Download Chapter 18

Chapter 17
Amines & Neurotransmitters
Nitrogen Chemistry
Nitrogen will readily form 3 covalent bonds (each atom already has 5 v.e-)
–Carbon forms 4 covalent bonds
–Oxygen forms 2 covalent bonds
Structure & Classification of Amines
Amines are derivatives of ammonia (NH3)
Functional group = NHx
Aromatic amines = aniline -->
Amine Nomenclature
IUPAC (longest chain = alkane)
–Primary: Alkanamine
# is used to ID location of fcn’l group on alkane chain
Can have diamines, etc.
–Secondary: N-alkylalkanamine
–Tertiary: N-alkyl-N-alkylalkanamine
Common
–Primary: Alkylamine
–Secondary: Alkylalkylamine
–Tertiary: Alkylalkylalkylamine
Multifunctional groups
Amine = substituent (amino),
Carboxylic acid
Aldehyde
Ketone
Alcohol
Amine
Isomers
–Skeletal (C atoms)
–Positional (NHx group)
Physical Properties of Amines
State: low MW = gases @ RT
–Smell like ammonia
high MW = liquids @ RT
–Bad odors
BP: alkanes<amines<alcohols
–Hydrogen bonding
Water solubility
–Low MW = v. soluble
–High MW = soluble
Amines are weak Bases
NH3 + HOH <==> NH4+ + OHammonium ion
+ HOH <==> CH3-NH3+ + OHmethylamine
methylammonium ion
methanamine
CH3-NH2
Amine Salts
–Acid + amine --> Amine salt + water (protonation)
+ HCl + CH3-NH2 --> CH3-NH3 Cl
methylammonium chloride
–Amine salt + base --> amine + salt + water (deprotonation)
+ CH3-NH3 Cl + NaOH --> CH3-NH2 + NaCl + HOH
Preparation of Amines
Alkylation in the presence of a base
–Ammonia + alkyl halide --> 1˚ amine
NH3 + CH3Cl --> CH3NH3+Cl- + NaOH --> CH3NH2 + NaCl + HOH
The primary amine will continue to react unless removed as produced.
–1˚ amine + alkyl halide --> 2˚ amine
–2˚ amine + alkyl halide --> 3˚ amine
–3˚ amine + alkyl halide --> quaternary ammonium salt
–Quaternary
ammonium salts may be biochemically important
Ex.: choline (growth reg.) & acetylcholine (nerve impulse
transmission)
Heterocyclic Amines
Nitrogen atoms are part of a ring system
Hemoglobin
-pyrrole derivative
Nicotine
- pyridine derivative
Caffeine
-purine derivative
Biochemically Important Amines
Neurotransmitters
–Acetylcholine, norepinephrine
–Dopamine, serotonin
Epinephrine - Adrenaline
Amphetamines - structurally related to adrenalin
Histamine
–Responsible for effects of hay fever & pollen allergies
–These effects are counteracted by antihistamines
Alkaloids - plant based amines
Nicotine, caffeine, cocaine
Chocolate
Quinine, atropine
Opium
–Codeine, Morphine (heroin)
What do you need to know?
–Structural characteristics (know the functional group)
Amines
Amides
Isomers
–Nomenclature (the rules for naming the molecules)
(Common) & IUPAC
Amines: (alkylalkylamine) N-alkylalkanamine
Amides: (alkylalkylamide) N-alkylalkanamide
–Physical properties (basic/simple)
pH; BP; Solubility; Flammability
Amines: higher pH; most are liquids @ RT
Amides: lower pH; most are solids @ RT
–Occurrence and uses (common)
Amines - Biochemical; Alkaloids
Amides - Urea; barbiturates; polyamides & polyurethanes
–Preparation (what basic reactions produce the molecules)
Amines - Rxn w/ alkyl halide (in base)
Amides - (amidification) Amine + C. Acid --> amide
–Characteristic reactions of the molecules
Amines - Protonation<==> Deprotonation
Amides - Hydrolysis (acidic & basic); polymerization




–
–

–
–





