11589 15 An ester, with the molecular formula C7H14O2, produced three signals when analysed by proton nmr. The data is provided in the table below: signal a b c chemical shift 4.1 1.2 1.1 integration ratio 2 3 9 splitting pattern quartet triplet singlet (a) (i) Explain why solvents which contain hydrogen atoms should not be used in nmr spectroscopy. Suggest a suitable solvent which could be used. [2] (ii) Give the name and formula of the molecule used in nmr spectroscopy as a standard. [2] (iii) State two reasons why the molecule identified in part (ii) is used. [2] 11589 [Turn over (b) (i) Explain which alkyl group in the ester produces signals a and b making reference to the spin-spin splitting pattern and the integration ratios. [3] (ii) Draw the alkyl group that would give rise to signal c. [1] (c) Draw the possible structure of the ester based upon the nmr data given. [2]