QUESTIONSHEET 1 E/Z (CIS/TRANS) ISOMERISM

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A2 LevelTOPIC 23 ANSWERS & MARK SCHEMES<strong>QUESTIONSHEET</strong> 22AMINESa) (i) CH 3NH 2+ H 2O ž CH 3NH 3+ OH (1)(ii) The high concentration of OH ions from the NaOH (1)disturbs equilibrium to the left hand side (1)to give molecules of CH 3NH 2, which is a gas (1)Maximum 2 marksb) Name of A Phenylammonium chloride (1)Name of B Phenylamine (1)+ -Equation 1 C 6H 5NH 2+ HCl → C 6H 5NH 3Cl (1)Equation 2 C 6H 5NH 3Cl + NaOH → C 6H 5NH 2+ NaCl (1)-+ -+ -+c) (i) Strength compared with ammonia Stronger (1)Reasons Electron releasing effect / +I effect of C 2H 5group (1)increases electron availability on the N atom (1)so that a lone pair of electrons on N is donated more readily (1)and a proton / H is more strongly accepted (1)Maximum 3 marks(ii) Strength compared with ammonia Weaker (1)Reasons Lone pair of electrons on N is drawn towards the benzene ring (1)so that electron availability on the N is reduced (1)Donation of the lone pair occurs less readily (1)+and a proton / H is less strongly attracted (1)Maximum 3 marksd) (i) Substitution / replacement of H on the N atom (1)by an acyl group / RCO (1)(ii) Ethanoyl chloride / ethanoic anhydride / benzenecarbonyl chloride (1)(iii) N-substituted amide / substituted amide / amide (1)(iv) Mark consequentially from (ii), e.g.CH 3COCl + C 6H 5NH 2→ CH 3CONHC 6H 5+ HCl (1)Accept C 6H 5NHCOCH 3
A2 LevelTOPIC 23 ANSWERS & MARK SCHEMES<strong>QUESTIONSHEET</strong> 23DIAZOTISATIONa) (i) Treatment of a primary aromatic amine with nitrous acid to form a diazonium salt (1)(ii) Compounds needed for diazotisation Sodium nitrite (1) and hydrochloric acid (1)Name of product Benzenediazonium chloride (1)Equation C 6H 5NH 2+ NaNO 2+ 2HCl → C 6H 5N≡N Cl + NaCl + 2H 2O (1)(iii) Optimum temperature 0-10 0 C (1)Problem if the temperature were too high Hydrolysis of benzenediazonium chloride (1)to give phenol (1)or decomposition of benzenediazonium chloride (1)to give chlorobenzene (1)Problem if the temperature were too low Slow / low rate of reaction (1)b) (i) Conditions Cold / ∼ 5 0 C (1)In alkaline solution / NaOH(aq) (1)+ -ObservationEquation(ii) Coupling (1)Red (½) precipitate (½)OH++N≡N Cl(1) (1)-N=NOH+ HCl (1)c) A would give a red precipitate (1)but B would not (1)
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QUESTIONSHEET 1 E/Z (CIS/TRANS) ISOMERISM

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