Fig. 4.1 shows how propane, C₃H₈, can be converted to propanoic acid, CH₃CH₂COOH. [Figure 4.1]

1. (a)(i)Reaction 1 in Fig. 4.1 takes place in the presence of sunlight. C₃H₈ + Cl₂ → CH₃CH₂CH₂Cl + HCl The reaction takes place via initiation, propagation and termination steps. Name the mechanism shown by reaction 1.[1]
2. (a)(ii)Complete the mechanism for reaction 1. Construct equations to describe the steps of the mechanism. initiation Cl₂ → 2Cl• propagation 1 propagation 2 termination ........................................................................................ → CH₃CH₂CH₂Cl[3]
3. (a)(iii)Reaction 1 is initiated by the bond fission of Cl₂. State the type of bond fission shown in the initiation step.[1]
4. (a)(iv)Compound Q is a by-product of reaction 1. [Structure of Q] Name Q.[1]
5. (a)(v)The molecular formula of Q is C₃H₆Cl₂. Identify the types of structural isomerism and stereoisomerism that a molecule with molecular formula C₃H₆Cl₂ can show. type of structural isomerism ................................................................ type of stereoisomerism ................................................................[2]
6. (b)State the reagent and solvent required for reaction 2.[1]
7. (c)(i)Reaction 3 takes place when CH₃CH₂CH₂OH is heated under reflux with acidified potassium dichromate(VI) solution. State the colour change that takes place in the reaction mixture.[1]
8. (c)(ii)Construct an equation to represent reaction 3. Use [O] to represent an atom of oxygen from the oxidising agent.[1]
9. (d)(i)CH₃CH₂COOH reacts with an unsaturated alcohol R to form unsaturated ester S. State the type of reaction that forms S.[1]
10. (d)(ii)The infrared spectrum of S is shown in Fig. 4.2. [Figure 4.2] Three absorptions in the infrared spectrum in Fig. 4.2 confirm that S is an ester and is unsaturated. • Write 1, 2 or 3 on Fig. 4.2 against each of these three absorptions. • Complete Table 4.1 to show which bond is responsible for each absorption that you have identified in Fig. 4.2. [Table 4.1][3]
11. (d)(iii)The mass spectrum of S shows the following peaks. [Table 4.3] Use Table 4.3 to calculate the number of carbon atoms in S. number of carbon atoms in S = ............................................................[1]

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