Selenoamides

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Selenoamides
General structure of primary selenoamides
primary selenoamide
General structure of secondary selenoamides
secondary selenoamide
General structure of tertiary selenoamides
tertiary selenoamide
R 1 , R 2 and R 3 are organic radicals ( alkyl , aryl or the like). The selenoamide group is marked in blue .

Selenoamides are organic chemical compounds . They are selenium analogues of amides and belong to the selenocarbonyl compounds .

The basic structure of their functional group consists of a selenium atom , which is bonded to a carbon atom by a double bond . The carbon atom is linked to a nitrogen atom by a single bond . The number of bonded hydrogen atoms depends on the number of substituents . A distinction can be made between unsubstituted, primary , secondary and tertiary selenoamides. The simplest representative of the selenoamides is selenoformamide, a derivative of formamide , which is exclusively substituted with hydrogen atoms . Primary selenoamides are singly (mono), secondary two (di) and tertiary three (tri) substituted, the substituents being organic radicals (e.g. alkyl , aryl, etc.). Selenoamides are generally colorless to pale yellow substances; their stability increases with the number of substituents. Due to their reactivity, primary selenoamides are suitable for the synthesis of heterocyclic selenium compounds, which in turn are used in the pharmaceutical industry (e.g. for the synthesis of selenazoles , selenazines). On the other hand, tertiary selenoamides are more stable and therefore easier to handle, so that they are used as a source of selenium for the production of chalcopyrite compounds. These in turn are used as active material in solar cells .

synthesis

Selenoformamide can be obtained by the action of phosphorus pentaselenide on formamide . While primary selenoamides were often synthesized from nitriles and hydrogen selenide in the past , the toxic hydrogen selenide is not used today . Instead, nitriles are reacted with triethylamine , pyridine , water and aluminum selenide .

Synthesis of primary selenoamides from nitriles

Both secondary and tertiary selenoamides can be made from selenoesters. When selenoesters are reacted with magnesium bromide salts of primary amines , a secondary selenoamide is formed. In order to obtain a tertiary selenoamide, the selenoester has to be reacted with a secondary amine .

Synthesis of secondary and tertiary selenoamides from selenoesters

Additionally , sodium hydrogen selenide or Woollins' reagent can be used to synthesize selenoamides.

Reactions

Primary selenoamides can be used as selenium carriers, so that they are used for the synthesis of ketones , selenium salts , selenides , selenazoles or selenazines. The hydrolysis of selenoamides leads to carboxylic acids . Acetic acid , for example, is obtained through hydrolysis of the primary selenoamide selenoacetamide .

Hydrolysis of primary selenoamides

Selenoamides can also be oxidized to selenodiazoles with iodine . The Eschenmoser coupling of selenoamides gives cyclic enamino esters. Moreover were Michael Addition of chiral , α-β-unsaturated selenoamides with organolithium compounds observed.

See also

Individual evidence

  1. ↑ a b c C. Paulmier: Selenium Reagents and Intermediates in Organic Synthesis . tape 4 . Pergamon Press, Oxford 1986, ISBN 0-08-032484-3 , pp. 77-79 .
  2. ↑ a b c d The Chemistry of Selenium Carbonyl Compounds . In: Dennis Liotta, FS Guzirc (Ed.): Organoselenium chemistry . Wiley, New York 1987, ISBN 0-471-88867-2 , pp. 294-299 .
  3. ↑ M. Koketsu, H. Ishihara: Synthesis of 1, 3-selenazine and 1, 3-selenazole and their biological activities . In: Current Organic Chemistry . tape 7 , no. 2 , 2003, p. 175-185 , doi : 10.2174 / 1385272033373102 .
  4. ↑ Mehmet Eray Erkan u. a .: Chalcopyrite thin films and solar cells prepared by using selenoamide as a selenium source . In: Thin Solid Films . tape 574 , January 1, 2015, p. 207–215 , doi : 10.1016 / j.tsf.2014.12.017 .
  5. ↑ a b A. Schönberg, A. Wagner: Production and conversion of sulfur compounds: Methods for the production and conversion of thioaldehydes and thioketones . In: sulfur, selenium, tellurium compounds (=  methods of organic chemistry (Houben-Weyl) . Volume IX ). 4th edition. Georg Thieme Verlag, Stuttgart / New York 1955, ISBN 3-13-195904-5 , p. 1207-1209 , doi : 10.1055 / b-003-125691 .
  6. ↑ Frank S. Guziec, Jr, Lynn James Guziec: Recent advances in the insertion and extrusion reactions of selenium and tellurium in organic compounds . In: Zvi Rappoport (Ed.): The chemistry of organic selenium and tellurium compounds (=  Patai's Chemistry of Functional Groups ). Volume 4, Part 2, 1986, ISBN 0-471-90425-2 , pp. 1361-1400 .
  7. ↑ Guoxiong Hua, J. Derek Woollins: Synthesis and reactivity of phosphorus-selenium rings . In: Angewandte Chemie . tape 121 , no. 8 , 2009, p. 1394-1403 , doi : 10.1002 / anie.200800572 .
  8. ↑ Toshiaki Murai: Thio-, Seleno-, Telluro-Amides . In: Shinzi Kato (Ed.): Chalcogenocarboxylic Acid Derivatives (=  Topics in Current Chemistry . Volume 251 ). Springer, Berlin / Heidelberg 2005, ISBN 3-540-23012-2 , pp. 247-272 , doi : 10.1007 / b101011 .
  9. ^ SR Hussaini, GB Hammond: Eschenmoser coupling reaction of selenoamides. Synthesis of enamino esters . In: Arkivoc . tape 2008 , no. 13 , July 8, 2008, p. 129 , doi : 10.3998 / ark.5550190.0009.d15 .
  10. ↑ Toshiaki Murai, Toshihiro Mori, Shinzi Kato: Diastereoselective Michael Addition of Organolithium Reagents to Chiral α, β- Unsaturated Selenoamides . In: Synlett . tape 1998 , no. June 06 , 1998, pp. 619-620 , doi : 10.1055 / s-1998-1749 .