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

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...

and a prominent professor at several universities, including those in

Munich Munich is the capital and most populous city of Bavaria, Germany. As of 30 November 2024, its population was 1,604,384, making it the third-largest city in Germany after Berlin and Hamburg. Munich is the largest city in Germany that is no ...

and

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. 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 of matter, state from solid to liquid. At the melting point the solid and liquid phase (matter), phase exist in Thermodynamic equilib ...

s, since named Thiele tube after him.

Biography

Thiele was born in Ratibor,

Prussia Prussia (; ; Old Prussian: ''Prūsija'') was a Germans, German state centred on the North European Plain that originated from the 1525 secularization of the Prussia (region), Prussian part of the State of the Teutonic Order. For centuries, ...

, now

Racibórz Racibórz (, , , ) 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, being the residence of the Duchy of Racibórz, Du ...

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

. Thiele studied

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

at the University of Breslau but later turned to chemistry, receiving his

doctorate A doctorate (from Latin ''doctor'', meaning "teacher") or doctoral degree is a postgraduate academic degree awarded by universities and some other educational institutions, derived from the ancient formalism '' licentia docendi'' ("licence to teach ...

from Halle in 1890 . He taught at the

University of Munich The Ludwig Maximilian University of Munich (simply University of Munich, LMU or LMU Munich; ) is a public university, public research university in Munich, Bavaria, Germany. Originally established as the University of Ingolstadt in 1472 by Duke ...

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 Double, The Double or Dubble may refer to: Mathematics and computing * Multiplication by 2 * Double precision, a floating-point representation of numbers that is typically 64 bits in length * A double number of the form x+yj, where j^2=+1 * A ...

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

resonance Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximu ...

that existed in

benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...

, 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. In 1899, Thiele was head of

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

at the

Bavarian Academy of Sciences The Bavarian Academy of Sciences and Humanities () is an independent public institution, located in Munich. It appoints scholars whose research has contributed considerably to the increase of knowledge within their subject. The general goal of th ...

. 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 an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...

s and

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

s with

cyclopentadiene Cyclopentadiene is an organic compound with the chemical formula, formula C5H6. It is often abbreviated CpH because the cyclopentadienyl anion is abbreviated Cp−. This colorless liquid has a strong and unpleasant odor. At room temperature, ...

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 ligan ...

s. He also recognized that these deeply colored species were related to but isomeric with benzene derivatives. In 1901 he discovered potassium cyclopentadienyl, but there was little interest in this topic before the discovery of

ferrocene Ferrocene is an organometallic chemistry, organometallic compound with the formula . The molecule is a Cyclopentadienyl complex, complex consisting of two Cyclopentadienyl anion, cyclopentadienyl rings sandwiching a central iron atom. It is an o ...

in 1951. According to one of his students Heinrich Otto Wieland, Thiele had a dislike of the chemistry of natural products.

References

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