Portmess Homework Q&S 65

Portmess Homework Q&S 65 - 3 1 2 4 Less stable...

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The axial methyl group in the cis stereoisomer is involved in unfavorable repulsions with the C-4 and C-6 axial hydrogens indicated in the drawing. ( b ) Both groups are equatorial in the cis stereoisomer of 1-isopropyl-3-methylcyclohexane; cis is more stable than trans in 1,3-disubstituted cyclohexanes. ( c ) The more stable stereoisomer of 1,4-disubstituted cyclohexanes is the trans; both alkyl groups are equatorial in trans -1-isopropyl-4-methylcyclohexane. ( d ) The f rst stereoisomer of 1,2,4-trimethylcyclohexane is the more stable one. All its methyl groups are equatorial in its most stable conformation. The most stable conformation of the second stereoisomer has one axial and two equatorial methyl groups. H 3 C CH 3 CH 3 1 2 4 More stable stereoisomer All methyl groups equatorial in most stable conformation CH 3 H 3 C CH
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Unformatted text preview: 3 1 2 4 Less stable stereoisomer One axial methyl group in most stable conformation CH 3 CH 3 H 3 C 1 2 4 CH 3 CH 3 H 3 C 1 2 4 CH 3 CH 3 CH 3 1 2 4 cis-1-Isopropyl-4-methylcyclohexane (less stable stereoisomer; methyl group is axial and involved in repulsions with axial hydrogens at C-2 and C-6) trans-1-Isopropyl-4-methylcyclohexane (more stable stereoisomer; both groups are equatorial) H 3 C CH(CH 3 ) 2 CH 3 H H CH(CH 3 ) 2 1 2 4 6 cis-1-Isopropyl-3-methylcyclohexane (more stable stereoisomer; both groups are equatorial) trans-1-Isopropyl-3-methylcyclohexane (less stable stereoisomer; methyl group is axial and involved in repulsions with axial hydrogens at C-1 and C-5) CH 3 CH(CH 3 ) 2 CH 3 CH(CH 3 ) 2 H H 1 5 3 CONFORMATIONS OF ALKANES AND CYCLOALKANES 59...
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This note was uploaded on 09/20/2011 for the course CHM 2210 taught by Professor Reynolds during the Spring '01 term at University of Florida.

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