Question

Question. Show how you would make the following ethers, using only simple alcohols and any needed reagents as your starting materials.

(a)1-methoxypropane

(b) 2-ethoxy-2-methylbutane

(c) 4-methylbenzyl cyclopentyl ether

(d) Trans-2-ethoxycyclohexanol

(e) The TIPS ether of (d)

(f) 4-methylcyclohexyl cyclopentyl ether

Short answer

(a)

(b)

(c)

(d)

(e)

(f)

Step-by-step solution

Step-1. Explanation of part (a):

Ethers exhibit a wide range of physical and chemical properties. An ether molecule has net dipole moment due to polarity of carbon-oxygen bond.Ether molecules are miscible in water. Ethers are generally unreactive in nature but when an excess of hydrogen halide is added to the ether, cleavage of carbon-oxygen bond occurs which leads to formation of alkyl halides.

In part (a), propan-1-ol on reaction with phosphorous tribromide produces bromopropane which further on reaction with methoxide ion forms the required product that is, 1-methoxypropane.

Formation of the required ether

Step-2. Explanation of part (b):

Ethers exhibit a wide range of physical and chemical properties. An ether molecule has net dipole moment due to polarity of carbon-oxygen bond. Ether molecules are miscible in water. Ethers are generally unreactive in nature but when an excess of hydrogen halide is added to the ether, cleavage of carbon-oxygen bond occurs which leads to formation of alkyl halides.

In part (b), 2-methylbutan-2-ol on reaction with ethanol in the presence of sulfuric acid undergoes unimolecular substitution reaction and forms the required product. Carbocation formed in this reaction is of 2-methylbutan-2-ol as tertiary carbocation is more stable than primary carbocation.

Formation of the required ether

Step-3. Explanation of part (c):

Ethers exhibit a wide range of physical and chemical properties. An ether molecule has net dipole moment due to polarity of carbon-oxygen bond. Ether molecules are miscible in water. Ethers are generally unreactive in nature but when an excess of hydrogen halide is added to the ether, cleavage of carbon-oxygen bond occurs which leads to formation of alkyl halides.

In part (c), p-tolylmethanol on reaction with cyclopentanol in the presence of sulfuric acid undergoes unimolecular substitution reaction and forms the required product. Carbocation formed in this reaction is of p-tolylmethanol as benzylic carbocation is more stable than secondary carbocation.

Formation of the required ether

Step-4. Explanation of part (d):

Ethers exhibit a wide range of physical and chemical properties. An ether molecule has net dipole moment due to polarity of carbon-oxygen bond. Ether molecules are miscible in water. Ethers are generally unreactive in nature but when an excess of hydrogen halide is added to the ether, cleavage of carbon-oxygen bond occurs which leads to formation of alkyl halides.

In part (d), cyclohexanol on reaction with sulfuric acid undergoes elimination and forms cyclohexene which on reaction with m-CPBA undergoes epoxidation at double bond and forms epoxide. Further treatment with methanol which acts as a nucleophile, gives the required product as methanol attacks at the carbon and initiates opening of epoxide from opposite plane to which epoxide is formed and we get trans product.

Formation of the required ether

Step-5. Explanation of part (e):

Ethers exhibit a wide range of physical and chemical properties. An ether molecule has net dipole moment due to polarity of carbon-oxygen bond. Ether molecules are miscible in water. Ethers are generally unreactive in nature but when an excess of hydrogen halide is added to the ether, cleavage of carbon-oxygen bond occurs which leads to formation of alkyl halides.

In part (e), TIPS ether of product obtained in part (d) is formed when the molecule is reacted with TIPSL in presence of base like triethylamine. TIPSL is the protecting group of alcoholic functional group and forms ether due to which reactivity of alcoholic group gets decreased.

Formation of the required ether

Step-6. Explanation of part (f):

Ethers exhibit a wide range of physical and chemical properties. An ether molecule has net dipole moment due to polarity of carbon-oxygen bond.Ether molecules are miscible in water. Ethers are generally unreactive in nature but when an excess of hydrogen halide is added to the ether, cleavage of carbon-oxygen bond occurs which leads to formation of alkyl halides.

In part (f), 4-methylcyclohexan-1-ol on reaction with cyclopentene undergoes oxymercuration-demercuration reaction and forms the required product.

Formation of the required ether