Advertisements
Advertisements
Question
Alcohols react with active metals e.g. Na, K etc. to give corresponding alkoxides. Write down the decreasing order of reactivity of sodium metal towards primary, secondary and tertiary alcohols.
Advertisements
Solution
Decreasing order of reactivity of sodium metal is:
1° > 2° > 3°
Alcohols react with sodium metal to form alkoxides and hydrogen is liberated:
\[\ce{R - O - H + Na -> RO - Na+ {+} 1/2 H2}\]
The order of reactivity of alcohols is primary > secondary > tertiary. This can be explained on the basis of cleavage of O – H bond. The alkyl groups are electron releasing groups (+I effect) and they increase the electron density around the oxygen. As a result, the electrons of O – H bond cannot be withdrawn strongly towards oxygen and O – H remains strong. Therefore, greater is the number, of alkyl groups present, smaller will be reactivity of alcohol.
APPEARS IN
RELATED QUESTIONS
Write the final product(s) in each of the following reactions:
Write the mechanism of the following reaction:
Give the equation of the following reaction:
Treating phenol with chloroform in the presence of aqueous NaOH.
Name the reagent used in the following reaction:
Benzyl alcohol to benzoic acid.
When 3-methylbutan-2-ol is treated with HBr, the following reaction takes place:
\[\begin{array}{cc}
\phantom{...................................}\ce{Br}\\
\phantom{..................................}|\\
\ce{CH3 - CH - CH - CH3 ->[HBr] CH3 - C - CH2 - CH3}\\
|\phantom{.........}|\phantom{...................................}|\phantom{...........}\\
\ce{CH3}\phantom{...}\ce{OH}\phantom{...............................}\ce{CH3}\phantom{.......}\\
\end{array}\]
Give a mechanism for this reaction.
(Hint: The secondary carbocation formed in step II rearranges to a more
stable tertiary carbocation by a hydride ion shift from 3rd carbon atom.)
Lucas reagent is ____________.
The compound which reacts fastest with Lucas reagent at room temperature is:
In the reduction \[\ce{R - CHO + H2 -> RCH2OH}\] the catalyst used is:
The compound which gives the most stable carbonium ion on dehydration is:
Mark the correct increasing order of reactivity of the following compounds with HBr/HCl.
| (a) |  |
| (b) |  |
| (c) |  |
Explain why is OH group in phenols more strongly held as compared to OH group in alcohols.
In Kolbe’s reaction, instead of phenol, phenoxide ion is treated with carbon dioxide. Why?
Ethers can be prepared by Williamson synthesis in which an alkyl halide is reacted with sodium alkoxide. Di-tert-butyl ether can’t be prepared by this method. Explain.
What happens when (CH3)3 C – OH is heated with Cu/573 K?
Write the chemical equation in support of your answer.
Which of the following alcohols will not undergo oxidation?
Write the mechanism of acid-catalysed dehydration of ethanol to yield ethene.
Write the mechanism of acid dehydration of ethanol to yield ethene.
Write the mechanism of acid dehydration of ethanol to yield ethene.
Write the mechanism of acid-catalysed dehydration of ethanol to yield ethene.
Write the mechanism of acid dehydration of ethanol to yield ethene.
