Chapter 8, Problem 55P

Interpretation Introduction

Interpretation:

The dicarboxylic which yields a meso compound and a racemic mixture is to be determined.

Concept Introduction:

Isomers are molecules which have same number of atoms but different arrangements of the atoms in space.

Stereoisomers have the same molecular formula, but the arrangement of atoms in the three-dimensional orientation is different.

Enantiomers are stereoisomers whose molecules have a chiral center and are mirror images of each other.

Diastereomers are stereoisomers that are not mirror images of each other. They are non-superimposable.

Molecules whose atoms are connected differently are called constitutional isomers.

Meso are those compounds whose molecules are superimposable on their image mirrors in spite of the presence of asymmetric carbon atom.

Chiral molecules are capable of rotating plane polarized light

The molecules which are superimposable or identical with their mirror images are known as achiral molecules, and achiral molecules are not capable of rotating the plane-polarised light.

Plane of symmetry is the plane that bisects the molecule in two equal halves, such that they are mirror images of each other.

Compounds having plane of symmetry are usually achiral as they do not have different atoms around the central carbon atom.

The stereoformula which is depicted in two dimensions, in which stereochemical information is not destroyed, is determined by the Fisher Projection formula.

The achiral compounds in which a plane of symmetry is present internally and which consist of chiral centres are known as meso compounds. However, they are optically inactive even though they contains two or more stereocenters. It has a d-configuration above the plane and an l-configuration below the plane, or vice versa.

A racemic mixture is a mixture that contains d-configuration and l-configuration in the same amount.

In double bond or cyclic compounds, if two same functional groups are present on the same side of the double bond or cyclic compound, the given compound can be labeled as cis.

If the two functional groups are present on the different sides of the double bond or cyclic compound, the given compound can be labeled as Trans.

Cis-trans isomerism exists in the compounds in which similar groups are present on the adjacent carbon atoms.

Electrophiles are electron deficient species which has positive or partially positive charge. Lewis acids are electrophiles which accept electron pair.

Nucleophiles are electron rich species which has negative or partially negative charge. Lewis bases are nucleophiles which donate electron pair.

Free radical is an atom, molecule or ion that has unpaired electrons which makes it highly chemically reactive.

Substitution reaction: A reaction in which one of the hydrogen atoms of a hydrocarbon or a functional group is substituted by any other functional group is called substitution reaction.

Elimination reaction: A reaction in which two substituent groups are detached and a double bond is formed is called elimination reaction.

Addition reaction: It is the reaction in which unsaturated bonds are converted to saturated molecules by the addition of molecules.

Fumaric acid is a trans-isomer. Therefore, when bromine is added to it, it is added to the opposite sides, (anti-addition) and hence, it yields a meso-compound.

Maleic acid is a cis-isomer. Therefore, when bromine is added to it, it is added to the same side because both the hydrogen atoms are on the same side, and hence, it yields a racemic mixture.