Moses Gomberg, Father of Radical Chemistry (1866- 1947)

20140721-8

Dr. Moses Gomberg

 

Moses Gomberg, one of the greatest chemists of the 20th Century, and a chemistry professor at the University ofMichigan, discovered an organic free radical in 1900 and affirmed what had been thought impossible. A century later, free radical organic chemistry researchers look back to Gomberg as the founder of their field. His work led to modern theories of the structure and reactivity of organic molecule – theories whose application has had tremendous impact on modern life.

 

Nineteenth century scientists speculated that there could be a free radical containing carbon – an organic free radical. But after many attempts to isolate it failed, they concluded they were wrong and that carbon must always be tetravalent (form four bonds). Moses Gomberg was trying to synthesize a carbon compound called hexaphenylethane when he inadvertently synthesized triphenylmethyl (trityl for short), a mysterious, highly reactive, unstable substance. He recognized that he had found the long-elusive free radical and showed that carbon is not always tetravalent – the then prevailing view. Gomberg published his findings in 1900, but the existence of triphenylmethyl and other organic free radicals remained in dispute for nearly a decade. They were viewed as a curiosity even after the scientific community recognized their existence. Not until the 1930s did free radicals enter the mainstream of organic chemistry.

 

We now know that organic free radicals are essential to the way in which some enzymes function in the human body. We know that organic free radicals are involved in the body’s aging process, in its healthy functioning, and in the development of cancer and other serious diseases. Understanding organic free radicals has helped us explain DNA synthesis in the body and many other natural phenomena, from food spoilage to the effects of sunburn. Organic free radicals also play a major role in the production of plastics, synthetic rubber and other widely used synthetic materials.

 

Gomberg’s life is of a genius striving toward goals, unobtainable for most because of seeming insurmountable odds. Undaunted, he overcame obstacles placed in his way, with intelligence and grace, a timeless story. Moses Gomberg, one of the world’s great organic chemists, chemistry professor and research scientist at the University of Michigan, was born in Elizabetgrad, Russian Empire, an area now in the Ukraine. Russia, at this time, was extremely unstable, by the previous period of Crimean Wars (Russia was the loser), constant battles to break away from the Ottoman Empire, freeing of the serfs by Czar Alexander II (adding greatly to competition for work). Napoleon had emancipated the Jews of Europe. By 1871, every European country, except Russia, had emancipated its Jewish population.

 

Czar Alexander II became the first Russian leader attempting to rid persecution of the Jews. During his reign, some Jews became well educated and successful in all businesses and talked about becoming integrated into Russian society. There was also talk among Jews (Zionism) about the possibility of a real homeland, back in the lands of Israel and Judea, to escape persecution forever. Pamphlets were distributed. Jews began buying land there, that Arab owners deemed unusable. Although the Russian pograms began in 1821, they reached a mass movement status in March 1881, the date Czar Alexander II was assassinated. Jews lost a protected status, and serious plans for a home without persecution became more real. In Russia, the backlash also became more real. Vicious anti-Semitic propaganda began, culminating in an atrocious book, put out by the Russian oligarchs, The Protocols of the Elders of Zion, supposedly the record of secret meetings of Jewish leaders, describing an alleged conspiracy to dominate the world. The conspiracy and its leaders, the so-called Elders of Zion, never existed. The book was proven to be a fraud on many occasions.

 

One month after the assassination of Czar Alexander II, on April 27, 1881, there was a violent pogrom against the Jewish citizens of Elisavetgrad, the town where the Gomberg family lived. A religious dispute at an inn sparked off the riot. The attack focused at first on the systematic destruction of Jewish shops and warehouses. The Jewish citizens tried to protect their businesses, but this only led to more outrage. The soldiers joined in the rioting rather than trying to stop it. After two days of attacks, many were killed, 500 houses and 100 shops were demolished and approximately 2,000,000 rubles’ worth of property were stolen or destroyed. The assassins encouraged mass rebellions and the situation in Russia became anarchic and chaotic for everyone. The Jews were blamed. This was the beginning of mass pogroms which broke out primarily in southern Russia in what is now Ukraine.

 

Moses Gomberg and his father, were accused of participating in an anti-government political group. Their property was confiscated. Somehow, the four Gombergs were able to flee to America, which was one of the alternatives to purchasing land from Arab sellers, in Palestine, through the Zionist movement. It is not known which of their relatives, remained behind. They settled in Chicago, without knowing a word of English. Moses Gomberg was 18 years old. His sister, Sonia was two years younger. Speaking no English, he worked at odd jobs, most involving menial labor. He toiled in the Chicago stockyards under the brutal conditions described in Upton Sinclair’s novel, The Jungle.

 

Through sheer force of will and brainpower, Gomberg learned English, completed his secondary education, and in 1886 entered the University of Michigan. He tried to enroll in a beginning course in physics, but the department head turned him down because he had no formal training in trigonometry. Three days later, he tried again. When the department again rejected him for the same reason, Gomberg insisted he knew the subject. The department head quizzed him, and was stunned to find that what he claimed was true. He had learned trigonometry in three days. He chose University of Michigan over Chicago, because he had to work his way through, and the jobs available in Michigan paid better than in Chicago. Moses entered the University of Michigan, where he obtained his B.Sc in 1890 and his doctorate, four years later, in 1894 under the supervision of A. B. Prescott. His thesis, titled “Trimethylxanthine and Some of its Derivatives“, dealt with the derivatization of caffeine. Appointed an instructor in 1893, Gomberg worked at the University of Michigan for the duration of his professional academic career, becoming chair of the Department of Chemistry from 1927 until his retirement in 1936. Dr. Gomberg served as President of the American Chemical Society in 1931.

 

 

20140721-9

Dr. Moses Gomberg

 

Moses Gomberg, one of the greatest chemists of the 20th Century, and a chemistry professor at the University ofMichigan, discovered an organic free radical in 1900 and affirmed what had been thought impossible. A century later, free radical organic chemistry researchers look back to Gomberg as the founder of their field. His work led to modern theories of the structure and reactivity of organic molecule – theories whose application has had tremendous impact on modern life.

 

Nineteenth century scientists speculated that there could be a free radical containing carbon – an organic free radical. But after many attempts to isolate it failed, they concluded they were wrong and that carbon must always be tetravalent (form four bonds). Moses Gomberg was trying to synthesize a carbon compound called hexaphenylethane when he inadvertently synthesized triphenylmethyl (trityl for short), a mysterious, highly reactive, unstable substance. He recognized that he had found the long-elusive free radical and showed that carbon is not always tetravalent – the then prevailing view. Gomberg published his findings in 1900, but the existence of triphenylmethyl and other organic free radicals remained in dispute for nearly a decade. They were viewed as a curiosity even after the scientific community recognized their existence. Not until the 1930s did free radicals enter the mainstream of organic chemistry.

 

We now know that organic free radicals are essential to the way in which some enzymes function in the human body. We know that organic free radicals are involved in the body’s aging process, in its healthy functioning, and in the development of cancer and other serious diseases. Understanding organic free radicals has helped us explain DNA synthesis in the body and many other natural phenomena, from food spoilage to the effects of sunburn. Organic free radicals also play a major role in the production of plastics, synthetic rubber and other widely used synthetic materials.

 

Gomberg’s life is of a genius striving toward goals, unobtainable for most because of seeming insurmountable odds. Undaunted, he overcame obstacles placed in his way, with intelligence and grace, a timeless story. Moses Gomberg, one of the world’s great organic chemists, chemistry professor and research scientist at the University of Michigan, was born in Elizabetgrad, Russian Empire, an area now in the Ukraine. Russia, at this time, was extremely unstable, by the previous period of Crimean Wars (Russia was the loser), constant battles to break away from the Ottoman Empire, freeing of the serfs by Czar Alexander II (adding greatly to competition for work). Napoleon had emancipated the Jews of Europe. By 1871, every European country, except Russia, had emancipated its Jewish population.

 

Czar Alexander II became the first Russian leader attempting to rid persecution of the Jews. During his reign, some Jews became well educated and successful in all businesses and talked about becoming integrated into Russian society. There was also talk among Jews (Zionism) about the possibility of a real homeland, back in the lands of Israel and Judea, to escape persecution forever. Pamphlets were distributed. Jews began buying land there, that Arab owners deemed unusable. Although the Russian pograms began in 1821, they reached a mass movement status in March 1881, the date Czar Alexander II was assassinated. Jews lost a protected status, and serious plans for a home without persecution became more real. In Russia, the backlash also became more real. Vicious anti-Semitic propaganda began, culminating in an atrocious book, put out by the Russian oligarchs, The Protocols of the Elders of Zion, supposedly the record of secret meetings of Jewish leaders, describing an alleged conspiracy to dominate the world. The conspiracy and its leaders, the so-called Elders of Zion, never existed. The book was proven to be a fraud on many occasions.

 

One month after the assassination of Czar Alexander II, on April 27, 1881, there was a violent pogrom against the Jewish citizens of Elisavetgrad, the town where the Gomberg family lived. A religious dispute at an inn sparked off the riot. The attack focused at first on the systematic destruction of Jewish shops and warehouses. The Jewish citizens tried to protect their businesses, but this only led to more outrage. The soldiers joined in the rioting rather than trying to stop it. After two days of attacks, many were killed, 500 houses and 100 shops were demolished and approximately 2,000,000 rubles’ worth of property were stolen or destroyed. The assassins encouraged mass rebellions and the situation in Russia became anarchic and chaotic for everyone. The Jews were blamed. This was the beginning of mass pogroms which broke out primarily in southern Russia in what is now Ukraine.

 

Moses Gomberg and his father, were accused of participating in an anti-government political group. Their property was confiscated. Somehow, the four Gombergs were able to flee to America, which was one of the alternatives to purchasing land from Arab sellers, in Palestine, through the Zionist movement. It is not known which of their relatives, remained behind. They settled in Chicago, without knowing a word of English. Moses Gomberg was 18 years old. His sister, Sonia was two years younger. Speaking no English, he worked at odd jobs, most involving menial labor. He toiled in the Chicago stockyards under the brutal conditions described in Upton Sinclair’s novel, The Jungle.

 

Through sheer force of will and brainpower, Gomberg learned English, completed his secondary education, and in 1886 entered the University of Michigan. He tried to enroll in a beginning course in physics, but the department head turned him down because he had no formal training in trigonometry. Three days later, he tried again. When the department again rejected him for the same reason, Gomberg insisted he knew the subject. The department head quizzed him, and was stunned to find that what he claimed was true. He had learned trigonometry in three days. He chose University of Michigan over Chicago, because he had to work his way through, and the jobs available in Michigan paid better than in Chicago. Moses entered the University of Michigan, where he obtained his B.Sc in 1890 and his doctorate, four years later, in 1894 under the supervision of A. B. Prescott. His thesis, titled “Trimethylxanthine and Some of its Derivatives“, dealt with the derivatization of caffeine. Appointed an instructor in 1893, Gomberg worked at the University of Michigan for the duration of his professional academic career, becoming chair of the Department of Chemistry from 1927 until his retirement in 1936. Dr. Gomberg served as President of the American Chemical Society in 1931.

 

 

20140721-9

Graduate student, Moses Gomberg, in 1890

 

In 1896-1897, he took a year’s leave to work as a postdoctoral researcher with Baeyer and Thiele in Munich and with Victor Meyer in Heidelberg, where he successfully prepared the long-elusive tetraphenylmethane. During attempts to prepare the even more sterically congested hydrocarbon hexaphenylethane, he correctly identified the triphenylmethyl radical, the first persistent radical to be discovered, and is thus known as the founder of radical chemistry. The work was later followed up by Wilhelm Schlenk. Gomberg was a mentor to Werner Emmanuel Bachmann who also carried on his work and together they discovered the Gomberg-Bachmann reaction. In 1923, he claimed to have synthesized chlorine tetroxide via the reaction of silver perchlorate with iodine, but was later shown to have been mistaken.

 

 

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Gomberg’s chemical lab at the University of Michigan, in 1877

 

Gomberg was the first to successfully synthesize tetraphenylmethane. This was accomplished by the thermal decomposition of 1-phenyl-2-trityldiazene to the desired product in 2-5% yield.

 

 

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Discovery of persistent radicals

 

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Seeking to prepare hexaphenylethane (5), Gomberg attempted a Wurtz coupling of triphenylmethyl chloride (1). Elemental analysis of the resultant white crystalline solid, however, uncovered discrepancies with the predicted molecular formula:

 

  Calculated Observed
 % Carbon 93.83 87.93
 % Hydrogen 6.17 6.04

 

Hypothesizing that had combined with molecular oxygen to form the peroxide, Gomberg found that treatment of (1; see above) with sodium peroxide was another means of synthesizing (4; see above). By performing the reaction of triphenylchloromethane with zinc under an atmosphere of carbon dioxide Gomberg obtained the free radical (2; see above). This compound reacted readily with air, chlorine, bromine and iodine. On the basis of his experimental evidence Gomberg concluded that he had discovered the first instance of a persistent radical and trivalent carbon. This was a controversial conclusion for many years as molecular weight determinations of (2; see above) found a value that was double that of the free radical. Gomberg postulated that some non-tetravalent carbon structure existed in solution because of the observed activity towards oxygen and the halogens. Gomberg and Bachmann later found that treatment of “hexaphenylethane“ with magnesium resulted in a Grignard reagent, the first instance of the formation of such a compound from a hydrocarbon. Studies of other triarylmethyl compounds gave results similar to Gomberg’s, and it was hypothesized that (2; see above) existed in equilibrium with its dimer hexaphenylethane (5; see above). However this structure was later disproven in favor of the quinoid dimer (3; see above).

 

Upon his death in 1947 Moses Gomberg bequeathed his estate to the Chemistry Department of the University of Michigan for the creation of student fellowships. In 2000, the centennial of his paper “Triphenylmethyl, a Case of Trivalent Carbon“, a symposium was held in his memory and a plaque was installed in the Chemistry Building at the University of Michigan designating a National Historic Chemical Landmark. In 1993, the Chemistry Department of the University of Michigan instituted the Moses Gomberg Lecture series to provide assistant professors an opportunity to invite distinguished scientists to the Chemistry department.

 

 

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Gomberg never married, living quietly, sharing a house in Ann Arbor with his sister Sonia, for his adult life. Her health began to fail around the time of his retirement, and he spent most of the rest of his life caring for her. She died when Gomberg was 71. Gomberg died on February 12, 1947, four days after his 81st birthday. Those who knew Gomberg remembered him as kind, generous and modest, as well as a man with strong convictions. He was unfailingly courteous.

 

In medicine, understanding free radicals, particularly those formed by oxygen, has illuminated the nature of oxidative stress – damage that results when free radicals form faster than the body removes them. This, in turn, has revealed ways human health can be improved – for example, by using antioxidants. We now recognize that many free radicals are essential components of enzymes in the body, while others can damage DNA, leading to cancer or other diseases. We know, for example, that free radicals formed by excessive exposure to the sun’s ultraviolet light can lead to cataracts.

 

Many free radical processes involve chain reactions that begin when an unpaired electron fails to find another unpaired electron with which it can easily bond. The free radical removes an atom (usually hydrogen) from another molecule, turning itself into a stable molecule; the molecule it attacked becomes a free radical. Such chain reactions are used to make environmentally friendly products such as recyclable automobile tires and soaps free of salts.

 

Gomberg’s free radicals leave a wide-reaching legacy.

 

Conventional polymerization continued to be used to produce nylon and other products. But free radical polymerization had advantages such as high tolerance of chemical impurities and extreme temperatures, and the ability to be used with a wide range of monomers (organic molecules). Today, free radicals are used to produce nearly half the polymers we use – materials used in everything from food wrapping to paint, adhesives, film, carpeting, piping, and more. Although Gomberg is best known for his discovery of organic free radicals, he made many other contributions to organic and applied chemistry. He developed new solvents for automobile lacquers, the first antifreeze compound used in cars, and a procedure for producing mustard gas during World War I. He received honorary degrees from the University of Chicago, Brooklyn Polytechnic Institute, and the University of Michigan, as well as three medals from the American Chemical Society: the Nichols Medal in 1914, the Willard Gibbs Medal in 1925, and the Chandler Medal in 1927. He was elected to the National Academy of Sciences in 1914, and served as president of the American Chemical Society in 1931.Click here to read more about the life of this genius.

 

 

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The Discovery of Organic Free Radicals by Moses Gomberg“ commemorative booklet produced by the National Historic Chemical Landmarks program of the American Chemical Society in 2000.

 

A Landmark Designation: The American Chemical Society designated the discovery of organic free radicals by Moses Gomberg as a National Historic Chemical Landmark in a ceremony at the University of Michigan in Ann Arbor, Michigan, on June 25, 2000, during the 100thanniversary of the discovery. The plaque commemorating the event reads:

 

In 1900, Moses Gomberg, Professor of Chemistry at the University of Michigan, confirmed the existence of a stable, trivalent organic free radical: triphenylmethyl. In so doing, he challenged the then prevailing belief that carbon could have only four chemical bonds. Gomberg’s discovery made a major contribution to theoretical organic chemistry and fostered a field of research that continues to grow and expand. Today, organic free radicals are widely used in plastics and rubber manufacture, as well as medicine, agriculture and biochemistry.

 

National Historic Chemical Landmark Honoring Professor Moses Gomberg Dedicated June 25, 2000, at the University of Michigan in Ann Arbor, Michigan. Commemorative Booklet)

 

 

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Portrait of Moses Gomberg (undated)

 

Sources: Moses Gomberg (University of Michigan Faculty History Project); Moses Gomberg, 1866-1947 (National Academy of Sciences); Wikipedia

 

 

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Portrait of Moses Gomberg. Courtesy Bentley Historical Library, University of Michigan. 

 

Landmark Designation and Acknowledgments

 

Landmark Designation

The American Chemical Society designated the discovery of organic free radicals by Moses Gomberg as a National Historic Chemical Landmark in a ceremony at the University of Michigan in Ann Arbor, Michigan, on June 25, 2000, during the 100thanniversary of the discovery. The plaque commemorating the event reads:

 

In 1900, Moses Gomberg, Professor of Chemistry at the University of Michigan, confirmed the existence of a stable, trivalent organic free radical: triphenylmethyl. In so doing, he challenged the then prevailing belief that carbon could have only four chemical bonds. Gomberg’s discovery made a major contribution to theoretical organic chemistry and fostered a field of research that continues to grow and expand. Today, organic free radicals are widely used in plastics and rubber manufacture, as well as medicine, agriculture and biochemistry.

 

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