The reaction (s) which give tert-butyl benzene among the following is/are (a) \(\mathrm{C}_{6} \mathrm{H}_{6}+\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Cl} \stackrel{\mathrm{AlCl}_{3}}{\longrightarrow}\) (b) \(\mathrm{C}_{6} \mathrm{H}_{6}+\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}_{2} \mathrm{OH} \stackrel{\mathrm{BF}_{3}}{\longrightarrow}\) (c) \(\mathrm{C}_{6} \mathrm{H}_{6}+\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CH} \stackrel{\mathrm{BF}_{3}}{\longrightarrow}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{6}+\mathrm{Me}_{2} \mathrm{C}=\mathrm{CH}_{2} \stackrel{\mathrm{HF}}{\longrightarrow}\)

The Friedel-Crafts Alkylation is a pivotal reaction in organic chemistry, especially for creating carbon-carbon bonds on aromatic compounds. It is named after Charles Friedel and James Crafts who first reported the reaction in 1877.

In simplified terms, this reaction involves the introduction or substitution of an alkyl group onto an aromatic ring, such as benzene. The alkyl group is typically derived from an alkyl halide, and the reaction is facilitated by a strong Lewis acid catalyst. The general mechanism begins with the formation of a highly reactive carbocation from the alkyl halide, which is then attacked by the aromatic ring through an electrophilic aromatic substitution process, ultimately adding the alkyl group to the ring.

This reaction has broad applications in the synthesis of complex organic molecules, ranging from pharmaceuticals to polymers. However, it comes with some limitations, such as rearrangement of the carbocation which can lead to by-products, and the inability of the reaction to proceed with particularly bulky alkyl groups or those that can't form stable carbocations.

Improvement Tips:

• Ensure that the alkyl halide can form a relatively stable carbocation which can be attacked by the benzene ring.
• Avoid using very bulky alkyl halides as they may not react well due to steric hindrance.
• Be aware that carbocation rearrangements can occur, so choose reactants and conditions that minimize such rearrangements if undesired.

Electrophilic Aromatic Substitution (EAS) is a fundamental type of reaction in which an aromatic compound undergoes substitution. In this mechanism, an atom, usually hydrogen, attached to an aromatic ring is replaced by an electrophile. The reaction proceeds in several stages: initial attack of the electrophile, formation of a cyclohexadienyl cation intermediate, and finally, deprotonation to restore the aromatic character of the ring.

EAS is characteristic for its versatility and is utilized for the introduction of various functional groups onto the aromatic ring. This mechanism underpins many classical reactions such as halogenation, nitration, sulfonylation, as well as the Friedel-Crafts alkylation and acylation.

For a successful reaction, the electrophile must be sufficiently reactive to form a bond with the aromatic ring, and a catalyst is often required to enhance the electrophile's reactivity. Catalysts such as Lewis acids can help stabilize the carbocation intermediate or generate a stronger electrophile by interacting with the substituent.

To improve this process:

• Choose electrophiles that are strong enough to react with the stable aromatic ring.
• Use appropriate Lewis acid catalysts to increase the reactivity of the electrophile.
• Control the reaction conditions to avoid over-substitution or side reactions, maintaining the regioselectivity of the product.

In the realm of chemical reactions, Lewis acid catalysts play a crucial role by accepting an electron pair, enabling many reactions that would otherwise be sluggish or non-viable. A Lewis acid is any species that can accept a pair of electrons to form a new bond, often a compound with an incomplete octet of electrons or a positively polarized atom.

These catalysts are instrumental in reactions like the Friedel-Crafts alkylation because they can enhance the electrophilicity of a potential electrophile. For example, aluminum chloride (AlCl3) or boron trifluoride (BF3) can interact with alkyl halides to produce a more reactive carbocation.

A key aspect of using Lewis acid catalysts is their ability to be highly specific and selective, which helps in producing desired products with fewer by-products. Their use can also sometimes lower the energy requirements of a reaction, making the process more efficient.

When incorporating a Lewis acid catalyst in a reaction, keep in mind:

• The choice of catalyst should align with the intended reaction mechanism and the required strength to activate the electrophile.
• The catalyst must be used under appropriate conditions to avoid deactivating interactions or unwanted side reactions.
• Post-reaction, the catalyst must be quenched or removed safely without interfering with the product.