TABLE OF CONTENTS An organic reaction is believed to take place by the attack of a reagent on the compound containing carbon; designated as a substrate (meaning a, substance lying below). An organic reaction may be represented as:
A substrate may be defined as the reactant that contains carbon atoms some of whose bonds with other atoms are broken and some new ones formed as a result of reaction with the attacking reagent.
The carbon bonds in the substrate molecule are broken to give fragments which are very reactive and constitute transitory intermediates. They may react with other similar species or with the molecules present in their environments, thus establishing new bonds to give the products.
It is seen that most of the attacking reagents bear either a positive or a negative charge. These would not attack the substrate successfully unless the latter somehow possessed oppositely charged centers in the molecule. So the substrate molecule must develop polarity on some of its carbon atoms and substituents linked together. This is made possible by the displacement of the bonding electrons resulting in the development of polarity in the substrate molecule. Such effects involving the displacement of electrons in the substrate molecule are referred to as electron displacement effects.
There are four types of electronic displacements in organic molecules:
It is the permanent displacement of electrons from a covalent bond toward the more electronegative element or group. When...
