Organic analysis

Compound X, C₄H₈O₂, has an IR absorption at 1740 cm⁻¹ and no broad absorption at 2500–3300 cm⁻¹. Its ¹H NMR spectrum shows:

δ / ppm	Integration	Splitting
4.1	2	quartet
2.0	3	singlet
1.2	3	triplet

Deduce the structure of X, explaining your reasoning.

Which IR absorption is characteristic of an O–H group in an alcohol?

An infrared spectrum shows a very broad absorption at 2500–3000 cm⁻¹ and a strong absorption at 1710 cm⁻¹. Identify the functional group and explain.

Propane and carbon dioxide both have Mr = 44. Explain how high-resolution mass spectrometry distinguishes them. (Precise masses: C 12.0000, H 1.0078, O 15.9949)

Describe chemical tests that would allow you to distinguish between propanal, propanone, propan-1-ol and propanoic acid. Give reagents and observations.

An IR absorption at 3230–3550 cm⁻¹ (broad) indicates

Describe a chemical test to show that a compound is a primary or secondary alcohol rather than a tertiary alcohol.

Explain how the fingerprint region of an IR spectrum is used to identify a compound.

The mass spectrum of a ketone has a molecular ion peak at m/z 58 and a large peak at m/z 43. Identify the ketone and the ion responsible for the peak at 43.

A student makes aspirin from 2-hydroxybenzoic acid and ethanoic anhydride. Describe how the crude product is purified by recrystallisation and how its purity and identity can be checked.

Benzene can be converted into phenylamine in two steps. Give reagents and conditions for each step, name the intermediate and describe a test for phenylamine.