NJC Organic Chem Structured revision set

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 1 Name: _____________________ Class: _____________ Organic Chemistry Revision Booklet (Structured Questions) Content Page 1 Organic Synthesis 2-35 2 Distinguishing Test 36-42 3 Reaction Mechanism 43-54 4 Amino acid and Proteins 55-59 5 Kinetics of Organic Chemistry 60-63 6 Acidity and Basicity of Organic Compounds 64-67 7 Isomerism 68-69 8 Organic Structural Elucidation 70-83

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 2 1) Organic Synthesis 1 The diagram below shows the synthetic pathway by which compound F may be prepared. The inorganic side product, which is produced together with compound F, is constantly removed from the reaction mixture. O2N Cl CH3 CH3 NH2 Cl CH3 CH3 NH2 OH CH3 CH3 C6H9OCl C6H9O2Cl A B C D E NH2 O CH3 O Cl CH3 F Step 1 Step 2 Step 3 (a) Give the structural formulae for compounds D and E. (b) Suggest the reagents and conditions for steps 2 and 3. (c) Draw the structures of the organic products formed when compound F is reacted with each of the following: (i) Br2(aq) (ii) KOH(aq), heat under reflux

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 3 2 The reaction scheme below shows the final stages in the synthesis of compound S. Cl COOH Cl CH2CH2OH R Q P S Cl NH O OH Cl s (a) Draw the displayed formulae of compounds R and Q. (b) Give the synthetic route, involving not more than three steps, from P to Q. In your answer, suggest the reagent(s) and conditions involved in each step and draw the structural formulae of the intermediate organic products. Name the type of reaction occurring at each step. (c) In the reaction of R and Q, another organic compound can also possibly be formed. Draw the structural formula of the organic compound and explain how its formation may arise.

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 4 3 There are four stereoisomers of compound P. P (a) What is the type of stereoisomerism exhibited by P? Draw the stereoisomers of P. (b) Q is a structural isomer of P in (a). Suggest the structures of Q, R, S, T and U in the reaction scheme below. Q (C11H12O2) aqueous HCl heat R (C3H6O2) + S U (C8H7OBr3) aqueous bromine T CH OH CHCH2CH CHOH H2 /Ni catalyst; heat

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 5 4 O OH CH2NH2 CH2C N C O CH2CH3C O CH3 H Q (i) Name the four functional groups in compound Q, other than the phenyl group. (ii) Draw the structural formulae of the compound(s) when compound Q is treated with o Cold HCl(aq) o Hot NaOH(aq) o 5 1-bromo-2-methylpropane undergoes a series of reactions as shown by the given flow scheme. (i) State the conditions needed for step 1. (ii) Explain as fully as you can why the conditions you stated in (i) are required. (iii) Draw the structures of compounds S, T and U. (iv) When an alkaline solution of complexed Cu2+(aq) is added to compound V, a reddish-brown precipitate is observed. Propose a 2-step synthesis for compound V from 1-bromo-2-methylpropane.

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 6 6 Transesterification is the process of exchanging the organic group R’ of an ester with the organic group R’’ of an alcohol. RCO2R’ + R’’OH → RCO2R’’ + R’OH (a) State the type of reaction taking place in transesterification. (b) Write an equation for the reaction between methyl ethanoate and ethanol. (c) Suggest which is the limiting reagent for the reaction in (b) to give a high percentage conversion of esters. Explain your answer. (d) The boiling points of methanol, methyl ethanoate and ethyl ethanoate are shown below. compound boiling point / oC methanol 65 methyl ethanoate 57 ethyl ethanoate 75 Account for the differences in the boiling point of methanol as compared to that of the esters. (e) Suggest a suitable method for separating a mixture of methyl ethanoate and ethyl ethanoate (f) Transesterification has been used industrially to prepare biodiesel from recycled vegetable oil. Suggest the organic products formed when the following molecule undergoes transesterification in the presence of methanol. (g) Similar methods can be used to synthesize amides by reacting esters with ethanolic ammonia. CH3CO2(CH2)xCH3 + NH3 → CH3CONH2 + CH3(CH2)xOH After 1.00 g of an ester, CH 3CO2(CH2)xCH3, is reacted completely with 25.0 cm 3 of 1.00 mol dm –3 ethanolic ammonia, the resultant mixture is titrated against 1.00 mol dm–3 dilute HCl. The titre value is 15.20 cm3. Determine the value of x.

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 7 7 To combat pollution and soaring fuel cost, car makers are experimenting with ethanol to help produce cars with lower carbon dioxide emissions and improve fuel economy. Ethanol is also often used in the synthesis of many organic compounds. (i) Write an equation for the complete combustion of ethanol. (ii) Write an equation for the synthesis of sodium methanoate from ethanol. (iii) Draw a dot–and–cross diagram of sodium methanoate. (iv) Suggest the structural formula of the organic compound formed when ethanol reacts with phosgene COCl2. In phosgene, the carbon atom is in the centre of the molecule and is attached to both chlorine atoms and to the oxygen atom. 8 In the table below, draw the structures of the organic products formed when compounds Y and Z react with the reagents stated below. compound reagent(s) organic product O N CH3 CH3 OH O Y KMnO4, dilute H2SO4 O N CH3 CH3 OH O Y HBr(g), heat HO OH NH2 Z propanoyl bromide

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 8 9 But-1-ene can be converted to compound E via the following series of reactions. Both compounds A and B produce a yellow precipitate on warming separately with aqueous alkaline iodine. (i) State the reagents and conditions for steps I and III. (ii) Draw the structural formulae of compounds B, D and E. (iii) Explain why the reaction in Step III produces an equimolar mixture of two stereoisomers of compound C.

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 9 10 Methionine is an α -amino acid which is essential to humans and is also used by plants to synthesise ethene. In the 1930s, Barger and Weichselbaum reported the synthesis of methionine using the sodium salt of ethyl phthalimidomalonate and 2 -chloroethyl methyl sulfide.

Organic Chemistry Revision Booklet (Structured Qn) 2024 National Junior College 10 (i) What types of reactions are steps 1 and 3? (ii) Compound X, C8H6O4, obtained as a by-product in step 5, is sparingly soluble in water. 1 mol of X reacts with exactly 1 mol of sodium carbonate. Give the structure of compound X. 11 Benzene is an aromatic hydrocarbon present in many compounds. A reaction scheme involving benzene derivatives is given below. Draw the structures of A to D and give the reagents and conditions for steps I to IV. OH CH2CH2Br OH CH2CH2CH2NH2 A B OH CH2CHO OH CH=CH2 OH CH2CH2COOH C OH CH2CH2CH(OH)CH3 D I II III ethanolic NaCN heat under reflux IV H2SO4(aq) heat under reflux NaOH(aq) heat under reflux LiAlH4 in dry etheracidified K2Cr2O7(aq), heat