Dialkyl ethers

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Dialkyl ethers
General structure of ethers
R 1 and R 2 are alkyl groups . The oxygen atom of the ether is marked in blue .

In chemistry, dialkyl ethers ( also alkoxyalkanes according to IUPAC ) are organic compounds that have an ether group as a functional group - an oxygen atom that is substituted by two alkyl radicals (R 1 -O-R 2 ). They do not contain any other heteroatoms or multiple bonds . The alkyl group includes methyl , ethyl, etc. Cyclic ethers such as B. tetrahydrofuran and tetrahydropyran are not included.

The diethyl ether (H 5 C 2 -O-C 2 H 5 ) is the best known dialkyl ethers, the colloquially often ether is named.

properties

Two representatives are gaseous at room temperature : dimethyl ether (bp .: −24.8 ° C) and ethyl methyl ether (b.p .: 7.4 ° C).

Ether structure M.p. [° C] Bp [° C]
Dimethyl ether H 3 C-O-CH 3 −138.5 −24.8
Diethyl ether H 5 C 2 -O-C 2 H 5 −116 35
Di- n -propyl ether H 7 C 3 -O-C 3 H 7 −122 90
Di- n- butyl ether H 9 C 4 -O-C 4 H 9 −95 141

Many dialkyl ethers are relatively inert, but in the presence of atmospheric oxygen under the influence of light - usually undesirable - they can form explosive ether peroxides . That is why dialkyl ethers are usually stored in brown bottles, tin cans or barrels over solid potassium hydroxide .

Classification

The dialkyl ethers can be classified into symmetrical and asymmetrical as well as straight and branched representatives.

Ether symmetrical asymmetrical
unbranched Structural formula of diethyl ether
Diethyl ether 		Structure of methyl n-propyl ether
Methyl n propyl ether
branched Structural formula of diisopropyl ether
Diisopropyl ether 		Structure of tert-amyl ethyl ether
tert -amyl ethyl ether

use

As anti- knock agents in petrol , methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) are of considerable economic and technical importance.

The dimethyl ether (H 3 C – O – CH 3 ) has practical importance as a propellant in spray cans.

Diethyl ether is often used as an extractant in chemical laboratories . The formation of Grignard reagents in the laboratory often takes place using diethyl ether as the solvent, which is directly involved in the Schlenk equilibrium .

Individual evidence

  1. ↑ Axel Zeeck: Chemie für Mediziner , 6th edition, Urban & Fischer Verlag in Elsevier, 2006, ISBN 978-3-437-44435-7 , p. 215.
  2. ↑ a b Entry on dimethyl ether in the GESTIS substance database of the IFA , accessed on April 10, 2017(JavaScript required) .
  3. ↑ Entry on ethyl methyl ether in the GESTIS substance database of the IFA , accessed on April 15, 2017(JavaScript required) .
  4. ↑ Entry on diethyl ether in the GESTIS substance database of the IFA , accessed on April 10, 2017(JavaScript required) .
  5. ^ Entry on di-n-propyl ether in the GESTIS substance database of the IFA , accessed on April 10, 2017(JavaScript required) .
  6. ↑ Entry on di-n-butyl ether in the GESTIS substance database of the IFA , accessed on April 10, 2017(JavaScript required) .
  7. ^ Organikum , Wiley-VCH Verlag GmbH, 23rd edition, 2009, p. 210, ISBN 978-3-527-32292-3 .
  8. ↑ Heinz GO Becker, Werner Berger, Günter Domschke, Egon Fanghänel , Jürgen Faust, Mechthild Fischer, Fritjof Gentz, Karl Gewald, Reiner Gluch, Roland Mayer , Klaus Müller, Dietrich Pavel, Hermann Schmidt, Karl Schollberg, Klaus Schwetlick , Erika Seiler, Günter Zeppenfeld: Organikum. Johann Ambrosius Barth Verlag, 1993, 19th edition, ISBN 3-335-00343-8 , p. 564.

Web links

Commons : Dialkyl Ethers  - Collection of pictures, videos and audio files