Walter Reppe
Walter Julius Reppe (b. 29 July 1892 in Goringen, d. 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, he obtained his doctorate in Munich in 1920.
In 1921, Reppe worked for BASF's main laboratory. From 1923, he worked on the catalytic dehydration of formamide to prussic acid 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 was 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.
Reactions at such low pressures did not correspond at all to the traditions at BASF, and one could expect no useful process engineering results. Reppe commented in 1949 retrospectively: "therefore the necessity resulted to break with all delivered opinions and to study first of all the acetylene decay with consideration of the most diverse test conditions of reason on, in order to determine suitable safety precautions, one safe working also in the industrial yardstick made possible." 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 interconnected reactions, known as Reppe chemistry.

# Reppe chemistry
The high pressure reactions catalysed by heavy metal acetylides, especially copper acetylide, or metal carbonyls is called Reppe Chemistry. Reactions can be classified into four large classes:
- The vinylization according to the equation:
File:Reppe-chemnistry-vinylization.png
- Preparing ethynyldiols from aldehydes according to the equation:
File:Reppe-chemistry-endiol.png
- Reactions with carbon monoxide:
File:Reppe-chemistry-carbonmonoxide-01.png
File:Reppe-chemistry-carbonmonoxide-02.png
This simple synthesis was used to prepare acrylic acid derivatives for the production of acrylic glass.
- The cyclic polymerization
File:Reppe-chemistry-benzene.png
File:Reppe-chemistry-cyclooctatetraene.png
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 and Karl Ziegler 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 acetylenes are expensive, high energy species relative to alkenes which are more cheaply produced.  Together with his contemporaries Otto Roelen, Karl Ziegler, Hans Tropsch, and Franz Joseph Emil 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.

# Publications
- Neue Entwicklungen auf dem Gebiet der Chemie des Acetylen und Kohlenoxyds (New developments in the area of the chemistry acetylene and carbon monoxide). Springer Berlin, Gottingen, Heidelberg. 1949.  184 pages.
- Reppe, W.; Schlichting, O.; Klager, K.; Toepel, T. (1948). "Cyclisierende Polymerisation von Acetylen I Uber Cyclooctatetraen". Justus Liebigs Ann. Chem.: 193.CS1 maint: Multiple names: authors list (link) .mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
- Reppe, W.; Schlichting, O.; Meister, H. (1948). "Cyclisierende Polymerisation von Acetylen II Uber die Kohlenwasserstoffe C10H10 C12H12 Azulen". Justus Liebigs Ann. Chem.: 93104.CS1 maint: Multiple names: authors list (link)
- Reppe, W.;  Schweckendiek W. J (1948). "Cyclisierende Polymerisation von Acetylen III Benzol, Benzolderivate und hydroaromatische Verbindungen". Justus Liebigs Ann. Chem.: 104116.CS1 maint: Multiple names: authors list (link)