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Amines

Explore the structure, nomenclature, and properties of amines in chemistry. Learn about their preparation methods, classification, and role in biochemistry. Discover the significance of amines in neurotransmitters, alkaloids, and more.

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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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