This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the solutions to Question 4. QUESTION 4 4.1 Compound B belongs to a homologous series that has a general formula C_nH_2n+1X. From the given information, Compound C is CH_3CHOH(CH_2)_2CH_3, which is pentan-2-ol. Reaction 2 converts Compound B to Compound C. This is a substitution reaction where a halogen is replaced by a hydroxyl group. Therefore, Compound B must be 2-bromopentane (CH_3CHBrCH_2CH_2CH_3). Reaction 1 converts Compound A to Compound B (2-bromopentane) by addition of HBr. Since 2-bromopentane is the major product, Compound A must be pent-1-ene (CH_2=CHCH_2CH_2CH_3) according to Markovnikov's rule. Reaction 3 converts Compound B (2-bromopentane) to Compound D via elimination. Compound D would be pent-2-ene (major product) or pent-1-ene. 4.1.1 Name the type of addition reaction that takes place. Reaction 1 is the addition of HBr to an alkene (Compound A). The type of addition reaction is Hydrohalogenation. 4.1.2 Apart from heat, write down ONE other reaction condition for this reaction. For the addition of HBr to an alkene, to ensure electrophilic addition and the major product according to Markovnikov's rule, the reaction is typically carried out in the absence of light. One other reaction condition is Absence of light (or dark). 4.2 Compound C is formed when compound A is treated with HBr in reaction 1. Reaction 1 is classified as an ADDITION reaction. Write down: (Note: There appears to be a typo in the question. Based on the diagram, Compound B is formed from Compound A in reaction 1, and Compound C is formed from Compound B in reaction 2. We will proceed with the interpretation that Compound B is formed in reaction 1 and Compound C is formed in reaction 2.) 4.2.1 The structural formula of compound A. Compound A is pent-1-ene. The structural formula of compound A is CH_2=CHCH_2CH_2CH_3. 4.2.2 TWO terms that describe reaction 2. Reaction 2 is the conversion of a haloalkane (2-bromopentane) to an alcohol (pentan-2-ol). Two terms that describe reaction 2 are Substitution and Hydrolysis. 4.2.3 TWO properties of the base used in reaction 2. Reaction 2 (hydrolysis of a haloalkane to an alcohol) typically uses a dilute aqueous strong base. Two properties of the base are Dilute and Aqueous. 4.3 With the aid of a catalyst, compound A can be converted directly to compound C without the formation of the intermediate compound B. Write down the: This refers to the direct conversion of pent-1-ene (Compound A) to pentan-2-ol (Compound C). This is the hydration of an alkene. 4.3.1 Name or formula of the inorganic REACTANT needed for this direct conversion. The inorganic reactant needed is water. Name: Water or Formula: H_2O. 4.3.2 Name or formula of a catalyst that can be used. The hydration of an alkene is catalyzed by a strong acid. Name: Sulfuric acid or Formula: H_2SO_4. (Phosphoric acid, H_3PO_4, is also acceptable). 4.3.3 Type of addition reaction that takes place. The addition of water to an alkene is called hydration. The type of addition reaction is Hydration. 4.4 In reaction 3, compound B is treated with concentrated sodium hydroxide, and the mixture is heated. Reaction 3 is the conversion of Compound B (2-bromopentane) to Compound D under conditions of concentrated sodium hydroxide and heat. These conditions favor elimination. 4.4.1 Name the type of reaction that takes place. The type of reaction is Elimination. 4.4.2 Using molecular formulae, write a balanced equation for reaction 3. Compound B is 2-bromopentane (C_5H_11Br). The reaction is elimination (dehydrohalogenation) with concentrated sodium hydroxide (NaOH) and heat. The products are an alkene (Compound D, C_5H_10), sodium bromide (NaBr), and water (H_2O). C_5H_11Br + NaOH conc. NaOH, heat C_5H_10 + NaBr + H_2O Last free one today — make it count tomorrow, or type /upgrade for unlimited.