NJC Polymer Part 2 Tutorial Answer

Polymers (Part 2) – Reactions of Functional Groups - Tutorial Alkanes 1 X and Y have a molecular formula of C4H9Br. Both X and Y can be formed from butane by the following reaction. 3 2 2 3CH CH CH CH ⎯⎯ → +XY (a) State the type of reaction undergone in the above reaction. Substitution (b) Suggest reagents and conditions necessary for the above reaction. Limited Br2, UV (c) Suggest the structural formula of X and Y. Structure of X: Structure of Y: X and Y are interchangeable 2 The complete combustion for alkane to produce carbon dioxide and water is an important exothermic reaction. Which line on the graph shows the relationship between the number of carbon atoms in the alkane and the number of moles of oxygen gas needed for complete combustion of the alkane? Ans : B CxHy + (x + y 4) ⎯→ xCO2 + y 2 H2O As number of carbon (x) increases, number of O2 required for combustion increases proportionately A B C D number of moles of oxygen gas 1 number of carbon atoms in alkane

Alkenes 3 One of the four isomers of C4H8 is shown below: A H2C=C (a) Draw the other 3 isomers of C4H8. cis trans (b) State which isomers are cis-trans isomers. 4 Limonene occurs in oil of lemons and is used to flavour citrus drinks. CH3 CH3 CH2 Limonene Give the structural formulae of the organic products, when limonene reacts with (a) H2(g) Reduction of alkene C=C to alkane (each C of C=C gain 1 H) (b) Describe a simple chemical test by which you could distinguish the following pairs of compounds. State the observation for the test and write equation for the reaction. Add Br2 in CCl4 (inert organic solvent). Orange red Br2 is decolourised for limonene, but not for . Equation: CH3 CH3 CH2 + 2 Br2 CH3 CH3 CH2Br Br Br Br H CH2CH3 Limonene and

Halogenoalkanes 5 The following reaction scheme shows the various reactions which bromopropane undergoes. I II CH3CH2=CH2 CH3CH2CH2Br CH3CH2CH2OH (i) State the type of reactions for steps I and II. Step I : Elimination Step II : Substitution (ii) State the reagent and condition for steps I and II. Step I : NaOH (or KOH) in ethanol, heat Step II : NaOH (or KOH) (aq), heat Alcohol 6 (i) Suggest the structural formula of the product of the following reactions and balance the equations. (ii) State the type of reaction undergo