Benzene can be prepared through several methods, primarily from coal and petroleum sources. One common method is the dehydrogenation of cyclohexane, where cyclohexane is heated in the presence of a catalyst to yield benzene. Another method involves the reaction of acetylene with an organo-nickel catalyst under pressure, which also produces benzene. Additionally, benzene can be synthesized by passing the vapors of alkanes, such as n-hexane or n-heptane, over a mixture of catalysts at high temperatures. In laboratory settings, benzene can be prepared by heating the sodium salt of benzoic acid with soda lime, distilling phenol with zinc dust, or hydrolyzing benzenesulphonic acid with superheated steam or dilute hydrochloric acid. These methods highlight the versatility and accessibility of benzene production in both industrial and laboratory contexts.
What is one of the primary industrial sources for the preparation of benzene?
Benzene is primarily obtained from coal and petroleum.
What is the process of dehydrogenation of cyclohexane used for?
The dehydrogenation of cyclohexane is used to convert cyclohexane into benzene by heating it in the presence of a catalyst.
How can benzene be synthesized from acetylene?
Benzene can be synthesized by passing acetylene under pressure over an organo-nickel catalyst at a temperature of around 70°C.
What catalysts are commonly used in the preparation of benzene from alkanes?
A mixture of catalysts such as Cr₂O₃, Al₂O₃, and SiO₂ is commonly used when passing vapors of n-hexane or n-heptane over them at high temperatures.
Describe a laboratory method for preparing benzene.
In the laboratory, benzene can be prepared by heating the sodium salt of benzoic acid with soda lime.
Which of the following methods is commonly used to prepare benzene from cyclohexane?
a) Hydrolysis
b) Dehydrogenation
c) Hydrogenation
d) Oxidation
Answer: b) Dehydrogenation
What catalyst is typically used in the reaction of acetylene to produce benzene?
a) Platinum
b) Nickel
c) Palladium
d) Iron
Answer: b) Nickel
Which of the following reactions can produce benzene in the laboratory?
a) Heating sodium benzoate with soda lime
b) Heating sodium chloride with water
c) Mixing ethanol with sulfuric acid
d) Distilling acetic acid with zinc
Answer: a) Heating sodium benzoate with soda lime
What is the primary industrial source of benzene?
a) Natural gas
b) Coal and petroleum
c) Biomass
d) Water
Answer: b) Coal and petroleum
Which of the following is NOT a method for preparing benzene?
a) Dehydrogenation of cyclohexane
b) Hydrolysis of benzenesulphonic acid
c) Combustion of benzene
d) Distillation of phenol with zinc dust
Answer: c) Combustion of benzene