Nitrogen-containing organic compounds

Amines

N atoms bound to >= 1 C-containing molecular fragment

• biologically significant (in amino acids, DNA, RNA)

• organic derivatives of ammonia (substituted ammonia)

• H-N can form HB

Classifying amines

no of R groups attached to N atom

Nomenclature of primary amines

1. locate longest C chain containing -NH2 group

2. change -e to -amine (do not remove -e for di/tri anime)

3. lowest number to C bearing NH2

4. add substituents to front

   (amines have low priority, as substituent: amino)

Bonding of amines

• polar covalent, form HB stronger than LDF in many molecules

• weaker than H2O (same extensiveness, O-H more polar)

• tertiary amines cannot form HB with its own molecules (can still form with water)

Boiling point of amines

higher than hydrocarbons as require more energy to overcome (HB)

Solubility of amines in water

• longer C chain → less soluble (>= 6C insoluble)

• all amines form HB with water

Smell of amines

sharp penetrating odour

• decaying animal tissue

• toxic, carcinogen, absorbed through skin

N-N-dimethylmethanamine

animal tissues

fish odour

Nicotine

• in tobacco

• stimulant

• habit forming, tar formation

Piperidine

in food seasoning (e.g. black pepper)

4-aminobenzoic acid

active ingredient in sunscreen

Amines as neurotransmitters

Serotonin - regulate sleep, mood, appetite and digestion

Popamine - brain reward system

amines as hormones

adrenaline

• synthesised by adrenal gland

• increase blood glucose level & heart rate

• contract blood vessels

• dilates air passages

• fight or flight response

Neutralisation of amines

React with acids to form salts (all amines can do neutralisation)

R-NH2 + HCl → R-NH3⁺Cl^-

Dissociation of amines

Weak base in water, similar to ammonia

R-NH2 + H2O → R-N⁺H3 + OH-

Salts of amines

similar physical properties as ionic compounds

• white crystalline solids

• high melting points

• more soluble in water than amines

• odourless (amine drugs in salt form)

amides

amine derivatives of carboxylic acids

RCOOH + R’NH2 (not tertiary) → RCONHR’

• conditions: heat

• note position of amide linkage

• polyamides (e.g. nylon)

Primary amide nomenclature

• carboxylic acid carbon is C1

• -oic acid → amide

melting point and boiling point

strong IMF, hence high melting and boiling point

Solubility

• if >= 6 - insoluble; if < 6 - soluble

• energy to break HB between water and HB/LDF between amide VS energy released by HB between water and amide

Natural amides