Ch 16 Amines Homework problems: 16.9, 16.10, 16.21, 16.25, 16.39, 16.40

Amines Carbon, Hydrogen, and Oxygen are the 3 most common elements in organic compounds Because of the wide distribution of amines in the biological world, Nitrogen is the fourth most common element.

Structure and Classification The functional group for amines is a Nitrogen bonded to alkyl groups and/or Hydrogen Amines are classified as 1 o, 2 o, or 3 o based on The number of alkyl groups bonded to the Nitrogen!!

Further Classification Amines are further classified as Aliphatic or Aromatic Aliphatic Amines: all carbons bonded to the nitrogen are derived from alkyl groups Aromatic Amines: one or more of the carbons bonded to the nitrogen are in an aromatic ring

Examples

Heterocyclic Amines An amine in which the Nitrogen is a member of a ring is classified as a Heterocyclic Amine When the Nitrogen is part of a regular ring, it is a Heterocyclic Aliphatic Amine When the Nitrogen is part of an aromatic rind, it is a Heterocyclic Aromatic Amine

Examples * Important building blocks for the amino bases in DNA and RNA **

DRUGS!!!! Amines are typically very important in drugs, both legal and illegal See Chemical Connections 16A and 16B to learn more!!!

IUPAC Nomenclature IUPAC names for 1 o aliphatic amines are derived just like alcohols, you drop the -e from the parent name and add -amine Use numbers to indicate location of amino

Aromatic Amines IUPAC keeps the common name Aniline:

2 o and 3 o Amines 2 o and 3 o amines are named as N- substituted primary amines The largest alkyl group bonded to the Nitrogen is taken as the parent amine The smaller groups are named as substituents and their locations are indicated with an N-

Examples

Amine Salts When four atoms or groups are bonded to the Nitrogen, the Nitrogen bears a positive charge. The cation is usually associated with an anion and presented as a salt

Naming Amine Salts The ending -amine is replaced by -ammonium and the name of the anion is added after.

Physical Properties Like Ammonia, low molecular weight amines have very sharp odors Amines are polar because of the difference in electronegativity between Nitrogen and Hydrogen and also between Nitrogen and Carbon. 1 o and 2 o amines have a Hydrogen bonded to a Nitrogen so they are capable of Hydrogen bonding to each other 3 o Amines do not have a Hydrogen bonded to Nitrogen so they can not Hydrogen bond to one another. All classes of amines can H-Bond with water and are therefore soluble in water!!

Reactions of Amines Basicity –Due to the lone pair of electrons on the Nitrogen, amines are weak bases and aqueous solutions of amines are basic. –Recall, a base is a substance that will accept a hydrogen in a reaction.

Reactions with Acids Amines react completely with strong acids to form water soluable salts.