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 (NH3) Functional group = NHx Aromatic amines = aniline --> Amine Nomenclature IUPAC (longest chain = alkane) – Primary – Primary Alkanamine – # is used to ID location of fcn’l group on alkane chain – Can have diamines, etc. Alkylalkylalkylamine N-alkyl-N-alkylalkanamine – Multifunctional groups Alkylalkylamine – Tertiary N-alkylalkanamine – Tertiary Alkylamine – Secondary – Secondary Common 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 CH3-NH2 + HOH <==> CH3-NH3+ + OHmethylamine methanamine methylammonium ion Amine Salts – Acid + amine --> Amine salt + water (protonation) HCl + CH3-NH2 --> CH3-NH3+Clmethylammonium 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 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 - 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) Theobromine - Greek (“theo” - god; “brosis” - food) The alkaloid atropine is obtained from the belladonna plant. Poppy 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 – – – Physical properties (basic/simple) pH; BP; Solubility; Flammability – – – – – Amides: (alkylalkylamide) N-alkylalkanamide Amines: (alkylalkylamine) N-alkylalkanamine 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