1. Carbocation rearrangements For each carbocation, circle if the carbocation rearranges or doesn't rearrange. If it rearranges, draw the arrow-pushing mechanism and the resulting carbocation. (a) (circle one): rearranges or doesn't rearrange H3C H y (b) (circle one): rearranges or doesn't rearrange F3C H ୪ H (c) (circle one): rearranges or doesn't rearrange H3C CH3 (d) (circle one): rearranges or doesn't rearrange zo H3CO CH3 CH3

2) a) Draw the product if Molecule A underwent a [3,3]-sigmatropic rearrangement. Hint, you may want to start by redrawing the starting materials in their reactive conformations. (4 points) Molecule A CH3 CH2 b) Show the complete, step-wise curved arrow mechanism for the above reaction. You may use H-B for any Broensted acid and B- for any Broensted base. You can maximize your chances of partial credit by providing a consistent numbering scheme for your carbons. (9 points)

5. Each of the following may participate in an elimination reaction, under the proper conditions. (a) Circle the alpha (a) carbon. (b) Circle the beta (B) carbon(s). (c) Draw the alkene product(s) that may form, with the new double bond between the a and B positions. (d) If more than one alkene product is possible, circle the most stable (Zaitsev) product. X tx + 3

2. Which one of these alkenes would be likely to experience a carbocation rearrangement when treated with aqueous acid (hydration)? A) B) C) D) None of these would undergo a rearrangement.

(a) Add curved arrows for each step to show how A is converted to theepoxy ketone C. (b) Classify the conversion of A to C as a substitution,elimination, or addition. (c) Draw one additional resonance structure forB.

Dehydration of 1,2,2-trimethylcyclohexanol with H2SO4 affords 1-tertbutylcyclopentene as a minor product. (a) Draw a stepwise mechanism that shows how this alkene is formed. (b) Draw other alkenes formed in this dehydration. At least one must contain a five-membered ring.

Draw the curved arrow mechanism for the reaction attatched

3. Will the following carbocations rearrang e? If so, draw the rearrangement using a curved arrow and the new carbocation. You may have to draw in the H-atom and its bond to properly illustrate the hydride shift. Two will not rearrange.

Please show the mechanism with arrow formalism.

6. a) For each of the following pairs of molecules, identify the stereochemical relationship. Are they enantiomers, diastereomers, constitutional isomers, or the same molecule. CH3 н— сно i) ii) CHO H3C-OH НО HO ОН CI H CI iii) iv) Br H H H CI H. Br CI CI CI b) Explain why carbocation A is formed in step 2, rather than carbocation B (formed by the mechanism shown below). A B