Adolf Karl Ludwig Claus
Encyclopedia
Adolf Karl Ludwig Claus (6 June 1838 – 4 May 1900) was a German
chemist
. He is known for his structure of benzene
proposed in 1867.
, Germany. Starting from 1850, he studied medicine in Marburg and later chemistry at the University of Marburg, with Hermann Kolbe. After spending a short time at the University of Berlin
, he worked with Friedrich Wöhler
at the University of Göttingen. He received his PhD in 1862, and in the same year changed his position and started working at the University of Freiburg
. He completed his habilitation
in 1866 and became assistant professor in the following year. With the retirement of Lambert Heinrich von Babo
, Claus succeeded him as full professor. He held that position until his retirement due to health problems in 1900. Clause died in Horheim near Wutöschingen
in the same year.
s, aromatic substitution
, oximes and theoretical considerations on the structure of organic molecules. Claus is best known for proposing a model of benzene
molecule in 1867.
In his model, the six carbon atoms of benzene form a hexagon with a hydrogen atom attached to every corner. To preserve valence 4 for carbons, the opposite corners of the hexagon are connected by single bonds. It took years of research before the three postulated structures of benzene – by Albert Ladenburg
(1869), August Kekulé 1865 and by Claus – found their place in organic chemistry. Ladenburg's prismane
and Claus' benzene
were both proven to be wrong. While the prismane was synthesized in 1973, calculations showed that the synthesis of Claus' benzene
is impossible.
Claus synthesized and determined the structure of several isomers of oxime
s. He described the isomerism by differences in the bond structure of the molecules whereas several other scientists found it more convincing to describe the difference by the relatively new concept of stereochemistry
. This scientific dispute lasted until his death in 1900.
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
chemist
Chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...
. He is known for his structure of benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
proposed in 1867.
Life
Claus was born in 1838 in KasselKassel
Kassel is a town located on the Fulda River in northern Hesse, Germany. It is the administrative seat of the Kassel Regierungsbezirk and the Kreis of the same name and has approximately 195,000 inhabitants.- History :...
, Germany. Starting from 1850, he studied medicine in Marburg and later chemistry at the University of Marburg, with Hermann Kolbe. After spending a short time at the University of Berlin
Humboldt University of Berlin
The Humboldt University of Berlin is Berlin's oldest university, founded in 1810 as the University of Berlin by the liberal Prussian educational reformer and linguist Wilhelm von Humboldt, whose university model has strongly influenced other European and Western universities...
, he worked with Friedrich Wöhler
Friedrich Wöhler
Friedrich Wöhler was a German chemist, best known for his synthesis of urea, but also the first to isolate several chemical elements.-Biography:He was born in Eschersheim, which belonged to aau...
at the University of Göttingen. He received his PhD in 1862, and in the same year changed his position and started working at the University of Freiburg
University of Freiburg
The University of Freiburg , sometimes referred to in English as the Albert Ludwig University of Freiburg, is a public research university located in Freiburg im Breisgau, Baden-Württemberg, Germany.The university was founded in 1457 by the Habsburg dynasty as the...
. He completed his habilitation
Habilitation
Habilitation is the highest academic qualification a scholar can achieve by his or her own pursuit in several European and Asian countries. Earned after obtaining a research doctorate, such as a PhD, habilitation requires the candidate to write a professorial thesis based on independent...
in 1866 and became assistant professor in the following year. With the retirement of Lambert Heinrich von Babo
Lambert Heinrich von Babo
Lambert Heinrich von Babo was a German chemist.-Life:Babo was the son of the agronomist Lambert Joseph von Babo and his first wife Karoline Ehrmann. The oenologist August Wilhelm von Babo was his half-brother...
, Claus succeeded him as full professor. He held that position until his retirement due to health problems in 1900. Clause died in Horheim near Wutöschingen
Wutöschingen
Wutöschingen is one of the 25 municipalities in the Waldshut district of Baden-Württemberg, Germany....
in the same year.
Work
Claus mostly worked in organic chemistry where his interests were very diverse and included alkaloidAlkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...
s, aromatic substitution
Substitution reaction
In a substitution reaction, a functional group in a particular chemical compound is replaced by another group. In organic chemistry, the electrophilic and nucleophilic substitution reactions are of prime importance...
, oximes and theoretical considerations on the structure of organic molecules. Claus is best known for proposing a model of benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
molecule in 1867.
In his model, the six carbon atoms of benzene form a hexagon with a hydrogen atom attached to every corner. To preserve valence 4 for carbons, the opposite corners of the hexagon are connected by single bonds. It took years of research before the three postulated structures of benzene – by Albert Ladenburg
Albert Ladenburg
Albert Ladenburg was a German chemist.-Biography:Ladenburg was a member of a well known Jewish family in Mannheim. He was educated at a Realgymnasium at Mannheim and then, after the age of 15, at the technical school of Karlsruhe, where he studied mathematics and modern languages...
(1869), August Kekulé 1865 and by Claus – found their place in organic chemistry. Ladenburg's prismane
Prismane
Prismane is a polycyclic hydrocarbon with the formula C6H6. It is an isomer of benzene, more specific: a valence isomer. Prismane is far less stable than benzene. The carbon atoms of the prismane molecule are arranged in the shape of a six-atom triangular prism. Albert Ladenburg proposed this...
and Claus' benzene
Claus' benzene
Claus' benzene is a hypothetical hydrocarbon and an isomer of benzene . It was proposed by Adolf Karl Ludwig Claus in 1867 as a possible structure for benzene at a time when the structure of benzene was debated...
were both proven to be wrong. While the prismane was synthesized in 1973, calculations showed that the synthesis of Claus' benzene
Claus' benzene
Claus' benzene is a hypothetical hydrocarbon and an isomer of benzene . It was proposed by Adolf Karl Ludwig Claus in 1867 as a possible structure for benzene at a time when the structure of benzene was debated...
is impossible.
Claus synthesized and determined the structure of several isomers of oxime
Oxime
An oxime is a chemical compound belonging to the imines, with the general formula R1R2C=NOH, where R1 is an organic side chain and R2 may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted oximes form a closely related family of compounds...
s. He described the isomerism by differences in the bond structure of the molecules whereas several other scientists found it more convincing to describe the difference by the relatively new concept of stereochemistry
Stereochemistry
Stereochemistry, a subdiscipline of chemistry, involves the study of the relative spatial arrangement of atoms within molecules. An important branch of stereochemistry is the study of chiral molecules....
. This scientific dispute lasted until his death in 1900.