Imide

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General structure of the imides (top), of N- organylphthalimide (middle) as an intermediate of the Gabriel synthesis and of phthalimide (bottom). R 1 to R 3 are hydrogen atoms or organyl radicals ( alkyl radicals, alkenyl radicals, aryl radicals, alkylaryl radicals, etc.). The imide group is marked in blue .

Imides (imido compounds) are a group of organic compounds with the functional group R – C (O) –NR – C (O) –R ,. They are therefore carboxamides with two acyl groups on the nitrogen.

In inorganic chemistry , compounds in which the divalent group = NH is bound to a metal or to other elements such as sulfur, boron, germanium or phosphorus, are used as metal imides ( e.g. lithium imide , Li 2 NH) or sulfur imides , borimides, phosphorimides, etc. . designated. Also Imidobischwefelsäure (Imidosulfonsäure, (HSO 3 ) 2 NH) is one of the imides.

The organic compounds with the group C = NH are called imines .

structure

The imido group has the form: R 2 -C (O) -NR 1 -C (O) -R 3 , where C (O) in each case represents a carbonyl function. R 1 , R 2 and R 3 are any organic radicals (such as alkyl or aryl groups ) or hydrogen atoms.

chemistry

The imido group is formed from two carboxylic acids (or one dicarboxylic acid ) and from ammonia or a primary amine . A frequently used imide is phthalimide , which is made up of phthalic acid and ammonia. If the radical R 1 is a hydrogen atom (R 1 = H), the imido group has a pronounced possibility of delocalizing the negative charge due to the strong −M effect of the two carbonyl groups in the event of deprotonation . Compared to the amido group (R 1 –CO – NR 2 R 3 ) the charge is thus better stabilized after the deprotonation and consequently the acid strength of the imide is greater. That is why the reaction of phthalimide with potassium hydroxide produces phthalimide-potassium, a salt that is used in the Gabriel synthesis as a nucleophile for the production of N- organyl phthalimides. The N- organyl phthalimides are then converted into more primary amines , usually by hydrazinolysis (heating with hydrazine ).

Individual evidence

  1. ^ A b Holleman, Wiberg: Basics and main group elements Volume 1: Basics and main group elements . Walter de Gruyter GmbH & Co KG, 2016, ISBN 978-3-11-049585-0 , p. 675 ( limited preview in Google Book search).
  2. ^ RJ Meyer: Germanium . Springer-Verlag, 2013, ISBN 978-3-662-11817-7 , pp. 38 ( limited preview in Google Book search).
  3. ^ RJ Meyer: Phosphorus Part C. The compounds of phosphorus . Springer-Verlag, 2013, ISBN 978-3-662-11551-0 , pp. 325 ( limited preview in Google Book Search).
  4. ^ Brockhaus ABC Chemie , VEB FA Brockhaus Verlag Leipzig 1965, p. 571.
  5. ^ Siegfried Hauptmann : Organic Chemistry , 2nd edition, VEB Deutscher Verlag für Grundstoffindindustrie, Leipzig, 1985, p. 490, ISBN 3-342-00280-8 .
  6. ^ Wilhelm Flitsch, R. Heidhues, H. Peters, E. Gerstmann, V. v. Weissenborn, H.-D. Bartfeld, B. Müter, K. Gurke Gurke: Imide, Imidoide and Enamide . Springer-Verlag, 2013, ISBN 978-3-663-19751-5 , p. 25 ( limited preview in Google Book search).