[amp_mcq option1=”Carbanion” option2=”Carbocation” option3=”Carbene” option4=”Free radical” correct=”option3″]
The correct answer is carbocation.
A carbocation is a positively charged carbon atom. It is formed when a proton (H+) is removed from a molecule, leaving behind a carbon atom with an incomplete octet. Carbocations are very reactive and can undergo a variety of reactions, including substitution, addition, and elimination.
In the preparation of diethyl ether from ethanol by treatment with H2SO4, the first step is the protonation of ethanol. This forms the ethyl carbocation, which is then attacked by the ethoxide ion (the conjugate base of ethanol) to form diethyl ether.
The reaction mechanism is as follows:
$$\ce{EtOH + H2SO4 <=> EtOH^+ + HSO4^-}$$
$$\ce{EtOH^+ + EtO^- <=> Et-O-Et + H2O}$$
The ethyl carbocation is a very reactive intermediate and can undergo a variety of reactions. In this case, it reacts with the ethoxide ion to form diethyl ether.
The other options are incorrect.
- A carbanion is a negatively charged carbon atom. It is formed when a pair of electrons is removed from a molecule, leaving behind a carbon atom with an incomplete octet. Carbanions are very reactive and can undergo a variety of reactions, including substitution, addition, and elimination. However, they are not formed in the preparation of diethyl ether from ethanol by treatment with H2SO4.
- A carbene is a neutral molecule with a carbon atom that has two unshared pairs of electrons. Carbenes are very reactive and can undergo a variety of reactions, including insertion, addition, and rearrangement. However, they are not formed in the preparation of diethyl ether from ethanol by treatment with H2SO4.
- A free radical is a molecule or atom with an unpaired electron. Free radicals are very reactive and can undergo a variety of reactions, including substitution, addition, and elimination. However, they are not formed in the preparation of diethyl ether from ethanol by treatment with H2SO4.