Amine vs. carboxylic acid protonation in ortho-, meta-, and para-aminobenzoic acid: An IRMPD spectroscopy study.

ABSTRACT: Infrared multiple photon dissociation (IRMPD) spectroscopy and computational chemistry are applied to the ortho-, meta-, and para- positional isomers of aminobenzoic acid to investigate whether the amine or the carboxylic acid are the favored sites of proton attachment in the gas phase. The NH and OH stretching modes yield distinct patterns that establish the carboxylic acid as the site of protonation in para-aminobenzoic acid, as opposed to the amine group in ortho- and meta-aminobenzoic acid, in agreement with computed thermochemistries. The trends for para- and meta-substitutions can be rationalized simplistically by inductive effects and resonant stabilization, and will be discussed in light of computed charge distributions based from electrostatic potentials. In ortho-aminobenzoic aci

SUBMITTER: Cismesia AP 

PROVIDER: S-EPMC5400370 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature