The Mole
... For anyone inspired to dig deeper into chemistry
Tasty chemistry
Josh Howgego discovers the chemistry of food with Peter Barham, the
scientist–cook who trains world-class chefs.
Issue 05 | SEPTEMBER 2012
In this issue
utrescine and
P
cadaverine
T he compounds
behind the
smell of
death
T aking a
gap year
Is it worth it?
Nitroglycerin
Making it safely and fast
Smart windows
Storing the sun’s energy
Jonathan Wills
Helping chemists to
protect their work
It’s not just taste that influences how enjoyable a meal is, visual appeal and other perceptions are
also important
‘So – I have to ask – what is your favourite food?’ I’m
sitting in the office of Peter Barham, a physics professor
at the University of Bristol, UK. I’m not usually so
interested in the food preferences of scientists, but
Barham is no ordinary scientist. He has a passion for
molecular gastronomy – applying science to food and
cooking. In fact, Barham is a professor of this subject
at the University of Copenhagen in Denmark. He also
mentored the chef Heston Blumenthal, who came to
him for advice when he was just starting out as a cook.
And (with a little help from some liquid nitrogen) he has
his name in the record books as the world’s fastest ice
cream maker.
‘Pea dust,’ is the response, and Barham looks like he’s
savouring the memory. ‘It’s something I helped devise
during a visit to Copenhagen,’ he explains. ‘The peas
are freeze-dried to remove all of the water and then
shaved extremely finely using a precision instrument.’
The result is super concentrated pea material that is so
fine it spontaneously diffuses into the nose as you lift
a spoonful to your mouth. According to Barham, the
combination of intense smell and taste gives a very
powerful ‘pea hit’.
I find the idea of a ‘pea hit’ hard to imagine, but
Barham’s answer illustrates an important point: when
it comes to food, it’s not just taste that determines
our experience. There are many other sensory inputs
involved. Barham tells me that even subtle factors such
as the colour of a plate can have a huge impact on our
perception of food. For example, a cooked breakfast
on a blue, plastic plate will feel less enjoyable than the
identical meal presented on a clean, white ceramic one.
Editor
Karen J Ogilvie
Assistant editor
David Sait
ChemNet content
Rio Hutchings
Production
Scott Ollington and Emma Shiells
Publisher
Bibiana Campos-Seijo
The Mole is published six times
a year by the Royal Society of
Chemistry, Thomas Graham
House, Cambridge,
CB4 0WF.
01223 420066
email: [email protected]
www.rsc.org/TheMole
© The Royal Society of Chemistry,
2012. ISSN: 2049-2634
www.rsc.org/TheMole
Registered Charity Number 207890
Gastronomers use liquid
nitrogen to prepare many
desserts, like ice cream
and caramel popcorn
panna cotta (seen right)
like curry or mustard as well as the coolness of menthol,
such as in toothpaste. Chemesthetic sensations persist
for many minutes, unlike taste and smell, which are
most intense for a few seconds after contact with the
chemical. This makes chemesthetic molecules powerful
tools for chefs.
Did you
know?
Interested in the science
of taste? The journal
Nature created a podcast
all about it. You can hear it
at http://bit.ly/LnjCbo
and listen to the
presenters enjoying
‘seaweed chips’, among
other delicacies.
The way food is prepared is also important, since
properties like texture have a strong influence on how
we perceive food. A great example is ice cream making.
The speed with which the water in ice cream freezes
determines the size of the ice crystals, and this in turn
determines the texture. Cooling slowly in a freezer gives
the crystals time to grow large, resulting in the slightly
grainy ice cream we are familiar with. But using ultra
cold liquid nitrogen at –198°C freezes the mixture in just
a few seconds and there is only enough time for very
small crystals to form. This gives an extremely smooth
ice cream.
Taste and smell – mediated by molecules
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But good texture is nothing without a pleasing taste and
smell – and these come from the molecules that make
up our food interacting with receptors in our mouth and
nose. A piece of food is composed of many thousands
of different molecules such as proteins, sugars and
carbohydrates, so it’s not always easy to link individual
molecules to particular tastes. And the complexity only
increases when we cook food, where the heat energy
allows the molecules to react, creating new ones.
But although there are millions of different food
molecules, our mouths actually have just five types
of taste receptor: salt, sweet, bitter, sour and umami.
Umami has only recently been acknowledged as a
separate taste. It’s best summed up as the taste of
savoury things, and it is found in foods like cheese and
seaweed. The taste comes from glutamic acid, and that’s
why many foods have monosodium glutamate (MSG)
added to them for extra flavouring.
Glutamic acid is
responsible for the
umami flavour. MSG is
the sodium salt of this
molecule
2 | The Mole | September 2012
Our noses, on the other hand, contain lots of different
olfactory (smell) receptors and so much of the flavour
of food is actually determined by its smell. This makes
the small molecules that waft up into our noses very
important for molecular gastronomers. Some chemicals
can also interact with receptors in the skin and mucous
membranes to elicit other sensations such as touch and
even pain. This process is called chemesthesis and it is
the mechanism by which we perceive the heat in food
Capsaicin (top) and
menthol (left) stimulate
the skin’s ‘heat’ and
‘cold’ receptors
Cooking with chemistry
Whether they realise it or not, all chefs are chemists.
They bring together chemicals and heat (cook) them so
they will react to make new, tasty or fragrant molecules.
For most of history, a trial and error approach to cooking
has worked excellently, but to carry fine dining into the
realms of science, a deeper understanding of these
chemical reactions is needed.
Perhaps it will come as no surprise that the first person
to make any headway in this area was from the great
foodie nation of France. Louis Maillard began studying
the reactions of sugars with amino acids in the 1900s.
There are many, many different types of sugar and 20
or so types of amino acid (mostly from proteins) in
our diet, which means the reactions between these
molecules produce an incredibly diverse range of
products. But the basic mechanism of the reaction is
usually the same.
First, the amino acid undergoes a condensation reaction
with the sugar (in its open chain form known as an
aldose, rather than its cyclic form) to form an amide.
After several proton transfer steps and the loss of
water from the molecule, a ketone called the Amadori
compound is formed.
The Amadori compound is a key intermediate formed
during cooking and roasting processes in a wide variety
of foods. In itself, it is not particularly flavoursome but
it can go on to make different products that are. The
conditions used in cooking could take these reagents
down any number of different routes to produce
completely different compounds, which makes things
interesting for the chef. In the example shown (Fig 1),
the acidic pH means that lots more hydroxyl (–OH)
groups are lost, which causes cyclic molecules to be
produced. Our example also contains some sulfur,
which would come from sulfur-containing amino acids
www.rsc.org/TheMole
Amino acid
Amadori compound
Acidic pH
-H2O
Ribose
High temperature
Roasted coffee
Toasted bread
like cysteine. This then reacts with the cyclic compounds
to form organosulfur compounds. The flavours that
these compounds give to foods are characteristic of the
crust of freshly baked bread, roasted coffee and roasted
meat. The state of the art in molecular gastronomy
at the moment is learning how to direct this reaction
towards specific compounds in order to achieve a
particular flavour.
Given how complex it all seems, I’m wondering whether
Barham has any tips that budding molecular gastronauts
can use in their own kitchen? ‘Well, I have three vacuum
pumps at home,’ he says, ‘but not everyone has access
to that sort of thing.’ However, good cooking is all about
thinking how diners will perceive your food, he says.
Studies have shown that – up to a certain point – diners
Roasted meat
enjoy complexity. So tricks like serving a mixed fruit
juice, for example, rather than simple orange juice, can
go a long way. But Barham says ‘tricks’ is a bad word,
‘because, really, it’s about understanding.’
We may be on the cusp of realising how little we
actually know about taste. It is only in the last 12 years
that the structures of our taste receptors have been
identified. And very recently scientists have discovered
these receptors are not just in our mouths, but also the
airways, gut and – rather strangely – even on sperm
cells. No one knows why. The way we experience
food depends on subtle interactions between food
molecules and our bodies. These new findings seem
to suggest that we are still far from fully understanding
this phenomenon.
Natural flavourings?
Interestingly, the molecules developed during the
cooking process are not ‘natural’ (in the sense that
they are not present in the food without cooking),
although most people would consider them as
such. Consumers are generally much more wary
of additive flavourings, which are actually more
‘natural’ and are often simply extracted from fruits
without chemical manipulation. Some natural
flavour enhancing ‘E-number’ compounds are
shown below.
Fig 1: In the Maillard
reaction (above) sugars
and amino acids react
together, break down
and recombine to form
complex mixtures of
products. Some of those
shown are responsible for
the ‘roasted’ flavours in
meat and bread
Did you
know?
The word for the fifth
taste, Umami, comes
from the Japanese
words ‘umai’ (delicious)
and ‘mi’ (taste). It was
named by Kikunae
Ikeda, who first noticed
that crystals of
glutamic acid were
responsible for the
taste in 1907. The name
wasn’t officially
adopted until 1985.
(Left to right) Inosinic acid (E630), lysine (E642) and maltol (E636)
www.rsc.org/TheMole
September 2012 | The Mole | 3
Did you
know?
Putrescine has been
shown to protect against
seizures in tadpoles, a
finding that may lead to
treatments for epilepsy in
the future.
Magnificent molecules
In this issue: putrescine and cadaverine
Cadaverine
Putrescine
Take a deep breath and hold your nose. Phillip Broadwith
presents the compounds behind the smell of death
Crime novelists and war reporters often refer to
the ‘smell of death’ when encountering a dead or
decomposing body. The characteristic odours of rotting
flesh are difficult to forget once experienced and are
generally recognised as being worth avoiding, but what
is it that makes a dead body smell so bad?
Find out more
podcasts from
Check out the
ld. Each week
or
Chemistr y W
ist or author
a leading scient
behind a
tells the stor y
und.
different compo
orld.org/
yw
tr
is
w w w.chem
compounds
What’s that smell?
Most of the smells we encounter are not caused
by single compounds. The smell of a decomposing
body is made up of all sorts of interesting molecules,
but amines and sulfur-containing molecules are the
stinkier components. Most of those amines come from
breakdown of the proteins in the corpse, and two of
them have such horrible odours that they have been
named putrescine (after the process of putrefaction)
and cadaverine (after the Latin word
for a corpse: cadaver).
Putrescine and cadaverine are
chemically very similar: they are
both diamines – molecules that
contain two amine groups. Both have
short hydrocarbon chains with a
primary amine group at each
end. The difference is
that putrescine has
four carbon atoms in
the chain between
the two amines,
whereas there
are five in
cadaverine.
These smells
will be found anywhere
protein is decomposing
4 | The Mole | September 2012
– that’s why the poo of meat-eating animals like cats
and dogs smells much worse than that of herbivorous
animals like rabbits or sheep: it contains more protein.
But these diamines are not just about corpses. They
are produced in normal living tissue as well, where
they help the process of cell division. The cadaverine
and putrescine that our own, living bodies produce
contribute a little to the smell of urine.
Putrid plastics
Putrescine is also produced on an industrial scale,
although it is definitely not used in the perfume
industry! It is, in fact, made into plastics. The industrial
process for making certain plastics such as nylon is
to take a diamine and another molecule that has a
carboxylic acid group at either end (a diacid). Reacting
these two molecules together makes long chain
polymers, in which the diamine and diacid building
blocks alternate, connected by amide bonds.
But where does industry get its putrescine from?
You may have an image of chemists harvesting smelly
amines from a pile of rotting bodies in a basement
somewhere but this belongs firmly in science fiction.
Industrially, putrescine is made from acrylonitrile
(2-propenenitrile) and hydrogen cyanide.
These two molecules are reacted together
to make succinonitrile, which is similar to
putrescine but contains fewer hydrogen
atoms. Hydrogenation then turns the
colourless waxy solid of succinonitrile into the foulsmelling putrescine.
If I were running that reactor plant I’d want to use up
that putrescine as quickly as possible – the smell of
death is not one you want to linger.
www.rsc.org/TheMole
Avogadro’s Lab
In this issue: Chemistry communications
The Mole team on the role of reading and developing
good communication skills
Communications play an important role in our lives as chemists. We need to read to find things out and to keep
up to date with new research and developments. We also need to record experimental findings accurately and
comprehensively so they can be understood by others. You don’t always need to read textbooks and journals to
keep informed and develop your communication skills. We have picked out a couple of books which should open
your eyes and mind to some of the weirder aspects of chemistry. These should dispel any myths that science is
boring and give you something worth discussing with your friends!
Electrified sheep
Alex Boese
Paperback: £8.39
Kindle: £4.96
http://amzn.to/MByKog
Free radicals: The secret
anarchy of science
Michael Brooks
Paperback: £5.12 | Kindle £4.86
http://amzn.to/TjIoLg
For those looking for a sensible
book concerning scientific
excellence, be warned –
you have picked the wrong
book! Electrified sheep quite
brilliantly explains some of
the more bizarre experiments performed in the name of
scientific discovery with lashings of intellectual humour
and a surprising amount of quality storytelling.
The premise of Free radicals
is to dispel the perception
that scientists are boring,
method-bound and inhuman –
unaffected by the randomness
of life; that scientific discoveries
are born from rigorous, formalised and methodical work,
under a strict set of rules known as the ‘scientific method’;
and scientists are somehow ‘different’ to normal people.
Each chapter begins with a story, some plausible, some
bordering on out of this world, but all are based on true
events and experiments. From the invention of the modern
battery, which involves questionable relations between
a man and his voltaic pile, to the creation of the optimal
chimpanzee butler and self experimentation.
Real-world science, argues Brooks, is a rough and
tumble affair, where erudite individuals buck the system
and break the rules. There are power struggles, ethical
dilemmas, substance abuse, corruption and sabotage – in
short, whatever it takes to come up with the next big thing.
He cites examples from across the gamut of sciences,
from theoretical physics – Albert Einstein using dodgy
assumptions and force of will to persuade the world of the
accuracy of his famous equation E = mc2 – to the possibly
deadly rivalry between chemists Gilbert Lewis and Irving
Langmuir that ended in Langmuir’s death from cyanide
poisoning. Suicide or murder? Perhaps we’ll never know.
The author has two rules of exclusion for the book: anyone
trying to be weird wasn’t weird enough for the book.
Also, no barbaric acts committed in the name of science
were permitted. However this doesn’t mean that it is not
without the odd disgusting bit. For example the section
Do-it-yourselfers is a rather more sinister approach to self
experimentation that can become quite gruesome.
All these strange and unusual items are well structured
and written with each section cleverly leading onto the
next. This is a book you can pick up and read from almost
anywhere if you find a section that tickles your curiosity.
Recommended for reading while travelling, sitting, eating
or for escaping into the random world of experimental
science – if banned from your usual laboratory.
Callum Saunders
www.rsc.org/TheMole
The book is fun and easy to read, with a good balance of
straightforward language and scientific content to keep
readers happy without skimping on detail. There is also a
useful reference section for those wishing to dig deeper.
Although Brooks’s frequent repetition of his central tenet
that scientists are secretly anarchists can become a little
tiresome, it does serve as a reminder that the excitement
of science comes from breaking new ground. And if you’re
doing that properly you should expect a bumpy ride.
Phillip Broadwith
Try these
too
Every molecule tells a story
Simon Cotton
Paperback: £32.31
http://bit.ly/CW_BR071202
The story of over 200
molecules and how they relate
to everyday life.
L itmus: short stories from
modern science
Ra Page
Paperback: £6.99
http://bit.ly/CW_BR111103
A group of authors, in
collaboration with scientists,
tell the stories of a range of
scientific discoveries and the
people behind them.
L ab coats in Hollywood:
science, scientists and
cinema
David Kirby
Hardback: £15.56 | Kindle: £14
http://bit.ly/CW_BR091110
Find out how scientific
consultants work with
directors to add authenticity to
the science portrayed in films.
S
tudy and communication
skills for the chemical
sciences
Tina Overton, Stuart Johnson
and Jon Scott
Paperback: £18.47
http://bit.ly/CW_BR051101
How to get the most out of
lectures, tutorials and
practical work.
Book prices were taken from Amazon.co.uk
in August 2012
September 2012 | The Mole | 5
Gap year
jobs
Any job you do in a gap
year is bound to help you
develop new skills, but if
you look around you may
be lucky enough to find a
science-related job. Here
is a couple of ideas to get
you started:
YINI (Year in Industry)
arrange paid placements
for gap year students in
UK science companies.
Check out their website
for more information:
http://bit.ly/P2u9XZ
School science
technician – for hands
on chemistry experience,
why not ask your school
if they have any
technician vacancies?
Top tips
Taking a gap year
Annette Hutchinson asks: ‘it is worth it?’
Is a gap year right for you?
Thirteen years of compulsory education is a long time, so
it is little wonder so many people choose to take a break
after school before going to university. From volunteering
or backpacking to paid employment, there are many ways
to fill a gap year, but how will it affect your prospects?
We’ve had a chat with some university admissions tutors,
recent graduates and chemistry employers so that you can
decide if a gap year is right for you.
What the universities say
Liam Cox, of the School of Chemistry at the University of
Birmingham, UK, says students who have taken a gap
year ‘often come back with a sense of maturity, better
organisation and time management skills, all of which lend
themselves to a subject like chemistry, where you do need
to be organised and plan your week ahead.’
Take a revision guide
with you if you go
travelling, and glance at it
every now and again.
A worry for some students is that they will forget
everything they learnt at school but Cox doesn’t see this as
a problem. ‘Different people take varying times to adjust
to things,’ he says. ‘So if you’ve forgotten your chemistry,
that might be your disadvantage, but somebody else is
struggling with getting out of bed for a nine o’clock lecture
when they’ve not got their mother to wake them up.’
Keep up-to-date by
reading magazines like
The Mole, Chemistry
World or New Scientist.
Deciding how to use your gap year is important. For
Bhakvik Patel from the University of Brighton, UK, it’s all
about variety. He’s encouraged by gap-year students who
break up their year with different ‘mini projects’. This gives
Keep up your chemistry
during a gap year
students a ‘more diverse
experience than someone
who’s going to just one
location for the year.’
Talking about gap-year plans in your UCAS personal
statement is a great way to sell yourself to admissions
tutors. The key thing is to relate your plans to the skills you
hope to develop. ‘Admissions tutors want to see what an
individual is going to gain from that experience and how
it’s going to contribute to their success in the future,’ says
David Read, director of undergraduate admissions at the
University of Southampton, UK.
What the graduates say
‘I changed completely. I was so much more confident,’
says recent graduate Amy Styring of her gap year. Before
studying archaeology and chemistry at university, Amy
worked for a few months to fund a trip to Brazil. She
had planned to do voluntary work at an archaeological
site there, but when this fell through at the last minute,
she ended up volunteering on a farm. Amy has used
this experience in job applications as an example of her
independence and initiative.
What the employers say
It may seem like a long time off, but before you know it,
you’ll be a applying for your first ‘proper’ job. So what do
your future bosses think of gap years?
‘As a recruiter, I look at how [a candidate’s] life
experiences contribute to their skill set and a gap year
may impact on that’ says Ian Bell, who works for Afton
Chemical Ltd. He says a gap year itself is neither positive
nor negative, ‘it’s what they’ve done with that luxury [of
having a gap year], that’s of interest.’
Jacquin Wilford-Brown, from International Paint Ltd,
says she often finds the qualities she’s looking for in
candidates who’ve taken a gap year: ‘If you’re talking to
someone who has taken a gap year, they often have more
experience that they can draw on and you can get a better
impression of who they are, and what they can do. If they
haven’t, they might still have the same qualities, but it
might just be harder to find out.’
istockphoto
So, whether you decide to take a gap year or not, you
won’t be disadvantaged when it comes to applying for
university or securing a job in chemistry. But if you do
decide to go for it, make sure you have a plan, so that you
can get the best possible experience from the year, and
develop skills that will help you in the future.
6 | The Mole | September 2012
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RSC ChemNet
membership
Dates for
your diary
ChemNet Events
L ook at what chemistry
has done for me
Rio Hutchings finds out what the RSC’s
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INSPIRED TO DIG
DEEPER INTO CHEMISTRY
Don’t be a dope
!
ISSUE 03 | MAY
2012
Nina Notman
talks to
2012 London Olympicthe scientists set to beat the
doping cheats
Games
at the
In this issue
Glucose
Energy for life
Avogadro’s lab
Make a sports
drink and join
in the Global Experiment
Meet the Universiti
es
Expert help to
find your
university course
Faces of chemistry
Looking behind
sport
performance research
Healthier sausages
Cutting edge chemistry
LONDON 2012
Careers advice
Access scientific careers
publications – advice on
topics such as writing
personal statements will
help you with your UCAS
application form.
The Mole
… FOR ANYONE
The main London
stadium which
will host the Olympics
this summer
‘We’ll catch you.’
This is the message
from the UK
government to
any athlete planning
hours a day, seven
to dope at this
summer’s Olympic
days a week during
Games in London.
Paralympic Games.
the Olympic and
Up to 400 samples
Doping means
each day, 6250
will be analysed
the use of illicit
in total – more
substances or methods
than any previous
to improve athletic
Games.
performance. It
The anti-doping
was banned in
lab is based at
1920s, and is still
the
the GlaxoSmithK
a growing problem
(GSK) site in Harlow,
line
in professional
sports. The constant
Essex. However,
the pharmaceut
company will not
pressure on athletes
ical
be running the
has driven the
to
win
development of
testing there. That
the job of David
novel and highly
is
Cowan, a professor
sophisticated doping
at King’s College
London’s Drug
techniques, as
Control Centre.
wannabe cheats
struggle to stay
With the help of
one step ahead
doping
experts from around
antiof the scientists
to expose them.
aiming
the world, Cowan
overseeing the
will be
150 analysts conducting
The lab
the tests.
The process
This year the chances
Approximately
of
half the athletes
than ever. A laboratory not being caught are smaller
competing, including
all Olympic medallists,
the size of seven
will be testing athlete’s
tennis courts
will provide urine
samples for anti-doping
and blood
urine and blood
samples 24
analysis. These
divided in two,
labelled with barcodes samples will be
(no names) and
0312MOLE -
FEATURE.indd
Editor
Karen J Ogilvie
Assistant editor
David Sait
ChemNet content
Rio Hutchings
Production
Scott Ollington
and Emma Shiells
Publisher
Bibiana Campos-Seijo
The Mole is published
six times
a year by the Royal
Society of
Chemistry, Thomas
House, Cambridge, Graham
CB4 0WF.
01223 420066
email: [email protected]
www.rsc.org/T
heMole
© The Royal Society
of Chemistry,
2012. ISSN: 2049-2634
www.rsc.org/The
Mole
Registered Charity
Number
1
207890
4/5/2012 12:17:48
PM
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Plus visit www.rsc.org/chemnet.
B
ASF – science in action/
industry visit
3 October 09:00–13:00
Bradford
Suitable for ages 16–18
See science in action at BASF,
the largest and most
productive single site chemical
plant in the UK.
http://bit.ly/LBl7xv
Y
orkshire museum –
chemistry, conservation
and collections
17 October 10:00–15:30
York
Suitable for ages 16–18
Join curators at the Yorkshire
Museum to find out why an
understanding of chemistry is
essential to caring for their
internationally significant
natural science collections.
http://bit.ly/QV1QAn
These events are supported
by an education grant as part
of the Reach and Teach
program funded by the
Wolfson Foundation.
e on a
To book a plac
t:
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org
c.
rs
E: events@
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43
3
T: 0122
and find more
or book online
e events at:
th
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emnet
w w w.rsc.org/ch
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rg
.o
sc
y.r
m
ht tp://
September 2012 | The Mole | 7
Cutting-edge chemistry
Find out more
Industrial nitroglycerin made fast and safe
out the
Learn more ab
troglycerin
ni
of
y
chemistr
ast from
with this podc
ld
Chemistr y Wor
0xW
Jo
O
y/
http://bit.l
control the decomposition products. And in the event
of something going very wrong, the resulting explosion
would be much smaller.
The microreactor is a hand-sized clear polymer tile with
an internal channel that meanders across the plane.
The internal channel has two entrances but only one
exit – the reactants are brought together at the start and
then mixed as they move through the microreactor by
turbulence caused by a complex pattern of grooves and
ridges on the sides of the channel.
Structure of nitroglycerin
Did you
know?
High purity
That said, this is not an approach for
bulk production of nitroglycerin. Low
grade product, primarily for the mining and construction
industries, can be made cheaply in bulk already. Where
this approach is a real advantage is in the manufacture
of smaller quantities of nitroglycerin at very high grades
for use in the pharmaceutical industry.
Andrew Turley
Nitrating hydrocarbons
Fraunhofer ict
Nitroglycerin is not only a
powerful explosive but
also a potent drug
(sometimes called
glyceryl trinitrate), widely
used for treating angina
and other heart problems.
Since the invention of nitroglycerin in the mid-19th
century, people have been trying to find safer ways
to manufacture this highly unstable liquid explosive.
Now, researchers at the Fraunhofer Institute for
Chemical Technology (ICT) in Pfintzal, Germany, have
come up with what might be the safest approach
yet – using microreactors to produce nitroglycerin
continuously rather than in batches. This is not only
safer but also quicker, facilitating a 10-fold increase in
production rate.
To scale up production, you simply add more
microreactors in parallel. A single microreactor
might be used to make 10–50 kg of
nitroglycerine per day. But the research
group in Pfinztal has experimented with
production at 2–3 tonnes per week by
‘numbering up’ the microreactors.
Nitroglycerin is made by adding glycerol, a simple
hydrocarbon with three hydroxyl groups, to a mixture
of sulfuric acid and nitric acid. The reaction is
extremely exothermic, and if the temperature gets too
high ‘runaway’ can occur, dramatically increasing the
risk of explosion.
Therefore manufacturers continually cool the reaction
mixture and – in the traditional batch process – add
the glycerol drop-by-drop to the acid to allow time for
the heat to dissipate and maintain an excess of acid,
essential to ensure complete nitration of the all the
hydroxyl groups.
Microreactors
Microreactors can be
used to produce explosive
materials much more
safely
8 | The Mole | September 2012
Switching to a continuous process in a microreactor
means working with much smaller quantities – safer
for several reasons. It makes it easier to control the
overall temperature and the degree of mixing, which
is important to avoid localised temperature variations
and dangerous ‘hotspots’. It also makes it easier to
www.rsc.org/TheMole
Did you
know?
Smart windows store sun’s energy
Polymers and plastics are
often thought of solely as
insulators. However,
polymers like polyaniline
can conduct electricity
due to their conjugated
electronic structure. Find
out more about
conducting polymers at
http://bit.ly/Mzo1IC
The energy storage
smart window can be
bent and flexed and
still do its job
Scientists in China have developed a smart window that
not only heats and cools a building, but can also act as
an energy storage device to power electrical equipment
within the building.
Smart windows are already in use in some buildings;
they are used to reduce energy consumption by keeping
the interiors cool and controlling the light levels within.
An example of this is in museums, where artefacts can
be damaged by too much sunlight.
Changing colour
Now, Zhixiang Wei from the National Centre for Nanoscience and Technology and colleagues have made a
window that combines a supercapacitor with a window
pane that changes colour in response to an electric
current. In bright sunlight, it absorbs and stores energy,
but when it is full to capacity, the window darkens
to limit the amount of light that enters. This controls
the temperature and brightness of the room and the
captured energy can be used to power equipment, such
as television screens. As the electricity is used up, the
energy storage smart window (ESS window) will lighten
and begin to absorb more sunlight to recharge itself.
The ESS window is made of polyaniline nanowire arrays,
which are deposited onto a transparent film that has
been coated with a conductive layer. The nanowires
www.rsc.org/TheMole
are then covered with a gel electrolyte layer to form an
electrode, and two electrodes are sandwiched together
to make a working device.
Flexible devices
Polyaniline has a high capacity and doesn’t cost
much to make, plus it has the added advantages of
being transparent and flexible. ‘Flexible devices are
attracting more and more attention because they are
lightweight, easy to roll up, and can be designed in
a more fashionable way. It is no doubt that a flexible
smart window like ours possesses these properties. For
instance, the ESS window can be rolled up like a curtain
if it is not being used,’ says Wei.
John Rogers, an expert in photonic devices from
the University of Illinois at Urbana-Champaign, US,
was cautiously optimistic about the work. ‘Such
technologies, if they can be made cheaply and in forms
that offer long-lived operation, could be valuable in
contexts ranging from automotives to homes,’ he says.
Have a go�
Electrochromic materials
change colour when an
electric current is applied.
Make your own
electrochromic polymer in
your school lab.
http://bit.ly/SJHvLF
Wei’s team is working on optimising their device by
trying different electrode materials and improving the
window’s electrochromic properties. They are also
looking at integrating a solar cell into the device to store
even more energy.
Holly Sheahan
September 2012 | The Mole | 9
Did you
know?
In Fight Club, Tyler
Durden is quite the
amateur chemist – as
well as his napalm
recipe, he also explains
how to make soap by
hydrolysing fat. Fat that
he steals from a
liposuction clinic!
On-screen chemistry
Napalm: its devastating effects –
on-screen and off
Jonathan Hare investigates these destructive chemicals
mixed with orange juice concentrate
that provides the sticky oil. Napalm’s
name comes from two of the compounds
used to make the oily gel in the first
preparations: naphthenic and palmitic
acids. Liquid fuels burn quickly, but mixing
them with a gel allows the fuel to burn
with a hot slow flame, thereby maximising
the damage it does to buildings,
vegetation and, of course, people.
‘I love the smell of
napalm in the morning’
The 1979 movie Apocalypse Now1 is about the horrors
and psychological trauma of the Vietnam War. A major
cause of trauma on both sides was the widespread
use of napalm – the chilling scenes of burning
fields, property and people from the news reels are
unforgettable. In the film, a US Army officer, Lieutenant
Colonel Bill Kilgore, exclaims ‘I love the smell of
napalm in the morning’. It’s an often quoted line, but
with knowledge of napalm’s devastating effects, it is a
viewpoint we should find appalling.
Combustible orange juice
Naphthenic acid (top)
Palmitic acid (bottom)
10 | The Mole | September 2012
In the 1999 film Fight Club, the character Tyler
Durden claims ‘if you mix equal parts of gasoline and
frozen orange juice
concentrate, you can
make napalm.’2 So what
is napalm and how is
it really made? Napalm
is a general name
for a thick oil or jelly
mixed with fuel such
as gasoline (petrol).
In Durden’s ‘recipe’,
the gasoline fuel is
The term ‘napalm’ is used for a number of
chemically distinct materials. Napalm B,
used extensively in the Vietnam war
(containing polystyrene and benzene) is
very sticky and can’t easily be removed
from skin. Versions of napalm B containing
white phosphorus will even burn
underwater (if there is trapped oxygen
in folds of cloth, for example) so even
jumping into rivers and lakes won’t help
those unfortunate souls attacked with this vile weapon.
Victims will either die from severe burns, from the
effects of the prolonged intense heat (heat stroke),
or possibly from carbon monoxide and phosphorus
poisoning from the fumes given off.
Total destruction
When it is dropped from an aircraft, a single napalm
‘bomb’ is capable of completely destroying an area
covering thousands of square meters. Napalm was
dropped on German and Japanese cities in the
second world war and used extensively by the US in
Vietnam from 1950s to 1970s. It is particularly feared
because, unlike standard bombs and bullets, it flows
and spreads very effectively – napalm is not easy to
escape. For example, it can form a river of burning
liquid that can flow into hidden underground trenches
like no other weapon.
Now that the use and appalling effects of napalm have
been well documented, many humanitarian groups
around the world are trying to ban its use.
References
1 Apocalypse Now, 1979, 20th Century Fox
2 Fight Club, see InfoChem, May 2007
www.rsc.org/TheMole
Jonathan Wills
Pathway to
success
Mewburn Ellis LLP
When you look at a door, you probably just see a door.
Perhaps an entrance, or a portal if you’re feeling particularly
imaginative. But would you see it as a ‘cover positioned by
an opening in a wall that can be moved to vary the extent
to which it blocks the opening’? Jonathan Wills might.
That’s because Jonathan is a patent attorney and, as such,
it’s his job to capture the defining points of new inventions
in precise detail to help the inventor get a patent.
But the door, of course, isn’t a new invention, and the
inventors who come to Jonathan are generally not
interested in carpentry. Instead, as a chemistry graduate,
Jonathan specialises in working with scientists to get
patents for their discoveries. Whether it’s a new drug to
cure malaria, a new material for more efficient batteries
or a chemical to clean up oil spills, ‘the idea of a patent is
that it lets a researcher protect their new and important
work,’ Jonathan explains. So when someone has a great
new idea or invention, getting a patent makes sure that
other people can’t steal it or copy it. Or at least if they do,
they’ll be in trouble.
why it’s clever. A lot of my day to day work is fighting with
the Patent Office to get patents approved.’
So Jonathan really has to know what he’s talking about,
which means he relies heavily on his chemistry knowledge.
‘I can’t do this job without being a chemist,’ he says.
‘Everything I’ve learned I’m using day to day. Scientists
need someone who can understand the complex research
they’re doing to explain it in the patent application.’
From lab to law
After studying for his chemistry degree and a PhD, Jonathan
admits that he decided he didn’t want to keep working in
the lab, but he still loved chemistry and didn’t want to leave
it all behind. Becoming a patent attorney was the perfect
opportunity to apply his scientific knowledge outside of the
laboratory, while still keeping up to date with science.
Jonathan also explains that although his chemistry degree
is essential, it’s just as important for patent attorneys to
have excellent communication skills and a cool head.
‘During the application process we ask applicants to
Argumentative
Sounds simple enough, but to write those patents Jonathan describe a simple invention to get an idea of how well
they can convey an idea. It’s all about asking them difficult
needs to have a detailed understanding of the work that’s
questions to see if they can still work under pressure.’ And
been done so he can figure out exactly what makes the
for those that have what it takes – there’s still a lot to learn.
invention special. And then he must describe, in careful
‘As a trainee patent attorney, you know all this stuff about
detail, how it works, or how it’s made and why it’s new,
science but absolutely nothing about law,’ says Jonathan.
brilliant, innovative or better compared to anything else.
‘So the first four years are all about learning law.’
But that’s just the beginning, because although Jonathan
writes the patent, it’s up to the Patent Office to decide if it
gets approved or not. And that’s when the arguments start.
‘[This job] is for people who like to have good arguments,’
says Jonathan. ‘It’s about trying to get your client a patent.
So you have to argue with the Patent Office about the
merits of the work. You have to explain why it’s different,
And even now, as a fully qualified patent attorney and a
partner at Mewburn Ellis LLP, the intellectual stimulation
Jonathan get from learning new things is still one of the
best parts of his job. ‘Next year I’m going out to Japan to
meet my clients there, so I’m just about to start Japanese
lessons in the next few weeks.’
Jennifer Wills
Jonathan is a patent attorney in
Cambridge. Philip Robinson finds
out how he helps chemists to protect
their work
2008–present
Chartered and European
patent attorney, Mewburn
Ellis LLP
2004–2008
Trainee patent attorney,
Mewburn Ellis LLP
2000–2004
PhD in chemistry at the
University of Cambridge
1995–2000
MChem at the University of
Edinburgh
1993–1995
Scottish Highers in
chemistry, biology, physics,
mathematics, German and
English
Find out more
out patents,
Learn more ab
d copyright
trade marks an
y
with this hand
guide to
intellectual
proper ty
aGip
http://bit.ly/W
In depth...
tailed look at
Take a more de
granted for a
is
how a patent
vation with this
chemical inno
than
ar ticle by Jona
iC0112pat
/E
ly
t.
bi
://
http
Mole
You can download The Mole at www.rsc.org/The
and copy it for use within schools
www.rsc.org/TheMole
September 2012 | The Mole | 11
£50 of vouchers to be won
Chemical acrostic
Complete the grid (contributed by Simon Cotton) by answering the
the 9 clues to find the answer in the shaded box, which will spell out
the key rare earth element in the tiny yet very strong magnets that
have many high-tech applications.
Puzzles
Wordsearch
1
2
Find the 31 words/expressions associated with catalytic converters
hidden in this grid (contributed by Bert Neary). Words read in any
direction, but are always in a straight line. Some letters may be used
more than once. When you have found all the words, use the remaining
letters to make a 13-letter word.
3
4
5
T
N
S
P
C
L
E
A
N
A
I
R
A
C
T
M
G
S
I
T
A
A
G
E
S
T
N
A
T
U
L
L
O
P
Y
T
S
R
I
N
M
L
S
G
R
O
S
I
M
N
L
L
R
R
T
R
I
I
E
I
A
O
C
E
S
C
O
A
A
O
O
I
Q
C
S
U
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S
A
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T
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S
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F
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D
A
C
A
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I
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A
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N
U
A
D
I
O
H
L
C
T
I
R
A
T
N
C
N
E
L
L
E
O
I
C
I
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E
H
B
M
H
U
M O
S
A
I
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N
B
M
N
H
D
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O
I
S
M
U
X
N
T
T
D
I
E
S
E
L
I
V
N
C
T
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2. The metal in Epsom salts.
I
I
E
E
Y
O
H
C
A
T
A
L
Y
S
T
R
A
3. One of the three transition metals in catalytic converters.
D
D
G
M M
C
P
E
T
R
O
L
E
U
F
U
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4. Unstable group 2 element.
A
E
Y
A
O
S
A
G
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X
Y
G
E
N
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C
A
5. The only metal that is a liquid at room temperature.
L
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A
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E
X
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A
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S
T
G
A
S
Y
E
T
AIR
AIR QUALITY
BIOFUELS
CARBON
CATALYST
CERAMIC
CERIUM OXIDE
CHEMIST
CLEAN AIR ACT
COATED
DIESEL
EMISSION
EXHAUST CYCLE
EXHAUST GAS
FUEL
GAS
GASOLINE
HYDROCARBON
MONOLITH STRUCTURE
NITROGEN OXIDES
OXYGEN
OXYGEN SENSORS
PALLADIUM CATALYST
PARTICULATE MATTER
PETROL
PHOTOCHEMICAL SMOG
PLATINUM CATALYST
POLLUTANTS
REDUCING
ROAD
VEHICLES
July wordsearch solution and winner
The winner was Imogen Rea from Buckinghamshire. The 9-letter word was MOLECULES.
Submit your answers online at
http://bit.ly/512ans
by Monday 8 October.
A correct answer for each puzzle, chosen at
random, will win a £25 Amazon voucher
6
7
8
9
1. Used to galvanise iron and make brass.
6. The most abundant metal ion in the oceans.
7. Which element is found in PVC but not in polythene.
8. Non-metallic element associated with vulcanology, but nothing to
do with Mr Spock.
9. Key element in the ITO material for touch-sensitive screens in
smartphones.
RSC ChemNet
RSC ChemNet ReAct question of the month
Why will table salt in water conduct electricity while
sugar in water will not?
To access resources and find the answer to the RSC
ChemNet ReAct question of the month, login with your
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