18. Carboxylic acids and derivatives
A section of Chemistry, 9701
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Butanedioic acid can be made in a three-step synthesis using ethane as the starting material. H C H H C ethane H H H Br C H H C A B H H C H H C butanedioic acid H H Br step 1 step 2 step 3 C C O HO O OH Describe the reagents and conditions needed for step1. Name the other product also formed in step1 which is an isomer of A. Give the structural formula of B.  State the reagents and conditions needed for step2. Butanedioic acid cannot be oxidised by a warm, aqueous solution of any commonly used oxidising agents but ethanedioic acid can. Identify the oxidising agent that could be used to oxidise ethanedioic acid. State the productof the reaction in . Compare and explain the relative acidities of hexanoic acid, hexan‑1‑ol and phenol. Methylpropanedioicacid is an isomer of butanedioicacid. C CH3 H methylpropanedioic acid C C O HO O OH The proton NMR spectrum of methylpropanedioic acid in CCl 4 is shown. δ / ppm δ 12.7 δ 3.3 δ 1.1 Identify the protons in the methylpropanedioic acid molecule that are responsible for each area of the proton NMR spectrum. δ 12.7 δ 3.3 δ 1.1  Name the splitting pattern shown at δ 3.3 and explain how it arises. The carbon‑13 NMR spectra of butanedioic acid, HO2CCH2CH2CO2H, and methylpropanedioicacid, HO2CCH(CH3)CO2H are different. State the number of peaks ● in the carbon‑13 NMR spectrum of butanedioic acid ● in the carbon‑13 NMR spectrum of methylpropanedioic acid.  
9701_w19_qp_42
THEORY
2019
Paper 4, Variant 2
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