Chapter Seventeen Amines and Amides

Amines and Amides Parachutist with a parachute made of the polyamide nylon. © Royalty-Free / CORBIS

Nitrogen The four most abundant elements in organic compounds are carbon, hydrogen, oxygen, and nitrogen Element Valence Electrons Bonds for an Octet Carbon 4 Hydrogen 1 Oxygen 6 2 Nitrogen 5 3

Amines Organic compounds of nitrogen N Classified as primary, secondary, tertiary NH2 = amino group CH3 CH3   CH3—NH2 CH3—NH CH3—N — CH3 ______ _______ ________

Amines and Amides cont’d Fig. 17.1 Classification of amines is related to the number of R groups attached to the nitrogen atom.

Naming Amines Classified as primary (RNH2), secondary (R2NH), or tertiary (R3N). Different than alcohols. primary amine secondary amine tertiary amine primary ROH secondary ROH tertiary ROH

Amines and Amides cont’d Aniline, the simplest aromatic amine. Aromatic amines are generally toxic.

Naming Primary Amines Identify the parent chain: the longest chain of carbons to which the nitrogen is attached Replace the “-e” ending of the alkane name with “-amine” Number the parent chain from the end closest to the nitrogen atom Identify the position of the nitrogen atom with a number Identify any substituents and their locations

Name the Following Amines cyclohexanamine 2-propanamine 1,4-butanediamine or 1,4-diaminobutane

Naming Secondary and Tertiary Amines Base name involves longest carbon chain attached to the nitrogen Other groups attached to the nitrogen have “N-” in front of the substituent names N-ethyl-N-methyl-ethylamine N-ethyl-N-methyl-cyclohexylamine

Amines and Amides cont’d Amine-amine hydrogen bonding.

Amines and Amides cont’d Low-molecular amines are soluble in water because of amine-water hydrogen bonding interactions.

Amines and Amides cont’d Ammonium ion has a tetrahedral structure, as does the quaternary ammonium ion.

Amines and Amides cont’d Fig. 17.8 Heterocyclic amines serve as “parent” molecules for more complex amine derivatives.

Amines and Amides cont’d Methoxyamphetamine Isopreternol

Basicity of Amines Like ammonia, amines act as weak __________ in water _____________ are proton acceptors When amines react with water, the products are a hydroxide ion and a substituted ammonium ion Substituted ammonium ion: an ammonium ion in which one or more alkyl, cycloalkyl, or aryl groups have been substituted for hydrogen atoms CH3NH2 + H2O CH3NH3+ + OH– methylammonium hydroxide Treating an amine salt with a strong base regenerates the amine

Neutralization Forms Amine Salts Neutralization with _______ gives ammonium salt CH3NH2 + HCl CH3NH3+ Cl– methylammonium chloride Amine salts are named by replacing the “amine” part of the name with “ammonium” followed by the name of the negative ion

Properties of Amine Salts Amine salts are: Solid at room temperature Soluble in water and body fluids The form used for drugs Ephedrine Hydrochloride Ephedrine HCl Sudafed Diphenhydramine hydrochloride Diphenhydramine HCl Benadryl

Other Amine Salts Cocaine is sold illegally as an amine salt Cocaine is reacted with NaOH to produce the free amine form, known as “crack” O C H 3 N + Cl- O C H 3 N Cocaine (“free base”) Cocaine Hydrochloride

Amines vs. Amides Amides have carbonyl groups next to the nitrogen. Amines have alkyl groups or hydrogens bonded to the nitrogen. amide amine

Classification of Amides Classification depends on the number of alkyl groups connected to the amide nitrogen atom

Amines and Amides cont’d Models of the simplest primary, secondary, and tertiary amides.

Amines and Amides cont’d The high boiling point of amides are related to the numerous amide-amide hydrogen bonding possibilities that exist.

Classify each as amine or amide.

Amines and Amides cont’d CC 17. 5

Alkaloids Physiologically active nitrogen-containing compounds Obtained from ____________ Used as anesthetics, antidepressants, and stimulants Many are ______________

Nicotine

Caffeine

Procaine

Preparations of Amines Amines can be prepared by adding an alkyl halide to ammonia in the presence of base Two step process: alkylation to produce the salt; reaction with NaOH to produce the amine NH3 + R-X  R-NH3+Cl- R-NH3+Cl- + NaOH  RNH2 + NaX + H2O

Preparation of Amines Ammonia + alkyl halide + NaOH primary amine Primary amine+ alkyl halide + NaOH  secondary amine Secondary amine+ alkyl halide + NaOH  tertiary amine tertiary amine + alkyl halide  quaternary ammonium salt

Alkylation Reactions

Preparation of Amides Amides are produced by reacting a carboxylic acid with ammonia or an amine (primary or secondary) “Amidification Reactions” Dehydration Reaction +  + H2O

Amidification Reactions Ammonia + carboxylic acid  primary amide Primary amine + carboxylic acid  secondary amide Secondary amine + carboxylic acid  tertiary amide

Reactions of Amides Amides undergo acid hydrolysis base hydrolysis carboxylic acid salt of carboxylic acid ammonium salt and an amine or ammonia

Reactions of Amides acid hydrolysis O  O HCl + H2O CH3COH + NH4+Cl– CH3CNH2 O NaOH  CH3CO– Na+ + NH3 base hydrolysis