Amines

amine

• nitrogen surrounded by hydrogens and/or r groups

• organic form of ammonia

ammonia

nitrogen surrounded by three hydrogens

primary amine

one r group, two hydrogens

secondary amine

two r groups, one hydrogen

tertiary amine

three r groups

alkaloids

naturally occurring amines

amines and neurochemistry

some naturally occurring amines are vital to neurochemistry

• adrenaline

• noradrenaline

• dopamine

modes of reactions for amines

1) act as base

2) act as nucleophile

what does the nitrogen atom of an amine carry

a partial negative charge on its lone pair

what does the lone pair of the nitrogen in an amine function as

a base (proton acceptor) or nucleophile (it has an extra electron)

primary amines nomenclature

1) name the alkyl group ending in “yl” followed by the suffix “amine”

• name of alkene, drop “ane,” add “amine”

2) named the same as alcohols but the amine suffix is used instead of “ol”

3) the term “amino” is used for the group as a substituent

if the amine is directly attached to an aromatic ring, what is the parent name

aniline

• nitrogen is carbon 1

• go in direction to get first substituent

secondary and tertiary amines nomenclature

1) name the alkyl groups followed by -amine suffix

• di or tri used if there are more than one of the same group

2) find the carbon parent chain and use the suffix, amine instead of “ane”

amines hybridization

sp3

paramonal

what amines are (not tetrahedral)

are nitrogen atoms with three different alkyl groups chiral

yes because they possess four different groups and the lone pair counts as a group

are amines superimposable

no

what is the boiling point of tertiary amines compared to primary and secondary

tertiary amines have a lower boiling point due to the lack of hydrogen bonding

amine solubility

if they have fewer than 5 carbons, they are typically soluble

basicity of amines

stronger bases than alcohols and ethers, they can be easily protonated by strong or weak acids and converted to acidic form

pka of amines

around 11

how is amine solubility enhanced

in the presence of an aqueous acid

• protonated ammonium ions are cations and therefore water soluble

how can amines be extracted from organic impurities

using an aqueous acid and converting them to corresponding ammonium ions

are heavier amines soluble in water

no

why is a delocalized lone pair less available for protonation

because of resonance, the lone pair can be moved all the way around ring

what does the presence of electron withdrawing groups do to basicity

decreases basicity

amide

nitrogen attached to carbonyl group

lone pair of amide

not considered to be basic/nucleophilic because it is extensively delocalized into the carbonyl group

physiological pH of amines

around 7.3, so primarily exist as ammonium ions

Henderson-Hasselbach equation purpose

calculates the ratio of amine to ammonium ion at a given pH

Henderson-Hasslebach equation

conjugate base/acid

preparation of amines

converting a carboxylic acid to amide, then reducing amide with LAH