Alkene compunds: Ozonolysis and Important questions for JEE

In this article we are going to share the various methods to prepare the alkene and specially the ozonolysis of alkenes to know the number and position of double bond present in the alkene compounds.

This material will be very much useful for the cbse class 12^th chemistry board, UP board class 12^th chemistry board exan and specially for the engineering entrance exams like JEE, WBJEE, VITEEE, UPSEE/UPTU and others

Alkene compounds are known as olefins (Olefins are examples of unsaturated hydrocarbons (compounds that contain only hydrogen and carbon and at least one double or triple bond).

This is the reason that Ethylene is known as olefiant gas.

Alkene compounds forms various types of isomers:

1. Chain isomers
2. Position isomers
3. Functional isomers
4. Geometrical isomers and
5. Optical isomers

Note: Metamers are not formed by Alkenes

Smallest optically active alkenes contain 6 carbon atoms and the example for the same compound is below:

In this article our main focus is on the OZONOLYSIS. Mean while here we will discuss some important points in relation with alkenes.

Alkenes can be prepared by:

1. Partial hydrogenation of Alkynes

2. Hydroboration reaction of alkynes

3. Use of elimination reactions like

• Dehydrohalogenation of alkyl halides

4. Dehydration of Alcohols

5. Dehalogenation of alkyl dihalides

6. Ammonium salt

7. Kolbe’s Electrolysis

In our coming articles you will get details of all the mentioned reactions and get an idea that how products can be formed by using these methods

Let’s have a look on the very important reaction of Alkene and see the products of this reaction. Hydration of alkenes is very important reaction through which different products are formed by changing the catalyst and reaction conditions

Addition of water on alkenes gives alcohols and the process is known as Hydration

Ozonolysis: ozonolysis of alkenes is used for the determination of position of double bonds and number of double bonds.

There are 2 types of hydrolysis of ozonide:

1. Hydrolysis in presence of reducing agent known as reductive hydrolysis

Reagent used in this reaction is Zn/CH₃COOH  or (CH₃)₂S

The possible products of this reaction are: Aldehyde or Ketone or mixture of Aldehyde and Ketone.

2. Hydrolysis in presence of oxidising agents lie:

H₂O₂, Ag₂O, Peroxide

The possible products of this reaction are: Carboxylic acid or Ketone or mixture of carboxylic acid and Ketone.

Below are the few important reactions which have been asked in verious engineering enytrance exams:

Q. Find out the product and write the IUPAC name of the product

Ans. The product of the above reaction is Cyclobutadiene whose IUPAC Name is 1, 3-Cyclobutadiene

Q. Find out the possible products from the following reactions

Ans. Followings are the products for above reactions

for first reaction the products are Acetone, Oxalic acid and Acetic acid

for second reaction the products are Acetone, Glyoxal and Acetaldehyde

Important Notes:

1. Ozone(O₃) is used to find out the position of double bonds in the Alkene compounds
2. Bromine (Br₂) is used to find out the presence of double bonds in the Alkene compounds

IIT JEE 2018: Ozone, structure, property and Important question