404 0.010 C(2)-C(3)-C(4) 119.3 0.7 C(4)-C(5) 1.366 0.015 C(2)-C(3)-C(8) 122.1 0.6 C(5)-C(6) 1.358 0.015 C(4)-C(3)-C(8) 118.6 0.7 C(6)-C(7) 1.389 0.015 C(3)-C(4)-C(5) 120.5 0.8 C(7)-C(8) 1.385 0.014 C(4)-C(5)-C(6) 121.0 0.9 C(8)-C(3) 1.402 0.011 0.2919(9) 0.9511 (8) 0.3123 (8) C(ll) 0.3358(7) 0.9864 (7) 0.4120(8)from the National Science Foundation (J.