Tag: ethers

Questions Related to ethers

Oxygen atom of ether is: 

chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

  1. very active

  2. replaceable

  3. active

  4. comparatively inert

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Correct Option: D
Explanation:
Oxygen atom of ether is comparatively inert.

 $C-O-C$ linkage is quite stable. Under ordinary conditions, ethers are not acted upon by dilute acids, bases and most of the oxidizing and reducing agents. 

Hence correct answer is option D.

$C _2H _5-O-C _2H _5 +  HI \xrightarrow {?}  C _2H _5-OH + C _2H _5-I$
Identify the reaction condition, in which reaction occur.

chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

  1. High temperature

  2. High vaccum

  3. Cold

  4. None of the above

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Correct Option: A
Explanation:

The cleavage of ethers takes places with concentration $HI$ or $HBr$ at high temperature.

Diethyl ether can be decomposed with:

chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

  1. $HI$

  2. $KMnO _4$

  3. $NaOH$

  4. $H _2O$

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Correct Option: A
Explanation:

On heating with concentrated Hydrogen iodide $(HI)$ the C-O bond in ethers breaks forming alcohol and alkyl iodide. For example,

 ${ C } _{ 2 }{ H } _{ 5 }-O-{ C } _{ 2 }{ H } _{ 5 }+HI\longrightarrow { C } _{ 2 }{ H } _{ 5 }-I+{ C } _{ 2 }{ H } _{ 5 }OH$

 On boiling with excess of concentrated Hydrogen iodide $(HI)$, Alkyl iodide is formed.

${ C } _{ 2 }{ H } _{ 5 }-O-{ C } _{ 2 }{ H } _{ 5 }+2HI\longrightarrow 2{ C } _{ 2 }{ H } _{ 5 }-I+{ H } _{ 2 }O$

When an ether is treated with $P _2S _5$, it gives:

chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

  1. thioalcohol

  2. thioether

  3. thioester

  4. thioacetal

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Correct Option: B
Explanation:

When an ether is treated with $P _2S _5$, it gives thioether.


$5C _2H _5-O-C _2H _5+P _2S _5\rightarrow\underset{Thioether}{5C _2H _5-S-C _2H _5}$

Hence option B isthe correct answer.

Ethers are heated with excess of conc. hydrogen halide to give alkyl halide, then the reactivity order of hydrogen halide is :

chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

  1. $HCl < HBr < HF$

  2. $HI > HBr > HCl $

  3. $HF < HCl < HBr $

  4. none of these

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Correct Option: B
Explanation:

When $HX$ is in excess and reaction is carried out at high temperature. Iodine is a good nucleophile, displaces an alcohol molecule by $SN^2$ mechanism thus $HI>HBr>HCl$

Ethyl phenyl ether on boiling with conc. HBr gives: 

chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

  1. phenol and ethane

  2. bromobenzene and ethane

  3. phenol and ethyl bromide

  4. bromobenzene and ethanol

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Correct Option: A

Ethers have lower boiling points than their corresponding isomeric alcohols because of?

chemistry hydroxy compounds and ethers physical properties of ethers ethers alcohols, phenols and ethers

  1. hydrogen bonding in alcohols that is absent in ethers due to low polarity

  2. hydrogen bonding in ethers due to high polarity

  3. insolubility of ethers in water due to less polarity

  4. inertness of ethers as compared to alcohols.

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Correct Option: A
Explanation:

Ethers ROR cannot form intermolecular Hydrogen bond due to the absence of H attached with the electronegative atom as N/O/F, but in case of alcohols, they have -OH which can undergo intermolecular hydrogen bonding and that increases their boiling point.

Thus, Ethers have lower boiling points than their corresponding isomeric alcohols because of hydrogen bonding in alcohols that is absent in ethers due to low polarity.

Correct order of boiling points among following is: $\underset{(X)}{CH _3(CH _2) _3CH _3}, \,\,\,\,\underset{(Y)}{C _2H _5OC _2H _5},\,\,\,\,\,\,\underset{(Z)}{CH _3(CH _2) _3OH}$

chemistry hydroxy compounds and ethers physical properties of ethers ethers alcohols, phenols and ethers

  1. X > Y > Z

  2. Y > X > Z

  3. Z > X > Y

  4. Z > Y > X

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Correct Option: D
Explanation:

The boiling point of a molecule depends on the strength of intermolecular interaction such as Vandewaal's attraction, hydrogen bonding etc.

Alkanes, such as $\underset{X}{CH _3(CH _2) _3CH _3}$, being non-polar have the weakest force of attraction called dispersion or London forces.
Ethers, such as $\underset{(Y)}{C _{2}H _{5}OC _2H _5}$, have small dipole moment or weakly polar thus have dipole-dipole interaction. This is stronger than the London forces.
Alcohols, such as $\underset{(Z)}{CH _3(CH _2) _3OH}$, are polar molecules, therefore, have strong dipolar interaction. Moreover, they form an intermolecular hydrogen bond that further increases the attraction (association).

Hence the order of their boiling point will be:
$\underset{(Z)}{CH _3(CH _2) _3OH}>\underset{(Y)}{C _{2}H _{5}OC _2H _5}>\underset{X}{CH _3(CH _2) _3CH _3}$

OR $Z>Y>X$

The_____ ethers are highly volatile and flammable.

chemistry hydroxy compounds and ethers physical properties of ethers ethers alcohols, phenols and ethers

  1. higher

  2. lower

  3. both A and B

  4. None of these

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Correct Option: B

The compound which has the lowest boiling point is: 

chemistry hydroxy compounds and ethers physical properties of ethers ethers alcohols, phenols and ethers

  1. $H _2O $

  2. $C _2H _5OH$

  3. $CH _3OH $

  4. $C _2H _5OC _2H _5$

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Correct Option: D