CHAPTER 8 AMINES

1. CHAPTER 8 AMINES

2. N Nitrogen AMINE: one or more organic groups bonded to nitrogen.

3. Primary (1°) - one C attached to N Secondary (2°) - two C attached to N Tertiary (3°) - three C attached to N

4. Structure & Classification • heterocyclic amine: An amine in which the nitrogen atom is part of a ring. • heterocyclic aliphatic amine: A heterocyclic amine in which the ring is saturated (has no C=C bonds). • heterocyclic aromatic amine: The amine nitrogen is part of an aromatic ring.

5. Naming Amines • Primary Amines 1. Determine the longest carbon chain containing the NH2 group 2. Drop the (e) from the alkane name and add amine to the end 3. Indicate the position of the NH2 group

6. Methanamine 2-Propanamine Cyclohexanamine

7. Name:

8. Secondary and Tertiary Amines Same attachments to nitrogen use di and tri

9. Secondary and Tertiary Amines Different attachments on the Nitrogen Root name is based on the longest carbon chain Other attachments are based on the alkyl name N before attachment name indicates it is on the nitrogen

10. Longest carbon chain? 2 carbons=ethanamine Other attachments on nitrogen? 2 methyls N,N-dimethylethanamine Longest carbon chain? 3 carbons=propanamine Other attachments on nitrogen? methyl N-methylpropanamine • Draw N-ethyl N-methylbutanamine

11. Physical Properties • Like ammonia, low-molecular-weight amines have very sharp, penetrating odors. • Trimethylamine is the pungent smell in rotting fish.

12. Physical Properties • Amines are polar compounds: • Both 1° and 2° amines have N-H bonds, and can form hydrogen bonds with one another. • 3° amines have no N-H bond and cannot form hydrogen bonds with one another.

13. Physical Properties • An N-H---N hydrogen bond is weaker than an O-H---O hydrogen bond, because the difference in electronegativity between N and H (3.0 - 2.1 = 0.9) is less than that between O and H (3.5 - 2.1 = 1.4). • We see the effect of hydrogen bonding between molecules of comparable molecular weight by comparing the boiling points of ethane, methanamine, and methanol.

14. Physical Properties, cont. • Amines can hydrogen bond with water, making smaller amine molecules water soluble.

15. Basicityof Amines • Like ammonia, amines are weak bases, and aqueous solutions of amines are basic. • The acid-base reaction between an amine and water involves transfer of a proton from water to the amine.

16. Reactions of Amines • The most important chemical property of amines is their basicity. • Amines, whether soluble or insoluble in water, react quantitatively with strong acids to form water-soluble salts.

17. Chemical Connections 16D, p. 426

19. Complete each acid-base reaction

20. Amine Neurotransmitters • Neurotransmitter – a chemical bridge between nerve cells.

21. Dopamine – synthesized from the amino acid tyrosine. Norepinephrine – synthesized from dopamine, may be associated with mental illness. • Serotonin – synthesized from the amino acid tryptophan, may be associated with mental illness.

23. Epinephrine (adrenaline)–Fight-or-flight hormone, released in response to pain, anger, or fear, increases blood glucose level for energy.

24. Amphetamines – nervous system stimulants, similar in structure to epinephrine.

25. Alkaloids – a class of nitrogen–containing organic compounds obtained from plants. • Examples include: • Nicotine – found in tobacco • Caffeine – found in coffee • and cola drinks

26. Opium – used to make codeine (in cough medicines), morphine (pain killer) and heroin.