Laboratory Methods of Organic Chemistry - Sciencemadness Dot Org

PKEPAKATION OF AN OLEFINE 107
HC1 HC1
>HC1.
ICJ~HC1
Whereas in benzene and in its derivatives tlie six substituents lie
in the same plane, namely, that of the ring, they are distributed in
cyclohexane in two planes parallel to that of the ring. Hence there
results a special type of spatial isomerism when two hydrogen atoms
united to different carbon atoms are replaced. The isomerism is caused
by the position of the two substituents, for they may lie in the same
plane (m-form), or one in each plane (irons-form). The phenomenon
is closely related to the cis-trans isomerism of the ethylenes, of which the
best-known example is that of maleic and fumaric acids.
Thus two stereo-isomeric forms of 1 : 4-dihydroxycyclohexane
(quinitol) are known :
H(\ HaH2 QH H H2
H2 H2
H2
H TT -11 11U XT XT xi
2 £±2 "-2 "-2
cis-Quinitol