Cis-Trans Isomerism in Cycloalkanes Constitutional isomers CH3 (different connections between atoms) CH3-CH-CH3 and CH3-CH2-CH2-CH3 Stereoisomers H3C CH3 H3C (same connections and but different three- dimensional geometry) CH3 LeingAlliRervd cis isomer trans isomer
cis isomer trans isomer Cis-Trans Isomerism in Cycloalkanes
Cis-Trans lsomerism in Cycloalkanes cis-trans isomers Stereoisomers that differ in their stereochemistry about a double bond or ring -cis-(Latin,"on the same side") -trans-(Latin,"across") H3C CH3 Br 5 H CH2CH3 cis-1,3-Dimethylcyclobutane trans-1-Bromo-3-ethylcyclopentane
cis-trans isomers ▪ Stereoisomers that differ in their stereochemistry about a double bond or ring ▪ cis- (Latin, “on the same side”) ▪ trans- (Latin, “across”) Cis-Trans Isomerism in Cycloalkanes
Worked Example 4.1 Naming Cycloalkanes Name the following substances,including cis-or trans- prefix (a) CH3 (b) H3C- H H
Name the following substances, including cis- or transprefix Worked Example 4.1 Naming Cycloalkanes
Worked Example 4.1 Naming Cycloalkanes Strategy (a) CH3 (b) H3C-1 H In these views,the ring is roughly in the plane of the page, a wedged bond protrudes up above the page,and a dashed bond recedes below the page.Two substituents are cis if they are both above or below the page,they are trans if one is above and one is below
Strategy In these views, the ring is roughly in the plane of the page, a wedged bond protrudes up above the page, and a dashed bond recedes below the page. Two substituents are cis if they are both above or below the page, they are trans if one is above and one is below Worked Example 4.1 Naming Cycloalkanes
Worked Example 4.1 Naming Cycloalkanes Solution (a) H CH3 (a)trans-1,3-Dimethylcyclopentane (b)cis-1,2-Dichlorocyclohexane (b)
Solution (a) trans-1,3-Dimethylcyclopentane (b) cis-1,2-Dichlorocyclohexane Worked Example 4.1 Naming Cycloalkanes