Carboxylic acids are a chemically and biologically important class of organic compounds. — Organic Chemistry Chemistry Question
Carboxylic acids
Carboxylic acids are a chemically and biologically important class of organic compounds.
Draw the constitutional (structural) formulae of all isomeric cyclobutanedicarboxylic acids and give the systematic names for these compounds.
Model Answer
Constitutional isomers:
There are three stereoisomers, I,II and III, of cyclobutane-1,2-dicarboxylic acid. Draw perspective or stereo formulas of I, II and III indicating the relative configuration of each molecule.
Model Answer
Stereoisomers:
Which pairs of stereoisomers I, II and III are diastereoisomers and which are enantiomers of each other?
Model Answer
Diastereomers are I, III and II, III. Enantiomeric pairs are I and II.
Which reaction can be used to determine the relative configuration of diastereoisomers?
Model Answer
On loosing water the cis-diastereomer forms the corresponding anhydride according to:
How may the enantiomers of cyclobutane-1,2-dicarboxylic acid be separated?
Model Answer
The trans-diastereomer can be precipitated with a optically active base.
Indicate the absolute configurations of each asymmetric centre on the structures of the stereoisomers I, II and III using the Cahn-Ingold-Prelog rules (R,S system).
Model Answer
Stereoisomers absolute configuration:
I: R,R; II: S,S; III: R,S