Question Video: Identifying the Name of the Acid Produced When Benzene Reacts with Concentrated Sulfuric Acid | Nagwa Question Video: Identifying the Name of the Acid Produced When Benzene Reacts with Concentrated Sulfuric Acid | Nagwa

Question Video: Identifying the Name of the Acid Produced When Benzene Reacts with Concentrated Sulfuric Acid Chemistry • Third Year of Secondary School

Benzene is reacted with concentrated sulfuric acid. The reaction produces an unidentified acid (X) and water. What is the name of the unidentified acid?

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Video Transcript

Benzene is reacted with concentrated sulfuric acid. The reaction produces an unidentified acid, X, and water. What is the name of the unidentified acid? (A) Benzoic acid, (B) cyclohexanesulfonic acid, (C) hexanoic acid, (D) salicylic acid, (E) benzenesulfonic acid.

When benzene reacts with concentrated sulfuric acid, a sulfo substitution or sulfonation reaction occurs. In a sulfonation reaction, parts of a molecule are removed and replaced with sulfo or SO3H groups. We can see from the provided reaction equation that the sulfonation of benzene is achieved by treating benzene with concentrated sulfuric acid under reflux for a few hours. During the reaction, one or more hydrogen atoms of the benzene ring is replaced with a sulfo group. So the unidentified acid X that is produced is composed of a benzene ring with one or more sulfo groups bonded to the benzene ring, depending on how many hydrogen atoms were replaced.

The product shown here is the result of monosulfonation, in which only one hydrogen atom was replaced with a sulfo group. The sulfonation of benzene belongs to a class of reactions known as electrophilic substitution reactions. In sulfonation, the electrophile is sulfur trioxide. And its attraction to the relatively negative delocalized electrons of the benzene ring helps to facilitate the reaction. One might think that a sulfonated benzene, like product X, would be called a sulfobenzene, when in fact the IUPAC name of this molecule is benzenesulfonic acid.

In conclusion, the name of the unidentified acid product of the provided reaction is answer choice (E), benzenesulfonic acid.

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