AQA Jun 2014 Paper 2 Q8

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section b answer all questions in the spaces provided do not write outside the box the carboxylic acid methylbutanoic acid is used to make esters for perfumes the following scheme shows some of the reactions in the manufacture of this carboxylic acid ch chch oh ch chch br reaction reaction ch chch cooh ch chch cn methylbutanoic acid reaction a one of the steps in the mechanism for reaction involves the replacement of the functional group by bromine a i use your knowledge of organic reaction mechanisms to complete the mechanism for this step by drawing two curly arrows on the following equation marks br h c ch ch o h h c ch ch br h o ch ch wmp jun chem do not write outside the box a ii deduce the name of the mechanism in question a i give the iupac name of ch chch br marks b reaction is an acid catalysed reaction in which water is used to break chemical bonds when the cn functional group is converted into the cooh functional group infrared spectroscopy can be used to distinguish between the compounds in this reaction deduce the name of the type of reaction that occurs in reaction identify one bond in ch chch cn and a different bond in ch chch cooh that can be used with infrared spectroscopy to distinguish between each compound for each of these bonds give the range of wavenumbers at which the bond absorbs use table a on the data sheet when answering this question marks question continues on the next page turn over wmp jun chem do not write outside the box c when methylbutanoic acid reacts with ethanol in the presence of an acid catalyst an equilibrium is established the organic product is a pleasant smelling ester ch chch cooh ch ch oh ch chch cooch ch h o an ester the carboxylic acid is very expensive and ethanol is inexpensive in the manufacture of this ester the mole ratio of carboxylic acid to ethanol used is to rather than to c i use le chatelier s principle to explain why a to mole ratio is used in your explanation you should not refer to cost marks extra space c ii explain how a catalyst increases the rate of a reaction marks extra space wmp jun chem

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