Chapter 27 Amines
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How do you name amines?
If primary and the amine is at the end of a chain, alkylamine If primary and the amine is at another position, 2-aminoalkane If secondary or tertiary, N-alkyl-N-alkyl-longest alkyl amine If all substituents are the same, no need for N, e.g triethylamine
Why can an amine react with acids?
Amines can act as bases. The lone pair of electrons on the nitrogen can accept a proton, to form a carbammonium ion, and a salt
Rank the basicity of different amines? Strongest to weakest
Alicyclic/ Aliphatic amines (more alkyls the stronger the base) Aromatic amines with another electron donating group Aromatic Amines - electrons delocalised Tertiary aromatic amines - no alkyls or hydrogens to donate electrons
What are the strongest type of amines in terms of basicity and why?
Tertiary, alkyls are electron donating Then secondary, then primary, then look at aromatic ones
How can you make a primary amine? Conditions?
1.Haloalkane and Ammonia, forms an Ammonium Salt 2. NaOH to deprotonate the salt Or would the excess mean the second step is not necessary? Excess ammonia to reduce further substitution, and Ethanol solvent to prevent nucleophilic substitution
Why does the NH3/Cl- not deprotonate the salt?
NH3 will but very slowly Cl- is a weaker base than NH3 so unlikely to OH- strongest, quickly removes the proton
Why does the synthesis of amines with haloalkanes result in multiple products?
Further substitution occur The amine formed still has a lone pair so can under nucleophilic substitution with more haloalkane Forms secondary, tertiary amines, and finally carbammonium ions with no lone pairs
How do you form phenylamine from benzene? What type of reaction is this?
Nitration with conc H2SO4/HNO3 Reduction : 1. Heat under reflux with Sn/HCl 2. NaOH to deprotonate Reduction, use brackets H for equation
How can you synthesise an amine from an alcohol?
Heat under reflux with NaBr/H2SO4 to form haloalkane React with NH3 in ethanol solvent, the deprotonate
What is an alpha amino acid?
An amino acid where there is one carbon between the COOH and the NH2
What types of reactions to amino acids under go?
COOH with Na/NaOH/NaCO3 to form a carboxylate salt NH2 with HCl to form an ammonium salt Esterification- forms an ester but also a AMMONIUM SALT as NH2 protonated from the catalyst
What is a zwitterion and when does it form?
A form of the amino acid where the COOH’s proton is donated to the NH2, overall neutral molecule At its isoelectric point , unique as acid/base chemistry of the R groups affects this
Why do amino acids have higher melting points than expected/ higher solubilities?
Zwitterion allows for ionic bonding, strong electrostatic force of attraction, lots of energy to overcome in giant ionic lattice Full charges allow greater interaction with water
How does an amino acid act as high/low pHs?
Low pH- acidic environments, so NH2 accepts a proton High pH- alkaline environments, so COOH donates a proton
How do you form amides and what is the side product?
Acyl Chlorides/Acid Anhydrides with NH3 or amines Forms an amide and an ammonium salt As the Cl- is a weaker base then NH3
What are the main types of isomerism and how can they be split further?
Structural- then Chain, Position, Functional group Stereoisomerism- Geometric (cis/trans) and Optical
What are optical isomers and how do they arise in organic compounds?
Non-superimposable mirror images, in organic, when a chiral carbon is present, a carbon bonded to 4 different groups In a ring, look for symmetry
How do you draw enantiomers of a chiral carbon?
Draw the dots and wedges Reflect this And keep the groups the same
How do enantiomers differ in their properties? How does a race mic mixture compare to this?
Each enantiomers will rotate plane polarised light into a different direction As a racemic mixture contains an equal amount of each enantiomers, the rotations will cancel out so the effect is not seen
What is the stereochemistry involved with SN1/SN2 and nucleophilic addition?
SN1- Racemic mixtures as equal chance of which side the nucleophilic will attack SN2- steric inversion, opposite enantiomer to the starting molecule Nucleophilic addition - Racemic, equal chance of being attacked above of below as a plane
What is a monomer?
A small molecule which can react with many other of this molecule to form a polymer
What is a polymer? What is a repeat unit?
Polymer- A large molecule formed from many repeating units of smaller molecules Repeat Unit- simplest unit of a polymer repeated to form the polymer
What is a condensation polymer and some examples?
The joining of monomers to form a large molecule of a repeating structure, with the removal of a small molecule such as water Polyesters, Polyamides
How can you make polyesters?
Need the functional groups: alcohol and either an Acyl Chloride or Carboxylic Acid With the same molecule- one of each, cannot see bond in repeat unit (n-1) water With two different molecules Diol and Dicarboxylic Acid, Diacyl, see one link, one not seen, (2n-1) water