Friedrich Karl Johannes Thiele (May 13, 1865 – April 17, 1918) was a German

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe t ...

and a prominent professor at several universities, including those 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 H ...

and

Strasbourg Strasbourg (, , ; german: Straßburg ; gsw, label=Bas Rhin Alsatian, Strossburi , gsw, label= Haut Rhin Alsatian, Strossburig ) is the prefecture and largest city of the Grand Est region of eastern France and the official seat of the ...

. He developed many laboratory techniques related to isolation of organic compounds. In 1907 he described a device for the accurate determination of

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depe ...

s, since named Thiele tube after him. Thiele was born in Ratibor,

Prussia Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was '' de facto'' dissolved by an ...

, now

Racibórz Racibórz (german: Ratibor, cz, Ratiboř, szl, Racibōrz) is a city in Silesian Voivodeship in southern Poland. It is the administrative seat of Racibórz County. With Opole, Racibórz is one of the historic capitals of Upper Silesia, bein ...

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...

. Thiele studied

mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...

at the

University of Breslau A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, ...

but later turned to chemistry, receiving his

doctorate A doctorate (from Latin ''docere'', "to teach"), doctor's degree (from Latin ''doctor'', "teacher"), or doctoral degree is an academic degree awarded by universities and some other educational institutions, derived from the ancient formalism ''li ...

from Halle in 1890 . He taught at the

University of Munich The Ludwig Maximilian University of Munich (simply University of Munich or LMU; german: Ludwig-Maximilians-Universität München) is a public research university in Munich, Germany. It is Germany's sixth-oldest university in continuous operati ...

from 1893 to 1902, when he was appointed professor of chemistry at

. He developed the preparation of glyoxal bis(guanylhydrazone). After Kekulé's proposal for benzene structure in 1865, Thiele suggested a "Partial Valence Hypothesis", which concerned

double A double is a look-alike or doppelgänger; one person or being that resembles another. Double, The Double or Dubble may also refer to: Film and television * Double (filmmaking), someone who substitutes for the credited actor of a character * ...

and triple carbon-carbon bonds with which he explains their particular reactivity. In 1899 this led to the prediction of the

resonance Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscilla ...

that existed in

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen a ...

, and he proposed a resonance structure, by using a broken circle to represent the partial bonds. Later this problem was completely solved with the advent of

quantum theory Quantum theory may refer to: Science *Quantum mechanics, a major field of physics * Old quantum theory, predating modern quantum mechanics * Quantum field theory, an area of quantum mechanics that includes: ** Quantum electrodynamics ** Quantum c ...

. In 1899, Thiele was head of

Organic Chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J. ...

at the

Bavarian Academy of Sciences The Bavarian Academy of Sciences and Humanities (german: Bayerische Akademie der Wissenschaften) is an independent public institution, located in Munich. It appoints scholars whose research has contributed considerably to the increase of knowledg ...

. With his associate Otto Holzinger, he synthesised an iminodibenzyl nucleus: two benzene rings attached together by a nitrogen atom and an ethylene bridge. He discovered the condensation of

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bon ...

s and

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...

s with

cyclopentadiene Cyclopentadiene is an organic compound with the formula C5H6.LeRoy H. Scharpen and Victor W. Laurie (1965): "Structure of cyclopentadiene". ''The Journal of Chemical Physics'', volume 43, issue 8, pages 2765-2766. It is often abbreviated CpH bec ...

as a route to

fulvene Fulvene (pentafulvene) is a hydrocarbon with the formula (CH=CH)2C=CH2. It is a prototype of a cross-conjugated hydrocarbon. Fulvene is rarely encountered, but substituted derivatives ( fulvenes) are numerous. They are mainly of interest as ligand ...

s. He also recognized that these deeply colored species were related to but isomeric with benzene derivatives. According to one of his students

Heinrich Otto Wieland Heinrich Otto Wieland (; 4 June 1877 – 5 August 1957) was a German chemist. He won the 1927 Nobel Prize in Chemistry for his research into the bile acids. Career In 1901 Wieland received his doctorate at the University of Munich while studyi ...

, Thiele had a dislike of the chemistry of natural products.

References

{{DEFAULTSORT:Thiele, Johannes 1865 births 1918 deaths People from Racibórz People from the Province of Silesia 19th-century German chemists Ludwig Maximilian University of Munich faculty University of Strasbourg faculty University of Breslau alumni University of Halle alumni 20th-century German chemists