Alfred Stock

Alfred Stock (July 16 1876 – August 12 1946) was a German inorganic chemist. He did pioneering research on the hydrides of boron and silicon, coordination chemistry, mercury, and mercury poisoning. The German Chemical Society's Alfred-Stock Memorial Prize is named after him.

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Life

Born in Danzig (Gdańsk) and educated at Berlin, he was nine years assistant of Emil Fischer before he became professor at the University of Breslau in 1900. In 1916 he succeeded Richard Willstätter as director at the Kaiser Wilhelm Institute for Chemistry in Berlin. After a severe mercury poisoning he became the director of the Chemistry Department at the Technische Hochschule in Karlsruhe from 1926 to 1936. He was renowned for his pioneering research on boron hydrides.^[1]

Research on the hydrides of boron and silicon

Stock began studying the boron hydrides - the boron hydrogen chemical compounds with general formula B_xH_y - since 1909 at Breslau. Due to their extreme reactivity and flammability in air, boron hydrides could not be purified until his development of methods for separation using high-vacuum manifolds around 1912. He performed similar work on the hydrides of silicon. The hydrides of boron and silicon represented the first family of binary compounds to approach the richness of hydrocarbons in terms of structural diversity. Not only did the boron hydrides exhibit challenging properties, their structures were also unusual. Elucidation of the structures and the associated bonding models dramatically expanded the scope of inorganic chemistry. Boron hydrides such as diborane later developed into a range of reagents for organic synthesis as well as a source of diverse ligands and building blocks for researchers.

Research on other areas of inorganic chemistry

In 1921, he first prepared metallic beryllium by electrolyzing a fused mixture of sodium and beryllium fluorides. This method made beryllium available for industrial use, as in special alloys and glasses and for making windows in X-ray tubes.

He was also influential in coordination chemistry. The term "ligand" (from ligare Latin, to bind) was first used by Stock in 1916.^[2] H. Irving and R.J.P. Williams adopted the term in a paper published in 1948.^[3] Monodentate, bidentate, tridentate characterized the number of ligands attached to a metal. Given the introduction of ligand concept, he was also able to further derive the idea of bite angle and other aspects of chelation.

The "Stock system," first published in 1919, was a means of nomenclature on binary compounds. In his own words, he considered the system to be "simple, clear, immediately intelligible, capable of the most general application." In 1924, a German commission recommended Stock system to be adopted with some accommodations. FeCl₂, which would have been named iron(2)-chloride according to Stock's original idea, became iron(II) chloride in the revised proposal. In 1934 Stock agreed to the use of Roman numerals but preferred keeping the hyphen and dropping the parentheses. Although this suggestion has not been followed, the Stock system remains in use worldwide.

Interests in mercury and mercury poisoning

He published over 50 papers on different aspects of mercury and mercury poisoning.^[4] He also introduced sensitive tests and devised improved laboratory techniques for dealing with mercury which minimized poisoning risk, possibly initiated by his chronic mercury poisoning in 1923. He became more vocal on protesting the mercury usage after realizing the toxicity of its organic derivatives. German dentists abandoned his warning in 1928 against copper amalgam usage. Nevertheless a paper from Fleischmann, in which removal of mercury in amalgam-related illness had led to complete recovery, supported his idea. (Deutsche Medizinische Wochenschrift 1928, No. 8). A committee was founded in Berlin to investigate cases of possible mercury intoxication and hence the term micromercurialism was first used.^[5]

Retirement and death

After retirement in 1936, he moved from Karlsruhe to Berlin. He died at Aken an der Elbe, a small town near Dessau, in August 1946 at the age of 70.

Posthumous recognition

In recognition of his contributions to the field of inorganic chemistry, the German Chemical Society (Gesellschaft Deutscher Chemiker) posthumously created in 1950 the Alfred-Stock Memorial Prize (Alfred-Stock-Gedächtnispreis). The prize, consisting of a gold medal and money, is awarded annually for "an outstanding independent scientific experimental investigation in the field of inorganic chemistry."^[6]

References