Making esters - Part 1 | Chemistry Tutorial
Summary
TLDRIn this chemistry lab at Curtin University, Alexandra Young demonstrates the production of ethyl ethanoate through esterification, a process used in perfumes and artificial flavorings. The video covers safety considerations, the addition of reactants like ethanol and acetic acid, and the use of sulfuric acid to shift equilibrium. It details steps including reflux, separation, drying with calcium chloride, and purification via distillation, culminating in measuring the yield of the fragrant ester.
Takeaways
- 🧪 The video is a chemistry lab demonstration by Alexandra Young, a lecturer at Curtin University, focusing on the synthesis of ethyl ethanoate.
- 🍾 Esters, like ethyl ethanoate, are known for their fragrant and fruity odors, making them useful in perfumes, nail polish removers, and artificial flavorings.
- 🔥 Safety is paramount; flammable alcohols and corrosive carboxylic acids are used, requiring precautions against fire and skin contact.
- 🌡 The esterification reaction is an equilibrium process, influenced by factors like reactant concentrations and the removal of water to shift the equilibrium towards product formation.
- 🧪 The use of sulfuric acid as a dehydrating agent helps remove water, a byproduct that would otherwise reduce the yield of ethyl ethanoate.
- 🔄 The setup for the reaction includes a round bottom flask, boiling chips for even heating and to prevent glassware cracking, and a reflux condenser for efficient product recovery.
- ♨️ Heating the reaction mixture under reflux facilitates the esterification process by speeding up the reaction and using the boiling points of reactants to prevent loss.
- 💧 After the reaction, water is added to the separating funnel to help isolate the product, as ethyl ethanoate is not water-soluble and will separate into a distinct layer.
- 🧪 Sodium carbonate is used to neutralize any leftover acetic acid or sulfuric acid, facilitating the separation of the organic layer containing the product.
- 🌟 Calcium chloride is added to the product to remove any residual water, ensuring the purity of ethyl ethanoate before the final purification step.
- 🔬 The final step involves distillation to purify the product based on differences in boiling points, with the collection of the fraction below 80 degrees Celsius being the pure ethyl ethanoate.
Q & A
What is the main objective of the chemistry lab session at Curtin University?
-The main objective of the lab session is to make ethyl ethanoate through processes such as esterification, isolation, and purification.
Why are esters often used in perfumes, nail polish remover, and artificial flavorings?
-Esters are used in these applications because they are very fragrant and often have fruity odors, making them ideal for scenting and flavoring purposes.
What safety considerations are mentioned for the experiment involving alcohols and carboxylic acids?
-The safety considerations include the flammability of alcohols, requiring them to be kept away from flames, and the corrosiveness of carboxylic acids, necessitating avoidance of skin contact.
What is the role of sulfuric acid in the esterification reaction?
-Sulfuric acid acts as a dehydrating agent, removing water from the reaction mixture, which according to Le Chatelier's principle, shifts the equilibrium to the right and increases the yield of the ester product.
Why are boiling chips added to the reaction setup?
-Boiling chips are added to provide a surface for bubbles to form, preventing the glassware from cracking due to bubble formation, and to ensure even heating of the reaction mixture.
What is the purpose of heating the reaction mixture under reflux?
-Heating under reflux speeds up the reaction by increasing the temperature and using a catalyst. It also prevents the loss of reactants and products with low boiling points by condensing the vapors back into the reaction mixture.
How is the product ethyl ethanoate isolated from the reaction mixture?
-Ethyl ethanoate is isolated by adding water to a separating funnel, shaking the mixture, and then running off the bottom layer, leaving the product in the top layer due to its lower density.
What is the purpose of adding sodium carbonate to the reaction mixture after the esterification reaction?
-Sodium carbonate is added to neutralize any leftover acetic acid or sulfuric acid present in the reaction mixture, facilitating the separation of the organic layer containing the product.
How is the presence of water in the product addressed during the purification process?
-Water is addressed by adding calcium chloride to the product, which reacts with any remaining water, causing it to clump and stick to the bottom of the container, thus separating from the organic product.
What is the final step in the purification process of ethyl ethanoate?
-The final step is distillation, where the product is transferred into a round bottom flask, heated, and the fraction below 80 degrees is collected, which is the purified ethyl ethanoate.
How is the yield of the product determined at the end of the experiment?
-The yield is determined by measuring the volume of the collected distillate in a measuring cylinder and then calculating the percentage yield based on the theoretical yield.
Outlines
🧪 Chemistry Lab Introduction and Esterification Process
In this segment, Alexandra Young, a lecturer at Curtin University, introduces a chemistry lab session at the Curtin Bentley campus. The focus is on synthesizing ethyl ethanoate using esterification, a process involving a carboxylic acid and an alcohol. Esterification is highlighted as a reversible equilibrium reaction, and strategies to increase product yield are discussed, such as using an excess of one reactant and adding a dehydrating agent like sulfuric acid to remove water, a byproduct that would otherwise shift the equilibrium and reduce yield. Safety precautions are emphasized, including the flammable nature of alcohols and the corrosive properties of carboxylic acids. The setup for the reaction includes adding ethanol, glacial acetic acid, and sulfuric acid to a round bottom flask, along with boiling chips to prevent cracking of the glassware due to uneven heating or bubble formation.
🌡️ Reflux and Isolation of Ethyl Ethanoate
This paragraph details the continuation of the esterification experiment, where the reaction mixture is heated under reflux to speed up the reaction. The setup includes a condenser to prevent the loss of volatile reactants and products by condensing the vapors back into the reaction mixture. After refluxing for 45 minutes, the reaction is cooled, and the next step involves isolating the product from the reaction mixture, which contains excess acid, water, and the catalyst. Water is added to a separating funnel to facilitate the separation of ethyl ethanoate, which has a lower density and remains in the top layer. The bottom layer is discarded, and sodium carbonate is added to neutralize any leftover acid. The process is repeated to ensure the purity of the organic layer containing the product.
🔬 Purification and Distillation of Ethyl Ethanoate
The final steps of the experiment involve purifying the ethyl ethanoate product through distillation. The product is transferred to a round bottom flask, taking care to exclude any drying agent like calcium chloride. The distillation setup includes a thermometer to monitor the temperature and prevent the product from exceeding its boiling point of 77 degrees Celsius. The distillation process relies on the differences in boiling points to isolate the product, with the vapors being condensed and collected in a conical flask placed in an ice bath to maximize product recovery. The distillation is carefully controlled to collect only the fraction below 80 degrees, which is the pure ethyl ethanoate. The experiment concludes with measuring the volume of the product obtained, which will later be used to calculate the percentage yield.
Mindmap
Keywords
💡Ethyl Ethanoate
💡Esterification
💡Le Chatelier's Principle
💡Flammable
💡Corrosive
💡Catalyst
💡Reflux
💡Boiling Chips
💡Separating Funnel
💡Sodium Carbonate
💡Distillation
💡Calcium Chloride
Highlights
Introduction to the chemistry lab at Curtin University and the process of making ethyl ethanoate.
Esters are used in perfumes, nail polish remover, artificial flavorings, and as solvents due to their fragrant and fruity odors.
Safety considerations for handling flammable alcohols and corrosive carboxylic acids in the lab.
The esterification reaction is reversible, and methods to increase the yield of ethyl ethanoate are discussed.
Use of an excess of acetic acid to shift the equilibrium according to Le Chatelier's principle.
The role of sulfuric acid as a dehydrating agent to remove water and shift the equilibrium towards product formation.
Setting up the reaction with ethanol, glacial acetic acid, and sulfuric acid in a round bottom flask.
Importance of boiling chips in preventing glassware from cracking and ensuring even heating.
Heating under reflux to speed up the reaction and prevent loss of reactants and products.
Isolating the product by adding water to the separating funnel and separating the layers.
Safety measures when handling the separating funnel to prevent pressure build-up.
Removing leftover acetic acid or sulfuric acid with sodium carbonate.
Drying the product with calcium chloride to remove traces of water.
Purification of the product using distillation based on differences in boiling points.
Monitoring the distillation process to collect the fraction below 80 degrees Celsius.
Measuring the volume of the produced ethyl ethanoate to calculate the percentage yield.
Invitation to learn more about studying chemistry or a science degree at Curtin University.
Transcripts
hi
i'm alexandra young and i'm one of the
lecturers here at curtin university
welcome to one of our chemistry labs
here at curtin bentley campus
today we are going to be making ethyl
ethanoate through a number of processes
such as esterification isolation and
purification
esters are prepared using a carboxylic
acid
and alcohol they are very fragrant and
often have fruity odors which make them
ideal for use in perfumes
nail polish remover and artificial
flavorings additionally
esters are often used as a solvent now
before we begin
we need to be aware of some safety
considerations alcohols are flammable
so we need to keep them away from any
flames
carboxylic acids are also corrosive and
we'll be using concentrated acids in
this experiment
so we also need to avoid skin contact to
make esoethanoa we start with ethanol
so we're using 15 mils today and glacial
acetic acid
we're using 20 ml today and pop that
into a round bottom flask
now as you can see in the equation the
esterification reaction is an
equilibrium reaction which means it's
reversible or can go both ways
so in order to increase the yield of our
product sls and 08
we can do a number of things to do so
firstly
if we use an excess amount or increase
the
reactance in our reaction for example
our acetic acid
according to le chatelier's principle it
will shift the reaction
to the right thereby increasing the
amount of our products here
you can also see that there's water
that's one of the products that's formed
now this is not great because
it will shift the equilibrium to the
left
thereby reducing the product that's
formed
so in order to remove that or minimize
that effect
we can try and get rid of the water and
we do that
by adding sulfuric acid which is a
dehydrating agent
that removes the water when the water is
removed
the equilibrium will shift to the right
according to le chatelier's principle
thereby increasing the amount of our
product that's formed so
we are at our fume hood and we're going
to set up our reaction now
so first thing i need to do is add our
ethanol which is 15 mils so
add that into our round bottom flask
we then now need to add our glacial
acetic acid
so we're adding 20 ml of glacial acetic
acid
and lastly we're going to add our
catalyst
or our sulfuric acid which is one meal
now before we actually set it up for
safety reasons we have to add some
boiling chips as well
and basically what these boiling chips
do
is they provide a surface for bubbles to
form
so that instead of bubbles bouncing on
the glassware
the bubbles bounce on the boiling chips
so this prevents the glassware from
cracking
another purpose of the boiling chips is
to also
provide um even heating of our reaction
mixture
so when we set up our reaction
there are two clamps all right
our bottom clamp is here that's where it
has to be tight on our
round bottom flask that's what's holding
it up you also see a second clamp here
now this clamp doesn't have to be tight
it's just there as a backup in case it
falls over
another thing to notice is here our
clamps are also
in this direction you'll see it's uh the
slopey bit is on the bottom that's also
a safety issue
just in case this is loose if it's loose
it'll fall
on the safety issue so we just have to
lower our reaction into our hot water
bath
and that's when it's going to be heated
now the reason why we heat it
is to speed up the reaction another way
to speed up the reaction is to add a
catalyst which we already have done
when we're heating this way it's
actually called heating under reflux
which is
a common technique used in synthesizing
a number of organic compounds
now what happens is we have our reaction
mixture
or our volatile compounds in the
reaction flask
when those volatile compounds boil there
are vapors that are produced
which rise up the condenser the cold
water
from the condenser then cools those
vapors
which allows the vapors to reform
as a liquid and it goes back into our
reaction mixture
now this is really important because if
this wasn't here
our reactants and our products which
have low boiling points will escape to
the atmosphere
which then will be lost our round bottom
flask
is connected to our condenser and this
condenser
is connected to a tap so we have our
our water coming out from the top so we
need to first turn on our water
check that the pressure is okay so now
our reaction set up is ready to go
so our our reaction has been refluxing
for 45 minutes
we've just turned off the heat and
lifted it up
out of the water bath for it to cool
down
now we can isolate our product so in our
reaction mixture there's quite a lot of
things
we have our product any excess acidic
acid that hasn't reacted
we have water which is also a product
and we also have our sulfuric acid which
was our catalyst in there
the ethanol that was one of our
reactants
should have all been used up um because
that was our limiting reagent
so we're now ready to actually do the
next step so because we have so many
different
components still in our reaction mixture
we actually want to isolate our product
and to do that we're going to add some
water
to our separating funnels
the reason why we do that is because
everything in our reaction mixture
is water-soluble except for our product
pour in our reaction mixture now there's
lots of safety aspects that we have to
consider when doing this
as you can see i haven't put the stopper
on because as soon as we put the stopper
on
what we'll do is we invert our
separating funnel
immediately release pressure in case
there's any gas built up in there
so i've just put the stopper on invert
and
quickly release pressure now in order to
ensure
that all our soluble components
enter our water our water we have to
shake it
and to do that you have one hand on the
stopper
the other one on your separating funnel
and shake
release pressure frequently just in case
there's some gas build up
so shake
release pressure and you do that three
or four times
always shake with the nozzle pointing
the back of the fume hood
for safety reasons as well all right
so then take the stopper off
and what you'll be able to see are two
layers we have a bottom layer
and a top layer our product ethyl
ethanoate has a
lower density than water so it will stay
in the top layer
we just slowly run off the bottom layer
until
the bottom of the line reaches the
stopcock
there we go and that's where our product
is
in the top layer now we repeat that one
more time
to ensure that all the water soluble
products will end up
in our water layer okay
so the next step is to remove any um
leftover acetic acid or sulfuric acid
that may be present
so we're just adding about five mils of
sodium carbonate
to our reaction mixture
invert release pressure straight away
and again shake
take off the stopper and let our
reaction mixture settle so at this point
any of our excess acid should have
reacted with the sodium carbonate that
we just added
so again we then run off our bottom
layer which is where the sodium
carbonate is
and any excess acid will be in our
bottom layer and our product will be in
our top
organic layer so we're almost there
so we have our product which we know
organic flour
however there may still be some traces
of water in there
so we need to remove that so what i'll
do is i'll just run
this into a clean
conical flask and
we add some calcium chloride the amount
we add depends on how much water we have
so we add enough so that when we swirl
it
the calcium chloride moves freely around
if there was water still in there
what happens is the calcium chloride
will react with the water
and it'll clump and stick to the bottom
so we've just
finished removing the water from our
product
and the next step is to purify our
product and we do that
using a distillation reaction so it's
set up here
we just have to transfer our product
into a round bottom flask
and taking care not to include any of
our
calcium chloride that we added to dry
the product
all right we'll just add a couple more
boiling chips
so this is our distillation setup and
there's lots of different components
our clamp tightly hooked onto our round
bottom clasp here
we've got a thermometer here with the
thermometer tip
just at the junction where it crosses
over here
our condenser which is the same
condenser we use for a reflux
but instead it's now horizontal and so
vertical
and then we've got a clean conical flask
that's in an ice bath over here
basically
what happens is as the reaction heats up
our product will boil our product has a
boiling point of 77 degrees
so we need to monitor our thermometer
temperature we don't want that
temperature getting above about 80
degrees
so we're going to be using the
differences in boiling points to isolate
or purify our product
so a product will boil first and produce
vapors
the vapors will rise up to this point
the condenser
with water running through it will
condense the solution back in condenser
vapors back into solution
it'll run down here and it'll be
collected in our conical glass here
now we also have an ice bath here and
that's just to
try and collect as much of our product
as possible
because there may be some residual
vapors that
are produced so we'll condense it
straight away and
collect our product in there so
to begin with we just need to turn our
water on there we go
water's on and crank up the
temperature and let it distill so what
we're going to do
is only collect the fraction that is
below 80 degrees
and that is what we know is our product
so our distillation's finished and we've
just turned off the heat and
risen the apparatus over here and the
last thing we have to do
is just work out or measure how much of
the product we made so to do that we
just put our collector distillate which
is in our conical flask over here
and pretty much work out how much we've
made
all right so just pour it in to a
measuring cylinder
to work out the volume
there we go
and we've made about
17 and a half and we can use that to
work out our percentage yield next
we hope you enjoyed learning about the
esterification experiment today
and found it knowledgeable in our next
video we'll be calculating the
percentage yield of our substance
if you'd like to find out more about
studying chemistry or a science degree
at curtin
head to study.curtin.edu
you
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