amines Flashcards
prefix for amine
amino-
suffix for amine
-amine
why are amines so reactive
lone pair of electrons on nitrogen due to N-H bond
what shape and bond angle around N
trigonal pyramidal
107 degrees due to lone pair on N
what kind of intermolecular forces do they have
hydrogen bonding due to polar N-H bond and lone pair of electrons on N atom
do amines have intermolecular forces which are stronger than or weaker than alcohols
weaker as N has a lower electronegativity than O –> weaker hydrogen bonding
what state are amines at 298 K
short chains are gases, longer chains are volatile liquids
what do amines smell of and why
fishy smell
rotting fish and flesh releases di- and triamines
which primary amines are soluble in water/alcohols
up to 4 carbon atoms, as they can hydrogen bond to water molecules. after this, non-polarity of hydrocarbon chains makes them insoluble
what kind of solvents are most other amines soluble in
less or non-polar solvents
solubility of phenylamine
not very soluble, due to the non-polarity of the benzene ring - C6H5 cannot form hydrogen bonds
how can/when do amines act as bases
when they bond with a H+ ion
how can/when do amines act as nucleophiles
when they bond with an electron-deficient C atom (donate lone pair from N)
what is the product from the basic action of an amine with water
RNH3+ ammonium ion, which forms a salt with an anion
is the product (ammonium ion) soluble in water
yes, as it is ionic so is attracted to the polar bonds in H2O
how could you regenerate the soluble amine from the ammonium salt
add a strong base (NaOH) –> removes H+ ions from ammonium ion
how could you regenerate the soluble amine from the ammonium salt
add a strong base (NaOH) –> removes H+ ions from ammonium ion
in order to be the strongest base, what must a particular amine have (out of a set of amines)
greatest electron density around the N atom making it a better electron pair donor (attracts protons more)
what does positive/negative inductive effect mean
positive inductive effect = donate electrons increase density around N
negative = remove electrons, decrease density around N
what effect do alkyl groups have
positive inductive effect - increase electron density around N –> stronger base
what effect do alkyl groups have
positive inductive effect - increase electron density around N –> stronger base
what effect do aryl groups have
negative inductive effect - decrease electron density around N –> weaker base
why are tertiary amines never good bases
they are insoluble in water
place these in order of base strength NH3, primary, secondary and phenylamine
secondary > primary > NH3 > phenylamine
how can primary amines then form secondary, tertiary amines and quaternary ammonium ions
multiple substitutions
primary amine is a nucleophile that attacks the original haloalkane
problems with using NH3 as nucleophile to haloalkane
not efficient as low yield of primary amine due to multiple substitutions
how would you maximise the yield of the primary amine
use excess ammonia
what type of mechanism is the reaction of a haloalkane with a cyanide ion
nucleophile substitution
what conditions does this reaction require and what product is formed
ethanol as a solvent
a nitrile is formed
how do you get from a nitrile to a primary amine
reduction using nickel / hydrogen catalyst
why is this a purer method of synthesising amines
only the primary amine can be formed
what conditions are needed to form nitrobenzene from benzene
concentrated H2SO4 and HNO3 to form the NO2 + ion for electrophilic attack
what conditions are needed to form nitrobenzene from benzene
concentrated H2SO4 and HNO3 to form the NO2 + ion for electrophilic attack
how do you form an ammonium chloride salt from nitrobenzene and what conditions are needed
reduce the nitrile using Sn / HCl –> forms an ammonium salt with Cl- ions
room temperature
nitrobenzene –> phenylamine
C6H5NO2 + 6[H] –> C6H5NH2 + 2H2O
what mechanism is used for forming amides from acyl chlorides and amines
nucleophilic addition/elimination
in which industries/products are amines used
dyes / nylon / drugs / synthesis of new molecules
what are catatonic surfactants and where are they used
quaternary ammonium salts, with a cation that is charged at one end (N+) and non-polar at the other
used in fabric/hair conditioner
how do catatonic surfactants work in fabric/hair conditioners
negative charges on the surface of the fabric/hair are attracted to the cation, removing them from the surface; prevents build up of static electricity and keeps hair flat and fabric smooth
