Chemistry Report: Oxidation and Esterification of Alkanes and Alcohols

This report provides a comprehensive overview of alkanes and alcohols, detailing their characteristics, reactions, and experimental procedures. It begins by discussing the properties of alkanes, including their role as fuels and their filtration from crude oil, and then delves into substitution reactions, explaining the process with examples like the reaction of ethane with chlorine. The report explores sigma and pi bonds, and their significance in determining the reactivity of organic compounds. The oxidation of alcohols is then examined, including the different products formed depending on the type of alcohol used and the conditions of the reaction. It includes a laboratory experiment on the oxidation of ethanol, detailing the apparatus, chemicals, procedure, observations, and results, along with a discussion of the reaction mechanism and the formation of aldehydes and carboxylic acids. Finally, the report discusses the formation of esters through esterification, involving the reaction between alkanoic acid and alcohol in the presence of sulfuric acid and concludes with a risk assessment for the laboratory experiments.

Alkanes
Characteristics of alkanes
Alkanes being a critical fuel its filtration are done from the crude material of unrefined
petroleum. Alkenes are created when long chain alkanes are 'broke' - and in light of the fact
that they are reactive, they are often used as the starting point for chemical reactions, such as
making plastics.
(Kissim, 2001)
The chemical behaviours of organic compounds are determined by functional groups which
are either an atom or group of atoms. It should be noted that organic compounds that will
have similar function group will have similarity on their chemical properties, example being
that compounds that do contain a function group of -OOH (carboxylic) will undergo similar
chemical reactions.
Always the functional group takes the suffix name, while the other functional groups are
considered as substituents and are use as the prefix name.

Process of substitution reaction
A simple demonstration of substitution reaction of the alkane is when ethane is reacted with
chlorine gas in the presence of light (UV light), the product will be 1-chloro methane and
hydrogen chloride gas will be formed.
CH3CH3 + Cl2 →CH3CH2Cl + HCl
Always an atom of the hydrogen atoms in the ethane will be replaced by a chlorine atom
through substitution. Single unpaired electrons are contained on the free radicals are atoms or
groups of atoms. (Crute, T.D, 2000).
Substitution reactions of methane with halogens
Example of halogen include, chlorine, bromine and frorine
The stages of substitution process to effectively take place involve;
1. Initiating the sunlight or UV light to break the chlorine molecules into their free
radical atoms, that is;
Chain initiation
The chain is initiated (started) by UV light breaking a chlorine molecule
into free radicals.
Cl2 2Cl
Chain propagation reactions
These are the reactions which keep the chain going.
CH4 + Cl CH3 + HCl
CH3 + Cl2 CH3Cl + Cl
Chain termination reactions
These are reactions which remove free radicals from the system
without replacing them by new ones.
2Cl Cl2
CH3 + Cl CH3Cl
CH3 + CH3 CH3CH3

2. Combination of the free radical atoms with alkyl group formed during carbon –
hydrogen breaking down from their respective alkane groups.
CH4 + Cl CH3 + HCl
Further propagation
3. The free radical formed at the end is eliminated from the product formed with their
presence due to excess use of the halogens to facilitate complete substitution
reactions.
Dichloromethane
Cl- + CH3Cl CH2Cl- + HCl
Cl2 + CH2Cl- CH2Cl2 + Cl-
Trichloromethane
Cl- + CH2Cl2 CH2Cl- + HCl
Cl2 + CHCl2- CHCl3 + Cl-
Tetrachloromethane
Cl- + CHCl3 CCl3- + HCl
Cl2 + CCl3- CCl4 + Cl-
(Crute, T.D, 2000)
Why alkanes undergo substitution reactions.
Sigma And Pi Bonds
A sigma bond is a covalent bond which is formed by the head on overlap of two atomic
orbitals. The combination of overlapping orbitals can be s-s, s-pz or pz-pz. Sigma bonding can
be a bonding interaction or an anti-bonding interaction. Bonding interaction results by the

overlapping of two atomic orbitals in the same phase whereas anti-bonding interaction occurs
by the overlapping in opposite phase.
A Pi bond is a covalent bond which is formed by the side-to-side overlap of two atomic
orbitals. The atomic orbital combinations can be px-px or py-py. Similar to the sigma bonding,
a pi bond can be bonding or anti-bonding.
Sigma bonds are relatively stronger when compared with pi bonds. Hence, pi bonds are easily
broken while sigma bonds aren't. There can be only one sigma bond between two particular
atoms in a molecule. But there can be a maximum of two pi bonds between two atoms in a
molecule. For example,
• If there is a single bond between two atoms, then the bond will be sigma bond.
• If there are two bonds, then one will be sigma and another will be pi bond.
• If there are three bonds, then one will be sigma bond and two will be pi bonds.
Presence of pi bonds keeps the corresponding atoms in a plane. Increasing number of pi
bonds will increase the electronegativity and % of ‘p’ character of the bond.
A sp2 hybridized orbital can have a one sigma and one pi bond and a sp hybridized orbital.
The “sp-sp hybridized orbital” can have one sigma and two pi bonds.
Types of Bond Number of Sigma BondsNumber of Pi Bonds
Alkane (C-C) 1 0
Alkene () 1 1
Alkyne ( )1 2

Write up
Oxidation of alcohol
Alcohol are organic substance that contain hydroxyl group of –OH as their functional group,
they can be oxidized by using acidified potassium dichromate in warm condition, to give a
product that do vary in accordance with the type of alcohol used, the following are type of
products formed with different type of alcohol used when oxidized.
2.2 Give the name and structural formula of the product of oxidation of a
given alcohol.
From the image above it is observed that oxidation of alcohol results into different type of
compounds depending on different conditions they are prepared from alcohol, but the
functional group will still remain to be ¿]
Laboratory experiment: oxidation of ethanol
Aim

To oxidize ethanol by using acidified sodium dichromate through first forming
aldehyde then further oxidation to ethanoic acid
2.2 Describe the reagents and conditions used in oxidation of alcohols.
Apparatus Chemicals
Goggles to be worn
Boiling tube (Note 1)
Dropping pipette
Test-tube rack
Test-tube holder
Bunsen burner
Heat resistant mat
Ethanol (IDA, Industrial Denatured Alcohol)
(HIGHLY FLAMMABLE, HARMFUL), 2 -
3 cm3, provided in small bottles
Acidified sodium dichromate(VI) solution,
10 cm3 (VERY TOXIC, CORROSIVE)
2.0 g of sodium bicarbonate
Procedure
a Place about 3 cm3 of acidified sodium dichromate solution in a boiling tube.
b Use a teat pipette to add 5 -7 drops of ethanol, with shaking.
c Cool the mixture in the tube under a tap. Note the sweetish smell of ethanal (acetaldehyde)
at first, then becoming sharper as oxidation continues and forms ethanoic acid (acetic acid).
d When the reaction has subsided, the mixture can be warmed gently; the smell of ethanoic
acid will become more noticeable.
Observation
 The colour of potassium dichromate which is
acidified by dilute sulphuric acid will change
its colour from orange to green solution
containing chromium (III) ions (Burkett,
Brown, Meloni, 2001)

The chemical equation shows how potassium changes color from orange to green
Cr2O72-(aq) + 14H+(aq) + 6e- 2←
→ Cr3+(aq) + 7H2O(l)
Orange green
 When the solution was waft to the nose a viger smell was felt
 When 2.0 g of sodium carbon was placed in the solution a fizzing sound was heard and a
gas was emitted.
Results
After heating:
(Burkett, Brown, Meloni, 2001)
Discussion
Formation of aldehyde will occur when excess alcohol will be used as compared to the
oxidising agent hence hindering further occurrence of oxidation process. .
The structural equation for this reaction is
A simplified version of representing oxygen from an oxidising agent is by using a sign of
[O]. That would produce the much simpler equation:

When excess oxidising agent is used and the solution is heated in the boiling tube the reaction
will be complete to lead to formation of carboxylic acid which is distilled off.
The equation below shows a full oxidation reaction of ethanol to ethanoic acid is:
When the secondary alcohols ( propan – 2- ol) is oxidized it leads to formation of ketones
(propane) (Burkett, Brown, Meloni, 2001)
it is observed that that for production of secondary alcohol, excess amount of oxidizing agent
should always used for it to react with alcohol at mild condition.
2) addition of sodium bicarbonate will results to formation of carbon dioxide if the gas will
be tested with wet blue litmus paper it will turn to red.
Fizzing sounds is as a result of formation sodium ethanoate.
CH3CHOOH + Na2CO3 => CH3CHOONa + CO2 + H2O

Conclusion
Types of alcohols that results to formation of aldehyde and ketones when oxidised.
(Core
y, E. J., & Schmidt, G, 1979).
Primary alcohols
When primary alcohols are oxidised they result to formation aldehydes or carboxylic acid as
per the condition used, the formation of carboxylic acid results after the formation of
aldehydes and further oxidation of the product aldehyde will result to formation of carboxylic
acid.
Primary alcohols are the alcohols in which hydroxyl group is attached to the
primary carbon of the alcohol molecule. This is the simplest form of alcohol.
Primary alcohols can be oxidized to form aldehydes (RCHO) under mild
conditions. However, when stronger oxidants are used, primary alcohols first
transform into aldehydes and then rapidly transform into carboxylic acids
(RCOOH). The reactivity of primary alcohol is less than that of a secondary
alcohol.
Example is the oxidation of ethanol to ethanal, the ethanol will further oxidized to ethanoic
acid as show below;

(Corey, E. J., & Schmidt, G, 1979).
Secondary alcohols
This type of alcohol when it is oxidized it leads to formation of a product of ketones as shown
below;
(Corey, E. J., & Schmidt, G, 1979).
Tertiary alcohols
This type of oxidation on its oxidation by acidified potassium dichromate does not change or
does not result to any product to be formed, this is due lack of hydrogen atom on the carbon
atom to hold the functional group.

Evaluation
Measurement of liquid chemical reaction is done using measuring cylinder to minimize
error caused dropper that will not give out the exact portions of measured content as a
result of greater adhesive force a the narrow end of its delivery to the test tubes.
Use electronic beam balance rather than manual beam balance in measuring solid chemicals
to void errors that may be caused from inaccurate balance to be achieved of the manual
beam balance.
Risk assessment
Activity Risk who haz
ard
Like
hood
total
total Reducing risk What to
do
Evaluation
of chemical
used
Sodium
carbonat
e
Irritating to
the eye
everyone 5 5 25 Wear gloves, lab
coat, Googles.
Add some small
water. Add lid if
required
Contact
teacher,
first aider,
Skin
contact:
put under
Use
electronic
beam
balance
rather than
manual

running
water for
20 min
beam
balance to
a void
errors that
may be
caused
from
accurate
balance to
be
achieved
Concentr
ated
sulfuric
acid
Causes severe
burns,
irritation to
the eye and
skin
everyone 5 5 25
Lowest
concentration and
smallest volume
should be used.
Wear protective
gloves and eye
protection.
put under
running
water for
10 mins
if in
contact
with eye.
If contact
on the
skin,
remove
contamina
ted
clothes,
then
drench
skin in
water
Measure
sulphuric
acid using
measuring
cylinder to
minimize
error
caused
dropper
that will
not give
out the
exact
portions of
measured
content as
a result of
greater
adhesive
force a the
narrow end
Breaking
Glass
4 4 16 Wear gloves,
googles and lab
coat to remain
safe
Contact
teacher
/lecturer
Ethanoic
acid
Causes burns
and irritates
the lungs
everyone 5 5 25 Use lowest
concentration and
smallest volume.
Wear protective
gloves and
googles
If in
contact
with the
eye, flood
the eye
with tap
water for
10
minutes.
Measure
ethanoic
acid using
measuring
cylinder to
minimize
error
caused
dropper
that will
not give