Chapter 18.11, Problem 22PTS

Interpretation Introduction

Interpretation:

The requirement of blocking group to accomplish the following conversions has to be illustrated.

           

Concept Introduction:

• The term Regioselectivity is referred as preference of a particular group to occupy a specific position in a compound. In case an aromatic ring has one or more than one substituents the position in the aromatic ring occupied by the incoming electrophile depends on various factors.

• A blocking group is a functional group which can be inserted on to the aromatic ring to direct the electrophile to a certain position. That is the phenomenon of using blocking groups is to obtain products with desired Regioselectivity.

• For example there are reactions in which we get mixture of ortho and para products. But we can obtain either ortho product alone or para product alone if we use blocking groups. If all the ortho positions are blocked we will get para product. If the para position is blocked and the required reaction is carried out we will end up with ortho product. After obtaining the product with the substituent at the desired position, the blocking group can be removed easily using the reagents applicable. Such groups which can be installed easily and removed easily function as blocking groups and have versatile usage in the synthesis of various ranges of organic compounds.