PURDIE, THOMAS

(b. Biggar, Lanarkshire, Scotland, 27 January 1843 d. St. Andrews, Scotland, 14 December 1916)

chemistry.

Purdie’s father, a banker, died in Thomas’s early childhood, and he was brought up by his mother, well supported by his paternal uncle, a wealthy Edinburgh businessman. He was educated at the Edinburgh Academy and after an abortive start at a business career, Purdie and his cousin traveled to South America, where in the 1860’s they purchased a farm in Argentina. After seven years a combination of bad harvests, political unrest, and Indian trouble brought the venture to a close, and Purdie returned to Britain. At the age of twenty-nine he enrolled in the Royal School of Mines in 1872. There he came under the influence of Thomas Huxley and Sir Edward Frankland. After his graduation with a B.Sc. in 1875, Frankland appointed Purdie demonstrator in the chemical laboratories of the Royal College of Science at South Kensington, a post he held for three years. In 1878 Purdie traveled to Germany to study at the University of Würzburg under Johannes Wislicenus. That same year he married Marianne Rotherham.

While studying for the Ph.D., Purdie met the Cambridge botanist Sydney Howard Vines and the chemists Percy Faraday Frankland and William Henry Perkin, Jr. After obtaining the Ph.D. at Würzburg in 1880, Purdie returned to England in 1881. Unable to obtain a university post, he taught chemistry at the grammar school of Newcastle-under-Lyme until 1884. In that year, aged forty-six, he succeeded to the chair of chemistry at St. Andrews University. Purdie was much influenced in his chemical career by the work of his mentor Wislicenus, who had led the extension and application of the stereochemical ideas of Jacobus Van’t Hoff and G. Bell in German universities. Purdie is best remembered for his role in the development of research into optical activity and stereochemistry in Britain at the turn of the century, and for the manner in which he built the small University of St. Andrews into a strong center for research in organic chemistry.

With J. Wallace Waller, Purdie demonstrated a method of resolving racemic lactic acid that was based on the use of strychnine. Following Pasteur’s work with tartaric acid, Purdie showed that racemic lactate can form supersaturated solutions, from which successive seeding with a trace of the optically active modification leads to the separation of the d - and l - forms in alternate crops.

In measuring the magnitude of molecular rotations in some chemical reactions, Purdie discovered an organic reaction that proved to be of great utility. He found that when a hydroxy compound such as an alcohol is treated with dry silver oxide and an alkyl iodide, alkylation of the hydroxy groups proceeds uniformly and smoothly. Purdie was quick to perceive that this “silver oxide” reaction might find extensive scope in work on the structure of sugars, and he directed the energies of his students and collaborators, most notably J. C. Irvine, into this channel. The principle underlying such constitutional studies can be expressed in general terms. By methylation, the free hydroxyl groups of the sugar complex can be protected. The estimate of the number, distribution, and stability of the hydroxyl groups gives definite evidence as to the structure of the parent substance. Walter Norman Haworth, who joined Purdie and Irving at St. Andrews in 1912, later used the methylation technique to establish the pyranose structure of methylglucose.

Purdie’s scientific work was recognized by his election as fellow of the Royal Society (1895) and of the Chemical Society (1875). He was vice president of the Chemical Society in 1899. He was awarded the L.L.D. from Aberdeen University in 1894 and retired from the administrative duties of his chair in 1909. Purdie died of heart failure in 1916.

BIBLIOGRAPHY

I. Original Works. Among Purdie’s important scientific papers are “Action of Sodic Alcoholates on Ethereal Fumarates and Maleates”, in Journal of the Chemical Society, 47 (1885), 855–878; “The Action of Metallic Alkylates on Mixtures of Ethereal Salts with Alcohols”, ibid., 51 (1887), 627–634; and “Resolution of Lactic Acid into Its Optically Active Compounds”, ibid., 61 (1892), 754–765, with James W. Walker. A further list is in Royal Society Catalogue of Scientific Papers, XVII, 1047.

II. Secondary Literature. P. F. F(rankland), “Thomas Purdie”, in Proceedings of the Royal Society, A101 (1922), iv–x; and J. C. Irvine, “Thomas Purdie”, in Journal of the Chemical Society, 111 (1917), 359–369.

Neil Davies Morgan