CL 27- amines, amino acids and polymers Flashcards
how does an amine act as a base?
the lone pair on N can accept a proton
ethanamine + HCl
equation and name of product
- CH₃CH₂NH₂ + HCl –> CH₃CH₂NH₃Cl
- ethylammonium chloride (a salt)
preparation of a primary amine
reactants and reasons
- chloroalkane
- react with excess ammonia (to prevent further substitution)
- use ethanol as a solvent (water will compete with ammonia to replace halogen so can’t be used)
preparation of ethanamine from chloroethane
equation
(ethanol on arrow)
CH₃CH₂Cl + 2NH₃ –> CH₃CH₂NH₂ + NH₄Cl
formation of a secondary amine
- chloroalkane
- primary amine
equation for the formation of diethanamine
CH₃CH₂Cl + 2CH₃CH₂NH₂ –> (CH₃CH₂)₂NH + CH₃CH₂NH₃Cl
formation of aromatic amines
steps
- nitration of benzene ring (conc HNO₃ and conc H₂SO₄)
- reduction of nitrobenzene- add reducing agent Sn/conc HCl
formation of phenylamine
equation
nitrobenzene + 6[H] –> phenylamine + 2H₂O
more mechanisms didn’t know where to put them
aliphatic amine extended C chain steps
- add KCN to a chloroalkane to form a nitrile (nucleophilic substitution)
- turn into an amine by adding H₂/Ni to saturate the triple CN bond
nitrile to carboxylic acid
reagents
- heat with dilute acid
- example of hydrolysis
propanenitrile to propanoic acid
equation
CH₃CH₂CN + 2H₂O + H⁺ –> CH₃CH₂COOH + NH₄⁺
refresher
stereoisomer
definition
same structural formula but different arrangement of atoms in space
optical isomer
definition
chemicals that are non-superimposable mirror images of each other
conditions for optical isomers
- must contain a chiral carbon ( 4 different groups joined to the same C)
- mirror images (easy way to draw)
- make sure when drawing 3D, there’s an obvious 107 degree angle, and 1 dashed 1 filled wedge
enantiomer
definition
one of a pair of optical isomers
racemate
definition
an exactly equal mixture of the two enantiamers
formula to find how many enantiamers per chiral carbon
2ⁿ , where n is the no. of chiral carbons
general formula for amino acids
RCH(NH₂)COOH
amino acids are amphoteic…
…they act as both an acid (COOH) and a base (NH₂)
equation of 2-aminopropanoic acid and HNO₃
CH₃CH(NH₂)COOH + HNO₃ –> CH₃CH(NH₃⁺)COOH NO₃⁻
equation of 2-aminopropanoic acid and KOH
CH₃CH(NH₂)COOH + KOH –> CH₃CH(NH₂)COOK + H₂O
products of a condensation reaction of aminoethanoic acid and ethanol with conc H₂SO₄
- (NH₃)CH₂COOCH₂CH₃
- amine group protonates because of acid catalyst
- H₂O
amide link
C=ONH
forming amides
two ways
- amine + carboxylic acid
- amine + acyl chloride
aminoethanoic acid + ethanoic acid
equation
CH₂(NH₂)COOH + CH₃COOH –> CH₃C=ONHCH₂COOH
to find monomers of polyamide…
…split polymer at the amide link (put water back in)
two monomers of a polyamide
- diamine
- dioic acid
to find monomers of polyester…
…split at ester link
two monomers of a polyester
- dioic acid
- diol
lactic acid (2-hydroxypropanoic acid) is made from
bacterial fermentation from plant starch or sugar
* therefore, renewable and not from crude oil
why are polyamides and polyesters photodegradeable?
- the C=O bond absorbs IR radiation
acid hydrolysis of polyesters
products
- monomer units
alkaline hydrolysis of polyesters
products
- alcohol monomer
- carboxylic acid SALT
acid hydrolysis of polyamides
products
- carboxylic acid
- ammonium salt of the amine (protonates)
alkaline hydrolysis of polyamides
products
- amine
- carboxylic acid salt
