a. Compound 4.1 reacts with hydrogen bromide (HBr) to give a compound with the molecular formula C₁0H₁3Br, as shown in the following reaction: 4.1 i. (2 marks) Draw chemical structures

of two potential products which may be formed in this reaction (ignore any stereochemical isomers). (You are strongly encouraged to use a drawing package to do so.) ii. (3 marks) Identify the major product. Explain briefly why the major product you identified is favoured (one sentence only). 4.2 CH3 iii. (4 marks) Draw a curly arrow mechanism for the formation of the major product. (You are strongly encouraged to use a drawing package to do so.) HBr b. Compound 4.2 was reacted with Br₂ in H₂O and three compounds were observed after completion of the following reaction: CH; Compound 4.3 4.4 Table 4.1 summarises the yield and molecular formula of the products (Compounds 4.3, 4.4 and 4.5). 4.5 B1₂ H₂O Table 4.1: The yields of Compounds 4.3, 4.4 and 4.5. C10H13Br Yield/% 90 8 4.3, 4.4 and 4.5 2 Molecular formula C11H13OBr C11H13 OBR C11H12Br2 i. (4 marks) Using flying-wedge notation, draw the structure of the products 4.3 and 4.4 for the reaction of Compound 4.2 with Br2₂ in H₂O. You are only required to draw one stereoisomer in each case, and you are not required to assign the stereochemical centres. ii. (3 marks) Explain why Compound 4.3 is the major product. (Two sentences only.) iii. (2 marks) A minor product (Compound 4.5) was also observed in the reaction. Using flying-wedge notation, draw the structure of the product 4.5. You are only required to draw one stereoisomer of the product, and you are not required to assign the stereochemical centres. c. The alkyne, Compound 4.6, can be reduced using Lindlar's catalyst: CH3 4.6 H₂ Lindlars Catalyst 4.7 i. (3 marks) Draw the structure of Compound 4.7 and label it with its stereochemical descriptor. ii. (2 marks) What catalyst would you use if you wanted to reduce Compound 4.6 to an alkane?