RI Organic.2 Remedial

Name: ………………………………………. ( ) Class: ……………. Date: ……………. Raffles Institution Year 6 H2 Chemistry 2025 Set A T2W9 – Carboxylic Acid and Derivatives, and Nitrogen Compounds Notes: Acidity (recap): Basicity: Selectivity of reactions involving carboxylic acids and derivatives, and nitrogen compounds:  Pre-ChemFocus Activity  • Familiarise yourself with the reactions involving carboxylic acid and its derivatives, and nitrogen compounds and its derivatives. • To view infopack at IVY > C2025 – H2 CHEMISTRY > Pages > [ChemFocus] Y6 T2W9 Carboxylic Acid and Derivatives, and Nitrogen Compounds > FIRST VIDEO ONLY

Hydrolysis of acyl chlorides, esters and amides: Amino acids, major species present at different pH:

Self-Check Questions 1 (a) Draw the intermediate compound and suggest reagents and conditions for the steps in the following reaction scheme. OH O N O H O O step 1 step 2 step 4 (C2H3OCl) step 3 Reagents and conditions Step 1: …………………………………………………………………………………… Step 2: …………………………………………………………………………………… Step 3: …………………………………………………………………………………… Step 4: …………………………………………………………………………………… (b) O O O CN HO2C CO2H Ostep 1 Reagents and conditions Step 1: …………………………………………………………………………………… (c) W: (C 7H12O3) HO2C CO2Hstep 1 step 2 Reagents and conditions Step 1: …………………………………………………………………………………… Step 2: …………………………………………………………………………………… Check your answers at IVY > C2025 – H2 CHEMISTRY > Pages > [ChemFocus] Y6 T2W9 Carboxylic Acid and Derivatives, and Nitrogen Compounds > Remaining videos

2 Draw the products formed from the acid or base hydrolysis of the following compounds. (a) O O HCl(aq) + heat (b) O O NaOH(aq) + heat (c) O O HCl(aq) + heat (d) O O NaOH(aq) + heat (e) N O HCl(aq) + H heat (f) N O NaOH(aq) + H heat

Tutorial Discussion Questions (to complete before Chemfocus session) 1a The reaction between acyl chlorides and hydrogen peroxide produces peroxyacids. The pKa values of four compounds are listed in the table below. name formula pKa water H2O 14.0 hydrogen peroxide H2O2 11.7 ethanoic acid CH3CO2H 4.8 peroxyethanoic acid CH3CO3H 8.2 Suggest an explanation for why • the pKa of H2O2 is less than that for water, • the pKa of CH3CO3H is greater than that for CH3CO2H ………………………………………………………………………………………………… …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………….[3] 2a Suggest a simple chemical test to distinguish between the following pair of compounds. A: B: …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………….…[2]

3a There are two pKa values associated with asparagine: α-carboxyl = 2.02 and α-amino = 8.80. asparagine H2Nb COOH NaH2O (i) Suggest two reasons to explain why Na is more basic than Nb. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… ………………………………………………………………………………………...[2] (ii) Identify the species of asparagine that is present at pH 1, 7 and 10. pH 1 pH 7 pH 10 [3]

Tutorial Practice Questions (to be attempted IN CLASS) 1b A student is provided with the following three compounds: A B C CH3COOH CH2ClCO2H CH3COCl When equal amounts of each compound were added to separate portions of water of the same volume, solutions are formed with pH values of 0.5, 2.5, and 3.0. Suggest, with explanations, which pH value is associated with each of A, B, and C. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ………………………………………………………………………………………………[2] 2b Suggest a simple chemical test to distinguish between the following pair of compounds. A: B: …………………………………………………………………………………………………. …………………………………………………………………………………………………. ………………………………………………………………………………………………[2]

3b There are three pKa values associated with lysine: 2.15, 9.16 and 10.7. lysine COOH NaH2 H2Nb (i) State and explain whether Na or Nb is more basic. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………[2] (ii) With the use of an equation, explain how a solution containing lysine at pH 10.7 can maintain pH when a small amount of H+ is added. Show the structure of lysine clearly in your answer. [2]

Self-Check Answers 1a Step 1: PCl5 or PCl3 or SOCl2 Step 2: Step 3: Step 4: , conc. H2SO4, heat 1b Step 1: KMnO4(aq), H2SO4(aq), heat (under reflux) OR K2Cr2O7(aq) H2SO4(aq), heat (under reflux) Note: acidic hydrolysis of ester and nitrile occurred, alongside oxidation of the alcohol after hydrolysis. 1c W: Step 1: KMnO4(aq), H2SO4(aq), heat (under reflux) Step 2: I2(aq), NaOH(aq) and heat, followed by HCl(aq)/ H2SO4(aq) Note: acid was added in step 2 to neutralise the –COO– to form –COOH. 2 (a) (b) HO2C O

(c) (d) (Note: 2 mol of NaOH will be required for the base hydrolysis of 1 mol of this ester) (e) (f)