amines Flashcards
what are amine
derivatives to ammonia one or more hydrogen are replaced by an alkyl group
why are they good as intermediate synthesis
as they are very reactive
what shape is ammonia
pyramidal molecules with a bond angle of 107 as a result of the lone pair of the electron
if amine are polar what does this mean
there is a difference in electronegativity between nitrogen and hydrogen so can form hydrogen bonding
compare the hydrogen bonding in water and in ammonia
hydrogen bonding is stronger in alcohols as oxygen is more electronegative than hydrogen
what are the states like in room temperature
shorter chains are gases at room temperature, and longer ones are volatile liquids and have a fishy smell
what are the solubility like
shorter amines are soluble in solvents
why
because they form hydrogen bonds and the hydrogen bonds in the amine and water can interact
what importance is the lone pair
it can form a bond with the h+ hen acting as a base
form a bond with a deficient carbon atom acting like a nucleophile
how do amine react with acids
they react to form salts
describe the products
they are ionic compounds that can crystallise as the water evaporates
what if a base is added to the salt
it removes the proton and regenerates the soluble amine
what is the base strength dependent on
how readily it will accept a proton
what do alkyl groups do
they release electron towards the nitrogen which is called the inductive effect
what does the inductive effect do to nitrogen
increases the electron density o nitrogen and makes it a better electron donor
why are tertiary amines not stronger than secondary amines
they are less soluble in water
how are primary amines formed
when ammonia reacts with halogenoalkane in nucleophilic substitution
how does a quaternary salt form
tertiary amine will react with halogenoalkane
why is this not an appropriate way to prepare an amine
as a mixture of primary/secondary and tertiary amine are formed that needs to be separated
how to ensure a larger yield of primary amine
using excess ammonia
whyat is the purer way of forming primary amine
reducing nitrile group to an amine group using a platinum or nickel catalyst with hydrogen
how does nitrobenzene form phenylamine
it is reduced by reacting with tin and hcl
as hcl is used what can also be form
the ammonium salt
how do we free up the primary amine
we react it with sodium hydroxide to form sodium chloride and phenylamine
what are quaternary amine used for
industrially to manufacture hair fabric and conditioners
why do they form cations
as they have a long hydrocarbon chain and a positively charged organic group
what do both wet hair and wet fabric do
pick up negative charges on their surface
so what does positive cations do
attract the negative charges to the wet surface forming a coating to prevent build up of static electricity
what does this keep
the surface of the fabric smooth and prevent flyaway hair in conditioner
why are they called cationic surfactants
because in aqueous solutions the ions cluster with their charged ends in water and their hydrocarbon tails on the surface
