7/29/2019 Organic Chem Q

1/4

1. An illegal drug, heroin, can be made from morphine.

(a)Suggest a reagent to convert morphine to heroin. Hence, comment on the yield ofheroin by this method.

(b)Heroin is reasonably insoluble in water. For medical use, weak acid will be addedto heroin to increase the solubility of heroin in blood. Explain this phenomenon.

(Hints : i. Heroin contains amine group, which is basic ; ii. Ions are more soluble

in water than molecule)

2. CH3OH, CH3CH2OH, CH3CHOHCH3 are three alkanols.(a)What will be the observable change when CH3CHOHCH3 is added to

potassium permanganate solution?

(b)All 3 alkanols will react with potassium permanganate solution, but only 1alcohol will produce acid. Which one? Write a chemical equation.

(c)Why acid cannot be produced using the other 2 alkanols.3. Consider the following setup for fermentation.

(a)Suggest what substance X is.(b)Write a equation for the reaction in conical flask.(c)Explain with reasons, why the concentration of product in the flask will never

exceed 15%.

(d)Suggest a method to increase the concentration of the product.(e)After concentrating the product to 98%, the product is highly flammable.

Suggest a chemical test to distinguish between this product and cooking oil,

7/29/2019 Organic Chem Q

2/4

which are all flammable.

4. Molecule X is an organic compound. Upon burning of 2g of X, 2.4 g of water and4.4g of carbon dioxide is produced. It is known that the molecular mass of X is

within 50-70g/mol . X can decolorize acidified potassium permanganate solution

and give a solution of pH 4.87. X cannot decolorize Br2(aq) under sunlight.

(a)Determine the formula of X and name the molecule.(b)Suggest a possible structure of X. Explain with reasons.(c)When X is heated with concentrated sulphuric acid, molecule Y is produced.

Suggest a chemical test to distinguish between X and Y. State the expected

results.

(d)Y is also able to undergo polymerization to form polymer Z, state the type ofpolymerization and draw the repeating unit of Z.

(e) Is polymer Z is a single compound ? Explain.5. (AL-09 I 8)3-methyl-1-butyl ethanoate, commoly known as isoamyl acetate, is a

naturally occurring compound having a banana odor and is used in food flavoring.

In an experiment to prepare the compound, 5.0cm3 of isoamyl alcohol is allowed

to react with 15.0cm3 of glacial acetic acid in the presence of a reagent L.

(i) Suggest what reagent L may be and give the reaction conditions.(ii) Calculate the mole ratio of alcohol to glacial acetic acid used .

(Given: density of isoamyl alcohol = 0.81 g cm-3 ; density of glacial

acetic acid = 1.05 g cm-3)

(iii) Draw a labelled diagram of the assembly of apparatus used.(iv) What are the major compounds present in the resulting mixture at the end

of the preparation.

(v) Outline the procedures to isolate isoamyl acetate from the resultingmixture. (It is known that isoamyl acetate cannot be effectively separated

from the resulting mixture by fractional distillation)

(vi) Suggest why isoamyl alcohol is NOT used in excess in this preparation.6. (AL- 07 II 6d)Polyethylene terephthalate (PET) is a polymer used in making

clothing fibres and soft drink bottles. The flow diagram below shows a route for

the synthesis of PET.

7/29/2019 Organic Chem Q

3/4

(1)Give the reagent(s) and conditions for steps 2,3,4.(2)Polyethylene naphthalate (PEN) is a polymer formed from naphthalic acid and

ethane-1,2,diol.

(I) Draw the structure of a repeating unit of PEN(II) Which polymer, PET or PEN, do you expect to be more rigid? Explain.

7. (AL04 I 5b)Plastic wastes can be used as a source of energy by incineration.The table below shows 2 calorific values of the two plastics.

Plastics Calorific value / kJ kg

-1

Polystyrene 46000

Polyvinyl chloride 18900

Suggest two reasons why the calorific value of PS is greater than that of PVC.

8. The acidity of an acid is determined by the stability of anion formed after reactingwith a base. Higher the stability of anion, higher the acidity. Consider

2-hydroxybenzoic acid and 4-hydroxybenzoic acid, compare the acidity of 2 acids.

(Hint : Formation of bonds can stabilize the anion more )

9. Give the name for the following molecule.a.

b. CH2BrCHBrCH2CCl3

7/29/2019 Organic Chem Q

4/4

10.The following is a flow chart showing the relationship of several carboncompounds,A, B, CandD.

Ethene B

C

burns in excess oxygen

reacts with steam, catalyst oxidize with oxygen

D

proces sX

burn in excess oxygen

(a) Name the productsA, B, Cand D.(b) Write an equation for the reaction that ethene is heated under limited oxygen.(b) Write the equations for the reactions.

(i) From ethene toA

(ii) FromA + CtoD

(iii) What reagent is used in processX? Write an equation for the reaction.

(d) Besides using ethene as a starting reagent for the production of other carboncompounds, can you suggest another commercial use for ethene? Explain with

appropriate equation.