Summary
Summary Unit 4 A3 Learning aim C: Explore manufacturing techniques and testing methods for an organic solid
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Lab ReportDate: Friday 23 April 2021
rd
Experiment Name: Preparation of Aspirin and test its’ Purity
Introduction:
What is an Aspirin (using functional group)?
An aspirin also known as acetylsalicylic acid, its commonly known to be an aromatic compound that
is known to be contain both carboxylic acids. Moreover, it is known to be an ester functional group &
aspirin is a weak acid it is kind of soluble in water. Also, aspirin can be made by reacting salicylic
acid & acetic anhydride in the of an acid catalyst. The structure of the aspirin it contains three groups,
the first being carboxylic acid functional group (R-COOH), ester functional group (R-O-CO-R’), the
aromatic group (benzene group) (Ausetute , 2021).
The scientific principles behind are that when the salicylic acid is the limiting reactant, and the acetic
anhydride is in excess. After the reaction as the heating is over, the excess unreacted acetic anhydride
will be destroyed by the use of water to the mixture, this is due to when water reacting with acetic.
Anhydride to form 2 molecules of the known acetic acid, as so when esterification reaction occurs and
is completed the water will be added to the mixture and so this causes the precipitation of the
acetylsalicylic acid and will react with any acetic anhydride. This is that the reflux condenser is a long
sealed glass tube, which is then surrounded by cold water, which is like a water jacket through which
cold water is pumped & then the hot gas produced rises up to the tube and as its cooled by the running
water, this causes the gas to condense and then return the mixture as liquid When setting up the
apparatus for reflux heating and warming with swirling until all the solid has dissolved & ensuring
that when swirling it, it does not cause the quick fit joints to come apart and leak & ensuring that it
warms up for 5 minutes, as the product will burn & then to add 5 cm 3 of cold water to the solution by
pouring it down the condenser & so how it tested for the production of the solid aspirin (laney, 2012).
The scientific principles behind & the techniques used in preparing & testing crystallising are things
like that of saturated solutions & supersaturated solutions is where a solution contains more than the
maximum amount of a solute that is then capable of then being dissolved at a given temperature. So,
the recrystallization of the excess dissolved solute in a supersaturated solution this can be initiated by
what is a small crystal of solute, what is rather known to be a seed crystal. This influence of
temperature on solubility of acetylsalicylic acid can be known to be the highest in acetone temperature
ranges, where the possibility of it is at T=326.3K , influence of polarity on solubility salicylic acid has
a higher purity compared to aspirin obtained from commercial salicylic acid & as recrystallization it is
used in polar e.g. ethanol& partially polar acetone and then the non-polar toluene, which this affects
the solvent properties of the obtained products., crystallisation, supersaturation, nucleation, growth,
, recrystallising used as a means of purifying solids, like aspirin which is an organic solid choice of
solvent for recrystallization, the minimum amount of solvent used, influence of rate of cooling on size
of crystals and presence of impurities. Moreover, method evaporation from a crystallising dish or
other suitable container, like the use of oven drying, use of chemical drying agents to remove water
from a solution in an organic solvent, distillation, rotary evaporation and the effect of reduced
pressure (Anon., 2021), (Huremovic, Srabovic, Catovic, Huseinovic, 2016), (Pearson, 2021),
(Innovareacademics, 2020).
The scientific principles behind & the techniques used in preparing & testing Büchner filtration is that
the flask with a modest hole in the bottom & the secondary container is placed on the top of the flask,
gently. The important aspect is the filter paper & as its placed the solids get segregated from the fluid
and for there is a vole with another vacuum that sucks the air out & once the mixture is poured into
the top container, due to the filter paper placed there, all solid particles adhere to the filter paper, and
the liquid freely flows then through the filter paper into the placed below. And so, the liquid goes in.
By having it first wet the solvent and this is to prevent the initial leakage, pouring fluid which is to be
filtered into another container through a vacuum, & for it to be moderate poured into as too much can
cause it to be sucked into the vacuum suction. Moreover, to filter liquid from solid, as so this to
remove unwanted solid from the liquid. The mixture of the liquid and solid is passed through the filter
for which has a piece of filter paper in the funnel, which acts as a filtering agent & so blocks the solid
particles, & the remains are passed into the collecting flask (What is a Buchner Funnel?, 2020).
The scientific principles behind & the techniques used in preparing & testing melting point is in the
temperature over a range of temperatures and boils over a range of temperatures, for then a pure
substance has a sharp melting point, for it to be pure it needs to melt at only the single one
temperature and for it to have a sharp boiling point, this means that it needs to boil at the same
temperature. The melting is when the temperature at which a solid change into a liquid & boiling
point is the temperature at which a liquid change into a gas. The technique used to find the purity
testing technique for aspirin for this is a can be prepared firstly for the melting point, is to place the
open end of the tube into the sample for it to be tested, so by having the aspirin inside the capillary
tube making sure that there is enough sample to determine the temperature of the melting point. Then
to make sure to allow the melting temperature to cool down before taken to run for a second sample,
this is to turn the melting-temperature to 1.0, ensuring to wait for the temperature to decrease about
10-15 degrees, before resetting it to 4.5 & then to make a comparison is to look up the melting point
of a pure aspirin to make a direct comparison (chemistryrussell, 2013).
Method:
Stage 1
• The apparatus was assembled for heating under reflux.
• About 1 g of 2-hydroxybenzoic acid was accurately weighed out into a dry Quickfit flask fitted with a
Quick fit stopper. The mass was recorded.
• In the fume cupboard 2 cm of ethanoic anhydride followed by 8 drops of concentrated phosphoric
3
acid were added.
• The apparatus was setup for reflux heating and was warmed with swirling until all the solid was
dissolved.
• The heating was stopped and was allowed to cool. Carefully 5 cm of cold water was added to the
3
solution by pouring it down the condenser.
Stage 2
• The flask was stand in a bath of iced water until precipitation appears to be complete.
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