Lactones are cyclic esters. Under suitable conditions, lactones form from molecules that have both an alcohol and a carboxylic acid functional group. Equation 1 shows an example of the formation of a lactone. [Equation 1 showing a molecule with -OH and -COOH forming a lactone and H₂O] Fig. 5.1 shows the synthesis of lactone P from compound M. [Figure 5.1 showing reaction scheme: M --(KMnO4)--> N(C6H10O3) --(NaBH4)--> 5-hydroxyhexanoic acid --(reaction 3)--> P]

1. (a)(i)M reacts with hot concentrated acidified KMnO4(aq) to form N, C₆H₁₀O₃, in reaction 1. Draw the structure of N.[1]
2. (a)(ii)N is reduced by NaBH₄ to form 5-hydroxyhexanoic acid in reaction 2. Construct an equation for reaction 2 using molecular formulae. In the equation, use [H] to represent one atom of hydrogen from the reducing agent.[1]
3. (a)(iii)Reaction 2 is a nucleophilic addition. Suggest why reaction 2 creates a mixture of two organic compounds.[2]
4. (a)(iv)Draw lactone P, the product of reaction 3.[1]
5. (b)A student monitors the progress of reaction 2 using infrared spectroscopy. Use Table 5.1 to suggest why it is difficult to distinguish between N and 5-hydroxyhexanoic acid using infrared spectroscopy. [Table 5.1: Functional group and characteristic IR absorption ranges][2]
6. (c)Unknown lactone Q is analysed using mass spectrometry. Table 5.2 shows information from the mass spectrum. [Table 5.2: peak (M+, M+1), m/e (72, 73), abundance (95.5, 3.15)] Use these data to deduce the structure of Q. Show your working.[2]

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