Amines Caffeine Nitrogen Chemistry l Nitrogen will readily

Amines Caffeine

Nitrogen Chemistry l 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 l Amines are derivatives of ammonia (NH 3) l Functional group = NHx l Aromatic amines = aniline -->

Amine Nomenclature l IUPAC (longest chain = alkane) l – Primary l Alkanamine l – # is used to ID location of fcn’l group on alkane chain – Can have diamines, etc. l l N-alkyl-N-alkylalkanamine – Multifunctional groups l Amine = substituent (amino), – – – Carboxylic acid Aldehyde Ketone Alcohol Amine Alkylamine – Tertiary N-alkylalkanamine – Tertiary l Alkylamine – Secondary l Common l Alkylalkylamine Isomers – Skeletal (C atoms) – Positional (NHx group)

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

Amines are weak Bases l NH 3 + HOH <==> NH 4+ + OHammonium ion l CH 3 -NH 2 + HOH <==> CH 3 -NH 3+ + OHmethylamine methanamine l methylammonium ion Amine Salts – Acid + amine --> Amine salt + water l (protonation) HCl + CH 3 -NH 2 --> CH 3 -NH 3+Clmethylammonium chloride – Amine salt + base --> amine + salt + water l (deprotonation) CH 3 -NH 3+Cl- + Na. OH --> CH 3 -NH 2 + Na. Cl + HOH

Preparation of Amines l Alkylation in the presence of a base – Ammonia + alkyl halide --> 1˚ amine l l NH 3 + CH 3 Cl --> CH 3 NH 3+Cl- + Na. OH --> CH 3 NH 2 + Na. Cl + 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 l 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 l Neurotransmitters – Acetylcholine, norepinephrine – Dopamine, serotonin l Epinephrine – Adrenaline – Amphetamines - structurally related to adrenalin l Histamine – Responsible for effects of hay fever & pollen allergies – These effects are counteracted by antihistamines

Alkaloids - plant based amines l Nicotine, caffeine, cocaine l Chocolate l Quinine, atropine l 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) l l l Carboxylic Acids Esters Phosphate Esters Amides Amines Isomers; Functional group isomers – Nomenclature (the rules for naming the molecules) l Common & IUPAC – – Amides: (alkylamide) N-alkylalkanamide Amines: (alkylamine) N-alkylalkanamine – Physical properties (basic/simple) l p. H; BP; Solubility; Flammability – – Acids ~ hydrogen bonding! Esters ~ no hydrogen bonding (a lot like ethers) Amides: lower p. H; most are solids @ RT Amines: higher p. H; most are liquids @ RT – Occurrence and uses (common) l l Acids - metabolic intermediates & products; antimicrobials Esters - flavors/fragrances; pheromones; medications – Phosphate esters Amides - Urea; barbiturates; polyamides & polyurethanes l Amines - Biochemical; Alkaloids Preparation (what basic reactions produce the molecules) l Acids - Oxidation of aldehydes; of alkyl benzene l Esters - Esterification (C. acid + alcohol); condensation polymerization l Amides - (amidification) Amine + C. Acid --> amide l Amines - Rxn w/ alkyl halide (in base) l – – Characteristic reactions of the molecules l l 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