All three organic compounds, V, W and X, have the empirical formula $\text{CH}_2\text{O}$. The number of carbon atoms in each molecule is indicated. On warming, V gives a brick red precipitate with Fehling’s reagent, whereas W and X do not. W is a liquid with a fruity smell. In X, the carbon atoms are joined directly to each other. X effervesces when it is shaken with $\text{Na}_2\text{CO}_3$(aq), but V and W do not.
(a)[1]
State the structural formula for V.
(b(i))[1]
Which functional group is found in W?
(b(ii))[1]
State the structural formula for W.
(c(i))[1]
$X$ is heated under reflux with acidified $\text{K}_2\text{Cr}_2\text{O}_7$ to give Y, and Y does not react with 2,4-dinitrophenylhydrazine reagent. State the structural formula of X.
(c(ii))[1]
State the structural formula of Y, the product obtained from X.
(d(i))
Warming X with a little concentrated sulfuric acid produces a small quantity of the cyclic compound, Z. Z has the molecular formula $\text{C}_6\text{H}_8\text{O}_4$. Suggest a displayed formula for Z.
(d(ii))[2]
Which type of reaction takes place when Z is formed from X?
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct answer: $V$ is $\text{HCHO}$” …