Which of the following compounds give more electrophilic substitution reaction? A) Benzyl cyanide B) Phenol.

Electrophilic Substitution Reaction:

These are important reactions in organic chemistry. The type of reaction in which a functional group is replaced by an electrophile. Electrophilic substitution reaction generally proceeds by the mechanism which contains three steps. In an Electrophilic substitution reaction, Hydrogen from the compound is replaced by an electrophile.

 An electrophile is a compound that is electron loving. Electro means electron and phile mean loving. An electrophile is basically an electron-deficient species that contains a positive charge on them. Electrophiles may react with nucleophiles. Electrophile and nucleophile are opposite terms. A nucleophile is basically a nucleus love has a negative charge on it. They are electron-rich species.

Properties Of Benzyl Cyanide:

Following are the properties of Benzyl Cyanide:

  • They are colorless only liquids
  • They have a density of 1.015 g/cm3
  • They have a melting point of −24 °C (−11 °F; 249 K).
  • Also, they possess a boiling point of 233 to 234 °C (451 to 453 °F; 506 to 507 K).

Properties of Phenol:

  • Phenol is an aromatic compound with a benzene ring in it.
  • Phenol possesses a peculiar smell.
  • These are water-soluble crystalline solids that have definite shape and volume in the 3-dimensional pattern.
  • They have low melting and high boiling point.

What is the Mesomeric effect??

The mesomeric effect is the effect that enables a ring to become stable. It may increase or decrease the electron density of the ring. So, it may enhance the electrophilic substitution reaction. There are some compounds that are attached to the benzene ring so that they may be activated or de-activated groups. If the ring is electron deficient then the +M effect dominated and they give electrons to the ring the stabilize charge density. If the ring is electron enriched the -M effect dominated and withdraws the electron from the ring to stabilize the charge density.

Which is more stable benzyl cyanide or phenol?

Structures of Benzyl cyanide and phenol:

The first structure shown is Benzyl chloride and the second one is phenol. Both stabilities are defined by the mesomeric effect.

Electrophilic substitution reaction

Electrophilic substituition reaction

The mesomeric effect contains two types of mesomeric effects that are +M effect and the -M effect. +M effect is shown by those compounds having lone pair on it and is directly attached to the benzene ring however on the other hand -M effect is shown by compounds that are directly attached to the ring and with the other compound that is more electronegative than that of compound attached to the benzene ring with pie bond.

In the structure of Phenol, oxygen contains lone pair on it so that it gives its lone pair to the ring yet the charge density of the overall ring increases. Therefore, it gives a substitution reaction. While in the structure of Benzyl cyanide there is no increase in charge density because carbon takes an electron from the benzene ring and nitrogen takes an electron from carbon so electronic charge density decreases.

By the following relation, it is clear that (Electron charge density is directly proportional to substitution reaction). Therefore, the increase in electronic charge density in phenol gives more substitution reactions.

So, B > A (Conclusion of the question)

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