OCR A Jan 2010 Paper 4 Q4

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4 An industrial chemist discovered five bottles of different chemicals (three esters and two carboxylic acids) that were all labelled C5H10O2. 10 The different chemicals had the structural formulae below. CH3CH2COOCH2CH3 (CH3)3CCOOH CH3COOCH(CH3)2 (CH3)2CHCH2COOH (CH3)2CHCOOCH3 (a) The chemist used both infrared and 13C NMR spectroscopy to identify the two carboxylic acids and to distinguish between them. How do both types of spectra allow the carboxylic acids to be identified and distinguished?[3] (b) The chemist analysed one of the esters by 1H NMR spectroscopy. The spectrum is shown below. expansion of multiplet centred at 2.7 ppm absorptionOCR 2010<br />
 Analyse the splitting patterns and the chemical shift values to identify the ester. 11 Give your reasoning. In your answer, you should use appropriate technical terms, spelt correctly. (cid:4)[6] [Total: 9]OCR 2010 Turn over<br />

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