Chapter 11 Amines PDF

John E. McMurry www.cengage.com/chemistry/mcmurry Chapter 11: Amines Edited by: Dr. Ahmed Khalil Department of Chemistry, College of Science King Faisal University, Saudi Arabia Email: [email protected]  Chapter 11: Amines Naming Amines § Alk...

John E. McMurry www.cengage.com/chemistry/mcmurry Chapter 11: Amines Edited by: Dr. Ahmed Khalil Department of Chemistry, College of Science King Faisal University, Saudi Arabia Email: [email protected]  Chapter 11: Amines Naming Amines § Alkyl-substituted (alkylamines) § Amines can be classified as primary (RNH2), secondary (R2NH), and tertiary (R3N), Depends on number of organic substituents attached to nitrogen  Naming Amines § Quaternary ammonium salts: Compounds that carry a positively charged nitrogen atom with four attached groups § Simple amines are named by adding the suffix - amine to the name of the alkyl substituent  Naming Amines § The suffix -amine can be used in place of the final -e in the name of the parent compound § Amines with more than one functional group are named by considering the –NH2 as an amino substituent  Naming Amines § Symmetrical secondary and tertiary amines are named by adding the prefix di- or tri- to the alkyl group § Unsymmetrically substituted secondary and tertiary amines § Named as N-substituted primary amines § Largest alkyl group is the parent name, and other alkyl groups are considered N-substituents  Structure and Properties of Amines § Amines with fewer than five carbon atoms are water- soluble § Primary and secondary amines form hydrogen bonds, increasing their boiling points  Basicity of Amines § Lone pair of electrons on nitrogen makes amines basic and nucleophilic § React with acids to form acid-base salts and they react with electrophiles Basicity of Some Common Amines  Synthesis of Amines § Reduction of nitriles, amides, and nitro compounds § Amines can be prepared by reduction of nitriles and amides with LiAlH4 (as Studied before )  SN2 Reactions of Alkyl Halides § Simplest method of alkylamine synthesis is by SN2 alkylation of ammonia or an alkylamine with an alkyl halide § Ammonia and other amines are good nucleophiles  Reductive Amination of Aldehydes and Ketones § Reductive amination: Treatment of an aldehyde or ketone with ammonia or an amine in the presence of a reducing agent  Reductive Amination § Ammonia, primary amines, and secondary amines through reductive amination reaction yield primary, secondary, and tertiary amines, respectively Hofmann and Curtius Rearrangements § Carboxylic acid derivatives can be converted into primary amines with loss of one carbon atom by both the Hofmann rearrangement and the Curtius rearrangement  Reactions of Amines § Primary and secondary amines can also be acylated by nucleophilic acyl substitution reaction  Hofmann Elimination § Silver oxide is used for the elimination step § Exchanges hydroxide ion for iodide ion in the quaternary ammonium salt, thus providing the base necessary to cause elimination  Orientation in Hofmann Elimination § Major product is the less highly substituted alkene § Non-Zaitsev result is probably steric § Due to the large size of the trialkylamine leaving group § The base must abstract a hydrogen from the most sterically accessible § Least hindered position Orientation in Hofmann Elimination  Summary § Amines are organic derivatives of ammonia § Amines are stronger bases than alcohols, ethers, or water § Alkylamines are prepared by SN2 reaction of ammonia or an amine with an alkyl halide or by Gabriel amine synthesis § Reductive amination is a reaction in which a ketone or an aldehyde is treated with an amine in the presence of a reducing agent such as NaBH4 § Amines result from Hofmann and Curtius rearrangements of carboxylic acid derivatives § Hofmann elimination - A process in which amines also undergo E2 elimination to yield alkenes, first quaternized by treatment with iodomethane and then heated with silver oxide