Amines Caffeine

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 (NH 3 ) Functional group = NH x 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 –Multifunctional groups Amine = substituent (amino), –Carboxylic acid –Aldehyde –Ketone –Alcohol –Amine Common –Primary Alkylamine –Secondary Alkylalkylamine –Tertiary Alkylalkylalkylamine Isomers –Skeletal (C atoms) –Positional (NH x group)

Physical Properties of Amines State: low MW = RT –Smell like ammonia – high MW = RT –Bad odors BP: alkanes<amines<alcohols –Hydrogen bonding Water solubility –Low MW = v. soluble –High MW = soluble

Amines are weak Bases NH 3 + HOH NH OH - ammonium ion CH 3 -NH 2 + HOH CH 3 -NH OH - methylamine methylammonium ion methanamine Amine Salts –Acid + amine --> Amine salt + water (protonation) HCl + CH 3 -NH 2 --> CH 3 -NH 3 + Cl - methylammonium chloride –Amine salt + base --> amine + salt + water (deprotonation) CH 3 -NH 3 + Cl - + NaOH --> CH 3 -NH 2 + NaCl + HOH

Preparation of Amines Alkylation in the presence of a base –Ammonia + alkyl halide --> 1˚ amine NH 3 + CH 3 Cl --> CH 3 NH 3 + Cl - + NaOH --> CH 3 NH 2 + NaCl + HOH The primary amine will continue to react unless it is removed as it is 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 Caffeine - pyridine derivative -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) The alkaloid atropine is obtained from the belladonna plant. Poppy Theobromine - Greek (“theo” - god; “brosis” - food)

What do you need to know? –Structural characteristics (know the functional group) Carboxylic Acids Esters Phosphate Esters Amides Amines Isomers; Functional group isomers –Nomenclature (the rules for naming the molecules) Common & IUPAC –Amides: (alkylalkylamide) N-alkylalkanamide –Amines: (alkylalkylamine) N-alkylalkanamine –Physical properties (basic/simple) pH; BP; Solubility; Flammability –Acids ~ hydrogen bonding! –Esters ~ no hydrogen bonding (a lot like ethers) –Amides: lower pH; most are RT –Amines: higher pH; most are RT –Occurrence and uses (common) Acids - metabolic intermediates & products; antimicrobials Esters - flavors/fragrances; pheromones; medications –Phosphate esters Amides - Urea; barbiturates; polyamides & polyurethanes Amines - Biochemical; Alkaloids –Preparation (what basic reactions produce the molecules) Acids - Oxidation of aldehydes; of alkyl benzene Esters - Esterification (C. acid + alcohol); condensation polymerization Amides - (amidification) Amine + C. Acid --> amide Amines - Rxn w/ alkyl halide (in base) –Characteristic reactions of the molecules Acids - Neutralization; Esterification; acid salts (rxn w/ SB or SA) Esters - Ester Hydrolysis (in acid); Saponification (in base) Amides - Hydrolysis (acidic & basic); polymerization Amines - Protonation Deprotonation