Moderate

Mixture of catalysts Cr2O3 + A?2O3 + SiO2 at 500?C are used when benzene is prepared from_______________?

Correct answer: B. N-hexane

  • A. acetylene
  • B. N-hexane
  • C. Benzene sulphonic acid
  • D. Sodium benzoate

Explanation

N-hexane undergoes catalytic dehydrocyclisation, losing hydrogen and forming a six-membered aromatic ring, benzene. The catalyst mixture is typically chromium oxide, aluminium oxide and silica at about 500 C. The likely mistake is acetylene, which forms benzene by cyclotrimerisation using a different preparation route and catalyst.

Last updated

About Benzene and Aromatic Compounds

Benzene has a planar ring of delocalised π electrons, giving aromatic stability and equal carbon-carbon bond lengths. The topic covers resonance, electrophilic substitution reactions such as nitration, halogenation, sulphonation and Friedel-Crafts reactions, along with substituent effects and the distinction between substitution in benzene and addition in ordinary alkenes.

Practise Chemistry of Hydrocarbons

1,091 free Chemistry of Hydrocarbons MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.

Exams that ask Chemistry questions like this

Chemistry is on 12 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.

Related questions