Question 1

Write the mechanism of the following reaction:

Accepted Answer

An equivalent of alcohol is protonated to its conjugate acid. Another equivalent of the alcohol then perform nucleophilic attack at carbon ( S_N2 ), leading to displacement of  water  OH_2  and formation of a new  C-O  bond results in formation of  ethoxy ethane .

Question 2

How do you convert the following:i) Phenol to Anisoleii) Ethanol to Propan-2-ol

Accepted Answer

i) Refer Imageii)  CH_3CH_2OH\xrightarrow{PCC}CH_3CHO\xrightarrow{CH_3MgI}CH_3-CH(OMgI)CH_3\xrightarrow{H_2O}CH_3-CH(OH)-CH_3      Ethanol                                                                                                                          Propan-2-ol

Question 3

Why ortho-Nitrophenol is steam volatile while para-Nitrophenol is less volatile?

Accepted Answer

Ortho nitrophenol is more volatile than para nitrophenol because O-Nitrophenol has intramolecular hydrogen bonding whereas para nitrophenol has inter molecular H bonding and so boils relatively at higher temperature.

Question 4

Arrange the following compounds in the increasing order of their acidic strength:p-cresol, p-nitrophenol, phenol

Accepted Answer

Electron-withdrawing group ( -NO_2 ) increases the acidic character of phenols. Electron withdrawing group withdraws the electrons, as a result, the electron density of phenol decreases. This weakens the O&#8212;H bond and thus the release of proton become easy which makes it more acidic. Hence the nitrophenol is a stronger acid than phenol.Electron-donating group ( =CH_3 ) decreases the acidic character of phenols. Electron donating group donate electrons to the phenol, as a result, the electron density of phenol increases. This strengthens the O&#8212;H bond and thus the release of proton become difficult which makes it less acidic. Hence the p-cresol (4-methylphenol) is less acidic than phenol and nitrophenol.Thus, p-nitrophenol has maximum acidic strength and p-cresol has least acidic strength. The order is shown below. p-nitrophenol > phenol > p-cresol.

Alcohols, Phenols And Ethers