PL Flashcards
carboxylic acids (and phenols) are strong enough acids to
react with strong bases to form salts
carboxylic acids reaction with carbonates
react to form water and CO2 in an acid-base reaction
redox reactions with carboxylic acids, phenols and alcohols
form salts with metals
polyesters
diols and dicarboxylic acids can be made into condensation polymers called polyesters
amines
have functional group NH2
strong smell of decaying fish
primary amines
have just one alkyl group
diamines
have two NH2 groups whichallow them to form condensation polymers
properties of amines
- lone pair on N is responsible for solubility in water and ability to act as bases
- can form H bonds with water molecules
- amines with larger alkyl groups are less soluble in water because they are unable to break the H bonds between water molecules
- lone pair can accept a proton from water to form a dative covalent bond - OH remains in solution so solutions of amines are alkaline
- react with acidic solutions by accepting a proton, solution will lose strong amine smell
primary amides
derivatives of carboxylic acids with the OH groups replaced by NH2
carboxylic acids reaction with ammonia
DOES NOT REACT
acyl chloride + ammonia»_space;
produces primary amide and HCl
secondary amides
H atom in NH2 group of a primary amide replaced with an R (alkyl) group
formation of secondary amides
primary amide + acyl chloride»_space; secondary amide + HCl
polyamides
aka nylons
diamines and dicarboxylic acids can react together to form polymer chains in polymerisation reactions
monomer units are linked together by secondary amide groups
alternative method of producing nylons
using diamine and dicarboxylic acid is slow
therefore, acyl chloride derivative of carboxylic acid is sometimes used
eg. decanoic acid»_space; decandioyl chloride
nylon using just one monomer
monomer must contain both a carboxylic acid group and an amine group
hydrolysis of esters
usually slow process but can be spread up by H2SO4 catalyst
requires water, produces alcohol and carbpxylic acid
alkali hydrolysis of esters
NaOH can be used to hydrolyse esters
ester reacts with hydroxie ion to produce alcohol and carboxylate salt
acid hydrolysis of primary amides
RCONH2 + H2O + H+»_space; RCOOH + NH4+
strong acid catalyst
acid hydrolysis of secondary amide
RCONHR’ + H2O + H+»_space; RCOOH + R’NH3+
strong acid catalyst
alkali hydrolysis of primary amides
RCONH2 + OH-»_space; RCOO- + NH3
uses sodium hydroxide
alkali hydrolysis of secondary amides
RCONHR’ + OH-»_space; RCOO- + R’NH2
optical isomerism of amino acids
due to presence of 4 different groups on central carbon atom
chirality and enantiomers
chiral centre
the carbon atom in an amino acid which is bonded to 4 different groups
the 4 groups can be bonded in different ways
enantiomers
mirror images of each other
BUT non-superimposable (not identical)
bonds must be broken to make them identical
amino acids in alkaline conditions
carboxyl group loses a proton
amino acids in acidic conditions
amine group accepts a proton
amino acids in neutral solutions
form zwitterions (act as buffers) carboxyl group is deprotonated and amine group is protonated
maintaining tertiary structure of proteins
id-id bonds between non-polar side chains on amino acids
hydrogen bonds between polar side chains
ionic bonds between ionisable side chains
covalent bonds between -SH groups to form disulphide bridges
enzymes
biological catalysts
lower activation enthalpy
(show higher specificity than inorganic catalysts)
bonds between enzymes and substrates
have to be weak so that th binding can readily be reversed to release product
usually H bonds or interactions between ionic groups
binding of substrate to enzyme may cause other bonds to weaken within the substrate
