Portmess Homework Q&S 68

Portmess Homework Q&S 68 - 2 CH 2 Cl has a dipole...

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( c ) At C-7 the bond that is trans to the methyl groups is axial (down). ( d ) At C-11 the bond that is trans to the methyl groups is equatorial (down). ( e ) At C-12 the bond that is cis to the methyl groups is equatorial (up). 3.35 Analyze this problem in exactly the same way as the preceding one by locating the axial and equa- torial bonds at each position. It will be seen that the only differences are those at C-1 and C-4. ( a ) At C-1 the bond that is cis to the methyl groups is axial (up). ( b ) At C-4 the bond that is cis to the methyl groups is equatorial (up). ( c ) At C-7 the bond that is trans to the methyl groups is axial (down). ( d ) At C-11 the bond that is trans to the methyl groups is equatorial (down). ( e ) At C-12 the bond that is cis to the methyl groups is equatorial (up). 3.36 ( a ) The torsion angle between chlorine substituents is 60 ° in the gauche conformation and 180 ° in the anti conformation of ClCH 2 CH 2 Cl. ( b ) All the individual bond dipole moments cancel in the anti conformation of ClCH 2 CH 2 Cl, and this conformation has no dipole moment. Since ClCH
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Unformatted text preview: 2 CH 2 Cl has a dipole moment of 1.12 D, it can exist entirely in the gauche conformation or it can be a mixture of anti and gauche con-formations, but it cannot exist entirely in the anti conformation. Statement 1 is false. 3.37–3.40 Solutions to molecular modeling exercises are not provided in this Study Guide and Solutions Man-ual. You should use Learning By Modeling for these exercises. SELF-TEST PART A A-1. Draw Newman projections for both the gauche and the anti conformations of 1-chloro-propane, CH 3 CH 2 CH 2 Cl. Sight along the C-1, C-2 bond (the chlorine is attached to C-1). A-2. Write Newman projection formulas for ( a ) The least stable conformation of butane ( b ) Two different staggered conformations of CHCl 2 CHCl 2 Gauche (can have a dipole moment) Anti (cannot have a dipole moment) H Cl H H H Cl Cl Cl H H H H Both methyl groups are up. CH 3 CH 3 d e c a b 11 12 7 1 4 H 62 CONFORMATIONS OF ALKANES AND CYCLOALKANES...
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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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