Question

Which compound on reaction with \(\mathrm{SbCl}_{5}\) can give an aromatic product?

Short answer

To determine which compound will give an aromatic product when reacted with \(\mathrm{SbCl}_{5}\), we must analyze the given compounds to identify one that will form a cyclic complex with alternating single and double bonds after the reaction. The resulting complex should also fulfill Huckel's rule, having \(4n+2\) 𝜋-electrons in its conjugated system. Once the specific compounds are provided, we can apply these steps to identify the compound that fulfills the criteria for forming an aromatic product upon reacting with \(\mathrm{SbCl}_{5}\).

Step-by-step solution

Understand the reaction with \(\mathrm{SbCl}_{5}\)

\(\mathrm{SbCl}_{5}\) is known as antimony pentachloride and acts as a strong Lewis acid. This means it can readily accept an electron pair from a Lewis base, like a chloride ion (\(\mathrm{Cl}^{-}\)) or an alkoxy group (\(\mathrm{R-O}^{-}\)). When it reacts with a compound containing a double bond or triple bond, it forms a cyclic complex due to its electron-accepting nature. We must remember this for the upcoming steps.

Understand aromaticity

Aromatic compounds are a class of organic compounds which have a cyclic structure and alternating single and double bonds in a conjugated system. The most well-known example of an aromatic compound is benzene (\(\mathrm{C}_{6}\mathrm{H}_{6}\)), which has six carbon atoms in a ring with alternating single and double bonds. For a compound to be considered aromatic, it must fulfill Huckel's rule, which states that an aromatic compound must have \(4n+2\) 𝜋-electrons in its conjugated system, where "n" is a non-negative integer.

Find the compound that reacts with \(\mathrm{SbCl}_{5}\) to give an aromatic product

To determine which compound will give an aromatic product when reacted with \(\mathrm{SbCl}_{5},\) we must examine the given compounds and identify the one that will form a cyclic complex with alternating single and double bonds following the reaction. Moreover, the resulting complex should fulfill Huckel's rule, having \(4n+2\) 𝜋-electrons in its conjugated system. We need the specific compounds to be able to analyze and compare their potential aromatic products. Once the specific compounds are provided, we can apply these steps to identify the compound that fulfills the criteria for forming an aromatic product upon reacting with \(\mathrm{SbCl}_{5}\).

Key concepts

Understanding Lewis Acids

Lewis acids are a fundamental concept in chemistry, especially when discussing reactions involving electron pairs. A Lewis acid is any substance that can accept an electron pair.
This means it has an empty orbital or can form a bond by accepting electron density. In the case of our exercise, antimony pentachloride (\(\mathrm{SbCl}_5\)) acts as a strong Lewis acid. This is because it has the ability to accept electrons from Lewis bases like \(\mathrm{Cl}^-\) or other structures with available electron pairs.
When \(\mathrm{SbCl}_5\) interacts with compounds containing double or triple bonds, it forms a cyclic complex. This cyclic nature arises because of its electron-accepting properties, which lead to the formation of stable aromatic structures.

Insights into Huckel's Rule

Huckel's rule is critical when examining aromatic compounds. It provides a guideline to determine if a compound is aromatic. According to this rule, a compound must have \(4n+2\) π-electrons.
"n" in this equation stands for a non-negative integer. This results in values like 2, 6, 10, etc., that help identify aromatic systems.
Take benzene, for example. It has six π-electrons, which fits perfectly into Huckel's rule. The alternating single and double bonds in a ring of benzene are a classic representation of an aromatic compound.
For our exercise, this rule helps identify which compound, when reacted with \(\mathrm{SbCl}_5\), forms a stable aromatic structure with \(4n+2\) π-electrons.

The Role of Antimony Pentachloride Reaction

The reaction of antimony pentachloride is unique because of its strong Lewis acid characteristics. Upon reacting with specific compounds, \(\mathrm{SbCl}_5\) can form stable aromatic products.
In a typical case, \(\mathrm{SbCl}_5\) interacts with conjugated systems containing double bonds. These systems must be cyclic and capable of rearranging into an aromatic structure.
The mechanism involves the donation of electron density from the conjugated system to the antimony, facilitating the transformation into a stable aromatic ring. Recognizing this reaction helps in predicting which compounds can become aromatic when treated with \(\mathrm{SbCl}_5\).

Exploring Conjugated Systems

Conjugated systems play a pivotal role in forming aromatic compounds. These systems are characterized by alternating single and double bonds. This setup allows for delocalization of π-electrons across the structure.
The extended π-network in conjugated systems is what allows these compounds to potentially become aromatic.
An essential part of identifying an aromatic product in our exercise is recognizing conjugated systems that can transition into stable, aromatic structures.
The presence of a conjugated system allows for the cyclic electron delocalization required by Huckel's rule, making the resultant complex fulfill the aromaticity criteria upon reacting with \(\mathrm{SbCl}_5\). A well-defined conjugated system is integral to forming a stable aromatic compound.