Making esters - Part 1 | Chemistry Tutorial

Summary

In 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

00:00

🧪 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.

05:01

🌡️ 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.

10:02

🔬 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.

Keywords

💡Ethyl Ethanoate

Ethyl ethanoate, also known as ethyl acetate, is an ester compound with the chemical formula CH3COOCH2CH3. It is a key product in the video's chemistry experiment and is known for its fruity odor, making it useful in perfumes, nail polish removers, and as a solvent. The script describes the process of synthesizing ethyl ethanoate through esterification, emphasizing its significance in the experiment.

💡Esterification

Esterification is a chemical reaction between a carboxylic acid and an alcohol, resulting in the formation of an ester and water. It is central to the video's theme, as the process is used to create ethyl ethanoate. The script explains that esterification is an equilibrium reaction, which can be influenced by factors such as reactant concentration and the removal of water.

💡Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change. In the context of the video, it is used to explain how increasing the concentration of reactants or removing the product water can shift the esterification equilibrium towards the formation of more ethyl ethanoate.

💡Flammable

The term 'flammable' refers to the ability of a substance to catch fire and burn easily. In the script, it is mentioned as a safety consideration when handling alcohols during the experiment, emphasizing the need to keep them away from flames to prevent accidents.

💡Corrosive

Corrosive substances are those that can cause damage to living tissue or materials upon contact. The script warns about the corrosive nature of carboxylic acids, particularly when using concentrated forms, and the importance of avoiding skin contact during the experiment.

💡Catalyst

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. In the video, sulfuric acid is used as a catalyst in the esterification reaction to speed up the formation of ethyl ethanoate by acting as a dehydrating agent that removes water, thus shifting the equilibrium.

💡Reflux

Reflux is a technique used in chemistry to apply heat to reactions over a period of time without the loss of volatile components. The script describes heating the reaction mixture under reflux to speed up the esterification process, with the use of a condenser to condense vapors back into the reaction mixture.

💡Boiling Chips

Boiling chips are small pieces of porous material used in distillation or boiling processes to prevent bumping, which is the violent boiling that can occur without nucleation sites. The script mentions their use to provide a surface for bubble formation, preventing damage to the glassware and ensuring even heating.

💡Separating Funnel

A separating funnel is a piece of laboratory equipment used to separate immiscible liquids of different densities. In the script, it is used to isolate ethyl ethanoate from the reaction mixture by separating the organic layer (containing the ester) from the aqueous layer.

💡Sodium Carbonate

Sodium carbonate, commonly known as washing soda or soda ash, is used in the script to neutralize any leftover acetic acid in the reaction mixture. It reacts with the acid to form a salt and water, facilitating the separation of the organic layer from the aqueous layer containing the neutralized acid.

💡Distillation

Distillation is a separation process based on differences in boiling points. The script describes using distillation to purify ethyl ethanoate by heating the mixture until the ester, which has a lower boiling point, vaporizes, then condenses and is collected separately from any impurities.

💡Calcium Chloride

Calcium chloride is a desiccant used to absorb water in the script. It is added to the product to remove any traces of water before the final distillation step. When water is present, it reacts with calcium chloride, forming clumps that can be easily identified and separated from the product.

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