When aniline dye was synthesized from coal tar, few studied what the manufacturing process left behind
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Excerpted from Toms River: A Story of Science and Salvation, by Dan Fagin. Copyright ? March 19, 2013, Bantam Books.
The very big idea that would transform Toms River and reshape the global economy was born in 1856 in the attic laboratory of a precocious eighteen-year-old chemistry student named William Henry Perkin, who lived with his family in London?s East End. It was Easter vacation, and Perkin was using the time off to work on some coal tar experiments suggested by his mentor at the Royal College of Chemistry, August Wilhelm von Hofmann.
No one in the world knew more about the chemical properties of coal tar than Hofmann, and coal tar was a very important compound to know about. It was, arguably, the first large-scale industrial waste. By the mid-1800s, coal gas and solid coke had replaced candles, animal oils, and wood as the most important sources of light, heat, and cooking fuel in many European and American cities. Both coal gas and coke were derived from burning coal at high temperatures in the absence of oxygen, a process that left behind a thick, smelly brown liquid that was called coal tar because it resembled the pine tar used to waterproof wooden ships. But undistilled coal tar was not a very good sealant and was noxious, too, and thus very difficult to get rid of. Burning it produced hazardous black smoke, and burying it killed any nearby vegetation. The two most common disposal practices for coal tar, dumping it into open pits or waterways, were obviously unsavory. But Hofmann, a Hessian expatriate who was an endlessly patient experimenter, was convinced that coal tar could be turned into something useful. He had already established a track record of doing so at the Royal College of Chemistry, where he was the founding director. Knowing that the various components of coal tar vaporized at different temperatures as it was heated, Hofmann spent years separating its many ingredients. In the 1840s, his work had helped to launch the timber ?pickling? industry, in which railway ties and telegraph poles were protected from decay by dipping them in creosote, made from coal tar. But the timber picklers were not interested in the lighter and most volatile components of coal tar, which were still nothing but toxic waste?more toxic, in fact, than undistilled coal tar. So Hofmann and his students kept experimenting.
One of those students was young William Perkin. Hofmann had him working on a project that involved breaking down some key components of coal tar to their nitrogen bases, the amines. Hofmann knew that quinine, the only effective treatment for malaria and thus vital to the British Empire, was also an amine, with a chemical structure very similar to that of several coal tar components, including naphtha. He also knew that bark from Peruvian cinchona trees was the only source of quinine, which is why the medicine was costly and very difficult to obtain. But what if the miracle drug could be synthesized from naphtha or some other unwanted ingredient of coal tar? Hofmann did not think it could, but he considered it a suitable project for his promising teenage prot?g?.
Perkin eagerly accepted the challenge; like his mentor Hofmann, he was an obsessive experimenter. Perkin set to work during his Easter vacation, while Hofmann was in Germany. Laboring in a small, simple lab on the top floor of his family?s home, Perkin decided to experiment with toluene, a toxic component of coal tar that would later play a major role in Toms River. Perkin isolated a derivative called allyl-toluidine, then tried to transform it into quinine by oxidizing it in a mixture with potassium dichromate and sulfuric acid. When he was finished, his test tube contained a reddish-black powder, not the clear medicine he was hoping to see. So Perkin tried again, this time choosing a simpler amine called aniline, which was derived from benzene, another coal tar component that would become notorious later. Once again, he mixed it with potassium dichromate and sulfuric acid, and again the experiment flopped. This time, a black, gooey substance was at the bottom of his test tube, and it certainly was not quinine.
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