The Crystal Structure of l-Alanine

The crystal structure of l-alanine, C3H7O2N, has been determined and refined by analysis of complete three-dimensional diffraction data from copper X-radiation. The crystals are orthorhombic with space group P21P21P21 ; the unit cell dimensions are a = 6.032, b = 12.343, c = 5.784 Å. Least-squares refinement of the positional parameters of all 13 atoms and of the individual anisotropic temperature factors of the six heavy atoms, using 581 observed reflections of non-zero weight, yielded a final R factor of 0.049. The structure bears a striking resemblance to that of dl-alanine, and involves the use of all available protons in hydrogen bonding, with lengths of 2.83, 2.85, and 2.81 Å.