Chemistry - Rings, Polymers and Analysis - F324 - Polymers and Synthesis (2) Flashcards
What is a peptide?
A peptide is a compound made of amino acids linked by peptide bonds.
How many amino acids are found in the human body?
20 different amino acids are found in the body.
Are amino acids soluble in acids or bases?
Amino acids are soluble in both acids and bases.
Define a zwitterion.
A zwitterion is a dipolar ionic form of an amino acid that is formed by the donation of a hydrogen ion from the carboxyl group to the amino group. Because both charges are present, there is no overall charge.
Define the isoelectric point.
The isoelectric point is the pH value at which the amino acid exists as a zwitterion.
If the amino acid is put at a pH that is more acid than its isoelectric point, what will happen?
If the pH is more acid than the amino acids isoelectric point then the amino acid behaves as a base and accepts a proton to form a positively charged ion.
If the amino acid is put at a pH that is more alkaline than its isoelectric point, what will happen?
If the pH is more alkaline than the amino acids isoelectric point then the amino acid will behave as an acid and donate a proton to form a negatively charged ion.
Proteins are long polypeptides of how many amino acids?
Proteins are polypeptides of more than 50 amino acids.
What is the result of acid hydrolysis of polypeptides and proteins?
During acid hydrolysis, the amino acids formed are positively charged because of the presence of H+ ions from the acid.
What conditions are used for the acid hydrolysis of polypeptides/proteins?
Traditionally the protein/polypeptide is heated under reflux with 6 moldm-3 HCl for 24 hours.
What conditions are used for the alkaline hydrolysis of proteins/polypeptides?
A solution of alkali in the form of aqueous sodium hydroxide is used at just above 100oC.
What is the result of alkaline hydrolysis of proteins/polypeptides?
Broken down into amino acids in the form of their sodium salts.
Define a stereoisomer.
Stereoisomers are species with the same structural formula but with a different arrangement of the atoms in space.
Define optical isomers.
Optical isomers (or enantiomers) are stereoisomers that are non-superimposable mirror images of each other.
In what type of molecules do optical isomers arise?
Optical isomers arise in organic molecules that contain a carbon atom attached to four different atoms.
What is a chiral carbon?
A chiral carbon is a carbon atom attached to four different atoms or groups of atoms.
A mixture of equal amounts of each optical isomer is called what?
A mixture of equal amounts of each optical isomer is called a racemic mixture.
What does condensation polymerisation require?
Condensation polymerisation requires monomers with two different functional groups.
What functional groups are needed in the monomers to make a polyester?
The hydroxyl and the carboxyl functional groups.
What functional groups are needed in the monomers to make a polyamide?
The carboxyl and the amine functional groups.
Addition polymers are made from how many types of monomer?
Addition polymers are made from one type of monomer.
If the monomer contains a double bond, then what type of polymerisation will occur?
If the monomer contains a double bond then addition polymerisation will occur.
What is the result of alkaline hydrolysis of polyesters?
Alkaline hydrolysis of polyesters results in each ester linkage being hydrolysed to the sodium salt of the carboxylic acid.
What is the result of acid hydrolysis of esters?
The monomer units of the polyester are produced.
When polyamides are hydrolysed in acid conditions, what is the result?
When polyamides are hydrolysed in acid conditions, the dicarboxylix acid is produced together with an ammonium salt of the diamine.
When polyamides are hydrolysed in basic conditions, what is the result?
When polyamides are hydrolysed in basic conditions, the sodium salt of the dicarboxylic acid and the diamine are formed.
What is a biodegradable polymer?
A biodegradable polymer is a polymer that breaks down completely into carbon dioxide and water.
What is a degradable polymer?
A degradable polymer is a polymer that breaks down into smaller fragments when exposed to light or heat or moisture.
What is/was seldane used for?
Seldane was one of the first antihistamines.
What did the other optical isomer in Seldane do?
The other optical isomer caused a potentially fatal heat condition in some patients.
What are the benefits of producing a single isomer with the correct pharmacological activity?
The risks from undesirable side effects are reduced and the drug doses may also be reduced.
Why is separation of two optical isomers difficult?
Separation is difficult because optical isomers usually have the same or similar physical properties - melting points, boiling points and solubilities.
What separation techniques tend to be used to separate optical isomers?
Separation techniques include the use of enzymes, electrophoresis and chromatography.
