Without aromatic compounds the world would be a less colourful place, many important dyes contain aromatic groups. Also many flourescent substances such as laser dyes and markers used for forensic purposes contain aromatic groups. Before we get going we need to consider the granddaddy of all aromatic things: Benzene. This is a colourless substance which I first came face to face with as a first year undergraduate when I did some chemistry which is severely banned in Swedish undergraduate chemistry.

I placed a large amount of magnesium turnings in a flask with some anhydrous benzene, I then added a solution of mercury chloride in acetone and watched the exotherm bring the mixture to reflux. After the exotherm died down, I added some more acetone and then boiled the mixture before allowing it to cool. After quenching with water and doing some more things I was rewarded with a large beaker packed with pinacol hydrate. This was my first experience of organic synthesis where I had to face down an exothermic reaction which had the potential to go into a thermal runaway, and the experience reinforced my resolve to become a synthetic chemist. I felt that it was possible to master atoms and molecules and make them do my bidding. Well sometimes I can get the atoms / molecules to do as I want them to.

But unless you can see into the ultraviolet, benzene is colourless according to extended Huckel calculations the pi orbitals of benzene are widely spaced. We have a energy gap of about 15 eV between the HOMO and the LUMO.

When we move to naphthalene then the ten pi orbitals. Now the energy gap is predicted to be 2.4 eV. This is clearly a smaller energy gap. I have used the software to calculate the pi orbital energies for anthracene and tetracene. These are hydrocarbons with more benzene rings.

I think that while the software has got some things wrong, it has got one important thing right, that is the fact that the energy difference between the pi orbitals in the larger hydrocarbons are smaller than in benzene. Below is a graph of the pi orbital energies as predicted by the extended Huckel software.

Pi orbital energies of aromatic hydrocarbons

Now if we calculate the average energy gap between the pi orbitals we get the following values for the hydrocarbons.

Benzene, 6.55 eV

Napthelene, 4.24 eV

Anthracene, 3.09 eV

Tetracene, 2.42 eV

What this means is that as the hydrocarbons become larger, because their pi systems are getting larger their absorption and emission of light will be shifted to longer and longer wavelengths. What happens when a photon of light is absorbed by one of these hydrocarbons is that an electron will be moved from the HOMO or some other filled orbital into an unfilled orbital. In the diagram below you can see a molecule being excited from the ground (S0, singlet 0) state into the first excited state (S1).

Light being absorbed thus making a vibrationally excited form of the first electronic excited state (S1)

Because of something called the Frank Condon effect the excited state will have vibrational energy. This is because the electrons move very quickly compared to the atoms. When the electrons are moved from one orbital to another the bonding changes instantly, as a result the atoms start to vibrate. This vibrational energy is typically lost before the electrons move orbital again. The reason I named the two states S0 and S1 is that they are singlet states where overall all the electrons are paired. They have no overall electron spin.

Next the vibrational energy is lost as the molecule goes down the vibrational states, this energy is lost as heat. Below we have the loss of vibrational energy.

Loss of vibrational energy

Then the excited molecule has a series of choices, it can then undergo an internal conversion where it changes from the vibrational ground state of the electronically excited state into a vibrationally excited state of the electronic ground state. This means in simple english that it changes all the energy associated with having the electron in the higher orbital into vibrational energy which makes it shake. Below I have drawn an enegy level diagram for this.

Internal conversion, all the energy from the electronic excitation is turned into heat

One of the alternatives to this is for the molecule to emit a photon of light and drop into the S0 state, because of the Frank Condon effect it has to drop into a vibrationally excited state of the electronic ground state (S0). Below we have a diagram which shows the change from the ground state of the S1 state to a vibrationally excited form of So. This process allows the emission of light with a longer wavelength than the original light.

Emission of light by moving from S1 to S0

As a result the florescence from a molecule will always have a longer wavelength than the light which excited the molecule in the first place. Now some of the smarter readers will know that a sodium doped bunsen flame is able to emit and absorb light of exactly the same wavelength, this is quite reasonable. The isolated gas phase atoms of sodium are single atoms, as a result they are exempt from the Frank Condon effects. A second way in which molecules can shift the light to longer wavelengths is to absorb photons which put the molecule into an excited state such as S2. The S2 state then decays into S1 which then can emit light. Below is a diagram which shows a system with two excited singlet states which can emit light from both the S2 to S1 and the S1 to S0 transitions.

A system with three singlet states

The take home message from today is that the bigger a pi system the closer the orbitials will be in energy, thus the difference between the energies of different states (S0, S1, S2 etc etc) will be smaller and as a result the longer the wavelengths of light which are absorbed and emitted by the pi system.

Florescence and pi system appear in funny places, those readers who are the same age as me might recall that in the 1980s a great storm of attention erupted when in 1983 someone claimed to have found Adolf Hitler’s personal diary for 1932 to 1945. It was found that the paper used for the diary contained chemicals such as optical brightness which were only brought onto the market after the end of world war two. Also the dyes used to stop fuel cheats use pi systems.

To be frank an absolute storm is starting to occur in France. It is all about a documentary film about autism in France. A women interviewed a series of professionals, three of these professionals are trying to sue her claiming that she has distorted their words. Unless the film maker has done a technically excellent hatchet job of editing these people to make them look like crazy monsters, it appears that some of the people interviewed in the film have some rather odd ideas.

I have seen some of the film and what I saw shocked me, there is a lady (Dr Genevie Loison) who is shown coming out with some odd ideas . Her comments are about the mother being a crocodile, that if children put their hands in the croc’s mouth then it is very bad, she also makes some statements about your father’s privates and the croc’s mouth. She also feels good when children beat the living daylights out of the croc.

I would sincerely like to know if Dr Genevie Loison stands by these ideas or has Sophie stitched her up with clever editing ? Are the ideas about the croc part of Freudian psychology ? I frankly do not know exactly what is and is not part of Freudian psychology but I do know something about Freud as a man.

My issue with the work of Sigmund Freud is that he was a drug abuser who seems to obsess on sexual matters and the urge to be great. I would like to point out that it is common knowledge that Freud was a cocaine abuser who may have had a rather unwholesome sex life. He wrote papers about the joys of doing cocaine, while he might have done some interesting work I have to ask if we should trust a cocaine abuser who has sex with his wife’s sister.

I would strongly suggest to my readers that they read the review of a book by Ms Thornton and this discussion about the “great man’s” life.

I would like to suggest that you might want to tune in to see a press conference about a court case which is coming up soon about Sophie Robert’s film. The court is likely to give a judgement this week.

I have had a discussion about Sophie Robert’s film with a student of english/british law. Before we get going I want to make it clear that I do not have the full facts about the case, neither am I able to give legal advice or a legal judgement on the matter. But I want to tell you about what I have found out so far and considered after talking to the law student.

Three of the people who gave interviews for the film have chosen to sue making the claim that Sophie has distorted their words in her film by means of editing.

According to www.supportthewall.org Sophie has been served with a court order which requires her to provide the court with all her footage which relates to the film she made. According to this web site she has refused to do so pointing out that as a journalist she is entitled to protect her sources. She also has complained that her case lacked due process, if this claim that a court issued such a court order without giving her a chance to put her side of the story then my level of respect for this court is very small.

A court which acts in a drastic manner without proper due process is the sort of thing we normally expect to find in a banana republic. I think it goes against many human rights and it also brings the court into disrepute. I hold the view that a judge who acts recklessly or in bad faith should enjoy no protection against either criminal or civil law, if anything he/she should be singled out for special harsh punishment as an example to others. My view is that those who know better and should display a good example to others should be regarded more harshly if they make a choice to transgress.

I hold the view that the court should only require a journalist to hand over their original footage which shows the three persons who have brought a law suit against her, anything more is a fishing trip and is not reasonable. I hold a view that unless the court can show that Sophie Robert is involved in terrorism, spying for a foreign power, serious crime or some other dire activity then they should respect the privacy of her sources.

If the three persons who have brought the lawsuit can show that by careful editing that Sophie has distorted their words then I think that they should be paid compensation and a court order to restrict the film should be issued. The degree of editing which could be used to blacken a persons name can vary. One extreme hypothetical example follows.

“Every spring I jack up my car and after putting it on axle stands, I swap the winter wheels for the summer wheels. I am careful to use the stands to make sure that the car does not fall on top of me if the jack fails. The other thing to be careful of is when I pull the jack out of the metal clip which holds it under my car boot, this metal clip is a hand ripper which has given me a few cuts in the past.“

Now if we take the audio of Mark Foreman talking about how like other drivers in Sweden he has to change his wheels twice a year we can make a statement which is rather different to the overall meaning of the paragraph about changing a car wheel. How about

I am jack the ripper

If this degree of tampering with a person’s words has occurred then it is a clear case for a law suit in my mind.

Things can be done in a more slick manner, it has been stated that Micheal Moore took footage from a series of different sources and edited it to make if look like Charlton Heston and the NRA are an insensitive bunch who showed contempt for the victims of the Columbine shooting at their big meeting which was shortly after the event. What ever you might think of Heston and the NRA I feel that Moore has behaved in a very bad way.

I think that the three suing Sophie need to prove that what they said was distorted to pervert the meaning of what they have said, if they fail to do so then I think that Sophie should sue the three for their vexatious or frivolous litigation.

People are getting hot and angry about censorship. Before we get started I need to point out that I am neither totally pro or anticensorship, I hold the view that for many problems in the world that “sunlight is the best disinfectant”. For example a free and open discussion of how the world will meet its needs for plastic, energy, petrol, drinking water and food is needed.

But at the same time we have a need to protect both society and individuals against information which has clear misuse potential. For example the exact security arrangements of the king of Sweden should not be made public, I hold the view that the less an assassin knows about the way in which the king is protected the less likely the assassin is to be able to harm the king. While some people might think that it does not matter if people know where you sleep and how many guards you have then they should consider the tale of monk who ran a antidrug program in the far east. He was very good at getting drug addicts to give up drugs, so successful that his life was under threat by those in the illegal drug industry. As a result he made it his habit to sleep in a different part of the monastery every night, this is clearly a quite reasonable precaution against being murdered. For this monk if his sleeping arrangements were leaked then his life could be in grave danger.

As well as information which has such clear misuse potential for the good of society we need to protect against some content which is bad for society as its release has the potential to harm the interests of people. For example the woman (Erin Andrews) in the USA sued a man (Michael David Barrett) who tampered with the peephole on her hotel room door before filming her in the nude. To me this is a clear case where Erin Andrews is in the right, she had a perfectly reasonable expectation that she could get changed in private in her hotel room and not be filmed by some perverted peeping tom who puts a film of you on the internet. I think it is quite reasonable for Erin to use criminal and civil law to prevent any further violation of her right to privacy by using what can be called “censorship”.

Also if you look at the sad sorry tale of Jane Longhurst, after very unpleasant death a man (Graham Coutts) was sent to prison for life. It was found that Mr Coutts had a very nasty porn addiction. He was in the habit of viewing porn which revolved around violent and degrading sex, the new UK law outlaws the worst forms of porn.

The author of ‘the joy of sex’ (Alex Comfort) joked that once the term “perverted sex” in a sex manual had the meaning of “sexual activity which the author of the book did not enjoy”, but he did state that some perversions are so harmful to society that they need to be outlawed. Now I suspect that some of my readers look at porn,  I sincerely hope none of them look at anything which would fall foul of sections 63 to 71 of the 2008 Criminal Justice and Immigration act.

Even if we assume that the majority of people can view this distasteful matter without turning into sexual criminals, it is possible that a minority of people after viewing such porn will be then more likely to commit a serious sexual crime. So I hold the view that to protect society we need to use censorship to prevent this dire porn being circulated in society. I am not alone in these views, the British Board of Film Classification have stated that they need to help to protect society from films which induce “moral harm“.

To quote from their website

“moral harm may be caused by, for example, desensitising a potential viewer to the effects of violence, degrading a potential viewer’s sense of empathy, encouraging a dehumanised view of others, suppressing pro-social attitudes, encouraging anti-social attitudes, reinforcing unhealthy fantasies, or eroding a sense of moral responsibility.“

But now we will get onto the big issue, in France a woman made a documentary about autism in her country. She interviewed a series of psychiatrists and psychoanalysis practitioners about the subject. Then using the interviews she made a feature film, but then Eric Laurent, Esthela Solano-Suarez and Alexandre Stevens (who were three of those interviewed for the film) have brought a court action against her.

These three people have claimed that Sophie Robert has distorted their words, they want the film to be banned. Prof Travis Thompson has spoken out in defence of the film. He is quoted as saying

“The theoretical notions expressed by the several psychoanalysts interviewed have no empirical foundation and would be amusing or simply embarrassing, if it weren’t for the fact that apparently many people take them seriously in France.“

I am unable to tell you what to think about Sophie’s film which can be viewed here. But I hold the view that the censorship debate about her film will be more important than any of the debate about porn or peeping toms. I would like to encourage my readers to keep an eye on this court case.

One camp hold a view that there is no such thing as copyright, these people hold a view that software, books, music and feature films no matter who wrote them (or invested money or time in them) should be free for all people to use. This is clearly wrong ! Some of the things which groups like the “pirate party” are trying to do may harm the interests of people who want to release / use software under more liberal terms. One very dangerous idea is to reduce copyright protection to only ten years, currently it is for life plus seventy years in the UK and Sweden. The worry I have is that any action to alter copyright law may undermine ‘copyleft’, copyleft uses copyright law to enable an author to release or wave some of their rights under copyright.

On the other hand there are those who want to enslave the whole world to a small series of companys which I will not be naming here. One example which was sad was the school teacher who tried to punish a boy for his use of an alternative operating system (Lynex). For your information here is the first reply of a leading person in the Lynex movement. He was later contacted by the teacher and after discussing the matter here are his later thoughts on the matter.

What I think happened was that the school teacher was so conditioned by the battle between the two camps that she instantly thought that a new non-microsoft operating system was illegal.

I have to say that some very publicly minded people have written software and other works which they have given away free to the world. For example Sir Humphry Davy refused to patent his safety lamp for coal miners, I suspect that this refusal to patent the lamp was an attempt to make the lamp as cheap as possible to enable as many people as possible to be able to work in safety in mines which are plagued with explosive concentrations of methane.

However some people who have put a great deal of time and money into inventing something such as software (how about Windows NT), a drug (how about AZT), a process (how about one for Cativa and Monsanto processes for acetic acid) or a new method of making drugs / fine chemicals (such as thionation reagents from P4S10 and butoxybenzene). These people after making such an effort want to get some money in return for their labours, which is only fair. So I think that copyright law is a reasonable way to make sure that people are rewarded for their legal efforts, if no reward existed for the creation of new ideas / books / music / films / inventions then many people who currently make these things would stop doing so as they would no longer have a means of making sure that they were rewarded.

To be frank with you I do not like the idea of people being able to steal the copyrighted works of others. When I was a university teacher in the UK I once had to deal with a plagiarism case, it was horrible. I view plagiarism as the intellectual version of stealing milk bottles from the house next door because you are too lazy to order or buy your own milk, it is deeply wrong. However in cases of commercial software which is neither marketed or supported then I think that maybe after ten or twenty years it should become public domain to prevent it going into a legal limbo where no person may make use of it either legally or illegally.

If you came to this link hoping for free pirated software then please understand that there is no illegal software here, please think before you pirate something the next time you are tempted to.

To be frank with you I do not like the idea of people being able to steal the copyrighted works of others. When I was a university teacher in the UK I once had to deal with a plagiarism case, it was horrible. I view plagiarism as the intellectual version of stealing milk bottles from the house next door because you are too lazy to order or buy your own milk, it is deeply wrong.

However sometimes the cure for a disease is worse than the disease, for example how about a dose of a potent anticancer drug associated with hair loss to cure unsightly hair on the back of your hands !? My answer to such a cure for hairy backs of hands would be to say “no thank you, what a stupid idea !”.

Sadly in the US a bill is being debated which might well be a dire cure which will cause more harm than the disease. The bill is PROTECT IP Act (PIPA) in the Senate and Stop Online Piracy Act (SOPA) in the House. You read one point of view about it and you can see a film about it here.

While I have nothing against a court order being obtained to close down a site if the site is based in the same state / country as the court. I do have a problem with the idea of a law which allows the creation of a censorship wall or a law which allows a US court to demand that search engines (or the DNS) block access to sites. I suspect that no real due process will exist and that as well as blocking the sites of a range of wrongdoers many innocent sites will be blocked in error.

I would suggest that the law should be improved in the following way, any person / company who can show that their site has been unfairly blocked or affected should be offered a remedy.  The person / company which filed the wrongful case against them should be required to pay for all costs, expenses and loss of earnings plus large punitive damages. The standard of proof for this counter claim should be no higher than that required for the original blocking order or the standard balance of probabilities (normal civil case) which ever is a lower standard of proof.

Today I gave my first chemistry lesson of the year to the first year undergraduates, now this is a basic course in chemistry which might make some of the more experienced chemists think something along the lines of ‘basic chemistry, it can not be that that important’. But I have to say that the fact that it is basic chemistry makes this statement very wrong.

While the basic course might be on a low level, we need to make sure that we give the students a strong foundation on which to build the “house of chemistry”. It is true that the wise man builds his house upon the rock while the foolish man builds his house upon the sand.

What the students need is a strong and robust rock which is able to take the weight of the things which they later learn. In common with house building it is very hard to repair the foundations after the house has been built. For those of you who do not know the process of foundation repair is known as underpinning, it is a slow and expensive process. What has to happen in underpinning is that a small hole is dug next to the building, and then the foundations at that spot are repaired. Then the hole is refilled and a new hole dug nearby to enable the next part of the building to be repaired. This is a long and slow process, any attempts to speed up the process by digging a big hole around the building can make the whole building fall down !

In the same way if a poor job is done in the first year chemistry class then the ‘house of chemistry’ will need a very expensive, difficult and irksome repair later. We need to avoid teaching anything which needs to be removed later, also we need to make sure that the students will be ready at the end of the course to move onto the next thing.

Today one of the students demonstrated that he is thinking about the chemistry in a deeper way, he asked how long a sacrificial anode would last. The is a open ended but good question, the problem is that without doing a series of experiments it is not possible to give an answer which is based on anything more than a wild stab in the dark.

The example he was asking about was a zinc coated steel water tank which is in contact with copper pipes. The tank contains a magnesium anode which is hanging on the end of a wire which is connected to the tank.

What I think is needed to answer this industrially important question would be a series of experiments to determine the corrosion potential and corrosion current associated with the zinc surface. Also the cathodic reaction on the surface of the copper pipes would need to be understood as would the anodic reaction on the surface of the magnesium block.

An easy way to deal with the problem would be to add the magnesium anode and then measure the current flowing through the wire from the tank using a zero resistance ammeter. This is an electronic device which uses op amps to measure the current. Based on the current, the weight of the block and the atomic mass of magnesium an estimate can be made of how long the block will last before a new block is needed.

This simple approach might be easy to use, but it has a series of disadvantages. It is possible to over protect some alloys, for example steel which is exposed to an excessive degree of cathodic protection will becomes brittle because of the formation of hydrogen. While a metal surface which is too far from the protective anode will be under protected and thus be subject to corrosion. I think that the student had wandered into a complex area which is addressed at length by Pierre the corrosion expert in his book.[1]

I feel that Pierre has done such a good job of explaining this topic that I feel I am unable to do nearly as well as him, I think rather than wasting some electronic ink with my attempts to paraphrase Pierre that it would be better if you read his text book if you want to know about cathodic protection.

I am sure that many of you will be aware of Godzilla the movie monster which was a dinosaur which got a dose of radiation and thus turned into the super monster. Also for those readers who were born in the 1980s there is the infinitely more annoying ‘teenage mutant ninja turtles’ who according to one version were pet turtles which encountered some exotic toxin which turned them into super turtles (more like irksome turtles). Here the toxin turned the turtles into super turtles.

Recently I saw a paper which asked the question of would normal bacteria after a dose of Fukushima radiation turn into super germs which would be immune to antibiotic drugs. The good news is that according to Shigeyuki Nakanishi, John E. Moore, Motoo Matsuda, Colin E. Goldsmith, Wilson A. Coulter and Juluri R. Rao in Ecotoxicology and Environmental Safety, 2012, volume 76, pages 169 to 174 it will not happen.

They found that radiation does not turn germs into super germs, I suspect that while the gamma rays may have increased the mutation rate because the microbes were not being subject to attack by antibiotics at the same time the increase in mutation rate did not make the germs evolve.

I suspect that if germs were never exposed to antibiotics that very few germs would be immune to the drugs, the reason is that the immunity to the drug does not give the germ an advantage if the drug is never present.

Also as many organisms evolve an immunity to a drug or a pesticide by changing their biochemistry to make it more “exotic”, the exotic biochemistry might give the organism a disadvantage when the biocide is absent.

For example penicillin stops germs by stopping them making the proteins needed for their cell membranes, if the germs change to have second new enzyme which the penicillin does not deactivate in addition to their normal enzyme then they will have to make a greater effort to grow as they will have to make two enzymes while normal germs only need to make one.

For example I saw an open university film about biology years ago which explained that normal grass can not tolerate copper, but the grass on a mine spoil head is a special grass which can tolerate copper. As a result the grass on the spoil heap is different to the normal grass in a field which is unable to grow on the spoil head.

Because the copper tolerant grass is less able to grow under normal conditions than the ordinary grass the copper tolerant grass is not able to take over the normal land. In the same way I suspect that radiation on its own will not make the germs evolve into antibiotic resistant germs.

I think that the only way to make the radiation turn the germs into antibiotic resistant germs would be to expose a culture of the germs to both radiation and the antibiotic at the same time.

Me and my wife have been watching some disaster films recently, last night we choose to watch “On the Beach” which is a ‘oh so not so joyous film‘ about the end of the human race. The human race is snuffed in the film (and in the novel) out by very intense fallout from a nuclear war.

This made me think about it for a moment, several things were wrong with the physics and the chemistry of the film.

1. The fallout takes many weeks to arrive in Auz, looking at a paper on bomb fallout by some workers from Kyoto, Kanazawa and Hiroshima Universities it is clear that the fallout will be more than 200 times less radioactive gram for gram after ten days than it would have been 2 hours after it was deposited as ‘heavy’ local fallout very close to the bomb detonation.

So by the time that the fallout would have got down under it would have lost much of its strength. In the book on the beach it took much more than ten days for the fallout to arrive in Auz. This means that the reduction in the radioactivity due to simple decay would be even larger.

I had taken a very simple view that no chemical separation would have occurred during the transport of the radioactivity from the bomb detonation to Auz.

2. Around about 10 to 100 days after detonation the majority of the gamma dose will be due to Te-132/I-132, Ba-140 / La-140, Zr-95 / Nb-95, Ru-103 and I-131. While the iodine (I) and tellurium (Te) are very mobile the barium (Ba) and zirconium are less mobile. A good rule of thumb is that the chemical form of an isotope twenty seconds after the detonation will determine how the isotope behaves.

100 % of the zirconium-95 will be in the form of yttrium-95 (half life ten minutes) at twenty seconds after detonation. The yttrium is very non volatile and is likely to be in the form of an solid oxide at that point. I suspect that it will be very likely to become part of the larger particles from things like soil which will fall to earth more quickly. As a result the local fallout close to the bomb will be enriched in zirconium-95 while the distant fallout will have less of this isotope.

The barium-140 will be formed from cesium-140 (half life one minute) which will be the form of this isobar twenty seconds after the detonation. The cesium is only a semi volatile so about 30 % will be in a solid form.

The ruthenium-103 (Ru) is formed by the decay of molybedum-103 (Mo), as the Mo-103 has a half life of seventy seconds it will dictate much of the behaviour of the Ru-103.  The boiling point of MoO3 is about 1160 oC which is lower than that of ZrO2 and Y2O3 (both about 4300 oC) and higher than what I would expect for of Cs2O. So as a result I much of the ruthenium-103 to be lost into solid particles. So the enrichment process may tend to deposit it in the local fallout.

Now according to the graphs published by Japanese workers if all the involatile forms of the radioisotopes are lost from the fallout then the dose absorbed over the ten to one hundred days the will be only three quarters of the dose which would have been suffered if no chemical fractionation had occurred.

Both of these effects would tend to protect the population down under by lowering their dose, I hold the view that a nuclear war would be a horrible event. But I do not think that a total extermination of mankind by fallout would be a certainty.

As we all know smoking is a nasty dirty habit, frankly it is ugly and very bad for your health. It has been known since the 1930s that smoking causes lung cancer, as a result the wretched smoke from evil herb has been examined with great care by scientists who are trying to work out the mechanism by which the ‘blacke stinking fume resembling the horrible Stigian smoke of the pit that is bottomelesse’ exerts its baneful effect on the cells in the human body.

I think that the great problem is that the smoke contains a range of different carcinogens, it contains cadmium oxide, polonium-210, benzopyrene and also N-nitrosoamines. The N-nitrosoamines are a very horrible class of carcinogens.

I was looking at a paper on the N-nitrosoamines associated with tobacco, one of the worst appears to be NNK [4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanone] which is formed from nicotine. It has been shown by M. Sleiman, L.A. Gundel, J.F. Pankow, P. Jacob III, B.C. Singer and H. Destaillats in Proceedings of the National Academy of Sciences of the United States of America, 2010. In this paper it was shown that nicotine stains on surfaces react with nitrogen oxides from air pollution (and smoking) to form N-nitrosoamines such as NNK. Below is shown an example of how one of the N-nitrosoamines forms from nicotine.

Synthesis of NNK from nicotine by nitrous acid

One of the other ways in which NNK can form is by hydroxylation of nicotine. This is likely to be a free radical process, when I was out walking my dog I was thinking about this reaction. The reaction will be likely to start by the removal of a hydrogen atom from the carbon connected to both the nitrogen atom in the five memebered ring and the pyridine (six membered ring). I will write more about this free radical mechanism another day