Chemistry 9701 · AS & A Level · Carbonyl compounds

Carbonyl compounds — practice question

Using modern telescopes of several kinds, astronomers have detected many molecules within dust clouds in space. Quite a few of these are organic molecules, and astronomers continually search for signs that amino acids, such as aminoethanoic acid, $\text{H}_2\text{NCH}_2\text{CO}_2\text{H}$, are present. One molecule already identified in these dust clouds is hydroxyethanal, $\text{HOCH}_2\text{CHO}$.
(a(i))[2]

Hydroxyethanal has two functional groups. Name each of the functional groups in hydroxyethanal as completely as you can.

(a(ii))[5]

For each functional group, choose a reagent that reacts with that group and not with the other functional group present. For each one, describe the observation expected when the reaction is carried out.

(b(i))[1]

Give the skeletal formulae for the organic compounds produced when hydroxyethanal is reacted separately with $\text{NaBH}_4$.

(b(ii))[1]

Give the skeletal formulae for the organic compounds produced when hydroxyethanal is reacted separately with $\text{Cr}_2\text{O}_7^{2-}/\text{H}^+$ under reflux conditions.

(c(i))[3]

In a school or college laboratory, hydroxyethanal can be changed into aminoethanoic acid in three steps: $\text{HOCH}_2\text{CHO} \rightarrow X \rightarrow Y \rightarrow \text{H}_2\text{NCH}_2\text{CO}_2\text{H}$. Use the likely reactions of the functional groups in hydroxyethanal to work out one possible pathway for this conversion. In the boxes below, draw the structural formulae of the intermediates $X$ and $Y$ that you suggest.

(c(ii))[2]

State the reagents for each of the three steps that you have chosen.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Identifies functional group 1 to be a primary alcohol

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