Y. Chen
1959
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Journal
Acta Chimica Sinica
Abstract
The apparent acid dissociation constants of N-phenylglycine and of N-α-naphthylglycinehave been determined by pH method at 25℃ in 30% ethanol solution in the presence of 0.10Msodium perchlorate.That of glycine was also determined under the same conditions for thepurpose of comparison.These amino acids were found to have comparable acid strengths,but their basicity is quite different.N-phenylglycine as a base is much weaker thanglycine as expected,while N-α-naphthylglycine shows very strong base strength which is inthe same order as that of the N-alkylglycines.This anomaly was explained in terms ofsteric effect due to the 8-hydrogen atom on the naphthalene ring upon the proton on theamino group.The lowering of dielectric constant of the solvent led to the decrease of both acid andbase strengths of glycine.