Halogenoalkanes react with a number of different reagents in nucleophilic substitution reactions. (a) A sample of potassium cyanide dissolved in ethanol is added to a sample of 1-bromobutane, CH3(CH2)3Br, and heated under reflux. A nucleophilic substitution reaction occurs and compound A is formed. (i) Name compound A. [1] (ii) What is meant by the term nucleophile? [1] (iii) Identify the nucleophile in this reaction. [1] (iv) Explain why this reaction is described as a substitution reaction. [1] (b) State the reagent(s) and conditions needed for CH3(CH2)3Br to react to form CH3(CH2)3NH2. reagent(s) conditions [2] (c) Equal amounts of three different halogenoalkanes are added to three separate test-tubes. An equal amount of aqueous silver nitrate and ethanol is added to each test-tube. The time taken for a precipitate to form is recorded for each halogenoalkane. halogenoalkane time taken for precipitate to form/s (CH3)3CCl 460 (CH3)3CBr 190 (CH3)3CI 40 (i) Describe and explain the trend in reactivity of the different halogenoalkanes shown in this experiment. [2] (ii) All three halogenoalkanes tend to react via the SN1 mechanism. Explain why the SN1 mechanism is favoured. [3] (iii) Identify a halogenoalkane which tends to react with an aqueous solution of silver nitrate and ethanol via the SN2 mechanism. [1] [Total: 12]