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

1–Carboxy–N,N,N–trimethylmethanamanium inner salt or anhydrous betaine, (CH3)3NCH2CO2, FW=117.15gmol−1, crystallizes in the orthorhombic space group Pnma with a=14.544(2)Å, b=6.859(3)Å, c=6.131(1)Å, V=611.7(3)Å3, Z=4, Dx=1.27Mgm−3, λ(MoKα)=0.71073Å, μ=0.091mm−1. The structure was resolved by direct methods and refined by least-square calculations to R=0.038 for 531 reflections. Observed changes in bond angles imply that there is a repulsion between nitrogen and oxygen. The melting point (measured at onset) is 570 K. FTIR spectra of anhydrous betaine and monohydrate were recorded. Clear differences were found between the two compounds based on infrared (i.r.) absorption bands sensitive to water.