Chemistry 9701 · AS & A Level · Carbonyl compounds

Carbonyl compounds — practice question

Crotonaldehyde, $\text{CH}_3\text{CH=CHCHO}$, is present in soybean oils.
(a)[5]

In the spaces provided, write the structural formula of the organic compound obtained when crotonaldehyde is treated separately with each reagent under suitable conditions. If you decide that no reaction takes place, enter "NO REACTION" in the space. Reagents: (A) $\text{Br}_2$ in an inert organic solvent; (B) $\text{PCl}_3$; (C) $\text{H}_2$ and Ni catalyst; (D) $\text{NaBH}_4$; (E) $\text{K}_2\text{Cr}_2\text{O}_7/\text{H}^+$.

(b)[3]

Crotonaldehyde is found in more than one stereoisomeric form. Draw the displayed formulae for the stereoisomers of crotonaldehyde. Name each isomer.

(c)[1]

Draw the skeletal formula of crotonaldehyde.

(d(i))[3]

The product of reaction E in the table opposite will react with a solution containing acidified manganate(VII) ions. Draw the structural formulae of the organic products when the reagent is cold, dilute.

(d(ii))[3]

The product of reaction E in the table opposite will react with a solution containing acidified manganate(VII) ions. Draw the structural formulae of the organic products when the reagent is hot, concentrated.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: A: $\text{Br}_2$ in inert organic solvent forms $\text{CH}_3\text{CHBrCHBrCHO}$.

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