Chem 102 1st Edition Lecture 19 Outline of Last Lecture I. Chapter 16: Lessons 6.1-6.4 : Bonding Characteristics of Nitrogen Atoms in Organic Compounds, Structure and Classification of Amines, Nomenclature for Amines, Isomerism for AminesOutline of Current Lecture II. 6.5- Physical Properties of AminesIII. 6.6- Basicity of AminesIV. 6.7- Reactions of Amines with AcidsCurrent Lecture6.5 Physical Properties of AminesPhysical State • The methylamines (mono-, di-, and tri-) and ethylamine are gases at room temperature • Most other amines are liquids at room temperature • Physical state summary for unbranched primary amines at room temperature and room temperature: Odor (Smell) • Methylamines (mono-, di-, and tri-) and ethylamine (gases) have ammonia-like smell. • Most other amines are liquids and have odors resembling that of fish (strong, disagreeable odors). - Foul smell from dead fish and decaying flesh is due to diamines released by the bacterial decomposition of protein. Boiling Point (B.P.) • B. P. Intermediate between alkanes and alcohols • Because of weaker H-bonding between H & N than H & O • 3o Amines have lower B. P. than 1o and 2o amines • H-bonding is not possible between the molecules of 3o amines • A comparison of boiling points of unbranched primary amines and unbranched primary alcohols:Solubility in Water • Amines with fewer than six carbon atoms are infinitely soluble in water. • Solubility results from hydrogen bonding between the amines and water. • Even tertiary amines are water-soluble because of its ability to form hydrogen bonds with water molecules 6.6 Basicity of Amines• Amines behave like NH3 and are basic: This behavior is due to the acceptance of H+ (proton) from an acid • In the example above water acts as an acid • The resulting solution is alkaline due to OH- ion and a substituted ammonium ion. – Ammonium and substituted ammonium ions form four bonds with N; therefore carries a + charge – Names of substituted ammonium ions are derived from the parent amine in which the “-e” of parent amine is replaced by “ammonium ion”. 6.7 Reactions of Amines with Acids• Amines are most basic type of organic compounds. • The reaction between an acid and a base (neutralization) results in formation of a salt. • Amines are bases and their reaction with an acid produces a salt (amine salt). – Amine + Acid -> Amine Salt • Amine salt: An ionic compound in which the positive ion is a mono-, di-, or tri-substituted ammonium ion (RNH3+, R2NH2+ or R3NH+) and the negative ion comes from an acid. • Names of amines salts are written in the following order: – Substituted amine followed by the name of anion • All amine salts are water soluble – This is why drugs of amines are administered in the form of amine