Couper received most of his early education at home and then went to Glasgow University for study in the humanities and classical languages.
Gallery of Archibald Couper
Old College, South Bridge, Edinburgh EH8 9YL, United Kingdom
In August 1852 Couper entered the University of Edinburgh, studying logic and metaphysics under Sir William Hamilton while continuing his language studies.
Old College, South Bridge, Edinburgh EH8 9YL, United Kingdom
In August 1852 Couper entered the University of Edinburgh, studying logic and metaphysics under Sir William Hamilton while continuing his language studies.
Archibald Scott Couper was a Scottish chemist. He proposed the tetravalency of carbon and the ability of carbon atoms to bond with one another.
Background
Couper was born on March 31, 1831, in Kirkintilloch, Scotland, the only surviving son of Archibald and Helen Dollar Couper. His father was the proprietor of a large cotton-weaving business that had been owned by the family for several generations.
Education
Couper received most of his early education at home and then went to Glasgow University to study in the humanities and classical languages. The summers of 1851 and 1852 he spent in Germany, and in August 1852 he entered the University of Edinburgh, studying logic and metaphysics under Sir William Hamilton while continuing his language studies.
During the year 1854-1855 Couper moved to Berlin, where, sometime before his departure for Paris in 1856, he chose chemistry as his field of major interest. He is known to have attended Sonnenschein’s lectures in analytical chemistry at the University of Berlin, and to have worked two months in his laboratory.
After moving to Paris in August 1856, Couper engaged in independent research in the laboratory of Charles Adolphe Wurtz. His first publication - on the bromination of benzene - appeared in August 1857. His other experimental paper, on salicylic acid, was published in 1858. Early in 1858 Couper asked Wurtz to have presented before the French Academy of Sciences a paper entitled “On a New Chemical Theory.” Wurtz, not a member of the Academy, procrastinated before finding someone to present it. In the intervening period Kekulé’s paper, dated 19 May 1858, appeared in Liebig’s Annalen. Couper’s paper - on essentially the same topic - was presented to the French Academy by J. B. A. Dumas in June and was published soon thereafter. Kekulé attacked the paper almost immediately, claiming priority and greater significance for his own work. He also questioned Couper’s researches on salicylic acid and, since Couper never answered, his name was long forgotten.
Couper complained to Wurtz about the delay in presenting his paper and was asked to leave the laboratory. He returned to Scotland in the fall of 1858 and accepted a position as second laboratory assistant to Lyon Playfair, professor of chemistry at Edinburgh University. Soon after beginning his duties he suffered a mental breakdown, underwent treatment, apparently recovered, and went on a fishing expedition, during which, reportedly due to extended exposure to the sun, his illness returned. He never fully recovered and lived in retirement for the remaining thirty-four years of his life.
Coming to chemistry from a study of philosophy and classical languages, Couper viewed the complex chemical formulas of his time as if they were words of a foreign language. Having ascertained these, the composition and structure of every possible word is revealed. By this mode of reasoning he deduced that carbon has a valence, or combining power, of two or four and that it has the power to form valence links with other carbon atoms, thus making possible carbon chains. These two principles are the foundation of the structural theory of organic chemistry. Kekulé had proposed the tetravalence of carbon the previous year. Couper then devised a pictorial representation of chemical compounds using dotted lines, solid lines, or brackets to show the linkings between atoms in the molecule. These formulas represent the first introduction of the valence line into organic formulas. Since Couper used an atomic weight of eight for oxygen, his formulas always contain a pair of oxygen atoms instead of the single atom used today.
In 1858 Couper introduced the first ring formula into organic chemistry, to represent the structure of cyanuric acid. Kekulé’s ring structure for benzene appeared in 1865. Couper’s formulas for salicylic and cyanuric acids show some of the carbons as having a valence of two. Couper maintained that several elements, such as carbon, notrogen, and phosphorous, exhibit multiple valence. Kekulé strongly opposed such a view.
Achievements
Views
Couper’s experimental paper dealt with the constitution of the benzene derivative salicylic acid, a subject that a number of chemists, including Kekulé, had been investigating. Treating the acid with phosphorus pentachloride, Couper claimed to have obtained the “trichlorophosphate de salicyle.” He proposed detailed structural formulas for the acid and its derivatives. This represented the first time that the relations between the individual carbon atoms of benzene had been depicted in a formula.
Connections
It is not known whether Couper had his own family.