Charles-Adolphe Wurtz and the Atomic Theory

Charles-Adolphe Wurtz (1817-1884)

Charles-Adolphe Wurtz (1817-1884)

On November 26, 1817, Alsatian French chemist and educator Charles-Adolphe Wurtz was born. Wurtz is best remembered for his decades-long advocacy for the atomic theory and for ideas about the structures of chemical compounds, against the skeptical opinions of chemists such as Marcellin Berthelot and Etienne Henri Sainte-Claire Deville. He is well known by organic chemists for the Wurtz reaction, to form carbon-carbon bonds by reacting alkyl halides with sodium, and for his discoveries of ethylamine, ethylene glycol, and the aldol reaction.

Early Years and Academic Career

Chalrles-Adolphe Wurtz was born in Strasbourg, where his father, Johann Jacob Wurtz, was a Lutheran pastor in the nearby town of Wolfisheim. He grew up in a rather modest but cultured home that was intellectually stimulating and part of a healthy agricultural community.[4] When he left the Protestant gymnasium at Strasbourg in 1834, his father allowed him to study medicine as next best to theology. He devoted himself specially to the chemical side of his profession with such success that in 1839 he was appointed Chef des travaux chimiques at the Strasbourg faculty of medicine. For the summer semester of 1842 he studied under Justus von Liebig at the University of Giessen.[6]

After graduating from Strasbourg as M.D. in 1843, with a thesis on albumin and fibrin, he went to Paris, where he first was referred by Jean Baptiste Dumas to Antoine Balard. In 1845, he became assistant to Dumas at the École de Médecine, and four years later began to give lectures on organic chemistry in his place. As there was no laboratory at his disposal at the Ecole de Médecine, he opened a private one in 1850. In the same year, he received the professorship of chemistry at the new Institut National Agronomique at Versailles, but the Institut was abolished in 1852 and Wurtz was appointed to the newly defined post of “organic and mineral chemistry”, and became dean of the Faculty of Medicine in 1866.

A Reform in Chemical Theory

Remarkable among Wurtz’s earliest discoveries was his fulfillment of Liebig’s prediction that there might be organic compounds analogous to ammonia and derivable from it by the replacement of hydrogen.[4] Influenced by such leading figures as Liebig and Dumas, by 1856 Wurtz became a powerful advocate of a reform in chemical theory then being led by Charles Gerhardt and Alexander Williamson, which took the idea of chemical atoms seriously, adopted atomic weights for the elements that strongly resemble the modern ones, and proposed a unitary schematic plan that opposed the dualistic theory derived from the work of Jöns Jacob Berzelius [1]. Soon thereafter, Wurtz also adopted the new structural theory that was developing from the work of younger chemists such as August Kekulé.[2] Wurtz’s first published paper was on hypophosphorous acid (1841), and the continuation of his work on the acids of phosphorus (1845) resulted in the discovery of sulfophosphoric acid and phosphorus oxychloride, as well as of copper hydride. But his original work was mainly in the domain of organic chemistry. Investigation of the cyanic ethers (1848) yielded a class of substances which opened out a new field in organic chemistry, for, by treating those ethers with caustic potash, he obtained methylamine, the simplest organic derivative of ammonia (1849), and later (1851) the compound ureas.

The Wurtz Reaction

In 1855, reviewing the various substances that had been obtained from glycerin, he reached the conclusion that glycerin is a body of alcoholic nature formed on the type of three molecules of water, as common alcohol is on that of one, and was thus led (1856) to the discovery of the glycols or diatonic alcohols, bodies similarly related to the double water type. In 1855, he published work on what is now known as the Wurtz reaction, a kind of coupling reaction that begins with a single electron transfer (SET) from sodium metal to the alkyl halide, which dissociates to form an alkyl radical and sodium halide salt. Another molecule of sodium performs another SET to the alkyl radical to form a nucleophilic carbanion. The carbanion then attacks another molecule of alkyl halide in a nucleophilic substitution reaction (SN2) to form the final coupled product and another molecule of sodium halide salt.[3]

In 1867 Wurtz and August Kekule prepared phenol. With Marcellin Berthelot he succeeded in making Paris one of Europe’s leading centres of chemical education.[4] In 1872 he discovered the aldol reaction and characterized the product as showing the properties of both an alcohol and an aldehyde, which was independently co-discovered by Alexander Borodin.

Later Years

For twenty-one years (1852–1872) Wurtz published in the Annales de chimie et de physique abstracts of chemical work done out of France. The publication of his great Dictionnaire de chimie pure et appliquée, in which he was assisted by many other French chemists, was begun in 1869 and finished in 1878. One of Wurtz’s most popular works was Latheorie atomique (1879). Its title denoted more than the atomic‐molecular theory of Avogadro or Ampere; it designated a theory that incorporated the idea of combining power or atomicity of the atoms–a new concept for which Wurtz had helped to clear the ground. He had done so by contributing to the notion of polyatomic organic radicals and by clarifying the distinctions between affinity, basicity, and atomicity.[4]

Wurtz was an honorary member of almost every scientific society in Europe. He was the principal founder of the Paris Chemical Society (1858), was its first secretary and thrice served as its president. In 1880, he was vice-president and in 1881 president of the French Academy of Sciences, which he entered in 1867. In 1881, Wurtz was elected life senator. Wurtz’s name is one of the 72 names inscribed on the Eiffel tower.

Charles Adolphe Wurtz died in Paris in 1884, aged 66.

James S. Nowick, Organic Chemistry 51C. Lecture 03. Reactions of Organometallic Reagents, [8]

References and Further Reading:

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