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Unformatted text preview: 3 -27 The more stable confonner p l aces the l arger group equatori al . (a) c;tH7
H CH2CH3 (b) 4�H] ----- �CH2CH]
H m ore stable CH3 H ( c) (CH 3hCH H
m ore stable (d) CH3 CH2CH3 H ----- � CH2CH' CH3
m ore stable H ... -- H] H 3C , C -CH H � CH2CH]
m ore stable H 3 -28 The key to detennining c i s and trans around a cyclohexane ring i s to see w hether a substituent group is "up " or "down" relative to the H a t the same carbon. Two "up" groups or two "down" groups will be c i s ; one "up " and one "down" w i l l be trans. Thi s works independent o f t h e confonnati on t h e molecule i s in ! (a) cis- l ,3-dimethylcyclohexane (d) cis- 1 ,3-di methylcyc l ohexane (b) cis- l ,4-dimethylcyclohexane (e) cis- l ,3-dimethylcyclohexane (c ) trans-I,2-dimethylcyclohexane (f) trans-I,4-dimethy l c yclohexane ( b) ;----f- CCCH3h � CH3 H ( c ) B ulky substi tuents like t-butyl adopt equatorial rather than axial posi tions, even i f that means altering the c onformation of the ring. The tw i st boat conformati on allows both bulky substituents to be "equatorial". H H CH 3 I C -CH 2 CH 3 I CH 3 H 51 ...
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This note was uploaded on 02/27/2010 for the course CHEM 140 taught by Professor Wade during the Spring '10 term at Whitman.
- Spring '10