Chemistry 9701 · AS & A Level · Organic synthesis

Organic synthesis — practice question

Menthone, $\text{C}_{10}\text{H}_{18}\text{O}$, is a cyclic ketone found in peppermint oil.
(a)[2]

On the formula above, use asterisks (*) to show any chiral centres present in the menthone molecule.

(b(i))[2]

Suggest suitable reagents for step 1 and step 2.

(b(ii))[4]

Suggest the structures of L and M, then draw them in the boxes above.

(c(i))[1]

Give the letter of the alkene that produced N in this reaction when heated with concentrated, acidified $\text{KMnO}_4\text{(aq)}$.

(c(ii))[1]

Suggest the structure of product P formed when the other alkene you drew is reacted with hot concentrated acidified $\text{KMnO}_4$.

(c(iii))[1]

Suggest one chemical test that would let you distinguish between N and P. State the reagent(s) and the observation.

(d)[3]

Chlorocyclohexane may be prepared by bubbling $\text{HCl(g)}$ through a solution of cyclohexene. Suggest, using a diagram, the mechanism of this 2-stage reaction. Include all full or partial charges, and show electron-pair movement with curly arrows.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Two chiral centres correctly identified

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