amines and amides Flashcards
define a ligand
a molecule or ion with a lone pair of electrons which can make a dative covalent bond with a metal cation forming a complex ion
what state are short chain primary amines at room temp
gas
why are short chain primary amines soluble in water
H bonds are possible between the amine H+ attached to the electronegative N atom and lone pair on H2O. also between RN:H2 and +H20
define a base
a proton acceptor
how does ammonia react with water to produce a basic solution (equation)
N:H3 +H20 –> NH4+ + OH-
(OH- makes the solution alkaline)
order of base strength (from lowest to highest)
phenylamine < NH3 < primary < secondary < tertiary
why is butylamine a stronger base than ammonia
alkyl group is weakly electron donating to lone pair on N. increases the electron density of the lone pair and makes it more available to a H+ ion
why is phenyl amine a weaker base than ammonia
N lone pair overlaps with the delocalised ring of the benzene group. this increases the electron density of the ring, reduces the electron density of the N lone pair. It is now less attractive to H+ ions.
which kind of mechanism is the preparation of amines with halogenoalkane and ammonia
nucleophilic substitution
why can ammonia act as a nucleophile
lone pair on the N
reaction details of ammonia and halogenoalkane (reagents and conditions)
reagents: halogenoalkane + excess conc ammonia dissolved in ethanol
conditions: heat in a sealed tube
what are the two steps of preparing amines from a halogenoalkane and ammonia
step 1: ammonia acts as a nucleophile
step 2: acts as a base releasing the free amine
what kind of reaction is the preparation of amines with a nitrile
reduction
what are the two ways of producing an amine from a nitrile
1 using hydrogen gas and a nickel catalyst
2 using LiAlH4 in dry ether followed by dilute acid
equation for reduction of nitrobenzene to phenyl amine
C6H5NO2 +6[H] -> C6H5NH2 + 2H2O
What is the reducing agent for the reduction of nitrobenzene to phenyl amine
Tin and concentrated HCl
step 1 of reduction of nitrobenzene to phenyl amine
add tin to nitrobenzene
add conc HCl with cooling
heat on a boiling water bath to complete the reduction
step 2 of reduction of nitrobenzene to phenyl amine
sodium hydroxide added
collect phenyl amine by steam distillation
shake with NaCl solid
separate organic layer
dry with K2CO3 solid
redistill using an air condenser
what is the functional group of an amine
R-NH2
what is the functional group of an amide
R-C=ONH2
which intermolecular forces do amides contain
London forces and H bonding
are amides soluble in water
yes due to H bonds
why are amides less basic than amines
in amides the lone pair is delocalised between the nitrogen and the oxygen due to resonance. This reduces the electron density on the nitrogen atom.
what kind of reaction is the preparation of amides
nucleophilic substitution
what are the 2 ways of preparing an amide
1 acyl chloride + ammonia
2 acyl chloride + amine
