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 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)

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

+ + OH-

ammonium ion

CH3-NH2 + HOH <==> CH3-NH3+ + OH-

methylamine methylammonium 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

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 AminesNitrogen 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 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