Nitrogen compounds, polymers, and synthesis Flashcards
(25 cards)
how do amines act as bases?
a lone pair of electrons is present on the nitrogen atom of amines, so they can accept a proton from acids, forming a dative bond
what are the reagents and conditions needed to prepare amines from nitrobenzenes? what typeof reaction is this?
tin and concentrated HCl, then NaOH
heat and reflux
this is a reduction reaction
how is the salt produced in amine preparation?
heating the nitrobenzene with tin and HCl produces the salt, then the NaOH is added to release the phenylamine from the salt
what side product is formed in the preparation of amines?
water
what is the base strength order for amines?
tertiary>secondary>primary>aromatic
what are the reagents and conditions needed for the preparation of amines by reduction of nitriles? what mechanism is this?
hydrogen
nickel catalyst
nucleophilic substitution
what are the reagents and conditions needed for preparation of amines by substitution of haloalkanes?
dissolve haloalkane in excess ethanolic ammonia, then add NaOH
heat under reduced pressure
what is the use of ethanol as a solvent in amine preparation by substitution of haloalkanes?
to prevent substitution by water to produce alcohols
why must ammonia be in a large excess in amine preparation by substitution of haloalkanes?
to prevent/limit the formation of secondary and tertiary amines by further reactions
what are the 3 ways to prepare an amine?
reduction of nitroarenes
reduction of nitriles
substitution of haloalkanes
why does further substitution occur?
amines are nucleophiles, so they can then attack other molecules
if there is a large excess of ammonia, which product is most likely to be formed and why?
there is excess ammonia and little RBr- this prevents further substitution so a primary mine is formed
if there is a large excess of bromoethane, which product is most likely to be formed and why?
there is little ammonia and excess RB- amines act as nucleophiles, so undergo further substitution until the fourth so a quaternary amine is formed
what functional groups do amino acids contain? what is the general formula?
the NH2 (amine) group and the COOH (carboxylic acid) group- therefore they are bifunctional compounds
(in alpha amino acids, these are attached to the same carbon)
RCH(NH2)COOH
are all amino acids optically active?
yes, except glycine
what are the acid/base properties of amino acids?
in acidic solutions, the COO- is protonated to give COOH
in alkaline solutions, the NH3+ is deprotonated to give NH2
what are the reagents and conditions needed for the esterification of amino acids?
COOH in the amino acid, alcohol, concentrated H2SO4
heat and reflux (additional purification of the ester product is often required)
what happens to the amine group during esterification?
it will also be protonated due to the presence of the acid catalyst needed (contains H+ ions)
what is condensation polymerisation?
when 2 different functional groups react, removing water and linking monomers together
how is a polyester formed?
a di-alcohol reacts with a di-carboxylic acid/di-acid chloride to produce a polymer with many ester bonds, releasing a molecule of water
how is a polyamide formed?
a di-amine reacts with a di-carboxylic acid/di-acid chloride to produce a polymer with many amide bonds, releasing a molecule of water
what are the uses of polyesters and polyamides?
fibres in clothes
are condensation polymers biodegradable?
yes, because they can be hydrolysed
also due to the C=O group they can absorb radiation, so are photodegradable too
are addition polymers biodegradable?
no because they are chemically inert, bringing disposal difficulties
