MU #1 Types of organic reactions include: addition, substitution, polymerization, esterification, fermentation, saponification, and combustion.

Addition reactions are reactions where unsaturated hydrocarbons react with atoms yielding a saturated hydrocarbon.

In halogenation an unsaturated hydrocarbon reacts with a halogen.

Example

H

H

Cl

Cl

\

/

|

|

C

=

C

+

Cl

—

Cl

---->

H

—

C

—

C

—

H

/

\

|

|

H

H

H

H

ethene

chlorine gas

1,2-dichoroethane

 

Cl

Cl

Cl

—

Cl

|

|

H

—

C

≡

C

—

H

+

---->

H

—

C

—

C

—

H

Cl

—

Cl

|

|

Cl

Cl

ethyne

chlorine gas

1,1,2,2-tetrachoroethane

 

In hydrogenation an unsaturated hydrocarbon reacts with hydrogen. Dehydrogenation reactions are the reverse of hydrogenation reactions. 

Example

H

H

H

H

\

/

platinum

|

|

C

=

C

+

H

—

H

---------->

H

—

C

—

C

—

H

/

\

|

|

H

H

H

H

ethene

hydrogen gas

ethane

 

H

H

H

—

H

platinum

|

|

H

—

C

≡

C

—

H

+

---------->

H

—

C

—

C

—

H

H

—

H

|

|

H

H

ethyne

hydrogen gas

ethane

Problems

1. What halocarbon is produced when ethene reacts with bromine gas?

2. Write the reaction that produces propane from propyne.

3. Write the reaction that produces 1,2-difluoroethane.

4. What halide is formed when 1 mole of ethyne reacts with 2 moles of I₂?

Substitution reactions are reactions where one hydrogen atom of a saturated hydrocarbon is replaced by a halogen.

Example

Problems

1. Write all the possible halides that could be produced by the reaction of propane with chlorine gas.

2. Write the reaction for the making of 2-iodobutane and hydrogen iodide.

In polymerization reactions monomers or single units are attached to each other to form long chains or polymers. Monomers have to have at least two functional groups, one at each end, so that an attachment can be accomplished.

Natural polymers are starch, cellulose, and proteins. Synthetic polymers are nylon, silicone, and polyethylene

In a condensation polymerization reaction monomers are bonded by a dehydration reaction (the removal of water)

Example

H

H

H

H

|

|

|

|

HO

—

C

—

C

—

OH

+

HO

—

C

—

C

—

OH

|

|

|

|

H

H

H

H

monomer

monomer

↓

H

H

H

H

|

|

|

|

HO

—

C

—

C

—

O

—

C

—

C

—

OH

+

H2O

|

|

|

|

H

H

H

H

polymer (dimer)

 

 In an addition polymerization reaction monomers of unsaturated compounds are bonded by "opening" a double bond in the carbon chain.

Example

&nb