4. Alkanes and Cycloalkanes

Draw Newman projections of the following molecules viewed from the direction of the blue arrows.

(c)

Given 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.]

(j) <IMAGE>

Using the Newman projections shown, draw each molecule in its line-angle drawing with all hydrogens and substituents shown. [Carbon b is behind carbon a in these structures.] Wedges and dashes should be used to indicate whether a substituent is coming out of, or going into, the plane of the page.

(b)

Draw the conformer that is present in greatest concentration.

Convert each Newman projection to the equivalent line–angle formula, and assign the IUPAC name. g.

(g)

(h)

c. Draw Newman projections of the two conformers of the trans isomer.

d. Which of the conformers predominates at equilibrium?

Draw a Newman projection, similar to Figure 3-25 down the C1—C6 bond in the ­equatorial conformation of methylcyclohexane. Show that the equatorial methyl group is also anti to C5. (Using your models will help.)

<IMAGE>

Draw the most stable Newman Projection of CH₃CH₂ CH₂OH through the C2 – C1 bond. 

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>

Given the first Newman projection and the direction and degree of rotation, fill in the resulting Newman projection. [One substituent has been labeled for you.]

(h)

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>

Given 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.]

(k) <IMAGE>

For rotation about the C-3---C-4 bond of 2-methylhexane, do the following:

a. Draw the Newman projection of the most stable conformer.

b. Draw the Newman projection of the least stable conformer.