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Which method of phenol preparation is described as commercially the most widely used worldwide?
The NCERT clearly mentions, 'Most of the worldwide production of phenol is from cumene.'
Laboratory preparation of phenols from benzene derivatives typically involves which general approach?
The NCERT states, 'In the laboratory, phenols are prepared from benzene derivatives by any of the following methods' and then lists methods like from haloarenes, benzenesulphonic acid, and diazonium salts, all of which involve replacing existing groups on the benzene ring with a hydroxyl group either directly or indirectly.
What is the common name for isopropylbenzene, which is used in the industrial production of phenol?
The NCERT specifies, 'Cumene (isopropylbenzene) is oxidised in the presence of air to cumene hydroperoxide.'
Besides phenol, what other important organic compound is obtained as a significant byproduct in the industrial production of phenol from cumene?
The NCERT states, 'It (cumene hydroperoxide) is converted to phenol and acetone by treating it with dilute acid. Acetone, a by-product of this reaction, is also obtained in large quantities by this method.'
Which of the following conditions is most suitable for the preparation of ethoxyethane from ethanol via acidic dehydration?
According to the NCERT text, 'For example, ethanol is dehydrated to ethene in the presence of sulphuric acid at 443 K. At 413 K, ethoxyethane is the main product.' Therefore, $\text{H}_2\text{SO}_4$ at 413 K favors ether formation.
The acidic dehydration of alcohols to form ethers follows which reaction pathway?
The NCERT states, 'The formation of ether is a nucleophilic bimolecular reaction (SN2) involving the attack of alcohol molecule on a protonated alcohol... The method is suitable for the preparation of ethers having primary alkyl groups only.'
Why is the dehydration of secondary and tertiary alcohols not suitable for preparing corresponding ethers?
The NCERT states, 'However, the dehydration of secondary and tertiary alcohols to give corresponding ethers is unsuccessful as elimination competes over substitution and as a consequence, alkenes are easily formed.' While bulkiness and $\text{S}_{\text{N}}1$ are related, the primary reason given in the text is the competition from elimination.
Which of the following statements is TRUE regarding Williamson synthesis for ether preparation?
The NCERT states, 'Ethers containing substituted alkyl groups (secondary or tertiary) may also be prepared by this method.' It also mentions, 'It is an important laboratory method for the preparation of symmetrical and unsymmetrical ethers. The reaction involves SN2 attack of an alkoxide ion on primary alkyl halide.'
To successfully prepare an ether via Williamson synthesis, the alkyl halide should ideally be:
The NCERT specifies, 'The reaction involves SN2 attack of an alkoxide ion on primary alkyl halide.' Using secondary or tertiary alkyl halides in Williamson synthesis often leads to elimination products due to competing reactions.
Which product is predominantly formed when ethanol is heated with concentrated sulfuric acid at 443 K?
The NCERT states, 'For example, ethanol is dehydrated to ethene in the presence of sulphuric acid at 443 K.' At higher temperatures, elimination (alkene formation) is favored over substitution (ether formation).
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