By reference to the formation of σ and π bonds, describe and explain the shape of a benzene molecule, C₆H₆.

1. (a)By reference to the formation of σ and π bonds, describe and explain the shape of a benzene molecule, C₆H₆.[3]
2. (b)(i)2,3-dimethylphenylamine can be prepared from 1,2-dimethylbenzene in two steps as shown. [Figure X.X] Step 1 is catalysed by H₂SO₄. Write an equation to show how H₂SO₄ generates the electrophile during step 1.[1]
3. (b)(ii)Draw the mechanism of the reaction between this electrophile and 1,2-dimethylbenzene to form M. Include all relevant curly arrows and charges. [Figure X.X][3]
4. (b)(iii)Write an equation to show how the H₂SO₄ catalyst is reformed.[1]
5. (b)(iv)For step 2, suggest the reagents and conditions and name the type of reaction. • reagents and conditions • type of reaction[2]
6. (c)(i)The drug mefenamic acid can be made using 2,3-dimethylphenylamine in an excess of 2-chlorobenzoic acid. [Figure X.X] Deduce the molecular formula of mefenamic acid.[1]
7. (c)(ii)Name the functional groups, apart from the benzene ring, in mefenamic acid.[1]
8. (c)(iii)Calculate the maximum mass of mefenamic acid that could be formed from 5.00 g of 2,3-dimethylphenylamine in this reaction. Give your answer to three significant figures. mass of mefenamic acid =[2]
9. (d)The position of substitution in the electrophilic substitution of arenes can be explained based on the stability of the intermediate cations formed in the first step. The example given involves the bromination of methylbenzene. [Figure X.X] Use this information and your knowledge about the stability of cations to suggest why the CH₃ group directs incoming electrophiles to the 2- and 4-positions in preference to the 3-position.[2]

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