Q13P Which of the following ethers ca... [FREE SOLUTION]

Chapter 14: Q13P (page 721)

Which of the following ethers can be formed in good yield by condensation of the corresponding alcohols? For those that cannot be formed by condensation, suggest an alternative method that will work.
(a) $诲颈产耻迟测濒鈥夆赌塭迟丑别谤$
(b) $别迟丑测濒鈥夆赌塶-辫谤辞辫测濒鈥夆赌塭迟丑别谤$
(c) $诲颈-蝉别肠-产耻迟测濒鈥夆赌塭迟丑别谤$

Short Answer

Expert verified

(a) $诲颈产耻迟测濒鈥夆赌塭迟丑别谤$ is a symmetrical ether and hence good yield can be produced by condensation method.

(b) $别迟丑测濒鈥夆赌塶-辫谤辞辫测濒鈥夆赌塭迟丑别谤$ is an unsymmetrical ether and hence good yield cannot be produced by condensation method. In such case, Williamson ether synthesis can eb used for good yields.

Step by step solution

Bimolecular condensation

The cheapest method for synthesizing simple symmetrical ethers is the acid catalyzed bimolecular condensation where two molecules of alcohols are joined with the loss of a small molecule like water. The alcohol must have an unhindered primary alkyl group to form an ether and also the temperature of the reaction should not be too high. Bimolecular condensation of alcohols is considered to be a poor synthetic method.

$\begin{array}{l} 2R 鈭� 翱贬鈥夆赌夆赌夆赌夆赌夆赌� \overset{H^{+}}{鈬�} 鈥夆赌夆赌夆赌夆赌塕鈭� O 鈭� 搁鈥夆赌夆赌夆赌夆赌� + {鈥夆赌夆赌夆赌塇}_{2} O \\ 补濒肠辞丑辞濒鈥夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌塭迟丑别谤鈥夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌墂补迟别谤 \end{array}$

Williamson ether synthesis

The most reliable and versatile method for synthesis of ethers is given by Williamson method. In this method, ${S_{N}}^{2}$ attack of an alkoxide ion takes place on an unhindered primary alkyl halide or tosylate. The yield is poor if secondary alkyl halide is used. The alkoxide is generally made by adding $狈补,鈥块鈥嬧赌夆赌塷谤鈥夆赌塏补贬$ to the alcohol.