A hydrocarbon $P$, with the formula $\text{C}_6\text{H}_{12}$, quickly decolourises bromine. When it is treated with hot, concentrated, acidified potassium manganate(VII) solution, one organic product, $Q$, is formed. $Q$ gives an orange precipitate with 2,4-dinitrophenylhydrazine, 2,4-DNPH reagent, but shows no reaction with Tollens’ reagent.
(a(i))[4]
Explain these observations in chemical terms.
(a(ii))[2]
Draw the skeletal formula of $P$ and state its name.
(a(iii))[2]
Draw the skeletal formula of $Q$ and state its name.
(b)[3]
Several structural isomers of $P$ also decolourise bromine, but only four of these structural isomers show geometrical (cis-trans) isomerism. Give the structures of any three structural isomers of $P$ that show geometrical (cis-trans) isomerism.
Worked solution & mark scheme
This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Bromine decolourisation shows alkene/unsaturation” …