M. A. Rosanoff
1906 Journal of the American Chemical Society  
IN THE celebrated memoir founding the science of stereochemistry,2 van't Hoff makes an important assumption concerning the optical activities of several asymmetric carbon atoms in a molecule. Referring to molecules made up of two similar asymmetric groups, he says: "The activity that each of these asymmetric carbon atoms contributes to the whole will be equal or opposite, say a and -a; so that the activity of the four isomers will be r e p resented by the expressions: ( I ) +a+a, (2) +a-a,
more » ... a+a, (2) +a-a, (3)-a+a, (4) -a-a." The assumption symbolized by these expressions is, that the two partial rotations are not themselves changed by addition to, or subtraction from, one another. Writing twenty years later,3 van't Hoff extends this assumption to molecules with several different asymmetric carbon atoms. "Thus," he says, "for the four pentose types, COH(CHOH),CH,OH, we should have the following rotations : No.
doi:10.1021/ja01970a008 fatcat:eqx5ueefjbaetalgm5lcsm5fnu