mesoform

Century Dictionary and Cyclopedia

1. n. In organic chemistry, a compound which contains two or more asymmetric (optically active) carbon atoms in the molecule, but which has its optical activity diminished or extinguished because one or more of the carbon atoms has the dextrorotatory and one or more the levorotatory configuration, thus more or less completely neutralizing each other's optical effect. Such compounds are also said to be internally compensated, in contradistinction from the racemic or externally compensated isomers. The two forms are distinguished, in practice, by the fact that the racemic isomer is capable of resolution into two optically active substances, which is not the case with the meso-compound.