Question

What is R effect?

Answer 1

R effect

• “The resonance effect is defined as ‘the polarity produced in the molecule by the interaction of two π-bonds or between a π-bond and lone pair of electrons present on an adjacent atom’. ”
• This effect is transmitted through the chain.
• There are two types of resonance designated as R effect.

Two types of R Effect

• +R effect or positive resonance effect: “The transfer of electrons in this effect is away from an atom or substituent group that is connected to the conjugated system.
• +R effect shown by aniline as follows:-

• -R effect or resonance effect:" This effect is observed when the transfer of electrons is towards the atom or substituent group attached to the conjugated system."
• -R effect is shown by nitrobenzene as follows:-