Cis-trans isomers, of cycloalkanes

Cis-trans isomers of cycloalkanes are a type of stereoisomer, also called geometric stereoisomers, in which substituents are on the same side ids) or on the opposite sides trans) of the ring. 

These stereoisomers are not readily interconverted by rotation around the double bond at room temperature. Like cis-trans isomers of cycloalkanes, they are configurational stereoisomers and can be separated from one another by distillation, taking advantage of the difference in their boiling points. 

Stereoisomers (Section 4.2) are compounds whose atoms are connected in the same order hut with a different arrangement in space. Among the kinds of stereoisomers we ve seen are enantiomers, diastereomers, and cis-trans isomers of cycloalkanes. Actually, cis-trans isomers are just one class of diastereomers because they are non-mirror-image stereoisomers ... 

Recognize, draw, and name cis-trans isomers of substituted cycloalkanes. 

In Section 11.3, we observed that the rotation around the carbon-carbon bonds of cycloalkanes was restricted. The consequence of the absence of free rotation was the formation of geometric or cis-trans isomers. The cis isomers of cycloalkanes had substituent groups on the same side of the ring (L., cis, "on the same side"). The trans isomers of cycloalkanes had substituent groups located on opposite sides of the ring (L., trans, "across from"). 

Cis and trans isomers of cycloalkanes furnish us with another example of stereoisomers that are diastereomers. Consider the following two compounds ... 

Stereoisomers have the same molecular formula and the same connectivity of atoms in their molecules, but different three-dimensional orientations of their atoms in space. The one example of stereoisomers we have seen thus far is that of cis-trans isomers in cycloalkanes (Section 3.7) and alkenes (Section 4.1C) ... 

Stereoisomers Compounds that have the same molecular formula, the same connectivity of their atoms, but a different orientation of their atoms in space. The term "stereoisomer"includes cis,trans isomers in cycloalkanes and alkenes as well as enantiomers, diastereomers, meso compounds, and atropisomers. Conformational isomers are also stereoisomers, whether they are isolable or not. 

The 1,2-diinethylcyclopropanes are members of a subclass of stereoisomers called cis-trans isomers. The prefixes cis- (Latin "on the same side") and tmns-(Latin "across") are used to distinguish between them. Cis-trans isomerism is a common occurrence in substituted cycloalkanes. 

A cycloalkane is a saturated cyclic hydrocarbon with the general formula C H2 . In contrast to open-chain alkanes, where nearly free rotation occurs around C, -C bonds, rotation is greatly reduced in cycloalkanes. Disubstituted cycloalkanes can therefore exist as cis-trans isomers. The cis isomer has both substituents on the same face of the ring the trans isomer has substituents on opposite faces. Cis-trans isomers are just one kind of stereoisomers—isomers... 

Stereoisomers have the same order of atom attachments but different arrangements of the atoms in space. Cis-trans isomerism is one kind of stereoisomerism. For example, two substituents on a cycloalkane can be on either the same (c/s) or opposite (trans) sides of the mean ring plane. Stereoisomers can be divided into two groups, conformational isomers (interconvertible by bond rotation) and configurational isomers (not interconvertible by bond rotation). Cis-trans isomers belong to the latter class. 

Geometric isomers are not restricted to compounds containing the C=C bond. Eor example, certain di-substituted cycloalkanes can exist in the cis and the trans forms. Label the following molecules as the cis and trans isomer of the same compound ... 

A cis-trans isomer is a t)rpe of stereoisomer. Stereoisomers are molecules that have the same structural formula and bonding pattern but different arrangements of atoms in space. A cycloalkane is in the cis configuration if two substituents are on the same side of the ring (either both above or both below). A cycloalkane is in the trans configuration when one substituent is above the ring and the other is below the ring. The cis-trans isomers are not interconvertible. 

Stereoisomers are compounds that have the same chemical formula and connectivity but a different arrangement of the bonds in space. In cycloalkanes, they are similar to cis-trans isomers in that they cannot interconvert without breaking a bond. It is easiest to show the stereoisomers of a cyclic compound by drawing the ring flat and not worrying about conformations. 

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