Crystal and molecular structure of anhydrous betaine, (CH3)(3)NCH2CO2

1-Carboxy-N,N,N-trimethylmethanamanium inner salt or anhydrous betaine, (CH 3)(3)NCH2CO2, FW = 117.15 gmol(-1), crystallizes in the orthorhombic space group Pnma with a=14.544(2) Angstrom, b=6.859(3) Angstrom, c=6.131(1) Angst rom, V = 611.7(3) Angstrom(3), Z = 4, D-x = 1.27 Mgm(-3), lambda(MoK alpha) = 0.71073 Angstrom, mu = 0.091 mm(-1). The structure was resolved by direc t methods and refined by least-square calculations to R = 0.038 for 531 ref lections. Observed changes in bond angles imply that there is a repulsion b etween nitrogen and oxygen. The melting point (measured at onset) is 570 K. FTIR spectra of anhydrous betaine and monohydrate were recorded. Clear dif ferences were found between the two compounds based on infrared (i.r.) abso rption bands sensitive to water. (C) 1999 Elsevier Science B.V. All rights reserved.