Walter Julius Reppe (29 July 1892 in Göringen – 26 July 1969 in Heidelberg) was a German chemist. He is notable for his contributions to the chemistry of acetylene.

Education and career

Walter Reppe began his study of the natural sciences University of Jena in 1911. Interrupted by the

First World War World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

, he obtained his doctorate in

Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the third-largest city in Germany, after Berlin and ...

in 1920. In 1921, Reppe worked for BASF's main laboratory. From 1923, he worked on the catalytic dehydration of formamide to

prussic acid Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an in ...

in the indigo laboratory, developing this procedure for industrial use. In 1924, he left research for 10 years, only resuming it in 1934.

Acetylene chemistry

Reppe began his interest in acetylene in 1928. Acetylene is a gas which can take part in many chemical reactions. However, it is explosive and accidents often occurred. Because of this danger, small quantities of acetylene were used at a time, and always without high pressures. In fact, it was forbidden to compress acetylene over 1.5 bar at BASF. To work with acetylene safely, Reppe designed special test tubes, the so-called "Reppe glasses" — stainless steel spheres with screw-type cap, which permitted high pressure experiments. The efforts ended finally with a large number of interrelated reactions, known as ''Reppe chemistry''.

"Reppe Chemie"

The high pressure reactions catalysed by heavy metal acetylides, especially copper acetylide, or metal carbonyls are called Reppe chemistry. Reactions can be classified into four large classes: * The vinylization according to the equation: : * Catalytic ethynylation of aldehydes: : * Reactions with carbon monoxide: : : This simple synthesis was used to prepare acrylic acid derivatives for the production of acrylic glass. * The cyclic polymerization or cyclo-oligomerization of acetylene to cyclooctatetraene, which is one of the most important applications of template reactions. The reaction occurs at a nickel(II) centre, where it is supposed that four acetylene molecules occupy four sites around the metal, and react simultaneously to give the product. : If a competing ligand such as

triphenylphosphine Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists ...

is present in sufficient proportion to occupy one coordination site, then room is left for only three acetylene molecules, and these come together to form benzene : This reaction provided an unusual route to benzene and especially to cyclooctatetraene, which was difficult to prepare otherwise. Products from these four reaction types proved to be versatile intermediates in the syntheses of lacquers, adhesives, foam materials, textile fibers, and pharmaceuticals could now be produced.

Post-war

After the Second World War, Reppe led the research of BASF from 1949 up to his retirement in 1957. From 1952 to 1966, he also sat on the supervisory board. He was also a professor at the University of Mainz and TH Darmstadt from 1951 and 1952 respectively. Together with

Otto Bayer Otto Bayer (4 November 1902 – 1 August 1982) was a German industrial chemist at IG Farben who was head of the research group that in 1937 discovered the polyaddition for the synthesis of polyurethanes out of poly- isocyanate and polyol. ...

and

Karl Ziegler Karl Waldemar Ziegler (26 November 1898 – 12 August 1973) was a German chemist who won the Nobel Prize in Chemistry in 1963, with Giulio Natta, for work on polymers. The Nobel Committee recognized his "excellent work on organometallic compound ...

he received the Werner von Siemens Ring in 1960 for expanding the scientific knowledge on and for the technical development of new synthetic high-molecular materials.

Legacy

Most of the industrial processes that were developed by Reppe and coworkers have been superseded, largely because the chemical industry has shifted from coal as feedstock to oil. Alkenes from thermal cracking are readily available, but acetylene is not. Together with his contemporaries Otto Roelen,

Hans Tropsch Hans Tropsch (October 7, 1889 – October 8, 1935) was a chemist responsible, along with Franz Fischer, for the development of the Fischer–Tropsch process. Life Tropsch was born in Plan bei Marienbad, Sudet-German Bohemia at that time part o ...

, and Franz Fischer, Reppe was a leader in demonstrating the utility of metal-catalyzed reactions in large scale synthesis of organic compounds. The economic benefits demonstrated by this research motivated the eventual flowering of organometallic chemistry and its close connection to industry.

References