Single Choice

An unknown alcohol is treated with the 'Lucas reagent' to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism?

ATertiary alcohol by $$S_{N}1$$
Correct Answer
BSecondary alcohol by $$S_{N}2$$
CTertiary alcohol by $$S_{N}2$$
DSecondary alcohol by $$S_{N}1$$

Solution

Lucas test in alcohol is a test to differentiate between primary, secondary and tertiary alcohols. It is based on the difference in reactivity of the three classes of alcohols with hydrogen halides. Reaction proceeds through carbocation formation as $$3^{0}$$ carbocation is highly stable. Hence, the reaction proceeds through $$S_{N}1$$ with $$3^{0}$$ alcohol.

SIMILAR QUESTIONS

Alcohols, Phenols and Ethers

From amongst the following alcohols the one that would react fastest with conc. $$HCl$$ and anhydrous $${Z}n{C}l_{2}$$, is:

Alcohols, Phenols and Ethers

An alcohol gave Lucas test in about 5 minutes. When the alcohol was treated with hot concentrated $$H_2SO_4$$, it gave an alkene of molecular formula $$C_4H_8$$ which on ozonolysis gives single product with molecular formula $$C_2H_4O$$. The structure of alcohol is:

Alcohols, Phenols and Ethers

Lucas test is given by an alcohol within 5 minutes. 0.22 g of which liberates 56 mL of $$ CH_4$$ at STP on treating with $$CH_3MgI$$.The structure of alcohol is:

Alcohols, Phenols and Ethers

Which of the following compounds reacts immediately with Lucas reagent?

Alcohols, Phenols and Ethers

Which alcohol will give immediate turbidity on shaking with HCl at room temperature?

Alcohols, Phenols and Ethers

An alcohol (A) gives Lucas test within 5 min. 7.4 g of alcohol when treated with sodium metal liberates 1120 mL of $$H_2$$ at STP. What will be alcohol (A)?

Alcohols, Phenols and Ethers

Which of the following alcohols reacts most readily with Lucas reagent?

Alcohols, Phenols and Ethers

Vinyl chloride and ethyl chloride can be distinguished by:

Alcohols, Phenols and Ethers

Which of the following will react fastest with Lucas reagent?

Alcohols, Phenols and Ethers

Explain the following behavior: Reactivity of all the three classes of alcohols with conc. HCl and $$ZnCl_2$$ is different.

Contact Details