150 years later: a look at Loschmidt's contributions to organic chemistry

摘要

Examining the structures presented by Loschmidt in 1861 shows that he portrayed organic structures in a visually appealing way, but the structures do not support several claims and accolades of Loschmidt's modern-day champions. There is serious doubt that Loschmidt viewed benzene as a planar cyclic array of six carbon atoms; he did not understand positional isomerism of benzene derivatives or the essence of geometric isomerism. He did not recognize that carbons of the C_6 nucleus could only be singly bonded to a substituent. Concerning his "prediction" of cyclopropane, Loschmidt may have been the first to consider a "circular" array of three atoms; this achievement must be viewed in the light of similar predictions for a cyclic dinitrogen oxide, tetracyclohexane, heptacyclononane, and a [1,1]-metacyclophane. His structures worked well for strings of sp~2-hybridized carbons or for molecules with chains of tri-substituted carbons. Loschmidt did not differentiate between the bond lengths of double and triple bonds, as claimed.