Protonated Carbonyl Groups: Viii. Alkyluracil Salts

Abstract

With 1,3-dimethyluracil and 1,3,6-trimethyluracil as models for nucleic acid bases, it was found by infrared spectroscopic methods that the site of protonation is a carbonyl group. Analysis of other evidence makes it lilcely that it is the carbonyl group in position 4. In 1,3,6-trimethyluracil salts, activation of the 5 position under acid conditions permits ready hydrogen-deuterium exchange.Some anomalous 2 base -1 acid salts with complex acids are considered in the light of basc pairing errors in nucleic acids.

Theoretical and pH dependent surface enhanced Raman spectroscopy study on caffeine

“…30 The hydrogen bonding formation at the N1, N3, or N7 atoms was excluded on the previously established grounds and from known experience with pyrrole salts. [31][32][33] Moreover, arguments based on carbonyl wavenumber shifts were already used in an earlier IR study 12 to rule out the carbonyl group protonation and to indicate the N9 atom as the only protonation site.…”

Acidic hydrolysis of deoxycytidine and deoxyuridine derivatives. General mechanism of deoxyribonucleoside hydrolysis

“…The value of -3.38 for the pKA of uracil was determined by spectroscopy by Katritzky and Waring (1962). The pKA value of -4.16 has been measured for 2thiouracil, and it has been estimated that uracil is probably slightly higher than this (Cook, 1966). On the other hand, pKA values of 0.5 and 0.0 (derived from unpublished spectroscopic determinations) have been reported for uracil and thymine monocations, respectively (Beaven et al, 1955;Cohn, 1955).…”