C27 Amines, Amino Acids, And Polymers Flashcards
How do you name amines?
-amine or amino-
Why are amines so reactive?
The lone pair of electrons on the Nitrogen - due to the polar N-H bond
What shape are amines around the N? Bond angle?
Trigonal Pyramidal
107*
Due to lone pair on N
What kind of IMF do they have and why?
Hydrogen bonding
Due to polar N-H bond and lone pair of electrons on N atom.
Do amines have intermolecular forces which are stronger than or weaker than alcohols? Why?
Weaker
As N has a lower electronegativity than O
So it therefore has weaker hydrogen bonding
How can/when do amines act as bases?
The lone pair on the Nitrogen accepts a proton
How can/when do amines act as nucleophiles?
When they bond with an a electron-deficient C atom (donate lone pair from N)
What is the product from the basic action of an Amine with water?
RNH3+ - ammonium ion, which forms a salt with an anion
In order to be the strongest base, what must a particular amine have (out of a set of amines)?
Greatest electron density around the N atoms, making it a better electron pair donor (attracts protons more)
What effect do Alkyl groups have (on electron density and base strength)?
Positive inductive effect - increase electron density around N -> stronger base
Place the following in order of base strength (in general): NH3, primary amine, secondary amine, phenyl amine
Secondary amine > primary amine > NH3 > Phenyl amine
How can primary amines form secondary and tertiary and 4* ammonium ions?
Multiple substitutions: primary amine is a nucleophile that attacks the original haloalkane ETC
Problems with this method= not efficient as low yield of 1* amine due to multiple substitutions
( how can 1* amines form 2,3 and 4* ammonium ions?
Multiple substitutions: primary amine is a nucleophile that attacks the original haloalkane etc)
What are the problems with this method?
Not efficient as low yield of 1* amines due to multiple substitutions
How would you maximise the yield of the primary amine?
Use excess ammonia
What type of mechanism is the reaction of a haloalkanes with a Cyanide ion?
Nucleophilic substitution
What type of mechanism is the reaction of a haloalkanes with a Cyanide ion?
Nucleophilic substitution
What conditions does the reaction of a haloalkane with a cyanide ion require? What is the product formed?
Ethanol as a solvent
A nitrile is formed
How do you get from a nitrile to a primary amines? (Reaction type, reagent and catalysts)
Reduction reaction
Using Nickel
Hydrogen catalyst
Why’s this a purer method of synthesising amines?
Only the primary amine can be formed
Why is the reduction reaction of a nitrile with Nickel using a purer method of synthesising amines?
Only the primary amine can be formed.
What conditions are needed to form Nitrobenzene from Benzene?
Concentrated H2SO4 and HNO3 to form the NO2+ ion for electrophilic attack.
How do you from an ammonium chloride salt from nitrobenzene? What conditions are needed?
Reduce the Nitrile using TIN/HCl -> forms an ammonium salt with Cl- ions
Room temperature
What mechanism is used for forming Amides from acyl chlorides and amines?
Nucleophilic addition/elimination
What are the 2 functional groups of amino acids?
NH2 and COOH (amine and carboxylic acid)
Are alpha amino acids chiral? Why?
Yes, one carbon has 4 different substituents. Except glycine, where R = H
Define a Zwitterion
Ions which have both a permanent positive and negative charge, but are neutral overall.
How do zwitterions occur in amino acids?
COOH is deprotonated -> COO-
NH2 is protonated -> NH3+
What happens to amino acids in acidic conditions?
Gains a proton on NH2 group
What happens to amino acids in alkaline conditions?
Loses a proton from COOH group
What is the peptide linkage?
-CONH-
What property must a carbon atoms have for the molecule to display optical isomerism about that Carbon atom?
4 different substituents attached to one carbon atom
What are the similarities and differences between 2 optical isomers?
Same atoms & bonds, but they’re non-superimposable mirror images of one another. Not identical in chemical properties necessarily.
Differ in the way they rotate plane polarised light. Rotate plane of polarisation by the same angle but in different directions.
What word is used to describe optically active molecules?
Chiral
What is condensation in terms of polymers?
Small molecule eliminated (usually H2O) to form a larger molecule.
How many monomers are condensation polymers usually formed from?
2
What properties do monomers forming condensation polymers have?
Each has 2 functional groups
Examples of condensation polymers?
Polyesters
Polyamides
Polypeptides
What is the linkage in a polyester?
Ester linkage
What molecule is eliminated in formation of a polyester?
H2O
What are the 2 monomers which form a polyester (generic names and structures)?
Diol and Dicarboxylic acid
Or
A molecule with both alcohol and a carboxylic functional groups
What is terylene used for?
As a fibre for making clothes
Which monomers is Terylene made from?
Benzene-1,4-dicarboxylic acid
And
Ethane-1,2-diol
What is the linkage in a polyamide?
Peptide linkage
Which molecule is eliminated when a polyamide is formed?
H2O
What are the 2 monomers used to form a polyamide?
Diamine and dicarboxylic acid
Examples of polyamides?
Nylon
Kevlar
Which monomers is Nylon-6,6 made from
1,6-diaminohexane
H2N—(CH2)4–NH2
Hexanedioic acid
HOOC—(CH204–COOH
If you’re making Nylon in the lab, what monomers would you use and why? What molecule is eliminated?
Use hexane-1,6-diacyl chloride as the rate of reaction is much faster. HCl is eliminated.
What is Kevlar used for?
In body armour (Bullet proof vests, stab vests), helmets (e.g. F1 drivers), oven gloves
Which monomers make up Kevlar?
1,4-diamniobenzene
And
Benzene-1,4-dicarboxylic acid
Why are poly(alkenes) not biodegradable?
Non-polar C-H and C-C bonds
Why is it bad to burn poly(alkenes)?
Releases CO2, CO, C (soot) and other toxic chemicals from monomers
Where do most poly(alkenes) end up?
Landfill sites
Why can condensation polymers be broken down?
They have polar bonds
How are condensation polymers broken down?
Hydrolysis (opposite of condensation)
What is the difference between addition and condensation polymerisation?
Condensation makes the polymer and eliminates a small molecule: addition polymerisation breaks C=C to form only 1 product ( just the polymer).
Explain hydrogen bonding between polyamides
Both C=O and N-H are polar bonds, as N’s electronegativity > H’s and O’s electronegativity > C’s
Hydrogen bonding between H delta + and O delta - in different molecules
Uses the lone pair of electrons on the O atom
Why do polyesters not show hydrogen bonding
All O-H bonds are removed during polymerisation
