Polymers & Synthesis

• Amino acids form polypeptides and proteins, vital for hormones and enzymes.
• The body has a mixture of 20 amino acids that can be assembled into proteins:
  -General formula of alpha-amino acid: RCH(NH2)COOH
• So the amino acid has a basic (NH2) and an acidic (COOH) group.
• These can react with each other to form an internal salt, known as a ZWITTERION.
• A proton is transferred from the acidic COOH to the basic NH2.
• But the zwitterion has no overall charge due to cancelling out.

• The zwitterion has no overall charge, at the isoelectric point.
• The isoelectric point varies with each amino acid.
  
• Amino acids are amphoteric, reacting with both acids and bases.
• At an acidic pH, the amino acid behaves as a base and accepts H+ forming a positive ion.
• At an alkaline pH, it behaves as an acid and dontates H+ forming a negative ion. 

• Amino acids join together by peptide bonds, to form peptides.
• This is a condensation reaction, where H2O is removed.
  
• Two peptides being formed together is called a dipeptide and so on.
• Proteins are simply long amino acids. generally with 50 amino acids or more. 

• Acid hydrolysis:
  -By using an aqueous acid, water is needed to break the bond.
  -The amino acids formed are positively charged due to the presence of H+ from the acid.
  
• Alkaline hydrolysis:
  -Solution of aqueous NaOH at 100 degrees C.
  -Broken down into their Na salts (Sort of cut off here but only clear image)
   

• Another form of stereoisomerism, but seperate to E/Z.
• Arises in molecules that contain a chiral carbon, that is, one that is connected to FOUR different groups of atoms.
• Two-mirror image arrangements of atoms in space are possible, that are non-superimposable and are called optical isomers - or enantiomers.
• To draw an enantiomer:
  
• These polarise light differently and may have slightly different affects to each other. 
• THIS OCCURS IN AMINO ACIDSSSSS.

• Condensation is the joining of two monomers with the removal of H2O/HCl.
• There are two different types of polyesters:
  1- Where there are two different monomers, one with two -COOH groups and one with two -OH groups.
  2- Where there is one monomer, with a -COOH and a -OH attached. 
   (Two different monomers)
   (One monomer, COOH and OH) 

•  (Amide linkage)
• The same as before it is possible to form a polyamide by using two different monomers or just the one single monomer:
  -Two different: A molecule with 2 COOH groups, and one with 2 NH2 groups.
  -One single; A molecule that contains both a COOH group and a NH2.
  (Nylon-6,6 formation) 

• Addition polymers:
  -Only one monomer used.
  -One product formed.
  -C=C functional group.
  -Forms polyalkene.
• Condensation:
  -One or two monomers used.
  -Uses COOH/OH or COOH/NH2.
  -Forms the polyester/amide and water.
   

• Hydrolysis of polyesters:
  1-With hot alkali(aq):
  -The sodium salt of the carboxylic acid.
  -The hydroxyl group.
  2-With hot acid(aq):
  -The monomer units.
• Hydrolysis of polyamides:
  1-With hot alkali(aq):
  -The sodium salt of the dicarboxylic acid.
  -The diamine.
  2-With hot acid(aq):
  -The dicarboxylic acid.
  -An ammonium salt of the diamine.
• Biodegradable polymers:
  -Made from renewable sources such as corn starch, and break down with water/light to form CO2 and H2O with the presence of bacteria.

Polyester alkakine hydrolysis:

I cannot find a decent picture of acid hydrolysis of polyamides but basically the diamine has NH3+, that is the hardest bit.