Ethers MCQ Quiz - Objective Question with Answer for Ethers - Download Free PDF

CONCEPT:

Cyclic Ethers and Isomerism

• Cyclic ethers are organic compounds that contain an oxygen atom within a ring structure.
• Isomers of cyclic ethers can include both structural isomers (different connectivity of atoms) and stereoisomers (same connectivity but different spatial arrangement).
• For a given molecular formula, isomer count depends on the number of possible ring sizes, substitution patterns, and stereoisomeric configurations.

EXPLANATION:

• Possible structures include:
  • Four-membered rings (oxetanes) with different substitution patterns.
  • Three-membered rings (epoxides) with different substitution patterns.
• Considering stereoisomerism:
  • Epoxides can have cis and trans stereoisomers due to the planar nature of the three-membered ring.
  • Oxetanes with different substitutions can also exhibit stereoisomerism.
• Upon counting all possible structural and stereoisomers:
  • Three-membered ring (epoxides): 6 isomers (including stereoisomers).
  • Four-membered ring (oxetanes): 4 isomers (including stereoisomers).
• Total number of isomers = 6 (epoxides) + 4 (oxetanes) = 10.

Therefore, the total number of possible isomers (both structural and stereoisomers) of cyclic ethers with the molecular formula C₄H₈O is 10.

CONCEPT:

Williamson's Synthesis

• Williamson's synthesis is a method used to prepare ethers by reacting an alkoxide ion with a primary alkyl halide.
• The general reaction is:

  R-O^- + R'-X → R-O-R' + X^-

• This method is not suitable for preparing ethers with tertiary alkyl halides because tertiary alkyl halides undergo elimination reactions (E2) rather than substitution reactions (S_N2).

EXPLANATION:

• In the given options:
  • 1) Methoxybenzene: Can be prepared using Williamson's synthesis.
  • 2) Benzyl p-nitrophenyl ether: Can be prepared using Williamson's synthesis.
  • 3) Methyl tertiary butyl ether: Can be prepared using Williamson's synthesis.
  • 4) Di-tert-butyl ether: Cannot be prepared using Williamson's synthesis because it involves tertiary alkyl halides which favor elimination.

Therefore, the correct answer is option 4: Di-tert-butyl ether cannot be made by using Williamson's synthesis.

CONCEPT:

Cleavage of Ethers with Hydrohalic Acids (HI)

• Ethers can be cleaved by hydrohalic acids (HX) to form alkyl halides and alcohols.
• The reaction mechanism involves protonation of the ether oxygen, followed by nucleophilic attack by the halide ion.
• The cleavage typically yields one molecule of alkyl halide and one molecule of alcohol, depending on the structure of the ether.

EXPLANATION:

• The starting compound is an ether with the structure Ph-CH₂-O-Ph (phenylmethyl phenyl ether).
• When treated with HI, the ether oxygen is protonated, making the ether bond more susceptible to cleavage.
• The cleavage results in the formation of a benzyl iodide (Ph-CH₂-I) and a phenol (Ph-OH).
• Thus, the products A and B are benzyl iodide and phenol, respectively.
• The correct products are shown in option 3.

The correct answer is Option 3.

CONCEPT:

Williamson's Synthesis

• Williamson's synthesis is a method for preparing ethers by reacting an alkyl halide with a sodium alkoxide.
• The general reaction is:

  R-X + R'-ONa → R-O-R' + NaX

• Where R and R' are alkyl groups, X is a halide (usually bromide or iodide), and Na is sodium.
• 

EXPLANATION:

• In the given example:

  → + NaI

  • CH₃-I (methyl iodide) is the alkyl halide.
  • (CH₃)₃ONa  is the sodium alkoxide.

Therefore, in Williamson's synthesis for the preparation of ethers, the compounds used are option 3

CONCEPT:

Williamson's Synthesis

• Williamson's synthesis is a method used to prepare ethers by reacting an alkoxide ion with a primary alkyl halide.
• The general reaction is:

  R-O^- + R'-X → R-O-R' + X^-

• This method is not suitable for preparing ethers with tertiary alkyl halides because tertiary alkyl halides undergo elimination reactions (E2) rather than substitution reactions (S_N2).

EXPLANATION:

• In the given options:
  • 1) Methoxybenzene: Can be prepared using Williamson's synthesis.
  • 2) Benzyl p-nitrophenyl ether: Can be prepared using Williamson's synthesis.
  • 3) Methyl tertiary butyl ether: Can be prepared using Williamson's synthesis.
  • 4) Di-tert-butyl ether: Cannot be prepared using Williamson's synthesis because it involves tertiary alkyl halides which favor elimination.

Therefore, the correct answer is option 4: Di-tert-butyl ether cannot be made by using Williamson's synthesis.

The correct answer is ether.Key Points

• Ether:-
  • It is a class of organic compounds that contains an oxygen atom between two alkyl groups.
  • The general formula for an ether is R-O-R', where .R and R' are alkyl groups
  • Ethers are commonly used as solvents in various industries, including pharmaceuticals, paints, and coatings.
  • Ethers are less reactive than alcohols, aldehydes, and ketones because the C-O bond is relatively stable.

Additional Information

• Alcohol:-
  • ​ A class of organic compounds that contains a hydroxyl (-OH) group attached to a carbon atom.
  • They are commonly used as solvents, disinfectants, and fuels.
• Aldehyde:-
  • ​ A class of organic compounds that contains a carbonyl group (-CHO) attached to a carbon atom at the end of the molecule.
  • They are commonly used in the production of plastics, resins, and dyes.
• Ketone:-
  • A class of organic compounds that contains a carbonyl group (-C=O) attached to a carbon atom in the middle of the molecule.
  • They are commonly used in the production of solvents, polymers, and pharmaceuticals.

Explanation:-

Ether will act as Nu and abstract the Hydrogen, creation Br- which will attack and result in formation of phenol.

CONCEPT:

Williamson's Synthesis

• Williamson's synthesis is a method used to prepare ethers by reacting an alkoxide ion with a primary alkyl halide.
• The general reaction is:

  R-O^- + R'-X → R-O-R' + X^-

• This method is not suitable for preparing ethers with tertiary alkyl halides because tertiary alkyl halides undergo elimination reactions (E2) rather than substitution reactions (S_N2).

EXPLANATION:

• In the given options:
  • 1) Methoxybenzene: Can be prepared using Williamson's synthesis.
  • 2) Benzyl p-nitrophenyl ether: Can be prepared using Williamson's synthesis.
  • 3) Methyl tertiary butyl ether: Can be prepared using Williamson's synthesis.
  • 4) Di-tert-butyl ether: Cannot be prepared using Williamson's synthesis because it involves tertiary alkyl halides which favor elimination.

Therefore, the correct answer is option 4: Di-tert-butyl ether cannot be made by using Williamson's synthesis.

CONCEPT:

Cyclic Ethers and Isomerism

• Cyclic ethers are organic compounds that contain an oxygen atom within a ring structure.
• Isomers of cyclic ethers can include both structural isomers (different connectivity of atoms) and stereoisomers (same connectivity but different spatial arrangement).
• For a given molecular formula, isomer count depends on the number of possible ring sizes, substitution patterns, and stereoisomeric configurations.

EXPLANATION:

• Possible structures include:
  • Four-membered rings (oxetanes) with different substitution patterns.
  • Three-membered rings (epoxides) with different substitution patterns.
• Considering stereoisomerism:
  • Epoxides can have cis and trans stereoisomers due to the planar nature of the three-membered ring.
  • Oxetanes with different substitutions can also exhibit stereoisomerism.
• Upon counting all possible structural and stereoisomers:
  • Three-membered ring (epoxides): 6 isomers (including stereoisomers).
  • Four-membered ring (oxetanes): 4 isomers (including stereoisomers).
• Total number of isomers = 6 (epoxides) + 4 (oxetanes) = 10.

Therefore, the total number of possible isomers (both structural and stereoisomers) of cyclic ethers with the molecular formula C₄H₈O is 10.

Concept:

In presence of r₂/EtOH, the reactant containing double bond undergoes electrophilic addition reaction via the formation of bromonium ion. On further attack of \(-\ddot{\underset{\scriptscriptstyle\centerdot\centerdot}{O}}\) Me on bromonium ion gives the addition product. 

The correct answer is ether.Key Points

• Ether:-
  • It is a class of organic compounds that contains an oxygen atom between two alkyl groups.
  • The general formula for an ether is R-O-R', where .R and R' are alkyl groups
  • Ethers are commonly used as solvents in various industries, including pharmaceuticals, paints, and coatings.
  • Ethers are less reactive than alcohols, aldehydes, and ketones because the C-O bond is relatively stable.

Additional Information

• Alcohol:-
  • ​ A class of organic compounds that contains a hydroxyl (-OH) group attached to a carbon atom.
  • They are commonly used as solvents, disinfectants, and fuels.
• Aldehyde:-
  • ​ A class of organic compounds that contains a carbonyl group (-CHO) attached to a carbon atom at the end of the molecule.
  • They are commonly used in the production of plastics, resins, and dyes.
• Ketone:-
  • A class of organic compounds that contains a carbonyl group (-C=O) attached to a carbon atom in the middle of the molecule.
  • They are commonly used in the production of solvents, polymers, and pharmaceuticals.

Explanation:-

Ether will act as Nu and abstract the Hydrogen, creation Br- which will attack and result in formation of phenol.

CONCEPT:

Williamson's Synthesis

• Williamson's synthesis is a method for preparing ethers by reacting an alkyl halide with a sodium alkoxide.
• The general reaction is:

  R-X + R'-ONa → R-O-R' + NaX

• Where R and R' are alkyl groups, X is a halide (usually bromide or iodide), and Na is sodium.
• 

EXPLANATION:

• In the given example:

  → + NaI

  • CH₃-I (methyl iodide) is the alkyl halide.
  • (CH₃)₃ONa  is the sodium alkoxide.

Therefore, in Williamson's synthesis for the preparation of ethers, the compounds used are option 3

Explanation:  

• Molecular formula is C₄H₈O , so the double bond equivalence is 1 , so the compound atleast contain 1 cyclic component or 1 double bond .
• But we need only isomers having cyclic components so all possible isomers of the cyclic ethers are illustrated below:- 

Conclusion:

Therefore , the total number of isomers considering both structural and stereoisomers, of cyclic ethers with the molecular formula C4H8O is 10