COCH 3. + HCl H 5 C 6. Not molecular formulae Not allow C. phenylethanone Ignore number 1 in name but penalise other numbers

Transcription

1 Not molecular formulae Not allow C 6 H 5 CH CO M. (a) (i) CH COCl + C 6 H 6 C 6 H 5 COCH + HCl OR phenylethanone Ignore number in name but penalise other numbers AlCl can be scored in equation Allow RHS as Allow + on C or O in equation but + must be on C in mechanism below Ignore curly arrows in balanced equation even if wrong Electrophilic substitution Page of 6

2 Allow (CH CO) O OR M arrow from within hexagon to C or to + on C + must be on C of CH CO in mechanism (b) + in intermediate not too close to C Gap in horseshoe must be centred approximately around C M arrow into hexagon unless Kekulé Allow M arrow independent of M structure, ie + on H in intermediate loses M not M Ignore base removing H for M Electron pair donor or lone pair donor Allow donator Allow lone pair used in description of (dative) bond formation (acid) anhydride Allow ethanoic anhydride but not any other anhydride [] Page of 6

3 M. (a) (nucleophilic) addition-elimination; (M for structure) (M4 for arrows and lone pair) (M not allowed independent of M, but allow M for correct attack on C+ if M show as independent first.) (+on C of C=O loses M but ignore δ+ if correct) (Cl removing Ft loses M4) (If MS lost above for wrong C chain, do not penalise same error again here) 5 (b) CH CH COCl + AlCl [CH CH CO] + + AlCl 4 ; (penalise wrong alkyl group once at first error) (position of + on electrophile can be on O or C or outside [ ]) (penalise wrong curly arrow in the equation or lone pair on AlCl ) (M arrow from within hexagon to C or to + on C) (don t penalise position of + on C of RCO+) (horseshoe must not extend beyond C to C6 but can be smaller) (+ not too close to C) (penalise M if CH chain wrong again but allow M and M) (M arrow into hexagon unless Kekule) (allow M arrow independent of M structure) (or can be gained in mechanism); Page of 6

4 (c) M CH CH COCl + H O CH CH COOH + HCl (penalise wrong alkyl group once at first error) M M r of CH CH COCl = 9.5 (if Mr wrong, penalise M only) M moles of CH CH COCl =.48/9.5 = 0.06 M4 moles NaOH = 0.06 = 0.0 (allow for conseq to wrong no of moles) M5 volume of NaOH = 0.0/0.4 = dm or 76. cm (with correct units) (if missed in M4 lose M5 also) [6] M. -chloropropane no visible change Accept small amount of precipitate or precipitate forms slowly. ethanoyl chloride white precipitate Accept large amount of precipitate or precipitate forms immediately. [] Page 4 of 6

5 M4. Mark Range The marking scheme for this part of the question includes an overall assessment for the Quality of Written Communication (QWC). There are no discrete marks for the assessment of QWC but the candidates QWC in this answer will be one of the criteria used to assign a level and award the marks for this part of the question Descriptor an answer will be expected to meet most of the criteria in the level descriptor 4-5 claims supported by an appropriate range of evidence good use of information or ideas about chemistry, going beyond those given in the question argument well structured with minimal repetition or irrelevant points accurate and clear expression of ideas with only minor errors of grammar, punctuation and spelling - claims partially supported by evidence good use of information or ideas about chemistry given in the question but limited beyond this the argument shows some attempt at structure the ideas are expressed with reasonable clarity but with a few errors of grammar, punctuation and spelling 0- valid points but not clearly linked to an argument structure limited use of information or ideas about chemistry unstructured errors in spelling, punctuation and grammar or lack of fluency (a) (i) M r of C 6 H 5 NH = 9 M r of CH COCl = 78.5 total M r of reagents = 64.5 % atom economy = 00 QWC = 00 = 5.0 % expected yield = = 7.6 kg % yield = 00 = 74. % Page 5 of 6

6 (iii) Although yield appears satisfactory (74%) % atom economy is only 5% QWC nearly half of the material produced is waste and must be disposed of QWC (b) (nucleophilic) addition-elimination QWC () 4 (c) HNO + H SO 4 NO + + H O + + HSO 4 [6] M5. (a) CH OH + CH CH COOH CH CH COOCH + H O (b) (nucleophilic) addition elimination NOT acylation ignore use of Cl to remove H + M for structure M4 for arrows and lone pair 4 Page 6 of 6

7 (c) allow C H 5 and CO allow CH CH COOCOCH CH or (CH CH CO) O (d) (i) faster/not reversible/bigger yield/purer product/no(acid) (catalyst) required anhydride less easily hydrolysed or reaction less violent/exothermic no (corrosive) (HCl) fumes formed or safer or less toxic/dangerous expense of acid chloride or anhydride cheaper any one (e) (i) C 8 H 8 O any two from Allow CO allow C 6 H 5 [] Page 7 of 6

8 Allow CH COOH or CH CO H M6. (a) M not allowed independent of M, but allow M for correct attack on C+ + rather than δ+ on C=O loses M If Cl lost with C=O breaking, max for M M for correct structure with charges but lp on O is part of M4 only allow M4 after correct/very close M ignore Cl removing H + 4 (b) (i) pentane-,5-diol Second e and numbers needed Allow,5-pentanediol but this is not IUPAC name Must show ALL bonds (iii) All three marks are independent M (base or alkaline) Hydrolysis (allow close spelling) Allow (nucleophilic) addition-elimination or saponification M δ+ C in polyester M reacts with OH or hydroxide ion Not reacts with NaOH (c) (i) Page 8 of 6

9 (nucleophilic) addition-elimination Both addition and elimination needed and in that order OR (nucleophilic) addition followed by elimination Do not allow electrophilic addition-elimination / esterification Ignore acylation (iii) any two from: ethanoic anhydride is less corrosive less vulnerable to hydrolysis less dangerous to use, less violent/exothermic/vigorous reaction OR more controllable rxn does not produce toxic/corrosive/harmful fumes (of HCl) OR does not produce HCl less volatile NOT COST List principle beyond two answers (d) (e) (i) ester Do not allow ether Ignore functional group/linkage/bond or twelve (peaks) (iii) Allow a number or range within these limits Penalize extra ranges given Ignore units Page 9 of 6

10 (f) (i) sulfuric acid sodium hydroxide hydrochloric acid ammonia X or blank ethanoic acid potassium hydroxide nitric acid methylamine X or blank 4 correct scores correct scores or correct scores 0 Pink to colourless Allow red OR purple OR magenta instead of pink Do not allow clear instead of colourless [] M7. (a) CH (CH ) 4 COOH Allow molecular formulae. CH OHCHOHCH OH Allow one mark only if formulae are swapped in position. (b) (c) Keeping the foodstuff dry Allow an answer which refers to removal of water from the environment. Do not allow dehydration / removal of water from the fat. They (antioxidants) react with free radicals And they are used up in the reaction / do not remain behind after reaction Lose one mark for any reference to catalysts can t slow down a reaction. (d) Mol of fat = (.78 / 806 =).45 0 Mol of NaOH =.68 0 = mol of fatty acid Mol of NaOH =.68 0 Mol of fat hydrolysed =. 0 Page 0 of 6

11 Mol of fat hydrolysed = (.68 0 / =). 0 Mass of fat hydrolysed = g Percentage hydrolysed = Percentage hydrolysed = Do not penalise precision at any point. Since there are a variety of approaches to this calculation, award four marks for a correct answer but it must be clear that there is some relevant working. The answer alone gets M4 only. Any incorrect use of the : ratio is CE lose M and M4. [9] M8. (a) nucleophilic addition 4 (b) (i) -hydroxybutanenitrile (allow for amide even if not C 4 H 7 NO, i.e. RCONH ) (if not amide, allow one for any isomer of C 4 H 7 NO which shows geometric isomerism) (c) (i) Page of 6

12 (iii) CH CH=CHCOOH [] M9. (a) (Nucleophilic) addition-elimination Minus sign on NH loses M(but not M4 also) M not allowed independent of M, but allow M for correct attack on C+ + rather than δ+ on C=O loses M If Cl lost with C=O breaking, max for M M for correct structure with charges but lp on O is part of M4 only allow M4 after correct/very close M For M4, ignore NH removing H + but lose M4 for Cl removing H + in mechanism, but ignore HCl shown as a product 4 propanamide (Ignore -- ) penalise other numbers penalise propaneamide and N-propanamide (b) Nucleophilic substitution Minus sign on NH loses M (not M4 also) + rather than δ+ on C=O loses M Page of 6

13 ALLOW SN so allow M for loss of Cl before attack of NH on C+ for M only allow M4 after correct/very close M For M4, ignore NH removing H + but lose M4 for Cl removing H + in mechanism, Propylamine (ignore number ) but ignore HCl shown as a product 4 or propan--amine or -aminopropane (number needed) penalise other numbers allow -propanamine (c) electron rich ring or benzene or pi cloud repels nucleophile/ammonia Allow C Cl bond is short/stronger than in haloalkane C Cl is less polar than in haloalkane resonance stabilisation between ring and Cl [] M0. (a) Mg + C 6 H 4 (OH)COOH (C 6 H 4 (OH)COO) Mg + H Accept multiples, including fractions. (b) Gas syringe / inverted burette over water / measuring cylinder over water Collection apparatus must show graduations or be clearly labelled (eg syringe, burette, measuring cylinder). [] M. (a) (i) CH OH Not molecular formula HOCH CH(OH)CH OH Page of 6

14 9CO + 9H O Or doubled C 7 H 5 COOCH + 7½ or 55/ O Consequential on correct right-hand side (b) (i) A 0.7 Ethanol 6.4 Water.6 No effect If wrong, CE= 0 Equal moles on each side of equation OR V cancels Ignore moles of gas (iii) M Must have all brackets but allow ( ) (iv) M If K c wrong can only score M4 for units consequential to their K c working in (b)(iv) M 0.55 (min dp) M4 No units [] M. (a) (i) propan(e)-,,-triol or,,- propan(e)triol not propyl ignore hyphen, commas Page 4 of 6

15 soaps allow anionic surfactant not cationic surfactant not detergents, not shampoos (b) (i) (bio)diesel Allow fuel for diesel engines not biofuel, not oils ignore anything else attached except any more H atoms. (iii) CH (CH ) COOCH + ½O 5CO + 5 H O OR C 5 H 0 O or 4/ not allow equation doubled [5] Page 5 of 6

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