Abstract
Gas-phase acidities of 15 aliphatic carboxylic acids, X CH -,COOH, have
been calculated using the MNDO method. Among the substituted groups exist
the electron donor alkyl groups and electron acceptor halogens. The average
error in acidity is within the experimental uncertainty of the data. Systematic
errors have been found for the substituents which form internal hydrogen
bondings. A reasonable correlation does exist between the gas-phase acidity
and the net atomic charges on the acidic hydrogens in the neutral form and the
net atomic charges and ionization potentials of the anions. There is no correlation
between the gas-phase acidity and HOMO and bandgaps
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