Reaction of benzene with isobutene in presence of sulphuric acid gives mainly

Benzene, denoted by the chemical formula C6H6, is a foundational hydrocarbon in organic chemistry known for its stability and unique ring structure. This stability comes from its delocalized electrons, which are spread over the ring in a phenomenon known as aromaticity. However, benzene can still undergo reactions, primarily electrophilic aromatic substitution (EAS), in which a substituent is added to the benzene ring. During an EAS reaction, benzene's pi electrons act as a nucleophile attacking an electrophile, leading to the temporary loss of aromaticity until the original structure is restored. It's this process that allows us to synthesize a plethora of other aromatic compounds from benzene.

In the presence of a strong acid like sulfuric acid, isobutene, which has the formula (CH3)_2C=CH2, can be transformed into a more reactive species. This is achieved through the formation of protonated isobutene. Essentially, isobutene gets 'protonated' when one of the hydrogen ions (protons) from the acid attaches to the carbon-carbon double bond, giving it a positive charge. This positive charge makes the molecule an electrophile or an electron-loving entity, thus enabling it to react with benzene, which has abundant electrons due to its conjugated pi system. Protonated isobutene is more reactive because it seeks to 'replace' its missing electron by bonding to other atoms or molecules, such as the benzene ring in our case.

Synthesizing tert-butylbenzene involves an electrophilic aromatic substitution where the electrophile protonated isobutene reacts with benzene. The benzene acts as a nucleophile and attacks the positive center of the isobutene, causing the substitution of one of benzene's hydrogen atoms. This eventually results in the attachment of a tert-butyl group ((CH3)_3C) to the benzene ring, successfully forming tert-butylbenzene. This transformation is typical in organic chemistry labs and is an example of how chemical reactions can be directed to obtain a desired product— in this case, one where the bulky tert-butyl group can affect the properties of the benzene ring it is attached to.

Sulfuric acid (H2SO4) acts as a catalyst in the synthesis of tert-butylbenzene from benzene and isobutene. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. Sulphuric acid, a strong acid, helps generate the necessary electrophile (protonated isobutene) and later gets regenerated at the end of the reaction. By adding a proton to isobutene and later accepting a proton from the intermediate, sulfuric acid drives the reaction forward without being used up, making it available to catalyze further reactions. In industrial and laboratory settings, such catalysts are crucial as they make chemical processes more economically viable by saving energy and resources.