Solution and Gas‐Phase Acidities of all‐trans (all‐E) Retinoic Acid: An Experimental and Computational Study

Abstract

Retinoic acid is of fundamental biological importance. Its acidity was determined in the gas phase and in acetonitrile solution by means of mass spectrometry and UV/Vis spectrophotometry, respectively. The intrinsic acidity is slightly higher than that of benzoic acid. In solution, the situation is opposite. The experimental systems were described theoretically applying quantum chemical methods (wave function theory and density functional theory). This allowed the determination of the molecular structure of the acid and its conjugate base, both in vacuo and in solution, and for computational estimates of its acidity in both phases.

Strengths of Acids in Acetonitrile

“…The origin of the compounds published by us earlier, as well as the pK a measurement methods, can be found from the following references: [5,[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The most comprehensive method description is given in ref [5].…”

Probing Reactivity with External Forces: The Case of Nitroacetamides in Water

“…Similar correlation approaches were used to predict the acidity constant values of organic compounds in organic and aqueous solutions [ 12 , 13 , 14 ]. Due to intrinsic limitations of such methods, and thanks to the advent of efficient computer hardware and software, researchers could explain extreme cases of particular interest by using, for instance, density-functional theory (DFT) [ 15 ]. Yet, the inclusion in such methods of explicit models of solvent is missing.…”