Tetraethyl Lead Synthesis Essay

It was discovered that successful reactions could be obtained between a wide variety of organometallic compounds and lead sulfide, lead oxide, and the lead salts of inorganic or organic oxy- and thioacids. Even mixed compounds of lead oxide and the lead salts of the organic oxyacids undergo reaction to form tetraethyllead. In particular, organometallic compounds of elements in Groups IA, IIA, IIIA, and IIB as well as the complex organometallic compounds derived from the elements in these groups, such as lithium tetraethylaluminum, are effective in reactions with nonhalide lead compounds of these types. Tetraorganolead yields vary with reaction conditions, reactants, and solvents used. Temperature conditions required to initiate reactions are mild and in some cases are as low as —24°C. Rates of reaction are moderate to rapid, depending on the reaction conditions. Solvents are desirable to improve either reaction control and/or contact between reactants when one or both are solids under normal conditions. Solvents which have been used successfully in these reactions include hydrocarbons, amines, ethers, esters, and chlorinated hydrocarbons. It is the aim of this paper to cite a number of examples, so that the reader can appreciate the broad scope of the reaction of organometallic compounds with nonhalide lead compounds.

In the fall of 1924, five bodies from New Jersey were delivered to the New York City Medical Examiner’s Office. You might not expect that to cause the chief medical examiner to worry about the dirt blowing in city streets. But it did.

To understand why you need to know the story of those five dead men, or at least the story of their exposure to a then mysterious industrial poison.

The five men worked at the Standard Oil Refinery in Bayway, New Jersey. All of them spent their days in what plant employees nicknamed “the loony gas building”, a tidy brick structure where workers seemed to sicken as they handled a new gasoline additive. The additive’s technical name was tetraethyl lead or, in industrial shorthand, TEL.  It was developed by researchers at General Motors as an anti-knock formula.

But, as I wrote in a previous post, men working at the plant quickly gave it the “loony gas” tag because anyone who spent much time inside showed signs of mental deterioration, from stumbling memory loss to sudden twitchy bursts of rage.  In October of 1924, workers in the TEL building began collapsing, going into convulsions, babbling deliriously. By the end of September, 32 of the 49 TEL workers were in the hospital; five of them died.

The problem, at that point, was that no one knew exactly why. Oh, they knew – or should have known – that tetraethyl lead was dangerous. As Charles Norris, chief medical examiner for New York City pointed out, the compound had been banned in Europe for years due to its toxic nature. But while U.S. corporations hurried TEL into production in the 1920s, they did not hurry to understand its medical or environmental effects.

Two years earlier, the U.S. Public Health Service had asked Thomas Midgley, Jr. – the developer of the leaded gasoline process –   all research into the health consequences of tetraethyl lead (TEL).

Midgley, a scientist at General Motors,  replied then that no such research existed. Two years later, he could gave the same answer. Although GM and Standard Oil had formed a joint company to manufacture leaded gasoline – the Ethyl Gasoline Corporation – its research had focused solely on improving the TEL formulas. The companies preferred to avoid the lead issue. They’d deliberately left the word out of their new company name to avoid its negative image.

In response to the worker health crisis at the Bayway plant, Standard Oil suggested that the problem might simply be overwork.  Unimpressed, the state of New Jersey ordered a halt to TEL production. And then the compound was so poorly understood,  state health officials asked the New York City Medical Examiner’s Office  to find out what had happened.

In 1924, New York had the best forensic toxicology department in the country; in fact, it had one of the few such programs period. The chief chemist was a dark, cigar-smoking, perfectionist named Alexander Gettler, a famously dogged researcher who would sit up late at night designing both experiments and apparatus as needed.

It took Gettler three obsessively focused weeks to figure out how much tetraethyl lead the Standard Oil workers had absorbed before they became ill, or crazy, or dead. “This is one of the most difficult of many difficult investigations of the kind which have been carried on at this laboratory,”  Norris said, when releasing the results. “This was the first work of its kind, as far as I know. Dr. Gettler had not only to do the work but to invent a considerable part of the method of doing it.”

Working with the first four bodies, then checking his results against the body of the last worker killed, who had died screaming in a straitjacket, Gettler discovered that TEL and its lead byproducts formed a recognizable distribution, concentrated in the lungs, the brain, and the bones. The highest levels were in the lungs suggesting that most of the poison had been inhaled; later tests showed that the types of masks used by  Standard Oil did not filter out the lead in TEL vapors.

Rubber gloves did protect the hands but if TEL splattered and made any direct with skin, it absorbed alarmingly quickly. The result was intense poisoning with lead, a potent neurotoxin. The loony gas symptoms were, in fact, classic heavy lead toxicity.

After Norris released his office’s report on tetraethyl lead, New York City banned its sale, and the sale of “any preparation containing lead or other deleterious substances” as an additive to gasoline. So did New Jersey. So did the city of Philadelphia.

Afraid that the trend would accelerate, that they would be forced to find another anti-knock compound, as well as losing considerable money, the manufacturing companies demanded that the federal government take over the investigation and develop its own regulations.

The manufacturers agreed to suspend TEL production and distribution until a federal investigation was completed. In May 1925, the U.S. Surgeon General called a national tetraethyl lead conference, to be followed by the formation of an investigative task force to study the problem. That same year, Midgley published his first health analysis of TEL, which acknowledged just a minor health risk: “compared with other chemical industries it is neither grave nor inescapable.”

It was obvious in advance that the federal task force was going to reach that same conclusion. The panel only included selected industry scientists like Midgely. It had no place for Alexander Gettler or Charles Norris or, in fact, anyone from any city where sales of the gas had been banned, or any agency involved in the producing that first critical analysis of tetraethyl lead.

In January 1926, the public health service released its report which concluded that  there was “no danger” posed by adding the compound to gasoline…”no reason to prohibit the sale of leaded gasoline” as long as workers were well protected during the manufacturing process.

The task force focused on the risks associated with every day exposure by drivers, automobile attendants, gas station operators, and found that it was minimal. It was true that lead had turned up in dusty corners of garages and that all the drivers tested showed trace amounts of lead in their blood. But a low level of lead could be tolerated, the scientists concluded. After all,  none of the test subjects showed the extreme behaviors and breakdowns associated with places like the looney gas building. And the worker problem could be handled with some protective gear.

There were critics, even then, insisting that this was a biased panel, too deliberately underestimating the risks, too willing to introduce lead into the environment. There was one cautionary note, though.  The federal panel warned that exposure levels would probably rise as more people took to the roads.  Perhaps, at a later point, the scientists suggested, the research should be taken up again. It was always possible that leaded gasoline might “constitute a menace to the general public after prolonged use or other conditions not foreseen at this time.”

But, of course, that would be another generation’s problem. In 1926, citing evidence from the TEL report, the federal government revoked all bans on production and sale of leaded gasoline. The reaction of industry was jubilant; one Standard Oil spokesman likened the compound to a “gift of God,” so great was its potential to improve automobile performance.

In New York City,  at least,  Charles Norris decided to prepare for the health and environmental problems to come. He suggested that the department scientists do a base-line measurement of lead levels in the dirt and debris blowing across city streets. People died, he pointed out to his staff; and everyone knew that heavy metals like lead tended to accumulate. The resulting comparison of street dirt in 1924 and 1934 found a 50 percent increase in lead levels – a warning, an indicator of damage to come, if anyone had been paying attention.

It was some fifty years later – in 1986 – that the United States formally banned lead as a gasoline additive. By that time, according to some estimates, so much lead had been deposited into soils, streets, building surfaces, that an estimated 68 million children would register toxic levels of lead absorption and some 5,000 American adults would die annually of lead-induced heart disease. As lead affects cognitive function, some neuroscientists also suggested that chronic lead exposure resulted in a measurable drop in  IQ scores during the leaded gas era.

Or, if you prefer, our long – and preventable –  loony gas era.

The second of a two part blog series on the early history of leaded gasoline. I discovered this while researching The Poisoner’s Handbook and I’ve always considered it a fascinating and troubling part of our forgotten chemical history.

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