Chemistry 9701 · AS & A Level · An introduction to AS Level organic chemistry
An introduction to AS Level organic chemistry — practice question
The molecular formula $\text{C}_4\text{H}_8\text{O}$ may correspond to several compounds with different functional groups, and these compounds can display different kinds of isomerism. Compounds H, J and K each have the molecular formula $\text{C}_4\text{H}_8\text{O}$. In each molecule of H, J and K, the carbon chain is straight and the molecule is not cyclic, and no oxygen atom is bonded to any carbon atom that is involved in $\pi$ bonding. When compound H is reacted with sodium metal, a colourless flammable gas is formed. Both J and K produce an orange-red precipitate on reaction with 2,4-dinitrophenylhydrazine reagent, but only K reacts with Fehling’s solution.
(a(i))
Suggest possible structural formulae for H, J and K. Three structural formulae are possible for H but only one for J and one for K.
(a(ii))
As well as being structural isomers of one another, some of the possible structures for H, J or K exhibit $cis$-$trans$ isomerism or are chiral.
Draw the displayed formulae of those isomers that show $cis$-$trans$ isomerism.
(a(iii))
Draw the displayed formulae of those isomers which are chiral, indicating in each case the chiral carbon atom with an asterisk (*).
Worked solution & mark scheme
This 0-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Accurate identification of structures H, J and K” …