Modern analytical techniques II

Compound Z, C₃H₆O₂, is an ester. Its ¹H NMR spectrum has a singlet at δ 8.0 (1H), a quartet at δ 4.2 (2H) and a triplet at δ 1.3 (3H). Its ¹³C NMR spectrum has three peaks. Identify Z and explain each feature of the spectra.

Explain how high-performance liquid chromatography (HPLC) separates components of a mixture and how they are identified.

An organic compound contains 54.5% C, 9.1% H and 36.4% O by mass. Its mass spectrum shows M⁺ at m/z 88. It reacts with sodium carbonate to produce CO₂. Its ¹H NMR spectrum shows a doublet (6H), a multiplet (1H) and a singlet (1H) at δ 11.5. Identify the compound.

A student used thin-layer chromatography to check the purity of aspirin she had made. (a) Describe how to carry out the TLC and calculate Rf values. (b) The product showed two spots: Rf 0.62 (matching pure aspirin) and Rf 0.35 (matching salicylic acid). Explain what this shows and how she could purify the product. (c) Give one other method to check purity, with the expected result for a pure sample.