Sessional paper solution

                                                      

Q. 1. Solve the following (ANY SIX) 06 marks

 
a)    The prefix R and S stand for Rectus and Sinister respectively.

b)    Define enantiomer. Give one example.

Stereoisomers whose molecules are non superposable mirror images of each other. Enantiomers have identical physical & chemical properties (e.g. melting point, boiling point, refractive index, solubility etc.)

Except 1) The direction of rotation of the plane of plane polarized light and 2) How they react with optically active reagents. e.g. Enzyme, Taste buds, scent Example:- (+)-limonene has smell of oranges and (-)-limonene smells like lemons.

 

 

c)    Give one example of each of linear and non linear tricyclic aromatic system. 

Anthracene and Phenanthrene 

d)    Give IUPAC name to following bridgehead compounds

e)    Give the end product of willgerodt reaction and DCC oxidation. 

f)    Write reaction for Wolff rearrangement.  

The Wolff rearrangement is an organic reaction used to convert an α-diazo ketone to a ketene using a uv light, or thermal conditions. The mechanism of the Wolff rearrangement is essentially one step which is initiated by the catalyst. The reaction involves a 1,2-shift to form the ketene product and release a molecule of nitrogen gas.

g)    What is meso compound? Give one example

Compound which contain at least two chiral centers but optically inactive called meso stereoisomers. A meso compound is one whose molecules are superimposable on their mirror images even though they contain chiral centers.

Example:-  2,3-dihydroxybutanedioic acid [ tartaric acid ]