19A.4 Flashcards
What are amides
they are compounds with the functional group of carbonyl group joined a an amino group
why does the amide functional group show basic character
because the carbonyl group alters the chemical character of the NH2 group, just like how it alter the chemical character of the OH group in carboxylic acids
what are the properties of amides
they are solids. the lower aliphatic amides are soluble in water because the have two electronegative atoms and polar bonds allowing them to form hydrogen bonds with water. and the carbon in the carbonyl group is very electron-deficient because its joined to both the oxygen and nitrogen
what is the nomenclature of amides
page 245
how do we prepare amides and the chemical reaction
by mixing acyl chlorides with concentrated aq ammonia where the lone pair of electrons on the nitrogen is highly attracted to the electron deficient carbon in the acyl group and the Cl would then combine with one of the hydrogens in ammonia to form HCl
the equation:
RCOCl + NH3 —–> RCONH2 +HCl
since the inorganic compound formed in prep of amides is acidic what will happen
the ammonia will react with the HCl
NH3 + HCl —> NH4Cl
what is the overall equation for the prep of amides considering the reaction between ammonia and HCl
RCOCl + 2NH3 —> RCONH2 + NH4Cl
what toe molecules are needed for the formation of polyamides
dicarboxylic acid and diamine
how does dicarboxylic acid and diamine react together.
so with the amine holding basic groups and the carboxylic acid holding acidic groups they react together to form a CONH group with the elimination of H2O
what is nylon 6,6 and why does it end with 6,6
the most common form of nylon and it ends with 6,6 to show that both monomers contain six carbons.
how do we prepare nylon 6,6
by mixing hexanedioic acid (also known as adipic) monomer with hexane-1,6-diamine (also known as 1,6-aminohexane) monomers where both monomer have the same number of CH2 group (6) with reactive groups at each end of the chain
what is the chemical reaction to make nylon 6,6
246
how do we make Kevlar
by having the monomer of 1,4 -aminobenzene react with the monomer of 1,4-benzendicarbonyl dichloride with the elimination of HCl
what is the chemical reaction for the formation of Kevlar
page 246
what is the use of Kevlar
it has many uses most known to be body armour (bulletproof and stabproof vests)
what are the properties of polyamides
- tend to be semi-crystalline
- thought materials with good thermal and chemical resistance (however they can be attacked by strong acids and alkalis because they contain an amide link (peptide link) which can be hydrolysed by acids and alkalis
- absorption of moisture from there surroundings
- the strong bonds of polyamides make polyamides chains themselves strong
when does the adsorption of moisture stop in polyamides
it continues until equilibrium is reached
what is the rs between moisture content, resistance, flexibility, strength and stiffness. (of poly amides)
as the moisture content increases the resistance and flexibility of the poly amide increases but the strength and stiffness decreases.
what is polyamide film (cling film) used in and why
- it is used in food packaging because of its toughness and since gas molecules don’t pass through it easily
- “boil-in-the-bag’ food packaging since it has high temp resistance
what is the addition polymerisation for the formation of poly(propenamide) and its monomer
its monomer is 2-propenamide (known as acrylamide) reaction is page 247
what are the uses of poly(propenamide)
- thickener and filler for facial surgery
- the polymer can be easily cross-linked with other chains, this produces a thick gel that has a larger capacity to absorb water, which can be used to make soft contact lenses
how can we prepare poly(ethanol)
by two steps:
step 1: the polymerisation of ethenyl ethanoate into poly(ethenyl ethanoate)
step 2: poly(ethenyl ethanoate reaction with methanol to form poly(ethanol) and methyl ethanoate in a process called ester exchange
the amount of ester exchange can be controlled by a
altering the tempc
is poly(ethanol) soluble in water
it has an OH so it can form hydrogen bonds in the water and it can be made soluble, but its solubility depends on the percentage of ester groups that have been replaced by OH groups, so in conclusion its solubility can range from insoluble to soluble in hot/warm water to soluble in cold water
