Conformations of N , N ‐diethyl‐β‐alanine and β‐alanine as a function of solvent

Conformational equilibria of N , N ‐diethyl‐β‐alanine were estimated from vicinal proton–proton coupling constants between the CH 2 CH 2 group in protic and aprotic solvents of different polarities. β‐Alanine was similarly studied in dimethyl sulfoxide (DMSO). In general, the results for both substances correspond fairly well with those reported earlier for β‐alanine in neutral and acidic aqueous solutions. There appeared to be little conformational preference for N , N ‐diethyl‐β‐alanine in any of the solvents used, ranging from water to dichloromethane. The exception was a moderate preference (66–73%) for the trans conformer displayed by the conjugate base of N , N ‐diethyl‐β‐alanine in all of the solvents studied. Copyright © 2004 John Wiley & Sons, Ltd.