nitrile

Examples of nitrile in the following topics:

• Nomenclature

  • Nitriles: Simple acyclic nitriles are named by adding nitrile as a suffix to the name of the corresponding alkane (same number of carbon atoms).
  • Chain numbering begins with the nitrile carbon .
  • A nitrile substituent, e.g. on a ring, is named carbonitrile. e.g.

• Preparation of Carboxylic Acids

  • Two other useful procedures for preparing carboxylic acids involve hydrolysis of nitriles and carboxylation of organometallic intermediates.
  • Both methods require two steps, but are complementary in that the nitrile intermediate in the first procedure is generated by a SN2 reaction, in which cyanide anion is a nucleophilic precursor of the carboxyl group.

• Other Reactions

  • One practical application of this behavior lies in the dehydration of 1º-amides to nitriles by treatment with thionyl chloride.

• Reduction

  • The only other reduction of a carboxylic acid derivative that is widely used is that of nitriles to 1º-amines.
  • In most nitrile reductions ammonia is added to inhibit the formation of a 2º-amine by-product.
  • The resulting nitrile intermediate is then reduced to a 1º-amine.
  • Nitriles are in fact a major product when less than a full equivalency of LiAlH4 is used.
  • Lithium aluminum hydride reduces nitriles to 1º-amines, as shown in the following equation.

• Reactions at the α-Carbon

  • Acid-catalyzed alpha-chlorination and bromination reactions proceed more slowly with carboxylic acids, esters and nitriles than with ketones.
  • The chiral alpha-carbon in equation #2 is racemized in the course of this exchange, and a small amount of nitrile is hydrolyzed to the corresponding carboxylic acid.
  • Acyl halides and anhydrides are more easily halogenated than esters and nitriles, probably because of their higher enol concentration.

• Related Carbonyl Derivatives

  • Although nitriles do not have a carbonyl group, they are included here because the functional carbon atoms all have the same oxidation state.

• Functionalized Organometallic Reagents

  • Thus the presence of hydroxyl, amino, carbonyl, nitro or nitrile functions in the halide precursor of a desired lithium or magnesium reagent presents a serious compatibility problem, as noted earlier for 5-bromo-1-pentanol.
  • The resulting dialkylzinc reagent tolerates some functional substituents (e.g. esters and nitriles), and undergoes carbonyl addition reactions with aldehydes and ketones provided a titanium(IV) catalyst is present.

• Background and Properties

  • The relatively high boiling points of equivalent 3º-amides and nitriles are probably due to the high polarity of these functions.

• Enolate Intermediates

  • Esters and nitriles are even weaker alpha-carbon acids than ketones (by over ten thousand times), nevertheless their enolate anions may be prepared and used in a similar fashion.

• Claisen Condensation

  • Transformations similar to the Claisen condensation may be effected with mixed carbonyl reactants, which may include ketones and nitriles as well as esters.
  • Equations #2, 3 & 4 below illustrate the use of such acceptors with ester, ketone and nitrile donor compounds.
  • The nucleophilic enol species from the nitrile in #4 may be written as: C6H5CH=C=N(–).