6.2.2 Amino acids, amides and chirality Flashcards
(11 cards)
What is the general formula of an α-amino acid?
RCH(NH2)COOH
What is formed when the carboxyl group of an amino acid reacts with an alkali?
A carboxylate salt (RCH(NH2)COO–) and water.
What is formed when the carboxyl group of an amino acid reacts with an alcohol in the presence of an acid catalyst?
An ester (RCH(NH2)COOR’) and water.
What is formed when the amine group of an amino acid reacts with an acid?
An ammonium salt (RCH(NH3+)COOH).
What is an amide?
A compound containing a CONH2 group, formed from a carboxylic acid and an amine.
What is the difference between a primary and secondary amide?
Primary amide: -CONH2, Secondary amide: -CONHR.
What is chirality?
A property of a molecule where it has a chiral centre (a carbon atom bonded to four different groups) and exists as non-superimposable mirror images.
How can you identify a chiral centre in an organic compound?
Look for a carbon atom bonded to four different groups.
What is optical isomerism?
A type of stereoisomerism where molecules exist as non-superimposable mirror images due to a chiral centre.
How can optical isomers be distinguished?
By their ability to rotate plane-polarised light in opposite directions: one enantiomer rotates light clockwise (+), the other counterclockwise (-).
How should 3D diagrams be drawn to illustrate stereoisomerism?
Using wedge-and-dash notation: solid wedge for bonds coming out of the plane, dashed wedge for bonds going into the plane, and straight lines for bonds in the plane.
