Dialkyl ethers
Dialkyl ethers |
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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 |
Diethyl ether |
Methyl n propyl ether |
branched |
Diisopropyl 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
- ↑ Axel Zeeck: Chemie für Mediziner , 6th edition, Urban & Fischer Verlag in Elsevier, 2006, ISBN 978-3-437-44435-7 , p. 215.
- ↑ a b Entry on dimethyl ether in the GESTIS substance database of the IFA , accessed on April 10, 2017(JavaScript required) .
- ↑ Entry on ethyl methyl ether in the GESTIS substance database of the IFA , accessed on April 15, 2017(JavaScript required) .
- ↑ Entry on diethyl ether in the GESTIS substance database of the IFA , accessed on April 10, 2017(JavaScript required) .
- ^ Entry on di-n-propyl ether in the GESTIS substance database of the IFA , accessed on April 10, 2017(JavaScript required) .
- ↑ Entry on di-n-butyl ether in the GESTIS substance database of the IFA , accessed on April 10, 2017(JavaScript required) .
- ^ Organikum , Wiley-VCH Verlag GmbH, 23rd edition, 2009, p. 210, ISBN 978-3-527-32292-3 .
- ↑ 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.