Methyl ketones

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General formula of methyl ketones

Methyl ketones are ketones which contain at least one methyl group as a residue of a non-terminal carbonyl group . Methyl ketones thus have the general formula CH 3 -C (O) -R. Methyl ketones are z. B .:

  • Acetone , the simplest methyl ketone with two methyl groups.
  • Butanone , also known as methyl ethyl ketone, is a methyl ketone.
  • Acetophenone , as the simplest aromatic methyl ketone.

Occurrence

Some types of microorganisms, such as molds such as Penicillium roqueforti, produce methyl ketones, which is used to create the aroma of blue cheese . Homologous methyl ketones are found as by-products of the auto-oxidation of fats and are held responsible for the "perfume frenzy".

properties

Low molecular weight methyl ketones are colorless, easily mobile liquids and, due to the polarity of the carbonyl group, are soluble in water. Low-molecular methyl ketones are characterized by a mostly pleasant, fruity-floral odor . Higher molecular weight methyl ketones are solids.

Due to the + I effect of the alkyl substituents on the carbonyl carbon atom, methyl ketones have a lower reactivity than aldehydes and do not tend to polymerize . In contrast to the aldehydes, there is no reaction with ketones in the Fehling and Tollens samples , since the ketone group cannot be further oxidized while retaining the carbon structure.

Manufacturing

It is produced by oxidation of secondary alcohols .

use

Methyl ketones are used in organic chemistry in a wide variety of sectors, e.g. B. in the haloform reaction , in which the methyl radical is split off to a certain extent and is replaced by a hydroxyl group . This creates the corresponding carboxylic acid and the corresponding trihalomethane is formed from the methyl radical . Acetone in particular is used as a solvent and as a cleaning agent.

Spectroscopy

Since the methyl ketones are a subgroup of the ketones, the characteristic bands of the C = O stretching vibration in the range from 1690 to 1750 cm −1 can be found in the IR spectra .

Individual evidence

  1. ↑ J. Schormüller: Textbook of food chemistry . Springer-Verlag, 2013, ISBN 978-3-642-65778-8 , pp. 73 ( limited preview in Google Book search).
  2. ↑ Ludwig Acker, Gerhard Bressau, Georg Benedikt Brubacher, Karl Maximilian Bürger, Stefan Diemair, Willibald Diemair, Klaus Doerffel, Rudi Franck, Hansfriedel Gudjons, Paul Joppien, Ludwig Kotter, Ernst Kröller, Hermvn Libert, Helmut Mühlschlegel, Titus Niedermaier, Konrad Pfeilsticker , Gerhard Pfleiderer, Wilhelm Postel, Hanspeter P. Probst, W. Rödder, Werner Schäfer, Leopold Schmid, Erich Schneider, Artur Seher, Hans Sommer, Helmut Thaler, Jean Paul Vuilleumier, Herbert Woidich: Analytics of food detection and determination of food Ingredients . Springer-Verlag, 2013, ISBN 978-3-642-46069-2 , pp. 655 ( limited preview in Google Book search).
  3. ↑ H.-D. Belitz, W. Grosch: Textbook of food chemistry . Springer-Verlag, 2013, ISBN 978-3-662-08306-2 , pp. 186 ( limited preview in Google Book search).
  4. ^ FA Carey, RJ Sundberg: Organic Chemistry , Wiley-VCH Verlag 2004, ISBN 3-527-29217-9 .
  5. ^ Louis F. Fieser and Mary Fieser: Organische Chemie , 2nd edition, Verlag Chemie 1982, pp. 405-406, ISBN 3-527-25075-1 .
  6. ^ Kurt Peter C. Vollhardt, Neil E. Schore: Organic chemistry . John Wiley & Sons, 2011, ISBN 3-527-32754-1 , pp. 873 ( limited preview in Google Book search).