Amines and Amides

• bases, substituted ammonia
• biologically significant: amino acids, DNA, RNA bases, alkaloids

R-NH₂

R₂-NH

R₃-N

R₄-N⁺X^-

• organic derivative of ammonia (NH₃) in which 1 or more hydrogen atoms have been replaced by an alkyl, acycloakly, or an aryl group (beneze ring)
• N has 5 valence e-, 3 covalent bonds, and 1 nonbonding electron pair
• N is also less electronegative than O
• N is one of the elements involved in the formation of H+ bonding

• N is very electronegative (although less than O)
• Results in:
• -N-H bond being very polar
• -hydrogen bonding being possible
• -high boiling points
• -amines being organic bases

• determined by the number of carbon atom directly boned to the N atom
• classified as: primary, secondary, or tertiary
• Note: t-butyl alcohol is a t-alcohol, while t-butyl amine is a primary amine

• different carbon atom arrangements produce isomers
• different positioning of the nitrogen atom on a carbon chain

• different partititioning of carbon atoms among the carbon chain
• ex: CH₃CH₂NHCH₂CH₃- diethyl amine
• CH₃NHCH₂CH₂CH₃- methylpropyl amine
• CH₃NHCH[2(CH₃)]

• Both common and IUPAC names are used
• Simple amines are named by listing the alkyl group or groups attched to the N atom in alphabetical order and adding the suffix -amine
• appears as 1 word
• prefix di and tri are used when identical groups are bonded to the N atom

• in diamines the final -e of the carbon chain is retained
• ex.1,4- butanediamine
• NH₂CH₂CH₂CH₂CH₂NH₂

• treat additional branches as a substituent on the nitrogen
• base name is based on longest chain that contains the amine
• name other chain as alkyl substituent of the N
• use N- at front of a branch name to indicate that substituant is on the nitrogen

• aniline is the simplest aromatic amine
• compounds are named as substituted anilines
• anitalic "N" is used to indicate that an alkyl group is attached to the nitrogen and not to the ring

• methylamines and ethylamines are gases at room temp & have ammonia like odor
• most other amines are liquid & have odor resembling fish
• have the ability to form H-bonding

boiling points are intermediate b/w those of alcohols and alkenes of similar molecular masses

low molecular mass amines are very soluble in water

• amines+acid--->salt
• ex. R-NH₂+HCl---> R-NH₃⁺ + Cl^-

NH₃ + water---> NH₄⁺ + OH^-

• substituted ammonia ions are always charged species rather than neutral molecules
• N atom in the structure participates in 4 bonds
• substituted ammonium ions have common names derived from the names of the "parent" amines w/ the words ammonium ion replacing amine
• -examples in notes

Al₂O₃ & heat

ex.ammonia+ ethyl bromide+ sodium hydroxide--->aminoethane+sodiumbromide+water

amine+water---> ammonium ion+hydroxide

amine salt+base--->amine+salt+water

• RNH₂+HCl--->RNH₃⁺ Cl^-
• Note: no H₂O os produced in this reaction
• Amine salts are the only product

• 1.salts exist as white crystalline solids
• 2.reliatively high melting points
• 3.salts are always more soluble
• 4.many drugs are prepared and administered as salts b/c of their solublitiy

R-C(=O)NH₂

drop -e ending and replace w/ -amide

amines react w/ acid chlorides or acid anhydrides to form amides

NH₃ & heat