chemessenger designed ver2

Issue #3, April 2015

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CheMessengerApril

#3 Issue

10 Molecules That Changed the World

7 Science Books for Everyone

Chemistry of Fireworks

Proteins for Strength

CHEMESSENGER2

L from Editor

Greetings and a warm welcome to the third issue of CheMessenger Magazine!

On behalf of the Chemistry Department at School of Science and Technology and NUCLEUS (Nazarbayev University Chemistry League Established for Undergraduate Students), I want to welcome all of you to the third issue of CheMessenger.

Dear reader, even if your area of work or studies is not anyhow related to Chemistry, you will enjoy reading articles such as “10 Molecules That Changed the World”, “Chemistry of Fireworks”, “7 Science Books for Everyone” or “Proteins for Strength”.

What you will also find in this issue of Chemessenger is the review of Natural Chemical Biology article about nematodes building towers to survive. To get students acquainted with ScifinderTM, a powerful search engine in chemical research, a brief introductory manual is included as well.

Finally, you will discover what activities our current senior students had during the summer semester at the University of Wisconsin-Madison, and how was it for Aliya, a 4th year student, to participate at the 249th International American Chemical Society (ACS) Conference in Denver, Colorado.

In the end of the issue, you will find Chemistry-related puzzles; send your solutions to [email protected] as soon as possible to win valuable prizes!

All the best,Murat Sultanov, Editor-in-Chief


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RESEARCH NEWS

A group of researchers at University of York have shown that thale cress (Arabidopsis thaliana) seedlings can reduce Pd(II) salts and produce nanoparticles. Plant seedling have been placed into K

2PdCl

4 solution

for 24 hours; Pd-containing nanoparticles up to 32-nm in size have been detected in the leaves. After washings, drying and grinding and the pyrolysis at 300°C in N

2,

nanoparticles were isolated.

Authors demonstrate not only the first production of Pd nanoparticles (PdNPs) by living plants, but the use of obtained

nanoparticles as an effective catalyst for Suzuki-Miyaura coupling reaction. For example, coupling reactions of 4-cyanophenyl bromide or chloride with phenylboronic acid showed excellent yields where conventionally used Pd(OAc)

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or Pd/C catalysts show low and moderate yields.

The presented method of plant-mediated metallic nanoparticles synthesis may represent a greener alternative to

Source: Andy Extance, ‘Plants bear palladium catalyst fruit’, 5 Feb 2014, Chemistryworld, RSC

http://www.rsc.org/chemistryworld/2014/02/plants-bear-palladium-catalyst-fruit-suzuki

(a) Thale cress plants form Pd nanoparticles after being exposed to K2PdCl4 solution (b) Accumulation of Pd nanoparticles in cell wall corners

‘Chemical plants’ produce palladium nanoparticles

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CHEMESSENGER

Zeolite-polymer composite adsorbs uremic toxins

Kidney failure is usually accompanied by high concentrations of waste products such as creatinine. Dialysis, which is widely used to clean blood, is very dependent on the quality of water, dialysate and special equipment, and is time-consuming.Mitsuhiro Ebara and his team from Japan developed a biocompatible polymer with embedded zeolite in it. Zeolite, a microporous aluminosilicate mineral with good adsorbent qualities, was trapped in a polymer by the electrospinning technique. Obtained mesh material was tested on creatinine adsorbtion ability, and it constituted 67% of the absorption capacity of free zeolites.

Controlling the crystallinity of the polymer-zeolite fibers to maintain them as insoluble and hydrophilic substance was the greatest challenge, says Ebara. His team calculated that 16 grams of this material is needed to remove all creatinine produced by human body in one day. Scientists now are designing a wrist-watch device which can be a more accessible and cheap alternative to dialysis.

The zeolite-poly(ethylene-co-vinyl alcohol) (EVOH) polymer mesh is hoped to be a potential blood-cleaning agent

Source: Rowan Frame, ‘Zeolite-polymer composite adsorbs uremic toxins, 19 Feb 2014, Chemistryworld, RSC

http://www.rsc.org/chemistryworld/2014/02/zeolite-polymer-composite-adsorbs-toxins-kidney-failure

RESEARCH NEWS


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INTERVIEWDr. Haiyan Fan-Hagenstein

How did you decide to study chemistry and obtain degree in it?

I liked chemistry even when I was in junior high school. It amazed me how chemistry is closely related to our daily life. I grew up in a desert area. I always thought about how to turn sand into quartz, simply because they have the same chemical formula.

What strategies did you use to be successful in college?

I paid attention at class and achieved 90% of learning at class. I finished my homework right away. I always read my notes in the evenings of the days when the lectures took place. I tried to understand the material on time and found some challenging questions and readings to practice on.

What was graduate school like?

The graduate school is like a refining furnace, where your knowledge, skills, your attitude towards academy and life are tested and refined. You have to be responsible, honest, and humble in order to really improve yourself and obtain valuable research and teaching experience and achievement. The graduate school is also fun where you can meet all kinds of personalities and discover your potentials and limits.

What is the best thing about being a chemist?

To be a Chemist, you look at things, life, and even the whole universe with a unique perspective. You seem understand things deeper and more extensive.

What do you like best about teaching at NU?

I enjoy the freedom of teaching here. I can

always deliver my teaching in the strategies that I believe to be the best for the students. I like the way that students respect their instructors.

What is the best way to study for your class?

1. Attend every class.2. Review after each class.3. Finish your homework independently.4. Go deep by reading some extra material and practice on some more challenging problems.5. Apply what you lean at class to explain your observations in different areas and to solve problem that you have never met before.

What do you value in people?

I highly value people who are responsible, honest, and humble. I value a student not by the grades he/she gets; I like students who are curious in chemistry, study to understand some fundamental theories and to apply them to their daily life practice. I value honesty more than high grades. I value inspiring thinking than simply memorizing some facts. I value a forgiving and loving spirit. I value the motivations that lead to the sincere service to others and to create/contribute knowledge, wealth, and wisdom to the society.

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10 molecules that changed the worldAspirin – C

9H

8O

4

With more than 100 billion tablets consumed every year, aspirin is the most popular drug in the world. In 1897, German chemist Felix Hoffman synthesized pure aspirin making it one of the first synthesized drugs. Aspirin is used not only against the cold, but from headache, pain, fever and heart attacks.

Polyethylene – (-C2H

4-)

n

Polyethylene is so widely used that it’s hard to imagine life without it – grocery bags, plastic bottles, cable insulators, even parts of chewing gum – all made of it. Depending on the conditions, polyethylene can be high- and low-density. For instance, high-density polyethylene (HDPE) is used for making various containers; one third of all toys are made from it.

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Sodium Chloride – NaClFrom ancient time, salt was used as a food additive to keep it fresh longer. Nowadays, in addition to domestic use, NaCl is widely consumed for the production of many chemicals. For example, chlorine (Cl

2) and NaOH are synthesized during

the electrolysis of water solution of NaCl. Sodium metal (Na) is obtained from the electrolysis of pure melted NaCl:2NaCl + 2 H2O ¬ Cl

2 + H

2 + 2NaOH

2NaCl ¬ 2Na + Cl2

2


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Ammonia – NH3

Famous Haber process allowed producing ammonia from H

2 and N

2 with platinum

catalyst; this led to the production of enough crop fertilizers so that estimated two billion people are not starving today.

Ethanol – C2H

5OH

About 2 billion people enjoy consuming alcohol worldwide, which makes people feel confident and see life in brighter colors. However, alcohol consumption by pregnant women may cause serious problems to a child. Apart from beverages, ethanol is also used as a solvent, antiseptic and fuel.

Penicillin – R-C9H

11N

2O

4S

British microbiologist Alexander Fleming in 1928 noticed that Petri dished that contained mould grew no bacteria, and discovered world’s first antibiotic. Wide use from 1940s allegedly saved 200 million lives from malicious diseases like syphilis or streptococcus caused infections.

Carbon Dioxide – CO2

Being discovered in 1750s, this gas is a culprit for global warming threat. For example, in 2012 alone, 31.6 billion tons of CO

2 were released to atmosphere.

Global warming may cause serious problems such as polar ice melting, rises in sea levels and mass extinctions.

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CHEMESSENGER

Iron – FeWe can count iron as the most used metal because accounts from 95% of worldwide metal production. Iron is a key component of automobiles, ships, trains, buildings and computers. Iron is known from ancient time, but its mass production began in 1856 when Henry Bessemer had invented the technology of steel production. Iron is also a microelement in human body since hemoglobin, which carries oxygen to cells, is a complex of porphyrin with Fe2+. In average, humans have 5-6 grams of iron in their organisms, which is enough to make a medium-sized nail.

Sodium Stearate – C17

H35

COONaSoap plays crucial role in our lives – it is capable of washing the dirt off our skin. The active ingredient – sodium stearate – is produced by the reaction of fat (fatty acid and glycerin ester) with NaOH. Because stearate has a hydrophobic ‘tail’ and charged hydrophilic ‘head’, it helps oily substances dissolve in water by wrapping up oily droplets with hydrophobic tails forming water-soluble micelle (see picture below).

The reaction scheme for sodium stearate formation

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Silicon – Si60 years ago, in 1954, first silicon transistor was constructed. In addition to being a key component of computer chips and circuits, it found the application in solar cells, waterproof seals and breast implants.

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PAPER REVIEW: NATURAL CHEMICAL BIOLOGY

Nematodes build waving towers for collective host finding

Scheme 1. Microscopic worms are able to secrete a very long chained wax ester and use it as means to aggregate themselves into a ‘tower’ to facilitate the search for a new beetle host

Scheme 2. (a) ~200 larvae dauer tower. (b) Small dauer tower (several dozens of larvae) uses a fruiting body of fungus (arrow) as a base for the tower. On the tip, a small waving individual can be seen (arrowhead). (c) a lower-magnification micrograph of a dauer tower (arrowhead) on a T. molitor beetle

Penkov S. and colleagues from Germany reported that certain nematodes are able to secrete an adhesive wax in order to build ‘towers’ by climbing on top of each other.

Pristionchus pacificus is the species of nematodes which parasite on beetles; they wait until the host insect dies to feed on its rotting flesh. There are several larval stages for the nematodes before they become mature. However, under adverse conditions such as food scarcity or heat, they can stop their growth and development and enter a

low-metabolism resting form called a dauer. These dauers, which can survive without food for months, actively seek a new host through a process called nictation – standing on the surface and waving.

Penkov et al discovered that these 5 μm long microscopic dauers can build massive ‘towers’ of up to 1000 individuals by attaching to one another. Resulting tower, which can extend up to 1 cm, can wave, or nictate, supposedly to increase the chance of being caught by another host.

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CHEMESSENGER

Authors proposed that hydrophobic interaction forces keep nematodes together so tight that even a mechanical interference cannot disrupt them. Upon treating the dauer tower with detergent

solution such as Triton X-100, it quickly dissociated into individual species. Moreover, placing the tower into hexane showed immediate dissociation (Scheme 3):

Scheme 3. (a) Tower placed in water does not dissociate. (b) Detergent solution disrupted the structure within minutes

Scheme 4. TLC of lipid extracts from different types of larvae. On the right – column-purified nematoil. SE, sterol esters; TAG, triacylglycerols; PL, polar lipids.

Lipids involved in dauer tower formation were isolated using extraction from water-hexane mixture. After phase separation, dauer larvae remained in aqueous phase, whereas the surface lipids were dissolved in the organic phase. Separately, dauer larvae were homogenized and total lipid mixture was obtained. Then obtained total and surface lipid mixtures were analyzed by TLC with highly hydrophobic running system.

As seen from Scheme 4, surface lipid lane contains a band (*** asterisks) that is absent in the 3rd lane belonging to total lipids from reproductive stage larvae. Mutant wsd-1 dauers contained less amount of this lipid. Combined, the evidence suggests that this compound is a positive regulator for the formation of dauer towers.

To identify the dauer-specific lipid, it was isolated from total dauer lipid extract through silica column and a pure lipid fraction was obtained on a milligram scale. Obtained ‘nematoil’ was analyzed by MS and a formula of C60H100O2N was proposed. High degree of unsaturation was confirmed by the strong retention in TLC on silver

salt-impregnated silica. Then, 1H and DOSY and a full set of 13C NMR analysis were performed. After all these manipulations, a structural formula was proposed; however, the positions of two isolated C=C double bonds were still ambiguous. To completely elucidate the structure, total synthesis was performed (Scheme 5):


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Proposed synthesis has an overall yield 32% with seven steps. Nematoil is a pseudosymmetric long-chain wax ester formed by condensation of nematyl alcohol with nematoic acid. All double bonds have cis stereochemistry and are symmetrically

positioned with respect to the ester bond. As seen from Scheme 6, carbon NMR shows exceptional similarity of spectra from natural and synthetic nematoil compound.

Scheme 5. Synthesis of nematoil (1). Reagents and conditions are listed in the Appendix

Scheme 6. Comparison of the 13C NMR spectra (150 MHz, CDCl3) in the olefinic region of natural (1) and synthetic nematoil (1)

To sum up, authors have shown that nematodes produce nematoil, a long-chained unsaturated wax ester with two 30-carbon chains with 12 double bonds, making it one of the longest known waxes in animals or plants. The finding of this article is that nematodes use the wax for aggregating into a tower to seek for a new host. The biosynthesis of this molecule is energetically costy – it requires at least 28 ATP and 68 NAD(P)H molecules per one nematoil molecule.

Large degree of unsaturation allegedly bestows

nematoil molecule a liquid state; for comparison, all very long saturated wax esters stay solid at ambient temperature. Another remarkable property of nematoil is that a larva coated with the wax doesn’t lose its locomotive abilities. A mechanism of tower building is still not clear; this process requires high coordination and synchronous behavior from each larva. How do they communicate – via pheromones or exogenous source such as a fruiting body? Another question for further investigations is whether nematoil serves as a hydrophobic coating material for a larva to prevent water loss and desiccation. The studies of dauer formation are proven to be useful for investigation of processes such as aging, energy homeostasis and the stress response.

APPENDIXScheme 5. Synthesis of nematoil (1).a: 1.26 equiv. DIBAL-H, CH2Cl2, 0 °C, 2 h, 89%; b: 3 equiv. TsCl, pyridine, 0 °C, 18 h, 84%; c: 1.4 equiv. KCN, DMSO, 70 °C, 1.5 h, 100%; d: 1.3 equiv. DIBAL-H, CH2Cl2, -20 °C, 1.5 h, 69%; e: 20 equiv. KOOC(CH2)6PPh3Br, 3 equiv. KOt-Bu, DMSO, THF, -10 °C, followed by addition of 1 equiv. 2 in THF, 2.3 h, 85%; f: 1.1 equiv. Et3N, 1.1 equiv. i-BuOOCCl, THF, -15 °C, 40 min, then 25 °C, 15 min, followed by -15 °C, 2 equiv. DIBAL-H, 1 h, 86%; g: 1.95 equiv. 3, CH2Cl2, 3.0 equiv. EDC•HCl, 2.2 equiv. DMAP, 25 °C, 3 h, 84%.

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CHEMESSENGER

Proteins for StrengthIf you go to gym, you’ve probably heard about protein powder. You can buy it in any nutrition store and all over the web. Protein powders are getting popular because they are an easy and convenient source of high-quality protein. They can come in different forms such as whey, soy and casein which will be the issue of this article.

Casein contains high concentration of proline residues which do not interact with each other. It has relatively little tertiary structure because there are no disulfide bridges. It is relatively hydrophobic which makes it poorly soluble in water. It is also insoluble in neutral salt solutions, readily dispersible in dilute alkali and in salt solutions. Casein protein can be found in milk as casein micelles. The caseins in the micelles are held together by calcium ions and hydrophobic interactions:

Figure 1. Casein micelle and submicelle structures

Whey protein is a mixture of globular proteins isolated as by-products of cheese production. This protein is typically a mixture of beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin and immunoglobulins. It exists in four major forms: concentrate (WPC), isolate (WPI), hydrolysate (WPH) and Native Whey.

1) Concentrates have low levels of fat and cholesterol but have highest levels of bioactive compounds among all four forms of whey. Whey concentrate have relatively high levels carbohydrates in the form of lactose as well— they are 29%–89% protein by weight. It has slightly milky taste.

2) Isolates are produced in order to remove the fat, and lactose, but have low levels of bioactive compounds. Like whey protein concentrates, whey protein isolates are mild to slightly milky in taste.

3) Hydrolysates are whey proteins that are predigested and partially hydrolyzed in order to be metabolized easier. Highly hydrolyzed whey may be less allergenic than other forms of whey. Assuming these advantages of hydrolysates, their cost is usually higher than others.

4) Native whey protein, the purest form of whey protein which has been extracted from skim milk and not a byproduct of cheese production, produced as a concentrate and isolate.

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Soy protein has high concentration of protein bodies, which comprises at least 60–70% of the total soybean protein. Soybeans contain a small but newly very significant 2S Albumin storage protein. Soybeans also contain biologically active or metabolic proteins, such as enzymes, trypsin inhibitors, hemaglutinins and cysteine proteases. Soy protein contains phytoestrogens which bind to estrogen receptors in the body.

Is it necessary to consume protein powder?

It is not an absolute requirement for gaining mass, but if the level of protein intake is not achieved a protein powder is suggested which will make life a lot easier. Getting all the protein from whole food can be inconvenient, especially if person has to eat 6 or more times a day to achieve the required level of protein intake. What can of protein should I use?

It really depends on the time of protein consumption. For example, whey protein is acknowledged for its fast digestion and high cystein content so the best time to consume it is before the workout, during the workout and immediately after the workout so that muscle tissue will not encounter catabolic state during the workout. Casein in turn, is slowly digested into the bloodstream so casein is used for all other times outside the workout (e.g.before going to sleep). Finally, soy protein is the most controversial of all protein types. Some studies have suggested that phytoestrogens in the content of soy protein lead to decreases in testosterone which in turn decreases the growth of muscle tissue. In addition, phytoestrogen found in soy is thought to change hormone balance, affects energy level and digestive system. Therefore, the consumption of soy protein is usually avoided by bodybuilders.

Reference List Kunz, C., Lonnerdal, B. (1990). Human-milk proteins: analysis of casein and casein subunits.

American Journal of Clinical Nutrition 51(1), 37-46. Retrieved from http://ajcn.nutrition.org/content/51/1/37.full.pdf+html

Exploring the DromeDairy: Camels and their milk. Retrieved from http://www.blogs.scientificamerican.com

Marshall, K. Therapeutic applications of whey protein. Alternative Medicine Review 9(2), 136-156. Retrieved from http://www.altmedrev.com/publications/9/2/136.pdf

2S Albumin Storage Proteins: What makes them Food Allergens? The Open Biochemistry Journal 2, 16-28. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2570561/

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CHEMESSENGER

I am thankful to Nazarbayev University that I had a chance to have a summer semester at the University of Wisconsin-Madison! Studying and living there was a great pleasure!

I took a Geoscience class with labs, which was a required course for students from NU and a Philosophy class as an elective course. Geoscience was focused on a group research project: during the semester we conducted analysis, and finally, we presented our observations and results in the form of a presentation.

The Philosophy course… Oh, I was not mistaken to take it! Though the course was extremely intensive (daily quizzes, homework essays, and reading assignments), our professor, Dr. Daniel Hausman, made it so interesting that we did not notice how the time flew! The discussion part of the Philosophy class was the most exciting for me! The class was divided into groups of four, and together with American students we discussed various moral, political and social

issues. During these discussions we shared our thoughts and feelings. Sometimes our opinions were similar, but sometimes we had completely different points of view! Therefore, every student had to persuade others to prove his/her way of thinking is closest to truth.

My Wisconsin roommate, Sa Bon, has become my best friend! She is from South Korea but studies at the University of Minnesota at the school of Business. We did everything together: going to the sports center, to the grocery, cafes, and museums. We liked to spend time just talking, talking, and talking ... about our lives. I know for sure that we will meet again in the future. We only need to find the place on this great planet, maybe, Kazakhstan, Korea or US? Oh, yes, and we also need to choose the time of meeting, of course! It was a great pleasure to be a part of the UW-Madison baseball team fans, to have a picnic with the UW-Madison students, to go kayaking! It was a really unforgettable experience!

STUDENT INTERVIEW:

Experience from UW Madison

Natalya Tsoy, 4th year Chemistry student

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7 Science Books for EveryoneScience is not only a discipline of reason, but also, one of romance and passion.

– Stephen Hawking

To understand some concepts of science, sometimes it is better to read one book written by a scientist than to explore thousands of school textbooks. Below you can

find a list of popular-science books that give a better understanding of discipline and at the same time are engaging and interesting to read.

Stephen Hawking “A Brief History of Time”

This book, written by great physicist S. Hawking, explains how the universe appeared and developed: from the Big Bang to Black Holes. Author gives answers to the eternal questions of our existence: How and why did the universe begin? Will it come to an end, and how?

Author discusses a lot of physics theories such as the uncertainty principle, physics of elementary particles and Black holes and possibility of time travel. However, the book is written in a way that even those who know nothing about physics and cosmology can understand its content. The only equation used is famous Einstein’s E=mc2 that explains the equivalence of mass and energy.

The book was first published in 1988, since that time it was translated to 35 languages, and more than 10 million copies were sold worldwide.

Primo Levi “The Periodic Table”

Primo Levi is an Italian chemist and writer who spent one year in a German concentration camp during World War II. In 2005 the Royal Institution of Great Britain called “The Periodic Table” the best science book ever written. However, the book resembles personal memoirs and contains elements of fiction that might be controversial for a science book.

The book contains 21 chapters each named after a chemical element. In the chapters author describes important properties of a particular element, making parallels with real life: he compares reactions in a test tube with the changes in the world. This is why fiction element is important. It shows what chemistry is and why we should understand it. If you want to see chemical discipline from a completely new perspective of reality, you are strongly advised to read this book.

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CHEMESSENGER

Richard Dawkins “The Selfish Gene”

R. Dawkins is an English biologist, writer and a professor at the University of Oxford. In his book he explains Darwin’s theory of gene-centered evolution of species.

What is significant about this work is that it was written at the time (1976) when biologists were making first attempts to understand the nature of gene and to decode the DNA sequence. It means that no complex biological terminology existed at that time.

So, Dawkins used a simple language to describe the concepts of evolution that interested him. Author explains the logic of evolution and natural selection from the perspective of a “heartless” biologist. He claims that genes are running the world; their replications and mutations decide how the world is organized. He calls these phenomena as “meme” and gives various analogies from human relationships to support his idea.

The book is a brilliant source to understand the nature of evolution on our planet.

Sam Kean “The Disappearing Spoon”

This book was written in 2010 by an American author from the New York Times magazine. Sam Kean collected all knowledge about the elements in Periodic Table, the compounds they form, the reactions between them and some significant properties of each.

However, the book is not only about the elements. It describes the chemistry of some usual compound around us. Author explains how color appears, how poisons work and why radiation exists. The whole course of chemistry, in general terms, is explained in one book.

Isaac Asimov “The Intelligent Man’s Guide to Science”

Famous American professor of biochemistry Isaac Asimov managed to give an overview on the history of science starting from assumptions of Greek philosophers to modern artificial intelligence inventions. Although the book contains too much information regarding different disciplines, it combines them in such a way that they supplement each other.

Author begins with cosmology and explains the physics of the universe. Then he moves to the biological diversity of our planet followed by the discussion of how important is the chemical composition of matter. Eventually, he moves to modern-day robotics and concludes with the statement that someday, the advanced “thinking” machines can replace human species.

The book is a great tool to understand how science creates the world around us.

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Steven Pinker “The Language Instinct: How the Mind Creates Language”

Famous psychologist S. Pinker describes human language as an instinct that evolved due to natural selection. From this point of view author discusses the development of language with time, the way children learn it and how the human brain interprets it. Using examples from real life combined with wide knowledge of species evolution, author proves that language is just a result of human adaptation and evolution just as the development of movement on two limbs.

Bill Bryson “A Short History of Nearly Everything”This is another book that attempts to explain how the universe got from Big Bang to what it is now. Entertaining thing about this work is that instead of explaining the origin of life from physical, chemical and biological perspectives, Bill Bryson uses other evidence from geology, mechanics and mathematics.

He researched the works of early archaeologists, anthropologists and mathematicians; he interviewed historians and geologists to understand the mechanisms of universe development. From this book you can see the known concepts from completely different perspective. It makes this book unique and interesting for broad audience.

References:http://www.goodreads.com/list/show/692.Best_Science_Books_Non_Fiction_Only “Best science books” by Goodreads http://www.theguardian.com/science/series/science-book-club Tim Radford reviews of classic popular science books

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CHEMESSENGER

Chemistry of FireworksBig events and holidays are always connected with joy, fun, and happiness, but they seem to be incomplete without… fireworks! They create a spectacular and fascinating show making us standing stared at the sky. But did you think about reasons for this beauty? So here we will know about a working mechanism of fireworks and the causes for their colorfulness. What are the components of the firework? There are two main parts of a usual aerial firework: shell and mortar. Shell, in turn, consists of the following components: container (shell casing), fuse, bursting charge, and stars.

Interesting factYou can calculate the distance in kilometers from you to the source of the firework calculating the seconds as soon as you see the firework and stop doing it when you hear the sound of the explosion. Then you should divide this number by 3 and you get your distance.

Note: Black powder – gun powderSource: http://www.pyrouniverse.com/consumer/howtheywork.htm

The launch of the shell happens from the mortar where the lifting charge of the black powder is located. The ignited fuse causes the lifting charge to fire. As a result of this explosion, the shell starts to rise and the time fuse is ignited from the lift charge. By the time the shell reaches its appropriate altitude the burst charge is ignited from the time fuse and explodes the shell. As you might guess, stars are hearts of the firework and responsible for the well-known color show. They are thrown in all directions and burn due to the shell’s explosion.

Color matters!Stars contain metal salts that are responsible for color of the firework. Along with the metal salts, stars are composed of oxidizing, reducing agents and binders. Oxidizing agents or oxidizers produce oxygen needed for reducing agents to produce gases and to excite metal salts to high energy states. Common oxidizers are nitrates, chlorates and perchlorates. They give up oxygen according to the following reactions:

2KNO3 ¬ K

2O + N

2 + 2.5O

2

Potassium nitrate2KClO

3 ¬ 2KCl + 3O

2

Potassium chlorateKClO

4 ¬ KCl + 2O

2

Potassium perchlorate

And oxygen reacts with the reducing agents, such as sulfur and carbon, via these reactions:C + O

2 ¬ CO

2 and S + O

2 ¬ SO

2

You may wonder why we need these reactions. The answer is that produced gases, carbon dioxide and sulfur dioxide, are hot and rapidly expanding. This fact enhances the ability of metal electrons to jump to the excited states.

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Now we are very close to reveal a secret of a color production in fireworks. It depends on two mechanisms: incandescence and luminescence. Incandescence is light resulted from heat. Heated compounds start to glow and emit initially infrared radiation, and then colors from the visible range, such as red, orange, and yellow. Luminescence, on the other hand, does not depend on heat. Electron of an atom or molecule absorbs energy; hence, it goes from the ground (non-excited) state to excited one. The electron cannot stay forever in this state, so it returns to the ground state and emits a particular amount of energy called photon. The photon’s energy determines the color produced.

Each element has its own amount of energy released which corresponds to a particular wavelength. For example, lithium salts emit light at 652 nm which is the wavelength of a red color. There is an inverse relation between energy and wavelength. Low energies correspond to long wavelengths in the orange/red end of the spectrum while high energies to short wavelengths in the blue/violet region. In the following table you can see the list of colors and their respective wavelengths that are produced after an explosion of particular substances.

Color

red

orange

yellow

green

blue

purple

Compound

strontium salts, lithium saltslithium carbonate, Li2CO

3 = red

strontium carbonate, SrCO3 = bright red

calcium saltscalcium chloride, CaCl

2

sodium saltssodium chloride, NaCl

barium compounds + chlorine producerbarium chloride, BaCl

2

copper compounds + chlorine producercopper(I) chloride, CuCl

mixture of strontium (red) and copper (blue) compounds

Wavelength (nm)

652

628

610-621

589

505-535

420-460

CAUTION FIREWORKS!

We so used to fireworks that we forgot about the danger they can cause. So let me remind you some simple and basic rules in handling fireworks. 1. Do not use fireworks with defects (e.g. wet ones)2. Do not break fireworks, burn in the fire, carry them in a pocket3. Do not keep fireworks close to heating devices4. Do not ignite fireworks under the trees, electricity cables, and/or close to flammable subjects5. Do not ignite unworked fireworks again6. Do not lean over the firework when igniting the fuse 7. Do not use fireworks in intoxicated condition and/or smoke near fireworks

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CHEMESSENGER

Across

4. Synthesized in 1982, compound C20

H20

has bond angles of 108o, which are close to that of methane (109.5o). Has a single signal in 1H NMR spectrum (singlet, 3.38 ppm)

7. Solid crystalline compound C8H8, kinetically stable, chemically reactive. Has the highest density of all hydrocarbons (1.29 g/cm3). If all hydrogens are replaced to –NO

2 groups, this derivative (C

8(NO

2)8) is a

high explosive.

10. Aromatic molecule entirely comprised of nitrogen atoms. 4-dimethylaminophenyl- derivative was synthesized in 1956 and forms complexes with metals.

11. Naturally occurring group of organic compounds. For example, heme, the pigment of blood cells, is its derivative. Mg2+ complex of this compound is known as chlorophyll.

Down1. Similar to the structure of graphite, this compound has good potential in fields of electronics and nano-technology due to its unique properties

2. C10

H16

, crystalline and colorless compound, found in trace amounts in oil

3. Platonic hydrocarbon with formula C4H

4, has

extreme angular strain

5. Also known as superbenzene, its solutions in organic solvents emit blue light fluorescence under UV light

6. Group of substances found in crude oil with huge molecular mass; used as paving materials on roads

8. Polycyclic alkane C10

H12

, syn-thesized in 1966

9. Bicyclic compound C8H

8, has a set of 6 p-orbitals

like benzene

Crossword Puzzle ‘Cyclic Compounds’


21

Organic Chemistry Puzzle

Here’s the transformation scheme for A – J (neutralization stages are omitted):

Determine the structures of compounds A – J.Send your solutions to [email protected]. Winners get valuable prizes!

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Editor-in-chief: Murat Sultanov

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