BackGiven the following structures, show the Newman projection that would result from looking down the indicated bond in the direction shown. [Orient yourself as if you were the eyeball looking down the bond. Some of the examples have been partially completed for you to fill in the rest.]
(b) <IMAGE>
Looking down the indicated bond, show the three most stable conformations and choose the one that is most stable. Be sure that the first Newman projection you show is the one you see initially (before rotation). [Why should none of your three Newman projections show eclipsed conformations?]
(b) <IMAGE>
For each of the following structures, which staggered Newman projection skeleton from Assessment 3.51 should you draw first to show what is seen when looking down the indicated bond?
(d) <IMAGE>
Convert each Newman projection to the equivalent line–angle formula, and assign the IUPAC name.
(c)
(d)
Using Newman projections, draw the most stable conformer for each of the following:
c. 3,3-dimethylhexane, viewed along the C-3---C-4 bond
For the following molecule, draw the Newman projection (around the 2,3-bond) with a dihedral angle of 180° between the bromine and hydrogen.
Conformational studies on ethane-1,2-diol (HOCH2–CH2OH) have shown the most stable conformation about the central C―C bond to be the gauche conformation, which is 9.6 kJ/mol (2.3 kcal/mol) more stable than the anti conformation. Draw Newman projections of these conformers, and explain this curious result.
Draw the conformer that is present in greatest concentration.
Looking down the indicated bond, show the three most stable conformations and choose the one that is most stable. Be sure that the first Newman projection you show is the one you see initially (before rotation). [Why should none of your three Newman projections show eclipsed conformations?]
(e) <IMAGE>