The proton affinity of proline analogs using the kinetic method with full entropy analysis.
The proton affinity of proline analogs, L-azetidine-2-carboxylic acid (Aze), L-proline (Pro), and L-pipecolic acid (Pip), have been measured using the Armentrout modification of the extended kinetic method in a quadrupole ion trap instrument. Experimental values of 223.0 +/- 1.5, 224.9 +/- 1.6, and 225.6 +/- 1.6 kcal/mol have been determined for the 298K proton affinities of Aze, Pro, and Pip respectively. High level theoretical calculations using both MP2 and B3LYP methods at a variety of basis sets were carried out in order to give theoretical predictions for the 298 K proton affinity and gas phase basicity of all three analogs. Recommended values for the gas phase basicity and proton affinity for proline based on our work and other recent determinations are 216 +/- 2 and 224 +/- 2 kcal/mol.
Kuntz
Andrew F
AF
Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, USA.
Boynton
Andrew W
AW
David
Geoffrey A
GA
Colyer
Kathryn E
KE
Poutsma
John C
JC
D019295:Computational Biology; D019277:Entropy; D007700:Kinetics; D008956:Models, Chemical; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry*; D011522:Protons; D021241:Spectrometry, Mass, Electrospray Ionization
D011522:Protons; D011392:Proline