Organic Chemistry

Problem # 332

Each of the carbocations below will spontaneously rearrange. Draw the structure of the expected rearrangement product.

Problem # 331

Rank the carbocations below in order of decreasing stability. (1 = most stable)

Problem # 324
 

Using curved hooks, draw a mechanism for the free radical bromination  reaction shown below.

Problem # 322
 

Using curved arrows, draw a mechanism for the SN1 reaction shown below.

Problem # 321
 

Using curved arrows, draw a mechanism for the SN1 reaction shown below.

 

Problem # 320

 

Let's perform conformational analysis on 2-methylbutane along the C2-C3 bond. We'll use the energy chart given below.

 

First, draw out the Newman projections along the C2-C3 bond, rotating the front carbon (C-2) by 60 degrees clockwise each time while keeping the back carbon (C-3) stationary.

According to the table above, how much energy does each conformation "cost?"

 

Second, make a plot of the total energy value for each Newman projection versus its dihedral angle.

 

Problem # 319

For a molecule to undergo an E2 reaction, the leaving group and the beta-proton must be in an anti-coplanar conformation (one atom straight up, the other straight down). Based on this, which compound undergoes E2 reaction with KOtBu faster? Why?

 

Problem # 318

Two stereoisomers of trimethylcyclohexane are shown below (compounds A and B). Compare cyclohexane chair forms to determine which isomer has a lower heat of combustion. Explain your reasoning.

 

Problem # 317

 

α-D-Glucose is shown below. Draw its two chair forms. Which conformation is more stable? Explain.

I recommend using the common convention wedge = "up" and dash = "down."

 

 

Problem # 315

 

Draw all possible resonance forms for each structure below. Use curved arrows.

Note that some structures only show charge, and not implied protons or lone pairs!