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

Carboxylic acids and derivatives — practice question

Butanedioic acid can be prepared by a three-step synthesis that begins with ethane.
(a)[1]

Describe the reagents and the conditions required for step 1.

(b)[1]

Name the other product formed in step 1 that is an isomer of A.

(c)[1]

Give B's structural formula.

(d)[2]

State the reagents and conditions needed for step 2.

(e(i))[1]

Identify the oxidising agent that could be used to oxidise butanedioic acid.

(e(ii))[1]

State the product(s) formed in (e)(i).

(f)[3]

Compare the relative acidities of hexanoic acid, hexan-1-ol and phenol, and explain them.

(g(i))[2]

Identify which protons in the methylpropanedioic acid molecule produce each part of the proton NMR spectrum at chemical shifts $\delta 12.7$, $\delta 3.3$ and $\delta 1.1$. The spectrum is recorded in $\text{CCl}_4$.

(g)

Methylpropanedioic acid is an isomer of butanedioic acid, and its proton NMR spectrum in CCl$_4$ is shown.

(g(ii))[1]

Name the splitting pattern at $\delta 3.3$ and explain its origin.

(g(iii))[1]

The carbon-13 NMR spectra of butanedioic acid, HO$_2$CCH$_2$CH$_2$CO$_2$H, and methylpropanedioic acid, HO$_2$CCH(CH$_3$)CO$_2$H, are different. State the number of peaks (a) in the carbon-13 NMR spectrum of butanedioic acid and (b) in the carbon-13 NMR spectrum of methylpropanedioic acid.

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