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Amines

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

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Amines

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  1. Amines Caffeine

  2. 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

  3. Structure & Classification of Amines • Amines are derivatives of ammonia (NH3) • Functional group = NHx • Aromatic amines = aniline -->

  4. 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 (NHx group) Amine Nomenclature

  5. 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

  6. Amines are weak Bases • NH3 + HOH <==> NH4+ + OH- ammonium ion • CH3-NH2 + HOH <==> CH3-NH3+ + OH- methylaminemethylammonium ion methanamine • 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

  7. 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 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 saltsmay be biochemically important • Ex.: choline (growth reg.) & acetylcholine (nerve impulse transmission)

  8. Heterocyclic AminesNitrogen atoms are part of a ring system Hemoglobin -pyrrole derivative Nicotine Caffeine - pyridine derivative -purine derivative

  9. 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

  10. Alkaloids - plant based amines • Nicotine, caffeine, cocaine • Chocolate • Quinine, atropine • Opium • Codeine, Morphine (heroin) Theobromine - Greek (“theo” - god; “brosis” - food) The alkaloid atropine is obtained from the belladonna plant. Poppy

  11. 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 solids @ RT • Amines: higher pH; most are liquids @ 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

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