Archibald Scott Couper
Encyclopedia
Archibald Scott Couper was a Scottish chemist who proposed an early theory of chemical structure and bonding. He developed the concepts of tetravalent carbon atoms linking together to form large molecules, and that the bonding order of the atoms in a molecule can be determined from chemical evidence.

Life and work

Couper was the only surviving son of a wealthy textile mill owner near Glasgow
Glasgow
Glasgow is the largest city in Scotland and third most populous in the United Kingdom. The city is situated on the River Clyde in the country's west central lowlands...

. He studied at the universities of Glasgow
University of Glasgow
The University of Glasgow is the fourth-oldest university in the English-speaking world and one of Scotland's four ancient universities. Located in Glasgow, the university was founded in 1451 and is presently one of seventeen British higher education institutions ranked amongst the top 100 of the...

 and Edinburgh
University of Edinburgh
The University of Edinburgh, founded in 1583, is a public research university located in Edinburgh, the capital of Scotland, and a UNESCO World Heritage Site. The university is deeply embedded in the fabric of the city, with many of the buildings in the historic Old Town belonging to the university...

 and intermittently in Germany during the years 1851-54. He began the formal study of chemistry at the University of Berlin in the fall of 1854, then in 1856 entered Charles Adolphe Wurtz's private laboratory at the Faculty of Medicine in Paris (now the University of Paris V: René Descartes
University of Paris V: René Descartes
Paris Descartes University, is one of the main Paris universities, with a strong focus on:* Medical Sciences...

).

Couper published his "New Chemical Theory" in French in a condensed form on 14 June 1858, then in detailed papers simultaneously in French and English in August 1858. Couper's idea that carbon atoms can link to each other following valence regularities was independent of a paper by August Kekulé
Friedrich August Kekulé von Stradonitz
Friedrich August Kekule von Stradonitz was a German organic chemist. From the 1850s until his death, Kekule was one of the most prominent chemists in Europe, especially in theoretical chemistry...

 proposing the same concept. (Kekulé had already proposed the tetravalence of carbon in 1857.) However, through a misunderstanding with Wurtz, Kekulé's paper appeared in print first, in May 1858, and so Kekulé captured the priority for the discovery of the self-linking of carbon atoms. When Couper angrily confronted Wurtz, Wurtz expelled him from the laboratory.

In December 1858, Couper received an offer of an assistantship from the University of Edinburgh. However, Couper's health began to decline after this disappointment. In May 1859 he suffered a nervous breakdown, and entered an institution as a private patient. Released in July 1859, he almost immediately suffered a relapse—it was said to have been from sunstroke—and was treated again until November 1862. But his health was now broken, and he did no more serious work, spending the last 30 years of his life in the care of his mother.

Couper's research differed from Kekulé's in several ways. He was open to the idea of divalent carbon, which Kekulé was not. He provided many more resolved formulas in his paper than Kekulé had, and in two cases even suggested (hetero)cyclical formulas, which could have influenced Kekulé in his later suggestion of the benzene ring. Couper adopted the atomic weight of oxygen as 8 rather than 16, so there are twice as many oxygen atoms in Couper's formulas as in those of Kekulé. Finally, Couper used dotted lines or dashes between the atoms in his formulas, approximating the appearance of later formula styles. In this respect, his work was probably influential on the early structural theorists Aleksandr Mikhailovich Butlerov and Alexander Crum Brown
Alexander Crum Brown
Alexander Crum Brown FRSE FRS was a Scottish organic chemist.-Biography:Born in Edinburgh, the half-brother of the physician and essayist John Brown, he studied for five years at the Royal High School, succeeded by one year at Mill Hill School in London...

.

External links

- See also Alembic Club Reprint #21, On a New Chemical Theory and Researches on Salicylic Acid.
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