Unit 4
Assignment B
Diana Duka
Laboratory techniques and Applications
Explore manufacturing and testing methods of an organic solid.
Synthesis of Aspirin
Aim
The aim of this assignment is to synthesise Aspirin using reflux skills, purification through
recrystallisation and assessing the purity of Aspirin produced by finding the melting point and
boiling point and using chromatography.
Introduction
The report will include the preparation of Aspirin and the scientific techniques used during
the manufacturing of the drug. It will include background research and the uses of aspirin
alongside with industrial and laboratory production, the different types of equipment used
and including a detailed description of the purity and yield obtained as well as what factors
affect the yield and purity of aspirin. The purity will be measured by chromatography and
finding the boiling and melting points of the sample. This will then be compared to published
values and a thorough evaluation of the techniques used during the experiment and how it
could have affected the results. During the experiment, previous scientific knowledge will be
applied to dilute, filter, crystallise and purify the sample.
What is wintergreen oil?
Wintergreen is a herb that is made into an oil by steaming the water-soaked leaves. The
herb is mainly used for pain relief,such as headaches, fever and flatulence. In the
manufacturing industry, it is used as a flavouring, such as mints, because it has a minty
flavour and smell. In industrial applications it is used for toothpastes and mouthwashes too.
This is because it has an active ingredient called methyl salicylate, which some researchers
say can work against bacteria. However, there are some risks that come with the oil; it can
be poisonous if ingested in large amounts, this includes absorbed by the skin. It can also
increase the effects of anticoagulants. (1.)
What is Ethanoic Anhydride?
Ethanoic anhydride, C4H6O3, is a chemical that is known to be an irritant, flammable and
corrosive. It is advised to keep the chemical away from the skin and clothes and keep away
,from open flames and hot temperatures. It appears as a clear and odourless liquid at room
temperature, which is derived from acetic acid. The chemical falls under the category;
acyclic carboxylic anhydride group, with a melting point of -73℃ and boiling point of 139℃. It
is also soluble in water but the dissolving process happens slowly. (2.)
What is Aspirin?
It is a drug used to treat pain, inflammation and fever, also known as acetylsalicylic acid, with
molecular mass of 180.16 and molecular formula of C9H8O4. It has a melting point of 135-
140℃ and the boiling point of 140℃.
This synthetic drug has been in industrial use for over 100 years. Researchers have said
that Aspirin may be given to those that have had a recent heart attack to decrease the
possibilities of another occurring and to reduce the side effects of a heart attack. It is
classified as an NSAID - non steroidal inflammatory drug - which fortunately makes the
platelets function differently, as it can make the blood less sticky so that it is less prone for
occurrence of blood clots. Mostly, Aspirin appears as crystalline powder that is odourless
with a bitter taste when ingested. When the drug is presented to humidity, it gets hydrolysed
and has the odour of acetic acid, also known as vinegar.
Acetylsalicylic acid can be purchased over the counter and is mainly used medically all
around the world, every day. As mentioned before, the drug is stable in air however, it
quickly reacts and decomposes as soon as it comes in contact with water or moisture. This
is why Aspirin is a fast acting anti-inflammatory drug that helps to reduce acute pain in
minutes when taken with a cup of water and some food before taking the medication. Aspirin
comes in two forms such as tablets (most common) and gel cap.
Reflux - it is the heating of an organic compound for a set amount of time.it is used in
experiments, laboratories and industries to give a higher yield of the organic compound.
Organic compounds are volatile and are easily lost or overheated, as it will evaporate over
time. The compound usually has low boiling points, which makes it easy to heat and take
little time to reach the boiling point. Whilst boiling the compound, the condenser used in
reflux, cools down the vapour given off.
Distillation - it is used to separate mixtures of different boiling points. This is done by
heating the compound. Some of the components will turn into a gas, which is collected as
vapour in the condenser. There is a process called double distillation, where the compound
is distilled twice to increase the purity of the product. There are different types of distillation
used in the industry, such as simple distillation, fractional distillation and destructive
distillation. It is used in the production of alcohol, paraffin, kerosene etc. (3.)
Purity and Yield
Purity
Purity can be measured by finding the boiling point and melting point of a substance. If the
stated melting and boiling points do not match the obtained points of the substance then it is
likely that the sample used was impure. The purity of a substance can also be measured by
chromatography to determine the amount of each component.
, Factors affecting the purity of Aspirin
● Contamination
● Quantity and quality of chemicals used
● Impurities
● Aspirin being exposed to moisture
Relevance to industrial manufacturing
During the manufacturing process it is important to test the purity of the sample.
Contamination of the product will force the industry to restart manufacturing because there
are impurities within the aspirin. If the quality of the chemicals used is low or the quantity is
not the same as written on the method of manufacture, then this may result in lower purity
because of the lower quality of chemicals used as well as the different quantity of chemicals
used, as it will disturb the equilibrium and have different concentrations of chemicals.
Yield
Percentage yield is measured to determine the amount of sample obtained. In industries this
can help to see if there are any mistakes made during the production, which affects the yield
of the product. ‘A measure of a chemical reaction's efficiency, as a ratio of moles of product
to moles of reactant. Usually expressed as a percentage. % Yield = Moles of product.’ (3.)
Factors affecting the yield of Aspirin
● Purity
● Loss of product
● Adding too much drying agent
● Position of equilibrium
Relevance to industrial manufacturing
The yield is also important in the industry because the chemicals used are at a much larger
scale. If the purity of the aspirin is low, then it will have a negative impact on the yield, as it
will decrease the overall yield. If during the production, the product is lost, it will also
decrease the yield and have a negative impact on the industry. Another factor affecting the
yield is the position of the equilibrium, which can be due to the quality and quantity of
chemicals used. If the quantity of reactants are different compared to the amounts stated,
then the equilibrium will be disturbed and decrease the yield of aspirin within the industry.
Comparison - Industrial vs. Laboratory Manufacturing
Industrial method Laboratory method
Raw materials ● Cornstarch ● Winter green oil
● Lubricant ● Sodium hydroxide
● Ethanoic acid ● Hydrochloric acid
● Toluene ● Ethanoic anhydride
● 2-hydroxbenzoic acid ● Conc. sulphuric acid
