Question

Position of double bond in alkene can be identified by:
A. Bromine water
B. Ammoniacal silver nitrate solution
C. Ozonolysis
D. Baeyer’s test

Answer 1

Hint: To answer this question, you must recall the properties and reactions of alkenes. The method used for the identification must form different products with terminal and non- terminal alkenes that can be distinguished easily using simple chemical reactions. It involves the use of a gas found in the stratosphere.

Complete step by step answer:
- Hydrocarbons can be classified widely into three categories which are alkanes, alkenes and alkynes.
- Alkanes are saturated organic compounds and contain only single bonds between the carbon atoms. However, alkenes and alkynes are unsaturated compounds and have double and triple bonds between the carbon atoms, respectively, in addition to single bonds. This difference in the bonding gives them different physical as well as chemical properties.
- Ozonolysis is an organic reaction in which the ozone molecule is used for breaking the unsaturated bond and converting it into a carbonyl group. In an ozonolysis reaction, the double bond breaks and an oxygen atom attaches to each of the carbon atoms. In reductive ozonolysis, we obtain carbonyl compounds as a product, that is, aldehydes or ketones.
- If the alkene under consideration is a terminal alkene then the product obtained on ozonolysis contains a formaldehyde. And if the alkene is not terminal, then the products obtained are both higher aldehydes. If we obtain ketones as a product of ozonolysis, then there is branching on the carbon atom.
Thus, we can determine the position of a double bond in alkene using ozonolysis.

Hence, the correct answer is C.

Note:
Ozone is an allotrope of oxygen and is less stable than oxygen. It has formed a very thin layer on the earth’s atmosphere and most of its concentration lies in the stratosphere. It is colourless to pale blue in colour and is soluble in carbon tetrachloride.