Amine oxides

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General structure of the amine oxides. The functional group is marked in blue . R 1 to R 3 are identical or different organyl radicals.

As amine-oxide , more specifically amine N oxide is referred to a group of chemical compounds having the functional group R 3 N + -O - - sometimes referred to as R 3 N → O (formerly also be wrong, R 3 N = O) written - contains. Amine oxides exist as derivatives of tertiary aliphatic amines and aromatic nitrogen compounds such as. B. pyridine .

properties

Amine oxides are very polar and therefore often solids. Amine oxides with a small molar mass are very soluble in water and poorly in non-polar organic solvents.

Amine oxides are weak bases with a p K a of about 4.5. The corresponding acid is R 3 N + -OH.

Amine oxides with three different alkyl radicals are optically active because, in contrast to the amines on which they are based, no inversion ( reversal of configuration ) is possible.

Occurrence

Amine oxides are found in nature as osmolyte and as oxidation products of tertiary amines. So contains z. B. Meat from sea ​​fish per kg 40 to 120 mg trimethylamine- N -oxide (TMAO). After the animals die, it is broken down bacterially to trimethylamine , which causes the typical unpleasant fish odor .

Manufacturing

Amine oxides are produced by oxidizing the corresponding amines with hydrogen peroxide or peracids (such as meta-chloroperbenzoic acid , peracetic acid , peroxomonosulfuric acid ).

use

Amine N oxides as found protecting group for amines such as a synthetic intermediate, as an oxidizing agent (eg. B. N -Methylmorpholin- N oxide ) or for modulating the electron distribution aromatic nitrogen-containing compounds in electrophilic substitution application. Amine oxides with one long-chain and two short-chain alkyl groups , such as N -dodecyl- N , N -dimethylamine oxide C 12 H 25 (CH 3 ) 2 NO, are used as surfactants .

Amine oxides can be used to titrate carbon - boron bonds and to work up hydroborations and L-selectride reductions.

Reactions

Individual evidence

  1. ↑ Entry on trimethylamine. In: Römpp Online . Georg Thieme Verlag, accessed on June 14, 2014.
  2. ↑ N. Meyer, W. Wykypiel, D. Seebach: Catalytic Osmium Tetroxide Oxidation of Olefins: cis-1,2-Cyclohexanediol In: Organic Syntheses . 58, 1978, p. 43, doi : 10.15227 / orgsyn.058.0043 ; Coll. Vol. 6, 1988, pp. 342-348 ( PDF ).
  3. ↑ Shaker Youssif: In Recent trends in the chemistry of pyridine N-oxides 2001 Link .
  4. ↑ Entry on nonionic surfactants. In: Römpp Online . Georg Thieme Verlag, accessed on June 14, 2014.
  5. ↑ Christoph Elschenbroich: Organometallchemie. 5th edition, Teubner Wiesbaden 2005, ISBN 3-519-53501-7 .
  6. ↑ K. Oesterreich, D Spitzner: In Short total synthesis of the spiro [4.5] decane sesquiterpene (-) - gleenol Tetrahedron 2002 , 58 , 4331-4334.
  7. ↑ J. Meisenheimer, Ber. 1919 , 52 , 1667.
  8. ↑ Michael B. Smith, Jerry March: In March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure Wiley-Interscience, 5th edition, 2001, ISBN 0-471-58589-0 .
  9. ↑ D. Grierson: In Organic Reactions 1990 , 39 , 85-295.
  10. ↑ M. Polonovski, M. Polonovski, Bull. Soc. Chim. France 41, 1190 (1927).
  11. ^ László Kürti , Barbara Czakó: Strategic Applications of Named Reactions in Organic Synthesis ; Elsevier Academic Press, Burlington-San Diego-London 2005, 1st edition; ISBN 0-12-369483-3 .

literature