Chemistry 9701 · AS & A Level · Carboxylic acids and derivatives

Carboxylic acids and derivatives — practice question

Some antibiotics are synthesised using $(\text{CH}_3)_3\text{CCHO}$.
(a(i))[1]

State the name of $(\text{CH}_3)_3\text{CCHO}$.

(a(ii))[1]

State the hybridisation of the carbon atom marked with an asterisk, $*$.

(b(i))[1]

Reaction 1 is an oxidation. Identify the reagent(s) and conditions used for reaction 1.

(b(ii))[3]

$\text{A}$, $(\text{CH}_3)_3\text{CCO}_2\text{H}$, is solid at room temperature. $\text{B}$, $\text{CH}_3\text{CO}_2(\text{CH}_2)_2\text{CH}_3$, is an isomer of $\text{A}$. $\text{B}$ is liquid at room temperature. Explain the different physical states of $\text{A}$ and $\text{B}$, referring to any intermolecular forces that may be present.

(b(iii))[1]

Give the balanced equation for the reaction of $(\text{CH}_3)_3\text{CCHO}$ with $\text{NaBH}_4$ to make $\text{S}$. Use $[\text{H}]$ to show one atom of hydrogen supplied by $\text{NaBH}_4$.

(b(iv))[2]

Draw the structure of the organic compound $\text{T}$ that reacts with $\text{A}$, $(\text{CH}_3)_3\text{CCO}_2\text{H}$, in reaction 2, to make $\text{U}$. Suggest a catalyst for reaction 2.

(c(i))[1]

$\text{X}$ and $\text{Y}$ each contain a carbonyl group. Complete the table with the expected observations for the reactions of $\text{X}$ and $\text{Y}$ with 2,4-DNPH.

(c(ii))[1]

Identify the functional group in $\text{Y}$ that is responsible for the recorded result with Fehling’s solution.

(c(iii))[1]

$\text{Y}$ has a chiral centre and exists as a pair of optical isomers. State what is meant by the term chiral centre.

(c(iv))[2]

Draw the optical isomers of $\text{Y}$ using the standard three-dimensional representation.

(c(v))[1]

Z, $\text{C}_5\text{H}_{10}\text{O}$, has a branched carbon chain. It shows geometrical isomerism. Complete the table with the bond responsible for each principal absorption in the infra-red spectrum of Z.

(c(vi))[3]

Draw the skeletal formula of Z.

(c(vii))[3]

X contains a carbonyl group. X reacts with HCN, in the presence of a small amount of NaCN, to form $(\text{C}_2\text{H}_5)_2\text{C(OH)CN}$ as shown. Draw the mechanism for the reaction of X with HCN. • Draw the structure of X and the intermediate. • Include all charges, partial charges, lone pairs and curly arrows.

(c(viii))[1]

State the role of NaCN in the reaction in (c)(vii).

Worked solution & mark scheme

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