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  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