Crystal and molecular structure of chloramphenicol

Chloramphenicol, C₁₁H₁₂Cl₂N₂O₅, is orthorhombic, space groupC222₁,a = 17.495(3),b = 7.321(2),c = 22.130(4) Å, andZ = 8. The structure was solved by direct methods and refined to a finalR value of 0.068 for 1186 counter-reflections. Estimated standard deviations for bond lengths and bond angles involving nonhydrogen atoms average 0.009 Å and 0.6 °, respectively. All the hydrogen atoms that are bonded to O or N and are available for hydrogen-bond formation take part in the hydrogen-bonding network. The crystals become brown in color on prolonged exposure to X-rays and -rays. Our structural investigation with colored crystal does not indicate any structural change.