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Recrystallization of Benzoic Acid Lab Report, Lab Reports of Chemistry

Filtration, evaporation, chromatography, recrystallisation

Typology: Lab Reports

2020/2021

Uploaded on 05/11/2021

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bg1
GlaxoSmithKline is a leading research-based pharmaceutical
company commit ted to excellence and i nnovation. We are
the second larges t life science company in the world a nd have
a leadership position in four major therapeutic areas anti-
infectives, gastrointestinal/metabolic, respiratory and central
nervous system .
The source of our com petitive advant age is the energy and
commitment of our e mployees. Our missi on is to improve the
quality of human l ife to enable people to do mor e, feel better and
to live longer.
World-wide we empl oy over 110,000 people and have 80
manufacturin g sites in 37 countrie s. At our Cork Site in
Currabinny, which was e stablished in 1975, we man ufacture
the active ingredients of medical compounds. Our Currabinny
facility empl oys over 500 people, ma ny of whom are engaged
in development chemistry, analytical and quality chemistry and
chemical and process engineering.
The Cork facilit y is a strategic global new product i ntroduction
site within GSKs ma nufacturing net work. We have a highly
automated manuf acturing facility, as well as an R& D Pilot Plant
with Pilot Plant Laboratories on site.
We are currently the p rimary product ion site for a number of
GSKs top selling drug s which treat illnesse s such as depression,
Type 2 Diabetes, Conges tive Heart Failure, Ulcers, H IV, Ovarian
Cancer, Breast Cancer, Parkinsons Disease and Arthritis.
GlaxoSmithKline also has a manufacturing and R&D facility in
Dungarvan, Co. Wate rford and sales and marketin g functions in
Dublin. GSK curren tly employs over 1,400 in Irelan d.
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Recrystallisation Benzoic Acid Determination Melting Point
of
and
of its
tapped sharply against the
desk causing the c rystals to
fall to the sealed en d. When
about 3 mm of crys tals are
in the base of the tube i t is
placed in the oil bat h. The
temperature at whi ch the
sample begins to mel t and
the temperature at w hich
it is completely me lted are
recorded.
To double check your
result, mix a samp le of
benzoic acid with s ome
pure benzoic acid. I f both
are pure benzoic aci d the
melting point wil l remain
the same but if the sa mple
is not pure benzoic ac id
then the melting po int will
be lowered.
How do I know I have a pure substance?
The melting point o f a substance is not the exac t point at which it melts
but rather the rang e of temperatur es from when th e samples sta rts to melt
until it has compl etely melted. The grea ter the range the more imp urities
present. A range of l ess than 1 °C indicates a pur e substance.
How is crystallisation used in industry?
The use of crystallisation in the pharmaceutical industry is an important
process for con trolling the physical propertie s, yield and purity of an
Active Pharmaceutical Ingredient (API). Many production processes
use c rystallisation in the nal stage of m anufacture to achie ve these
targets. Rece nt advances in crys tallisation proc ess monitoring allow f or
a better unders tanding of the process. Thes e advances allow crystals
with spec i c physical pro perties, for example par ticle size a nd shape,
to be created. It is pos sible to produce crys tals of varying par ticle size,
shape and form polymorphs of the same substance, bu t only one will be
suitable for drug d evelopment and manufac ture.
In industry, the way an API is ltered and dried can have a very signi cant
impact on the physic al properties of the ma terial.
Calculating the percentage yield
After the cr ystallisation process the amo unt of sample will have been
reduced as impur ities have been remove d. To calculate how much of the
pure substance w as present in the initia l impure sample, the percentage
yield is calculated.
Mass of pure samp le (after recr ystallisation )
Mass of impure sa mple (before recr ystallisati on)
The percentage y ield is a good indica tor of the purity of th e initial
sample. A high perce ntage yield implie s a low concentrati on of
impurities, whe reas a low percentage yield indica tes a sample with a
lot of impurities .
Producing pure substanc es is a very importan t process,
especially in the pharmaceutical industry. Separating
insoluble solids from sol vents is easily achieved usi ng a
simple technique called ltration. Soluble solids again
are easily separated f rom solvents by evaporation, and
chromatography is used to separate a mixture of l iquids. But
what happens when we have two s oluble solids that we want
to separate? In this lesson we wi ll look at recrystallisation, a
commonly-used process in the pharmaceutical industr y.
What is recrystallisation?
Recrystall isation is a very im portant puri cation technique, purifying
substances by re moving unwanted by-pr oducts. It is also u sed
to manufacture t he correct crys tal size and shape of a m aterial.
These factors can have a very signi cant impact on how a
medicine acts w hen taken by a patient. T he same principles a nd
techniques of rec rystallisation c an be applied both on a labor atory and
industry scale.
What are the principles behind
recrystallisation?
The process depe nds on two principles; the f act that substances tend
to be more soluble in a hot so lvent than in cold solve nt, and that each
solute tends to behave as thou gh it were alone in the solvent .
How do I know what solvent to use?
Using the correc t solvent is a very important p art of the process. The
solute must be inso luble in the solvent at room te mperature, and as the
temperature of the s olvent increase s, the solubility o f the solute also
increases. It is a lso important that the im purities present are solub le in
the solvent at room temperature and insoluble at higher temperatures.
An excellent subs tance for showing t his process is benzoi c acid
(C6H5COOH). A molecul ar crystal rather than an ion ic crystal, shown
by its low melting po int of 122 °C, benzoic acid is u sed as an anti-
microbial agent and is found in tooth pastes, mouthwashes, cosme tics
and deodorants.
Impure benzoic aci d contains the impur ities phthalic ac id and
benzylbenzoa te. If the impure sampl e is dissolved in a mi nimal volume of
hot solvent in this case boiling water and ltered to remove insoluble
impurities, the re sulting solution will con tain dissolved benzoic ac id as
well as dissolved i mpurities.
Upon cooling, the be nzoic acid crys tals comes out of sol ution as its
solubiluty in th e solvent decreas es. The impuritie s will remain in solut ion
and can be ltered off.
It is very impor tant when carr ying out this experim ent that rubber glove s
are worn, because org anic substances can b e absorbed through t he
skin, and as well, gogg les should be worn to protec t your eyes from hot
liquids which may s pray out from the ask.
to be created. It is po ssible to produce crys tals of varying par ticle size,
polymorphs
suitable for drug d evelopment and manufac ture.
to be created. It is po ssible to produce crys tals of varying par ticle size,
shape and form
polymorphs
suitable for drug d evelopment and manufac ture.
targets. Rece nt advances in crys tallisation proc ess monitoring allow f or
a better unders tanding of the process. Thes e advances allow crystals
with spec i c physical prop erties, for example par ticle size a nd shape,
use c rystallisation in the nal stage of m anufacture to achie ve these
targets. Rece nt advances in crys tallisation proc ess monitoring allow f or
use c rystallisation in the nal stage of m anufacture to achie ve these
targets. Rece nt advances in crys tallisation proc ess monitoring allow f or
use c rystallisation in the nal stage of m anufacture to achie ve these
targets. Rece nt advances in crys tallisation proc ess monitoring allow f or
How can we check the purity of
our substance?
A pure s ubstance has a xed melting point while an impure substanc e
melts over a wide ran ge of temperatures an d at a lower temperature
than the pure subst ance. The melting points of almos t all substances
are available in tab les.
To check the melting poin t place a few cryst als of the sample on an
aluminium block which has a thermometer inserted. Use a hot plate
to heat the block slow ly. Watch the crystal s carefully and not e the
temperature at wh ich they begin to melt and the temper ature at which
they have all melted. C ompare this value wit h the value found on the
bottle of pure sub stance. Ano ther method of c hecking the me lting point of
crystals is to u se a narrow capillar y tube in an oil bath. The c apillary tube
has one end open and th e other end sealed. The open end is p ressed
into ne crys tals o f the substan ce and the turned upside down and
Beaker containing benzoic acid dissolved in
minimum amount of boiling water
Filter funnel with fluted filter paper to
speed up the filtrarion process. Insoluble
impurities left behind as residue
Conical flask with hot concentrated
benzoic acid solution which still contains
soluble impurities
Fig.1 Filtration to remove insoluble impurities
Pure benzoic acid cystals
Büchner funnel
Büchner flask
Water containing soluble impurities
Fig.2 After cooling, the remaining solution is ltered off
Fig.1 Finding the melting
point of benzoic acid
Percentage yield = x 100
You can nd out more about the work of
GlaxoSmithKline at www.gsk.com,
www.gsk.com/worldwide/ie.htm or at www.sta.ie
GlaxoSmithKline is a leading research-based pharmaceutical
company co mmitted to exc ellence an d innovation. We ar e
the second l argest lif e science co mpany in the worl d and have
a leadership position in four major therapeutic areas anti-
infectives, gastrointestinal/metabolic, respiratory and central
nervous s ystem.
The source o f our competi tive advant age is the ene rgy and
commitme nt of our employe es. Our miss ion is to improve th e
quality o f human life to e nable people t o do more, feel be tter and
to live longer.
World-wid e we employ over 110,000 peop le and have 80
manufac turing sites i n 37 countrie s. At our Cork Si te in
Currabinny, whi ch was esta blished in 1975, we man ufacture
the active ingredients of medical compounds. Our Currabinny
facilit y employs over 5 00 people, ma ny of whom are en gaged
in development chemistry, analytical and quality chemistr y and
chemical and process engineering.
The Cork fac ility is a s trategic glo bal new produ ct introduc tion
site withi n GSKs manufa cturing net work. We have a hig hly
automated m anufactu ring facili ty, as well as an R &D Pilot Plant
with Pilot Plant Laboratories on site.
We are current ly the primar y produc tion site for a nu mber of
GSKs top selli ng drugs which treat illn esses such as depres sion,
Type 2 Diabetes, Co ngestive He art Failur e, Ulcers, HI V, Ovarian
Cancer, Breast Cancer, Parkinsons Disease and Arthritis.
GlaxoSmithKline also has a manufacturing and R&D facili ty in
Dungarv an, Co. Waterf ord and sales a nd marketing f unctions i n
Dublin. GSK c urrently em ploys over 1,400 in Ir eland.
���������������������
������ ��������������
���������������������
������� ��������������
Recrystallisation Benzoic Acid Determination Melting Point
of
and
of its
tapped sharply against the
desk causi ng the crystals to
fall to the sea led end. When
about 3 mm of cr ystals a re
in the base of t he tube it is
placed in th e oil bath. The
temperatu re at which the
sample beg ins to melt and
the tempera ture at which
it is comple tely melted a re
recorded.
To double check your
result, mi x a sample of
benzoic aci d with some
pure benzoic a cid. If both
are pure benzo ic acid the
melting poi nt will remai n
the same but i f the sample
is not pure ben zoic acid
then the mel ting point wil l
be lowered.
How do I know I have a pure substance?
The meltin g point of a subs tance is not t he exact poin t at which it me lts
but rather t he range of tempe ratures from w hen the sample s starts to m elt
until it has c ompletely melted. T he greater the range th e more impurities
present. A r ange of less th an 1 °C indica tes a pure subst ance.
How is crystallisation used in industry?
The use of crystallisation in the pharmaceutical industry is an important
process fo r controlli ng the physic al proper ties, yield a nd purity of a n
Active Pharmaceutical Ingredient (API). Many production processes
use crystallisa tion in the nal stage of manufacture to ac hieve these
targets. R ecent advances in c rystallisatio n process monitorin g allow for
a better un derstan ding of the proc ess. These a dvances all ow cryst als
with speci c physic al prop erties, for example particle size and shape,
to be created. I t is possibl e to produce cr ystals of varying p articl e size,
shape and form polymorphs of the same substa nce, but only one will be
suitable f or drug develo pment and manu facture.
In industry, the way an API is ltered and dried can have a very signi cant
impact on th e physical pro pertie s of the materia l.
Calculating the percentage yield
After th e crysta llisation p rocess the a mount of samp le will have bee n
reduced as i mpurities have been r emoved. To calculate how much o f the
pure subst ance was present in the i nitial impure sample, th e percentage
yield is calculate d.
Mass of pur e sample (after re crystallisa tion)
Mass of imp ure sample (before r ecrystallis ation)
The percen tage yield i s a good indica tor of the puri ty of the init ial
sample. A high p ercentag e yield implie s a low concen tration of
impuritie s, whereas a l ow percent age yield indi cates a sampl e with a
lot of impuri ties.
Producing pure substances is a ver y important process,
especially in the pharmaceutical industry. Separating
insoluble solids f rom solvents is easily achieved using a
simple technique called ltration. Soluble solids again
are easily separated from solvents by evaporation, and
chromatography is used to separate a mix ture of liquids. But
what happens when we have two soluble solids that we want
to separate? In this lesson we will look at recr ystallisation, a
commonly-used process in the pharmaceutical industry.
What is recrystallisation?
Recrys tallisat ion is a very im portan t purifi cation technique, purifying
substan ces by removin g unwanted by-p roducts. I t is also used
to manufac ture the corr ect crys tal size and s hape of a mater ial.
These factors can have a very signifi ca nt impact on how a
medicine ac ts when ta ken by a patient. T he same princ iples and
technique s of recrys tallisat ion can be app lied both on a la borator y and
industry scale.
What are the principles behind
recrystallisation?
The proces s depends on t wo princip les; the fac t that subst ances tend
to be more solub le in a hot solvent th an in cold solv ent, and that e ach
solute tends to behave a s though it wer e alone in the sol vent.
How do I know what solvent to use?
Using the cor rect solve nt is a very imp ortant p art of the pr ocess. The
solute must b e insoluble in the solvent a t room temper ature, and as th e
temperatu re of the solve nt increase s, the solubi lity of the so lute also
increase s. It is also imp ortant t hat the impuri ties prese nt are soluble i n
the solvent at room temperature and insoluble at higher temperatures.
An excellen t substanc e for showing t his proces s is benzoic acid
(C6H5COOH). A mo lecular cr ystal rat her than an io nic cryst al, shown
by its low melt ing point of 122 °C, be nzoic acid is u sed as an anti-
microbial agent and is found i n toothpas tes, mouthwa shes, cosme tics
and deodorants.
Impure benzo ic acid cont ains the impu rities pht halic acid and
benzylbe nzoate. If the impur e sample is dissol ved in a minimal volum e of
hot solvent – in this case boi ling water – and fi lte red to remove insoluble
impuritie s, the result ing solutio n will conta in dissolve d benzoic aci d as
well as diss olved impuri ties.
Upon cooli ng, the benzoic a cid crys tals comes o ut of soluti on as its
solubilut y in the solvent dec reases. The impur ities will remain in s olution
and can be fi ltered of f.
It is very im portant when ca rrying out this ex periment that rubbe r gloves
are worn, bec ause organic subst ances can b e absorbed t hrough the
skin, and as we ll, goggles sho uld be worn to protect your eye s from hot
liquids whi ch may spray ou t from the fl ask.
to be created. I t is possible to produce c rystal s of varyin g particl e size,
polymorphs
suitable f or drug develo pment and manu facture.
to be created. I t is possible to produce c rystal s of varyin g particl e size,
shape and form
polymorphs
suitable f or drug develo pment and manu facture.
targets. R ecent advances in c rystallisatio n process monitorin g allow for
a better un derstan ding of the proc ess. These a dvances all ow cryst als
with speci c physica l prop erties, for example particle size and shape,
use crystallisa tion in the nal stage of manufact ure to achie ve these
targets. R ecent advances in c rystallisatio n process monitorin g allow for
use crystallisa tion in the nal stage of manufact ure to achie ve these
targets. R ecent advances in c rystallisatio n process monitorin g allow for
use crystallisa tion in the nal stage of manufact ure to achie ve these
targets. R ecent advances in c rystallisatio n process monitorin g allow for
How can we check the purity of
our substance?
A pure substance has a fi xed melting point while an i mpure subst ance
melts over a w ide range of tem peratures a nd at a lower tempe rature
than the pure s ubstance . The melting p oints of almo st all subst ances
are availabl e in tables.
To check the meltin g point place a f ew cryst als of the sam ple on an
aluminium block which has a thermometer inserted. Use a hot plate
to heat the blo ck slowly. Watch the c rystal s carefull y and note the
temperatu re at which the y begin to melt a nd the tempera ture at which
they have all mel ted. Compar e this value wi th the value fou nd on the
bottle of p ure substan ce. Another met hod of checki ng the melting po int of
cryst als is to use a narrow capi llary tube in an oil ba th. The capillary t ube
has one end op en and the othe r end sealed. T he open end is pre ssed
into ne crysta ls of the substance and the turned upside down and
Beaker containing benzoic acid dissolved in
minimum amount of boiling water
Filter funnel with fluted filter paper to
speed up the filtrarion process. Insoluble
impurities left behind as residue
Conical flask with hot concentrated
benzoic acid solution which still contains
soluble impurities
Fig.1 Filtration to remove insoluble impurities
Pure benzoic acid cystals
Büchner funnel
Büchner flask
Water containing soluble impurities
Fig.2 After cooling, the remaining solution is fi ltered off
Thermometer
Benzoic acid crystals
Aluminium block
Bunsen burner
Fig.1 Finding the melting
point of benzoic acid
Percentage yield = x 100
You can nd out more about the work of
GlaxoSmithKline at www.gsk.com,
www.gsk.com/worldwide/ie.htm or at ww w.sta.ie
pf3
pf4

Partial preview of the text

Download Recrystallization of Benzoic Acid Lab Report and more Lab Reports Chemistry in PDF only on Docsity!

Glaxo comp the s a lea infect nervo

The comm qualit to live

World manu Curra the a facilit in de chem

The C site w autom with P

We a GSK’ Type Canc

Glaxo Dung Dubli

and

of its

tapped sharply against the desk causing the crystals to fall to the sealed end. When about 3 mm of crystals are in the base of the tube it is placed in the oil bath. The temperature at which the sample begins to melt and the temperature at which it is completely melted are recorded.

To double check your result, mix a sample of benzoic acid with some pure benzoic acid. If both are pure benzoic acid the melting point will remain the same but if the sample is not pure benzoic acid then the melting point will be lowered.

How do I know I have a pure substance?

The melting point of a substance is not the exact point at which it melts but rather the range of temperatures from when the samples starts to melt until it has completely melted. The greater the range the more impurities present. A range of less than 1 °C indicates a pure substance.

How is crystallisation used in industry?

The use of crystallisation in the pharmaceutical industry is an important process for controlling the physical properties, yield and purity of an Active Pharmaceutical Ingredient (API). Many production processes use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for a better understanding of the process. These advances allow crystals with specific physical properties, for example particle size and shape, to be created. It is possible to produce crystals of varying particle size, shape and form polymorphs of the same substance, but only one will be suitable for drug development and manufacture.

In industry, the way an API is filtered and dried can have a very significant impact on the physical properties of the material.

Calculating the percentage yield

After the crystallisation process the amount of sample will have been reduced as impurities have been removed. To calculate how much of the pure substance was present in the initial impure sample, the percentage yield is calculated.

Mass of pure sample (after recrystallisation) Mass of impure sample (before recrystallisation)

The percentage yield is a good indicator of the purity of the initial sample. A high percentage yield implies a low concentration of impurities, whereas a low percentage yield indicates a sample with a lot of impurities.

Producing pure substances is a very important process,

especially in the pharmaceutical industry. Separating

insoluble solids from solvents is easily achieved using a

simple technique called filtration. Soluble solids again

are easily separated from solvents by evaporation , and

chromatography is used to separate a mixture of liquids. But

what happens when we have two soluble solids that we want

to separate? In this lesson we will look at recrystallisation , a

commonly-used process in the pharmaceutical industry.

What is recrystallisation?

Recrystallisation is a very important purification technique, purifying substances by removing unwanted by-products. It is also used to manufacture the correct crystal size and shape of a material. These factors can have a very significant impact on how a medicine acts when taken by a patient. The same principles and techniques of recrystallisation can be applied both on a laboratory and industry scale.

What are the principles behind

recrystallisation?

The process depends on two principles; the fact that substances tend to be more soluble in a hot solvent than in cold solvent, and that each solute tends to behave as though it were alone in the solvent.

How do I know what solvent to use?

Using the correct solvent is a very important part of the process. The solute must be insoluble in the solvent at room temperature, and as the temperature of the solvent increases, the solubility of the solute also increases. It is also important that the impurities present are soluble in the solvent at room temperature and insoluble at higher temperatures.

An excellent substance for showing this process is benzoic acid (C 6 H 5 COOH). A molecular crystal rather than an ionic crystal, shown by its low melting point of 122 °C, benzoic acid is used as an anti- microbial agent and is found in toothpastes, mouthwashes, cosmetics and deodorants.

Impure benzoic acid contains the impurities phthalic acid and benzylbenzoate. If the impure sample is dissolved in a minimal volume of hot solvent – in this case boiling water – and filtered to remove insoluble impurities, the resulting solution will contain dissolved benzoic acid as well as dissolved impurities.

Upon cooling, the benzoic acid crystals comes out of solution as its solubiluty in the solvent decreases. The impurities will remain in solution and can be filtered off.

It is very important when carrying out this experiment that rubber gloves are worn, because organic substances can be absorbed through the skin, and as well, goggles should be worn to protect your eyes from hot liquids which may spray out from the flask.

to be created. It is possible to produce crystals of varying particle size, polymorphs suitable for drug development and manufacture.

to be created. It is possible to produce crystals of varying particle size, shape and form polymorphs suitable for drug development and manufacture.

targets. Recent advances in crystallisation process monitoring allow for a better understanding of the process. These advances allow crystals with specific physical properties, for example particle size and shape,

use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for

use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for

use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for

How can we check the purity of

our substance?

A pure substance has a fixed melting point while an impure substance melts over a wide range of temperatures and at a lower temperature than the pure substance. The melting points of almost all substances are available in tables.

To check the melting point place a few crystals of the sample on an aluminium block which has a thermometer inserted. Use a hot plate to heat the block slowly. Watch the crystals carefully and note the temperature at which they begin to melt and the temperature at which they have all melted. Compare this value with the value found on the bottle of pure substance. Another method of checking the melting point of crystals is to use a narrow capillary tube in an oil bath. The capillary tube has one end open and the other end sealed. The open end is pressed into fine crystals of the substance and the turned upside down and

Beaker containing benzoic acid dissolved in minimum amount of boiling water

Filter funnel with fluted filter paper to speed up the filtrarion process. Insoluble impurities left behind as residue

Conical flask with hot concentrated benzoic acid solution which still contains soluble impurities

Fig.1 Filtration to remove insoluble impurities

Pure benzoic acid cystals

Büchner funnel

Büchner flask

Water containing soluble impurities

Fig.2 After cooling, the remaining solution is filtered off

Thermometer

Benzoic acid crystals

Aluminium block

Bunsen burner

Fig.1 Finding the melting point of benzoic acid

Percentage yield = x 100

You

Glax

www

Recrystallisation ofBenzoic Acid D

and

Producing pure substances is a very important process,

especially in the pharmaceutical industry. Separating

insoluble solids from solvents is easily achieved using a

simple technique called filtration. Soluble solids again

are easily separated from solvents by evaporation , and

chromatography is used to separate a mixture of liquids. But

what happens when we have two soluble solids that we want

to separate? In this lesson we will look at recrystallisation , a

commonly-used process in the pharmaceutical industry.

What is recrystallisation?

Recrystallisation is a very important purification technique, purifying

substances by removing unwanted by-products. It is also used

to manufacture the correct crystal size and shape of a material.

These factors can have a very significant impact on how a

medicine acts when taken by a patient. The same principles and

techniques of recrystallisation can be applied both on a laboratory and

industry scale.

What are the principles behind

recrystallisation?

The process depends on two principles; the fact that substances tend

to be more soluble in a hot solvent than in cold solvent, and that each

solute tends to behave as though it were alone in the solvent.

How do I know what solvent to use?

Using the correct solvent is a very important part of the process. The

solute must be insoluble in the solvent at room temperature, and as the

temperature of the solvent increases, the solubility of the solute also

increases. It is also important that the impurities present are soluble in

the solvent at room temperature and insoluble at higher temperatures.

An excellent substance for showing this process is benzoic acid

(C

6

H

5

COOH). A molecular crystal rather than an ionic crystal, shown

by its low melting point of 122 °C, benzoic acid is used as an anti-

microbial agent and is found in toothpastes, mouthwashes, cosmetics

and deodorants.

Impure benzoic acid contains the impurities phthalic acid and

benzylbenzoate. If the impure sample is dissolved in a minimal volume of

hot solvent – in this case boiling water – and filtered to remove insoluble

impurities, the resulting solution will contain dissolved benzoic acid as

well as dissolved impurities.

Upon cooling, the benzoic acid crystals comes out of solution as its

solubiluty in the solvent decreases. The impurities will remain in solution

and can be filtered off.

It is very important when carrying out this experiment that rubber gloves

are worn, because organic substances can be absorbed through the

skin, and as well, goggles should be worn to protect your eyes from hot

liquids which may spray out from the flask.

How can we check the purity of

our substance?

A pure substance has a fixed melting point while an impure substance

melts over a wide range of temperatures and at a lower temperature

than the pure substance. The melting points of almost all substances

are available in tables.

To check the melting point place a few crystals of the sample on an

aluminium block which has a thermometer inserted. Use a hot plate

to heat the block slowly. Watch the crystals carefully and note the

temperature at which they begin to melt and the temperature at which

they have all melted. Compare this value with the value found on the

bottle of pure substance. Another method of checking the melting point of

crystals is to use a narrow capillary tube in an oil bath. The capillary tube

has one end open and the other end sealed. The open end is pressed

into fine crystals of the substance and the turned upside down and

Beaker containing benzoic acid dissolved in

minimum amount of boiling water

Filter funnel with fluted filter paper to

speed up the filtrarion process. Insoluble

impurities left behind as residue

Conical flask with hot concentrated

benzoic acid solution which still contains

soluble impurities

Fig.1 Filtration to remove insoluble impurities

Pure benzoic acid cystals

Büchner funnel

Büchner flask

Water containing soluble impurities

Fig.2 After cooling, the remaining solution is filtered off

Glaxo comp the s a lea infect nervo The comm qualit to live World manu Curra the a facilit in de chem The C site w autom with P We a GSK’ Type Canc Glaxo Dung Dubli

and

of its

tapped sharply against the desk causing the crystals to fall to the sealed end. When about 3 mm of crystals are in the base of the tube it is placed in the oil bath. The temperature at which the sample begins to melt and the temperature at which it is completely melted are recorded. To double check your result, mix a sample of benzoic acid with some pure benzoic acid. If both are pure benzoic acid the melting point will remain the same but if the sample is not pure benzoic acid then the melting point will be lowered.

How do I know I have a pure substance?

The melting point of a substance is not the exact point at which it melts but rather the range of temperatures from when the samples starts to melt until it has completely melted. The greater the range the more impurities present. A range of less than 1 °C indicates a pure substance.

How is crystallisation used in industry?

The use of crystallisation in the pharmaceutical industry is an important process for controlling the physical properties, yield and purity of an Active Pharmaceutical Ingredient (API). Many production processes use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for a better understanding of the process. These advances allow crystals with specific physical properties, for example particle size and shape, to be created. It is possible to produce crystals of varying particle size, shape and form polymorphs of the same substance, but only one will be suitable for drug development and manufacture. In industry, the way an API is filtered and dried can have a very significant impact on the physical properties of the material.

Calculating the percentage yield

After the crystallisation process the amount of sample will have been reduced as impurities have been removed. To calculate how much of the pure substance was present in the initial impure sample, the percentage yield is calculated. Mass of pure sample (after recrystallisation) Mass of impure sample (before recrystallisation) The percentage yield is a good indicator of the purity of the initial sample. A high percentage yield implies a low concentration of impurities, whereas a low percentage yield indicates a sample with a lot of impurities.

Producing pure substances is a very important process,

especially in the pharmaceutical industry. Separating insoluble solids from solvents is easily achieved using a simple technique called filtration. Soluble solids again are easily separated from solvents by evaporation , and chromatography is used to separate a mixture of liquids. But what happens when we have two soluble solids that we want to separate? In this lesson we will look at recrystallisation , a commonly-used process in the pharmaceutical industry.

What is recrystallisation?

Recrystallisation is a very important purification technique, purifying substances by removing unwanted by-products. It is also used to manufacture the correct crystal size and shape of a material. These factors can have a very significant impact on how a medicine acts when taken by a patient. The same principles and techniques of recrystallisation can be applied both on a laboratory and industry scale.

What are the principles behind

recrystallisation?

The process depends on two principles; the fact that substances tend to be more soluble in a hot solvent than in cold solvent, and that each solute tends to behave as though it were alone in the solvent.

How do I know what solvent to use?

Using the correct solvent is a very important part of the process. The solute must be insoluble in the solvent at room temperature, and as the temperature of the solvent increases, the solubility of the solute also increases. It is also important that the impurities present are soluble in the solvent at room temperature and insoluble at higher temperatures. An excellent substance for showing this process is benzoic acid (C 6 H 5 COOH). A molecular crystal rather than an ionic crystal, shown by its low melting point of 122 °C, benzoic acid is used as an anti- microbial agent and is found in toothpastes, mouthwashes, cosmetics and deodorants. Impure benzoic acid contains the impurities phthalic acid and benzylbenzoate. If the impure sample is dissolved in a minimal volume of hot solvent – in this case boiling water – and filtered to remove insoluble impurities, the resulting solution will contain dissolved benzoic acid as well as dissolved impurities. Upon cooling, the benzoic acid crystals comes out of solution as its solubiluty in the solvent decreases. The impurities will remain in solution and can be filtered off. It is very important when carrying out this experiment that rubber gloves are worn, because organic substances can be absorbed through the skin, and as well, goggles should be worn to protect your eyes from hot liquids which may spray out from the flask. to be created. It is possible to produce crystals of varying particle size, polymorphs suitable for drug development and manufacture. to be created. It is possible to produce crystals of varying particle size, shape and form polymorphs suitable for drug development and manufacture. targets. Recent advances in crystallisation process monitoring allow for a better understanding of the process. These advances allow crystals with specific physical properties, for example particle size and shape, use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for

How can we check the purity of

our substance?

A pure substance has a fixed melting point while an impure substance melts over a wide range of temperatures and at a lower temperature than the pure substance. The melting points of almost all substances are available in tables. To check the melting point place a few crystals of the sample on an aluminium block which has a thermometer inserted. Use a hot plate to heat the block slowly. Watch the crystals carefully and note the temperature at which they begin to melt and the temperature at which they have all melted. Compare this value with the value found on the bottle of pure substance. Another method of checking the melting point of crystals is to use a narrow capillary tube in an oil bath. The capillary tube has one end open and the other end sealed. The open end is pressed into fine crystals of the substance and the turned upside down and Beaker containing benzoic acid dissolved in minimum amount of boiling water Filter funnel with fluted filter paper to speed up the filtrarion process. Insoluble impurities left behind as residue Conical flask with hot concentrated benzoic acid solution which still contains soluble impurities Fig.1 Filtration to remove insoluble impurities Pure benzoic acid cystals Büchner funnel Büchner flask Water containing soluble impurities Fig.2 After cooling, the remaining solution is filtered off Thermometer Benzoic acid crystals Aluminium block Bunsen burner Fig.1 Finding the melting point of benzoic acid Percentage yield = x 100

You

Glax www

GlaxoSmithKline is a leading research-based pharmaceutical

company committed to excellence and innovation. We are the second largest life science company in the world and have a leadership position in four major therapeutic areas – anti- infectives, gastrointestinal/metabolic, respiratory and central nervous system. The source of our competitive advantage is the energy and commitment of our employees. Our mission is to improve the quality of human life to enable people to do more, feel better and to live longer. World-wide we employ over 110,000 people and have 80 manufacturing sites in 37 countries. At our Cork Site in Currabinny, which was established in 1975, we manufacture the active ingredients of medical compounds. Our Currabinny facility employs over 500 people, many of whom are engaged in development chemistry, analytical and quality chemistry and chemical and process engineering. The Cork facility is a strategic global new product introduction site within GSK’s manufacturing network. We have a highly automated manufacturing facility, as well as an R&D Pilot Plant with Pilot Plant Laboratories on site. We are currently the primary production site for a number of GSK’s top selling drugs which treat illnesses such as depression, Type 2 Diabetes, Congestive Heart Failure, Ulcers, HIV, Ovarian Cancer, Breast Cancer, Parkinson’s Disease and Arthritis. GlaxoSmithKline also has a manufacturing and R&D facility in Dungarvan, Co. Waterford and sales and marketing functions in Dublin. GSK currently employs over 1,400 in Ireland. � �

Determination Melting Point

and

of its tapped sharply against the desk causing the crystals to fall to the sealed end. When about 3 mm of crystals are in the base of the tube it is placed in the oil bath. The temperature at which the sample begins to melt and the temperature at which it is completely melted are recorded. To double check your result, mix a sample of benzoic acid with some pure benzoic acid. If both are pure benzoic acid the melting point will remain the same but if the sample is not pure benzoic acid then the melting point will be lowered. How do I know I have a pure substance? The melting point of a substance is not the exact point at which it melts but rather the range of temperatures from when the samples starts to melt until it has completely melted. The greater the range the more impurities present. A range of less than 1 °C indicates a pure substance. How is crystallisation used in industry? The use of crystallisation in the pharmaceutical industry is an important process for controlling the physical properties, yield and purity of an Active Pharmaceutical Ingredient (API). Many production processes use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for a better understanding of the process. These advances allow crystals with specific physical properties, for example particle size and shape, to be created. It is possible to produce crystals of varying particle size, shape and form polymorphs of the same substance, but only one will be suitable for drug development and manufacture. In industry, the way an API is filtered and dried can have a very significant impact on the physical properties of the material. Calculating the percentage yield After the crystallisation process the amount of sample will have been reduced as impurities have been removed. To calculate how much of the pure substance was present in the initial impure sample, the percentage yield is calculated.

Mass of pure sample (after recrystallisation) Mass of impure sample (before recrystallisation)

The percentage yield is a good indicator of the purity of the initial

sample. A high percentage yield implies a low concentration of impurities, whereas a low percentage yield indicates a sample with a lot of impurities. to be created. It is possible to produce crystals of varying particle size, polymorphs suitable for drug development and manufacture. to be created. It is possible to produce crystals of varying particle size, shape and form polymorphs suitable for drug development and manufacture. targets. Recent advances in crystallisation process monitoring allow for a better understanding of the process. These advances allow crystals with specific physical properties, for example particle size and shape, use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for

Thermometer Benzoic acid crystals Aluminium block Bunsen burner Fig.1 Finding the melting point of benzoic acid Percentage yield = x 100

You can find out more about the work of

GlaxoSmithKline at www.gsk.com, www.gsk.com/worldwide/ie.htm or at www.sta.ie

Glaxo comp the s a lea infect nervo

The comm qualit to live

World manu Curra the a facilit in de chem

The C site w autom with P

We a GSK’ Type Canc

Glaxo Dung Dubli

and

of its

tapped sharply against the desk causing the crystals to fall to the sealed end. When about 3 mm of crystals are in the base of the tube it is placed in the oil bath. The temperature at which the sample begins to melt and the temperature at which it is completely melted are recorded.

To double check your result, mix a sample of benzoic acid with some pure benzoic acid. If both are pure benzoic acid the melting point will remain the same but if the sample is not pure benzoic acid then the melting point will be lowered.

How do I know I have a pure substance?

The melting point of a substance is not the exact point at which it melts but rather the range of temperatures from when the samples starts to melt until it has completely melted. The greater the range the more impurities present. A range of less than 1 °C indicates a pure substance.

How is crystallisation used in industry?

The use of crystallisation in the pharmaceutical industry is an important process for controlling the physical properties, yield and purity of an Active Pharmaceutical Ingredient (API). Many production processes use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for a better understanding of the process. These advances allow crystals with specific physical properties, for example particle size and shape, to be created. It is possible to produce crystals of varying particle size, shape and form polymorphs of the same substance, but only one will be suitable for drug development and manufacture.

In industry, the way an API is filtered and dried can have a very significant impact on the physical properties of the material.

Calculating the percentage yield

After the crystallisation process the amount of sample will have been reduced as impurities have been removed. To calculate how much of the pure substance was present in the initial impure sample, the percentage yield is calculated.

Mass of pure sample (after recrystallisation) Mass of impure sample (before recrystallisation)

The percentage yield is a good indicator of the purity of the initial sample. A high percentage yield implies a low concentration of impurities, whereas a low percentage yield indicates a sample with a lot of impurities.

Producing pure substances is a very important process,

especially in the pharmaceutical industry. Separating

insoluble solids from solvents is easily achieved using a

simple technique called filtration. Soluble solids again

are easily separated from solvents by evaporation , and

chromatography is used to separate a mixture of liquids. But

what happens when we have two soluble solids that we want

to separate? In this lesson we will look at recrystallisation , a

commonly-used process in the pharmaceutical industry.

What is recrystallisation?

Recrystallisation is a very important purification technique, purifying substances by removing unwanted by-products. It is also used to manufacture the correct crystal size and shape of a material. These factors can have a very significant impact on how a medicine acts when taken by a patient. The same principles and techniques of recrystallisation can be applied both on a laboratory and industry scale.

What are the principles behind

recrystallisation?

The process depends on two principles; the fact that substances tend to be more soluble in a hot solvent than in cold solvent, and that each solute tends to behave as though it were alone in the solvent.

How do I know what solvent to use?

Using the correct solvent is a very important part of the process. The solute must be insoluble in the solvent at room temperature, and as the temperature of the solvent increases, the solubility of the solute also increases. It is also important that the impurities present are soluble in the solvent at room temperature and insoluble at higher temperatures.

An excellent substance for showing this process is benzoic acid (C 6 H 5 COOH). A molecular crystal rather than an ionic crystal, shown by its low melting point of 122 °C, benzoic acid is used as an anti- microbial agent and is found in toothpastes, mouthwashes, cosmetics and deodorants.

Impure benzoic acid contains the impurities phthalic acid and benzylbenzoate. If the impure sample is dissolved in a minimal volume of hot solvent – in this case boiling water – and filtered to remove insoluble impurities, the resulting solution will contain dissolved benzoic acid as well as dissolved impurities.

Upon cooling, the benzoic acid crystals comes out of solution as its solubiluty in the solvent decreases. The impurities will remain in solution and can be filtered off.

It is very important when carrying out this experiment that rubber gloves are worn, because organic substances can be absorbed through the skin, and as well, goggles should be worn to protect your eyes from hot liquids which may spray out from the flask.

to be created. It is possible to produce crystals of varying particle size, polymorphs suitable for drug development and manufacture.

to be created. It is possible to produce crystals of varying particle size, shape and form polymorphs suitable for drug development and manufacture.

targets. Recent advances in crystallisation process monitoring allow for a better understanding of the process. These advances allow crystals with specific physical properties, for example particle size and shape,

use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for

use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for

use crystallisation in the final stage of manufacture to achieve these targets. Recent advances in crystallisation process monitoring allow for

How can we check the purity of

our substance?

A pure substance has a fixed melting point while an impure substance melts over a wide range of temperatures and at a lower temperature than the pure substance. The melting points of almost all substances are available in tables.

To check the melting point place a few crystals of the sample on an aluminium block which has a thermometer inserted. Use a hot plate to heat the block slowly. Watch the crystals carefully and note the temperature at which they begin to melt and the temperature at which they have all melted. Compare this value with the value found on the bottle of pure substance. Another method of checking the melting point of crystals is to use a narrow capillary tube in an oil bath. The capillary tube has one end open and the other end sealed. The open end is pressed into fine crystals of the substance and the turned upside down and

Beaker containing benzoic acid dissolved in minimum amount of boiling water

Filter funnel with fluted filter paper to speed up the filtrarion process. Insoluble impurities left behind as residue

Conical flask with hot concentrated benzoic acid solution which still contains soluble impurities

Fig.1 Filtration to remove insoluble impurities

Pure benzoic acid cystals

Büchner funnel

Büchner flask

Water containing soluble impurities

Fig.2 After cooling, the remaining solution is filtered off

Thermometer

Benzoic acid crystals

Aluminium block

Bunsen burner

Fig.1 Finding the melting point of benzoic acid

Percentage yield = x 100

You

Glax

www

Examination Questions

Junior Certificate 2005, Technology - Higher

Section B, Question 2

(concerning the design and function of two different potential dividers)

Section C, Question 4

(concerning robotics, remote control, sensor feedback in relation to the

Mars Lander)

Junior Certificate 2004, Technology - Higher

A student is required to produce a circuit which will turn on a water pump

when low water levels are detected by a sensor.

The components listed below are available to construct the circuit.

LED Sensor Transistor, Resistor 2K2, Resistor 330R, Motor (pump),

Variable resistor, 9V battery

1. Using the sensor and the variable resistor, sketch the circuit diagram for

the potential divider required in this circuit.

2. Name and explain your choice of material for the sensor.

3. Explain why a variable resistor is used in the potential divider.

4. Indicate clearly which pins on the variable resistor should be used in

the potential divider.

Junior Certificate 2001, Technology - Higher

Section B, Question 2

(concerning the design and operation of a temperature alarm: an

incomplete circuit diagram was given and students were expected to

complete it and explain how it functioned.)

2001 Junior Certificate Technology Higher Level

The sketch shows a circuit for a high temperature alarm.

(i) Identify the components ‘X’ any ‘Y’

State the purpose of component ‘Y’ in the circuit.

S

Z

+9 V

Y

R

0 V

X

Why is a transistor used in this circuit?

How can the cathode of the LED be correctly identified?

(ii) If the maximum permitted current for the LED is 0.02 A, show how to

calculate the value of the resistor ‘R’ required for the circuit.

Which of the following values should be used for resistor ‘R’?

The fourth band in a resistor is either silver or gold. What does the

colour of this band indicate?

(iii) Name and sketch the symbol for the component which should be

located at ‘Z’.

For further examples of past paper questions

check www.sta.ie

Did You Know?

  • The invention of the battery by Alessandro Volta in 1800 provided

curious experimenters with a source of steady electric current

whose properties they explored. During the 19th century much of the

basic theory of electricity was developed and many applications of

electricity were invented: electromagnet (1820), electric motor (1821),

theory of electricity generation (1831), electric light (1878), first power

station (1879), first hydroelectric power station (1882), first alternating

current generator (1888), electricity distribution system (1893), electric

vacuum cleaner and washing machine (1903). All these devices are

classed as electric.

  • The invention of the diode in 1904 could be described as the beginning

of electronics. Unlike wires, electric lights and electromagnets,

diodes conducts electricity in one direction only and their operation

cannot be adequately explained except in terms of electrons. Another

development along the same lines, the triode, enables weak signals

to be amplified. These vacuum tube diodes and triodes (or ‘valves’ as

they were called) were the building blocks of electronics for about fifty

years.

  • Solid-state semiconductor devices began to replace valves in the

1950s—crystal diodes at first and transistors some years later. In the

1960s the first integrated circuits came on the market and in 1972 the

first commercial microprocessor chip was released.

  • Although the distinction between electric and electronic devices is not

sharp, the word electronic is nowadays usually reserved for devices

whose operation depends on solid-state semiconductors. On this

basis an ordinary electric lamp is ‘electric’ but it could be argued that

a CFL lamp is ‘electronic’.

  • Transistors are the active components in many ‘transistorised’ devices

such as radios, tape recorders, etc. Increasingly they are integrated

into more complex ‘chips’. The transistor is the solid state successor

to the triode valve and following its invention it gradually replaced the

vacuum tube in most applications. The invention is usually attributed

to William Shockley, John Bardeen and Walter Brattain who in 1947

produced the first practical transistor device. However similar devices

had been described in 1928 and 1934 but it seems that they were not

manufactured. In contrast to the triode, the transistor is a solid device

and its invention marked the beginning of solid-state physics.Today

transistors are the basic subunits in most integrated circuits (ICs or

‘chips’) including microprocessors.

Revise the Terms

Can you recall the meaning of these terms? Reviewing the

terminology is a powerful aid for recall and retention.

Electricity; electric circuit; current; voltage; battery; switch;

automatic; sensor; component; thermostat; bimetallic strip;

temperature; pressure; humidity; potential divider; in series;

resistor; resistance; electronic; thermistor; LDR; calibrate; speaker;

microphone; electric motor; electric generator; transducer; volt;

millivolt; computer; operating system; computer network; ad hoc

network; mote; wireless communication; pH probe; chemical

sensor

Check the Glossary of Terms for this lesson at www.sta.ie

ental Monitoring