Show how the following ethers might be synthesized using (1) alkoxymercuration-demercuration and (2) the Williamson synthesis. (When one of these methods cannot be used for the given ether, point out why it will not work.)

  1. 2-methoxybutane
  2. Ethyl cyclohexyl ether
  3. 1-methoxy-2-methylcyclopentane
  4. 1-methoxy-1-methylcyclopentane
  5. 1-isopropoxy-1-methylcyclopentane
  6. Tert-butyl phenyl ether

Short Answer

Expert verified

Alkoxymercuration-dermercuration is a reaction in which an alkene reacts with an alcohol in the presence of mercuric acetate to form an alkoxymercury intermediate which is then reduced with sodium borohydride to produce an ether.

Williamson ether synthesis is a SN2reaction in which an alkoxide ion is a nucleophile that displaces a halide ion from an alkyl halide to give ether.

In part (a), preparation of 2-methoxybutane takes place from alkoxymercuration-demercuration and Williamson ether synthesis. (1) indicates alkoxymercuration-demercuration mechanism while (2) indicates Williamson ether synthesis.

Step by step solution

01

Step-1. Explanation of part (a):

Alkoxymercuration-dermercuration is a reaction in which an alkene reacts with an alcohol in the presence of mercuric acetate to form an alkoxymercury intermediate which is then reduced with sodium borohydride to produce an ether.

Williamson ether synthesis is a SN2reaction in which an alkoxide ion is a nucleophile that displaces a halide ion from an alkyl halide to give ether.

In part (a), preparation of 2-methoxybutane takes place from alkoxymercuration-demercuration and Williamson ether synthesis. (1) indicates alkoxymercuration-demercuration mechanism while (2) indicates Williamson ether synthesis.

02

Step-2. Explanation of part (b):

Alkoxymercuration-dermercurationis a reaction in which an alkene reacts with an alcohol in the presence of mercuric acetate to form an alkoxymercury intermediate which is then reduced with sodium borohydride to produce ether.

Williamson ether synthesis is a SN2reaction in which an alkoxide ion is a nucleophile that displaces a halide ion from an alkyl halide to give an ether.

In part (b), preparation of ethoxycyclohexane takes place from alkoxymercuration-demercuration and Williamson ether synthesis. (1) indicates alkoxymercuration-demercuration mechanism while (2) indicates Williamson ether synthesis.

03

Step-3. Explanation of part (c):

Alkoxymercuration-dermercurationis a reaction in which an alkene reacts with an alcohol in the presence of mercuric acetate to form an alkoxymercury intermediate which is then reduced with sodium borohydride to produce ether.

Williamson ether synthesis is a SN2reaction in which an alkoxide ion is a nucleophile that displaces a halide ion from an alkyl halide to give ether.

In part (c), preparation of 1-methoxy-2-methylcyclopentane takes place from Williamson ether synthesis. Alkoxymercuration is not practical here, the product does not have Markovnikov orientation required for alkoxymercuration-demercuration. (2) indicates Williamson ether synthesis.

04

Step-4. Explanation of part (d):

Alkoxymercuration-dermercurationis a reaction in which an alkene reacts with an alcohol in the presence of mercuric acetate to form an alkoxymercury intermediate which is then reduced with sodium borohydride to produce ether.

Williamson ether synthesis is a SN2reaction in which an alkoxide ion is a nucleophile that displaces a halide ion from an alkyl halide to give ether.

In part (d), preparation of 1-methoxy-1-methylcyclopentane takes place from alkoxymercuration-demercuration and Williamson ether synthesis. (1) indicates alkoxymercuration-demercuration mechanism while (2) indicates Williamson ether synthesis.

Preparation of the product

05

Step-5. Explanation of part (e):

Alkoxymercuration-dermercurationis a reaction in which an alkene reacts with an alcohol in the presence of mercuric acetate to form an alkoxymercury intermediate which is then reduced with sodium borohydride to produce ether.

Williamson ether synthesis is a SN2reaction in which an alkoxide ion is a nucleophile that displaces a halide ion from an alkyl halide to give ether.

In part (e), preparation of 1-isopropoxy-1-methylcyclopentane takes place from alkoxymercuration-demercuration only. Williamson ether synthesis would give a poor yield of product as halide is on a secondary carbon. (1) indicates alkoxymercuration-demercuration mechanism.

Preparation of the product

06

Step-6. Explanation of part (f):

Alkoxymercuration-dermercurationis a reaction in which an alkene reacts with an alcohol in the presence of mercuric acetate to form an alkoxymercury intermediate which is then reduced with sodium borohydride to produce ether.

Williamson ether synthesis is a SN2reaction in which an alkoxide ion is a nucleophile that displaces a halide ion from an alkyl halide to give ether.

In part (f), preparation of tert-butoxybenzene takes place from alkoxymercuration-demercuration. Williamson ether synthesis is not feasible because mechanism is not possible with tertiary halides or halobenzene. (1) indicates alkoxymercuration-demercuration mechanism .

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Most popular questions from this chapter

Question: Both LiAlH4and Grignard reagents react with carbonyl compounds to give alkoxide ion intermediates (that become protonated in an aqueous workup). Those alkoxides can react with 1o or methyl alkyl halides or tosylates to give ethers. Show how the following ethers can be formed in this two -step process. As starting materials, you may use any reactants containing 8carbons or fewer.

Mustard gas, Cl-CH2CH2-CH2CH2-Cl, was used as a poisonous chemical agent in World War I. Mustard gas is much more toxic than a typical primary alkyl chloride. Its toxicity stems from its ability to alkylate amino groups on important metabolic enzymes, rendering the enzymes inactive.

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(a) Draw the enantiomers of propylene oxide.

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(c) Propose a mechanism for the base-catalyzed hydrolysis of pure (R)-propyleneoxide.

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Question. Predict the products of the following reactions.

(a) Sec-butyl isopropyl ether + conc. HBr, heat

(b) 2-ethoxy-2-methylpentane + conc. HBr, heat

(c) di-n-butyl ether + hot conc. NaOH

(d) di-n-butyl ether + Na metal

(e) ethoxybenzene + conc. HI, heat

(f) 1,2-epoxyhexane +

(g) trans-2,3-epoxyoctane +

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(a) When ethylene oxide is treated with anhydrous HBr gas, the major product is 1,2-dibromoethane. When ethylene oxide is treated with concentrated aqueous HBr, the major product is ethylene glycol. Use mechanisms to explain these results.

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