The Test for the double bond: cyclohexene from cyclohexane- Organic chemistry first semester lab Author: Dr. Robert Craig The purpose of this laboratory experiment is to obtain the ability to distinguish whether a compound is either an alkane or an alkene. A variety of tests were performed in order to be able to differentiate

1. The Test for the double bond: cyclohexene from
cyclohexane- Organic chemistry first semester lab
Author: Dr. Robert Craig
The purpose of this laboratory experiment is to
obtain the ability to distinguish whether a
compound is either an alkane or an alkene. A
variety of tests were performed in order to be able
to differentiate.

2. Introduction
• Most of the alkanes from petroleum are used
to produce energy by combustion, but a few
percent are converted to industrially useful
compounds by controlled reactions with
oxygen or chlorine. The alkanes are inert to
attack by most chemical reagents and will
react with oxygen and halogens only under
special conditions of radical initiated reactions

3. Introduction
• At room temperature an alkane such as
butane will not react with chlorine. In order
for this reaction to occur a precisely oriented
four-centered collision of the Cl2 molecule
with the butane molecule must occur with
two bonds broken and two bonds formed
simultaneously. It is unlikely that the
necessarily precise orientation of the two
molecules will be found.

4. Introduction
• At room temperature an alkane such as
butane will not react with chlorine. In order
for this reaction to occur a precisely oriented
four-centered collision of the Cl2 molecule
with the butane molecule must occur with
two bonds broken and two bonds formed
simultaneously. It is unlikely that the
necessarily precise orientation of the two
molecules will be found.

5. Procedure
• The purpose of this laboratory experiment is
to obtain the ability to distinguish whether a
compound is either an alkane or an alkene. A
variety of tests were performed in order to be
able to differentiate.

6. Procedure
• Test A required 1.0 mL of purified ligroin,
1.0mL of unpurified ligroin, and 1.0mL of
cyclohexene. The three amounts were each
placed in its own test tube and 5-6 drops of
3% Bromide in Dichloromethane were placed
in each. The three test tubes were observed
and any changes were noted.

7. Procedure
• Test B required three samples of a 3% aqueous
solution of Bromine. The three amounts were
each placed in its own test tube. Two of the
test tubes were treated with 1 mL of purified
ligroin, one being kept in the dark and the
other in the light. The other test tube was
treated with 1 mL of cyclohexene. The three
test tubes were observed and any changes
were noted.

8. Procedure
• Test C required 1.0 mL of purified ligroin,
1.0mL of unpurified ligroin, and 1.0mL of
cyclohexene. The three amounts were each
placed in its own test tube and 1 drop of a
solution containing 1% Potassium
Permanganate and 10% Sulfuric Acid was
placed in each. The three test tubes were
observed and any changes were noted.

9. Procedure
• Test D required 1.0 mL of purified ligroin and
1.0mL of cyclohexene. The two amounts were
each placed in its own test tube and cooled in
an ice bath. To each, 1 mL of concentrated
sulfuric acid was added. The test tubes were
shaken and any changes were recorded

10. Procedure
• Test F required 0.178 grams of NBromosuccinide and 0.080g of Cyclohexane.
This mixture was placed in a test tube, in
another test tube 0.2mL of chilled water and
0.080g of concentrated sulfuric acid were
mixed. The cold solution was transferred to
the first test tube and any results were noted.

11. Procedure
• Test G required the experimentation of three
unknowns. The three unknowns were each
placed in its own test tube were allowed to
perform any of the above tests to identify
them. Whereas I chose to add 5-6 drops of 3%
Bromide in Dichloromethane were placed in
each. The three test tubes were observed and
any changes were noted.

12. Observation and results
Pure Ligroin
Slow or no reaction
Decolorization & Presence
No Decolozation
of HBr
(in dark) - no reaction
(Pure ligroin in light) -
Decolorization occurred.
2 layers:Dark red layer on
yes reaction
top and clear Orange layer
Red layer dissipates &
at the bottom.
Bromine Water
Slow or no reaction
Decolorization & Presence
in
Reaction was very fast
Reaction was fast
Bromide
Dichloromethane
Un-pure Ligroin
of HBr
3%
Cyclohexene
formation of Dark red
spots in clear orange
liquid.
Acid Permanganate Test
Clear liquid,was a fast
Warm, reaction occurred.
Warm,
(1%Kmn &1 drop of 10%
reaction
Clear liquid with a brown
occurred
precipitate at the bottom.
Clear liquid with a pink
sulfuric acid)
precipitate
bottom.
Sulfuric Test
Reaction was very fast,
No reaction
HOT
No Decolorization.Ligroin
One
black
layer.Decolorization
N/A
in top layer & Sulfuric acid
in bottom layer.
occurred.
Formation
Bromohydrin
of
a
(N-Bromo Succinimide) -
(water/sylfuric acid ) -was
Reaction Occurred
a reaction, HOT
Yellow
top
Bromohydrin.
layer-
Pink bottom layer.
Water &Sulfuric acid.
N/A
reaction
at
the

13. Observation and results
Bromine Water
Reaction was fast
(in dark) - no reaction
(Pure ligroin in light) -
Decolorization occurred.
2 layers:Dark red layer yes reaction
on top and clear Orange Red layer dissipates &
layer at the bottom.
formation of Dark red
spots in clear orange
liquid.
Acid Permanganate Test
Clear liquid,was a fast Warm, reaction occurred.
Warm,
reaction
(1%Kmn &1 drop of 10% reaction
Clear liquid with a brown occurred
sulfuric acid)
precipitate at the bottom. Clear liquid with a pink
precipitate
bottom.
at
the

14. Observation and results
Sulfuric Test
Reaction was very fast, No reaction
HOT
No Decolorization.Ligroin
One
N/A
black in top layer & Sulfuric
layer.Decolorization
acid in bottom layer.
occurred.
Formation
Bromohydrin
of
a (N-Bromo Succinimide) - (water/sylfuric acid ) -was N/A
Reaction Occurred
Yellow
top
Bromohydrin.
a reaction, HOT
layer- Pink bottom layer.
Water &Sulfuric acid.

15. Observation and results
Testing the Unknown By (unknown 1) –
using 3%
(unknown 2) –
Bromide in Decolorization occurred There
Dichloromethane
in seconds
was
(unknown 3)no
color There was no color
change , neither the change
and
the
solvents separated.
didn’t
mix
solvents
with each other.

16. Identification of unknowns
• Identification of unknowns
• All unknowns were tested using 3% Bromide
in Dichloromethane. Therefore unknown #1
decolorized in seconds indicating color change
which gave the conclusion that it is an alkene.

17. Identification of unknowns
• While unknown #2 was tested with the same
reagent didn’t have a color change but didn’t
spate layers in the mixture giving the
conclusion that it is a mixture of alkane and
alkene.(because it has qualities of both
groups).Finally unknown #3 was concluded as
an alkane due to no reaction and the
separation of layers of 3% Bromide in
Dichloromethane and unknown #3.