3032-11-9Relevant academic research and scientific papers
Reactions with Betaines, XXIII. Reactions of Nitrogen- and Sulphur-Betaines with Reactive Halides
Wittmann, Helga,Ziegler, Erich
, p. 103 - 112 (1988)
Trimethylammonium acetic betain (1) reacts with phenacyl bromide and ethyl bromoacetate, respectively, to give the ester bromides 2 and 7.These can be hydrolyzed with aqueous sodium hydrogencarbonate at 20 deg C to yield besides 1 both C-benzoyl-methanol (3) and the glycolic acid ester 8, respectively.The reaction can also be performed in one step by reacting the betain (1) (with can act as a base) in a double molar ratio with the active halide. - Keywords: Trimethylammonium acetic acid betain; Trimethylammonium acetic acid phenacyl ester bromide; Trimethylammonium acetic acid acetoxy ethyl ester bromide; Phenacyl alcohol; Ethyl glycolate
Equilibrium Acidities and Homolytic Bond Dissociation Energies of the Acidic C-H Bonds in N-Substituted Trimethylammonium and Pyridinium Cations
Zhang, Xian-Man,Bordwell, Frederick G.,Puy, Michael Van Der,Fried, Herbert E.
, p. 3060 - 3066 (2007/10/02)
Equilibrium acidities (pKHAs) of the cations in sixteen N-substituted trimethylammonium salts, one N-phenacylquinuclidinium salt, eight N-substituted pyridinium salts, and N-(ethoxycarbonyl)-isoquinolinium bromide, together with the oxidation potentials of their conjugate bases, have been determined in dimethyl sulfoxide (DMSO) solution.The acidifying effects of the α-trimethylammonium groups (α-Me3N+) and the α-pyridinium groups (α-PyN+) on the adjacent acidic C-H bonds in these cations were found to average about 10 and 18 pKHA units, respectively, in DMSO.The homolytic bond dissociation energies of the acidic C-H bonds in these cations, estimated by the combination of the equilibrium acidities with the oxidation potentials of their corresponding conjugate bases (ylides), show that the α-trimethylammonium groups destabilize adjacent radicals by 2-6 kcal/mol, whereas α-pyridinium groups stabilize adjacent radicals by 3-6 kcal/mol.The effects of α-pyridinium groups on the stabilization energies of the radicals derived from these cations were found to be ca. 4-10 kcal/mol smaller than those of the corresponding phenyl groups, whereas their effects on the equilibrium acidities of the cations were 5.4-13.1 pKHA units larger.The pKHA value of tetramethylammonium cation (Me4N+) was estimated by extrapolation to be about 42 in DMSO.
