Today I will talk about a genius of chemistry. The master of pollution! The man who prevented our car engines of exploding. He was such a poisoner! The guy who permitted to our fridges to works well without exploding. You mean this guy who made the big hole in the ozone layer? A genius of chemistry The guy was just randomly mixing stuffs! Yep… it won’t be easy. The man who poisoned Mankind, wishing to save Mankind. Thomas Midgley Midgley ? Midgley ? Thomas. He was born in the USA in 1889 and obtained his degree in mechanical engineering in 1911. And he was fascinated by the periodic table of the elements. He always had such a table in his pocket. Really. In 1916 he was working for a company building electrical generator working with gazoline, used in farms, for producing electricity directly on site. The main issue of these generators was in the engine, there was often a knocking. Knocking occurs when the engine is far too hot and the gazoline/air mix ignites too early, when the piston is still rising up into the cylinder. It creates a shockwave lessening the engine efficiency and potentially damaging it. Then Thomas Midgley came with an idea A very weirdish idea. The idea is to make the fuel red in order to reduce engine knocking. The very first compound he had in his lab was iodine. Actually: di-iodine. Two iodine atoms connected together. This is a deep purple colored solid. So, he added di-iodine to the fuel Which became red
And bingo! The knocking stopped. Conclusion from Thomas Midgley? The red color prevents the early ignition of the air/gazoline mixture. However when he tried other colourants… it wasn’t working! Until he tried iodoethane. A linear molecule made of 4 carbon atoms, 9 hydrogen atoms and 1 iodine atom. And, iodoethane prevented again the engine knocking. Conclusion ? Mea culpa. The iodine atom seems to prevent knocking. This was an intellectual shock in Midgley’s career. He then said something so… wonderful! « During my studies, I had the opportunity of studying the periodic table of the elements, and I printed it into my memory as a very useful tool for my research. We gave up with the trial and error method for a procedure based on the periodic table. Previsions started to fulfill our needs instead of ending up in disasters. » The guy is actually a mechanical engineer. He learnt chemistry by more or less randomly mixing products. We gave up with the trial and error method We gave up with the trial and error We gave up Actually he gave up of not giving up randomly mixing products. He noticed the anti-knocking properties of the elements were so organized: The more to the right of the table, the more the anti-knocking property
Plus je vais vers la droite du tableau, plus le pouvoir antidétonant augmente The more to the bottom of the table, the more the anti-knocking property. As well. Back in the days, the periodic table was not as complete as nowadays. The area of interest is around here. The trouble is, the at this place the elements are metals. And metals are not soluble in gazoline. Gazoline is an organic compound, because it is made of carbon and hydrogen. In chemistry, similar thing go together. For mixing metal into gazoline, one has to associate carbonated molecules to this metal. One will synthesize an organometallic compound. Organs=>carbon. Metallic=>metal. Here we go! With these data, Midgley noticed that a very efficient compound was diethyl telluride. one telluride atom bearing two chains of 2 carbons and 5 hydrogens each. The result was… unexpected. That’s was happens while mixing everything. Telluride compounds smell garlic, and inhaling or ingesting even a minute amount, gives a strong garlic smell. Breathing, sweating, other things smell garlic. Thomas Midgley was Garlicman for a while. Therefore, he gave up with telluride compounds and focalized his research on lead. Really? Lead? This is poisonous. Yes… He chose tetraethyl lead 1 lead 8 carbons 20 hydrogens And tetraethyl lead was… very, very efficient. A perfect anti knocking mean. The knockings immediately stopped. They stopped. But something else has just started. All the lead injected into the engine will be rejected from the engine into the atmosphere. Actually, several hundreds of thousands of metric tons of lead have been released into the air. And lead is really harmful for the body. Even minutes amounts will provoke mental disorder to kids. It attacks the newborn brain. And the years passing by, lead was everywhere. Everywhere. You are the champion! This wasn’t done on purpose. Thomas Midgley didn’t though about this. He wanted to give a better life to people by arranging their motors, but he could not predict one will later find his leaded product over the north pole or on montains. Finally, tetraethyl lead has been forbidden in the late 1990’s. Anyway! He was an awesome inventor, and after touching gazoline engines, he started to play with refrigerators. I have a bad feeling about this. You can. I will quickly explain how a fridge actually works. There is a closed circuit containing a gas, one part of the circuit is outside the fridge and the other part is inside it. Outside the fridge, the gas is compressed and becomes liquid. This liquid flows into the pipes inside the fridge, pressure is released, the gas is decompressed. Releasing pressure absorbs heat. If it absorbs heat, it make things colds. The gas flows into the outside circuit, there it is compressed, and compression releases heat. That’s why the back of a fridge is hot. Actually, the heat from inside the fridge has been transferred to the outside. In the early 20th century fridges used as a cooling gaz either propane, ammonia ou sulfure dioxide. These products can burn or corrode the pipes. So back in the days, there were lots of fridge accidents due to dramatic explosions. Well well. And now comes Midgley the inventor! He wishes an anti-knocking product in the fridges? Like tetraethyl lead? Hmmm… more or less. He took the periodic table and looked at the top right elements. Why? Because there are quite cheap, that’s why! Its empirical rule was: The more to the right, the less flammable. The more to the top, the less toxic. So he decided to choose compounds made of carbon, fluorine and chlorine. CFC. And for Midgley, the ideal compound was dichlorodifluorocarbon. Chemins do really love long and complicated names. Dichlorodifluorocarbon was commercialized under the trade name freon. Precisely, freon R12. There were many types of freons. It was the perfect gas. Low boiling point, not toxic, non flammable. Ideal. So ideal that he proved this gas to be non toxic by breathing it and blowing a candle for extinguishing the flamme. Freons were a great commercial success and were used for many decades in fries. Worldwide. Theses gases are so harmless for the body, that they are still is use as a carrier gas for salbutamol. Awesome! He finally made something great, he polluted air with his lead but he gave freons to the world? Mmmm… No. Apparently chemists noticed in the 1970’s that these gases are depleting the ozone layer. They were banned in 1987 as refrigerant gases. For salbutamol, they are still in use, because their is nothing better. But for fridges: game over. The man who poisoned the world… Did he at least had some regrets at some point? Actually no. One can not condemn him as well. At the time when tetraethyl lead and freons were discovered, these were wonderful scientific discoveries. Back in the days, this was genius. There was no mean of predicting the harmful consequences decades later. Thomas Midgley is the man having the most influence on the Earth’s atmosphere. Alone. Anyway, he did not had time to see the bad consequences of his discoveries. He caught poliomyelitis in the 1940’s, and he became half paralyzed. I made a cable system on his bed, for easing its life, and was accidentally strangled with it in 1944. Sorry, the vaccine against polio was discovered in 1955. Sad story!