Chemical Technology Questions and Answers - Isopropanol and Acetone

1. How is industrial isopropanol manufactured?
a) Hydration of propylene
b) Fermentation of molasses
c) Contact process
d) Linde’s process

Answer: a
Explanation: Isopropanol is manufactured by the hydrolysis of propylene. Propylene is absorbed in a tray tower filled with sulfuric acid to produce isopropyl acid sulphate. Ethanol is manufactured by fermentation of molasses. Oxygen is manufactured by Linde’s process whereas sulfuric acid is manufactured by contact process.

2. Which compound is used to decrease the temperature in the absorber during the manufacture of isopropanol by hydration of propylene?
a) Refrigerated brine
b) Cold water
c) Sulphuric acid
d) Nitric acid

Answer: a
Explanation: Refrigerated brine is used to control the temperature in the absorber. Jacketed arrangement is used in order to circulate the refrigerated brine in the cooling jacket. Brine is used since it has an ability to reach low temperatures without freezing problem.

3. How do we remove the presence of acidic impurities in the manufacture of isopropanol?
a) Wash water
b) Caustic wash
c) Sulphuric acid
d) Phosphoric acid

Answer: b
Explanation:The isopropanol vapours consists acidic impurities which can be removed with the help of a caustic wash tower. Caustic wash generally consists of caustic soda. Sulphuric acid is used as an absorber in hydration of propylene.

4. Acetone can be prepared from isopropanol. True or false.
a) True
b) False

Answer: a
Explanation: IPA (Isopropanol) is used as an intermediate for the preparation of acetone. One phenol process gives acetone as co product.

5. What is the by product produced in the manufacture of isopropyl alcohol by indirect hydration of propylene?
a) Isopropanol
b) Isopropyl ether
c) Acetic acid
d) Fumaric acid

Answer: b
Explanation:In the manufacture of isopropanol propylene is sulphated to produce isopropyl acid sulphate which on hydrolysis produces diiospropyl sulphate which finally produces isopropyl ether as a by-product.

6.Which among the following methods is not used for the manufacture of acetone?
a) Catalytic hydrogenation of isopropanol
b) Oxidation of butane
c) Oxidation of propylene
d) Hydration of propylene

Answer: d
Explanation:Acetone is widely manufactured by catalytic hydrogenation of isopropanol or oxidation of butane or oxidation of propylene or fermentation of molasses. Isopropanol is manufactured by
hydration of propylene.

7. Combined oxidation dehydrogenation is a better alternative to dehydrogenation of isopropanol for the manufacture of acetone.
a) True
b) False

Answer: a
Explanation: A mixture of air and isopropanol vapour is passed through a catalyst usually silver at 400°C. This method can be used as an alternative to the common method as it produces a better yield.

8. What is the ideal pressure for the manufacture of acetone by dehydrogenation of isopropanol?
a) 50-100atm
b) 900-1000atm
c) 250-350atm
d) 3-4atm

Answer: d
Explanation: The reaction is favoured at low pressure to reduce reactor size and water circulation load for a given plant capacity.

9. What is purity of acetone produced by the dehydrogenation of isopropanol?
a) 50%
b) 60%
c) 80%
d) 99%

Answer: d
Explanation: Acetone produced is 99% pure with 90% yield. Fractionalization increases the purity of acetone.

10. Which catalyst is used in Wacker’s process?
a) Copper
b) Arsenic
c) Palladium (II) chloride
d) Silver

Answer: c
Explanation: In Wacker’s process ethylene is oxidized to acetaldehyde which is finally oxidized to acetone in the presence of catalyst (Palladium (II) chloride.) This reaction is considered as the first homogeneous catalysis with organopalladium chemistry applied.