Alkenes

Question 1

How are Alkenes prepared involving the alcohol?

Answer 1

Alkenes are prepared through the beta elimination of hydrogen from alcohol in the presence of concentrated H2SO4 and heat. Reaction

Question 2

How are Alkenes prepared involving alkanes?

Answer 2

Alkenes are prepared through the elimination of hydrogen from alkanes by heating them to high temperature (750°C). Reaction.

Question 3

How alkenes prepared through the involvement of halo alkanes?

Answer 3

Alkenes are prepared by the dehydrohalogenation of haloalkanes in the presence of alcoholic base.

Reaction

Question 4

How do alkenes react with hydrogen?

Answer 4

Alkenes undergo addition reaction with hydrogen in the presence of a catalyst such as Platinum.
Reaction

Question 5

How do alkenes react with hydrohalides?

Answer 5

Alkenes react with hydrogen halides in the presence of organic solvents (e.g. CHCl3) to form haloalkanes.

Reaction

Question 6

State Markonvnikov’s rule

Answer 6

For an unsymmetrically substituted alkene undergoing addition hydrogen halide addition, the hydrogen of the halide is added to the carbon of the double bond with the greater amount of hydrogen atoms.

Question 7

How do alkenes react with water?

Answer 7

Alkenes undergo addition reaction with water in the presence of an acid to form alcohol.

Reaction

Question 8

What are halohydrins?

Answer 8

These are hydrocarbons which have the -OH functional group and halogen atom on carbon atoms which are adjacent to each other.

~These are hydrocarbons with a carbon atom bearing a -OH functional group and a carbon bearing a halogen adjacent to each other.~

Question 9

How are Alkenes converted to halohydrins?

Answer 9

Alkenes are converted to halohydrins by the reaction of said alkenes with a aqueous solution containing the desired halogen.

Reaction.

Question 10

How do alkenes undergo polymerisation reaction?

Answer 10

Alkenes undergo polymerisation reaction upon reacting with attacking reagents or free radicals.

Reaction.

Question 11

What are the methods of preparing alkenes?

Answer 11

1. Heating alkanes to high temperature (750°c)
2. Dehydrohalogenation of akylhalides in the presence of alcoholic base (NaOCH₂CH₃ and CH₃CH_2OH)
3. Dehydration of alcohol with heated, concentrated H2SO4.

Question 12

What are chemical reactions alkenes undergo?

Answer 12

1. Ozonolysis (not addition)
2. Addition reaction with water to form alkanol.
3. Polymerisation with the help of benzoyl radicals.
4. Conversion to halohydrins.
5. Epoxidation with the aid of peroxides.
6. Addition reaction with hydrogen in the presence of platinum catalyst to form alkanes.
7. Addition of hydrogen halides to form alkylhalides in the presence of organic solvent (CHCl3)