Fulvene

Fulvene , the parent compound of the group of substances fulvenes

Fulvenes are a subgroup of hydrocarbons in organic chemistry . They can be systematically referred to as methylenecyclopentadienes. Johannes Thiele was the first to describe them.

presentation

Simple fulvenes are formed by condensation of cyclopentadiene with carbonyl compounds . Derivatives of fulvene substituted on the exocyclic carbon atom can be prepared from cyclopentadiene and other carbonyl compounds (e.g. aldehydes - such as acetaldehyde - or ketones ).

properties

Fulvenes are intensely colored and very reactive compounds that can be used as synthetic building blocks and ligands in organometallic compounds . The parent compound of the group of substances is the eponymous fulvene (5-methylene-1,3-cyclopentadiene), a highly toxic, yellowish, oily liquid that polymerizes easily. The fulvenes were discovered in 1900 by the chemist Johannes Thiele . Fulvene itself is yellow in color, dimethylfulvene is bright orange. Fulvenes are characterized by crossed conjugated double bonds and, like the azulenes, belong to the hydrocarbons with a non-alternating conjugation system. They have considerable dipole moments and have a low resonance energy and are therefore quite reactive. They behave like intermediates between aromatic and unsaturated aliphatic compounds. They are easily be hydrogenated and are subject to auto-oxidation and polymerization . On the other hand, in the five-membered ring they enter into substitution reactions like aromatics. The fulvene compound class also includes the fulvalenes , pentalenes and other condensed systems such as azulenes in a broader sense .

literature

Johannes Thiele: About ketone reactions in the Cyclopentadiene . In: Reports of the German Chemical Society . tape 33 , no. 1 , January 1900, p. 666–673 , doi : 10.1002 / cber.190003301113 ( digitized on Gallica ).

Individual evidence

^ Fritz Straus: Johannes Thiele (1865-1918) . In: Reports of the German Chemical Society. A department . 75, No. 6, 1927, p. 102.
^ John B. Buckingham, Dictionary of Organic Compounds, Sixth Edition, ISBN 978-0-412-54090-5
^ Paul Walden, Carl Graebe: History of organic chemistry since 1880 . Springer-Verlag, 2013, ISBN 978-3-662-28693-7 , pp. 825 ( limited preview in Google Book search).
↑ Spektrum.de: Fulvene - Lexikon der Chemie , accessed on September 23, 2015.

[1] Fritz Straus: Johannes Thiele (1865-1918) . In: Reports of the German Chemical Society. A department . 75, No. 6, 1927, p. 102.

[2] John B. Buckingham, Dictionary of Organic Compounds, Sixth Edition, ISBN 978-0-412-54090-5

[Paul_Walden,_Carl_Graebe-3] Paul Walden, Carl Graebe: History of organic chemistry since 1880 . Springer-Verlag, 2013, ISBN 978-3-662-28693-7 , pp. 825 ( limited preview in Google Book search).

[spektrum.de-4] Spektrum.de: Fulvene - Lexikon der Chemie , accessed on September 23, 2015.