Alcohols, Phenols and Ethers

Methyl vinyl ether under anhydrous condition at room temperature undergoes addition reaction .

NOTE : $OH$ group activities the benzene nucleus and

$C{H_3}OH + {C_6}{H_5}MgBr\buildrel \, \over \longrightarrow C{H_3}O.MgBr + {C_6}{H_6}$ v

Only those alcohols which contain $ - CHOHC{H_3}$ group undergo haloform reaction. Among the given options only $(b)$ contain this group, hence undergo haloform reaction.

NOTE : This is Riemer-Tiemann reaction and the electrophile is dichlorocarbene.

The structure of benzene sulphonic acid and $p$-nitrophenol are given below.

Both benzene sulphonic acid and $p$-nitrophenol are strong acids whereas, $\mathrm{NaHCO}_3$ is alkaline in nature.

When both benzene sulphonic acid and $p$-nitrophenol reacts with base like $\mathrm{NaHCO}_3$, neutralisation reaction occur. The chemical equations representing the chemical reaction are shown below:

The reaction between benzene sulphonic acid and $\mathrm{NaHCO}_3$ yields sodium salt of benzene sulphonic acid along with water and carbon dioxide.

The products formed during the reaction between $p$-nitrophenol and $\mathrm{NaHCO}_3$ are sodium salt of $p$-nitrophenol, water and carbon dioxide.

$ \text { The structure of all four alcohols is given below. } $

The 1, 2-dihydroxybenzene has second OH group attached at ortho position. The 1, 2-dihydroxybenzene will participate in intramolecular hydrogen bonding as both OH groups are attached at adjacent position as shown below.

Whereas 1, 3-dihydroxybenzene and 1, 4-dihydroxybenzene form intermolecular hydrogen bonding as shown below:

$ \,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\text { Intermolecular } \mathrm{H} \text { bonding in 1, 4-dihydroxybenzene } $

The strength of intermolecular hydrogen bonding is higher in 1, 4-dihydroxybenzene as compared to that of 1,3-dihydroxybenzene and 1,2-dihydroxybenzene. Thestrengthofhydrogen bonding is higher in 1, 3-dihydroxybenzene than 1,2-dihydroxybenzene.

The monohydroxy benzene will not participate in hydrogen bonding; hence, will have least boiling point.

Also, the strength of intermolecular hydrogen bonding is higher than that of intramolecular hydrogen bonding. Hence, 1, 4-dihydroxybenzene has highest stability amongst four compounds. The correct order of these four compounds in terms of increasing boiling points is hydroxy benzene, 1, 2-dihydroxybenzene, 1, 3-dihydroxybenzene and 1,4-dihydroxybenzene.

The increasing order of boiling points of above mentioned alcohols is IV $<$ I $<$ II $<$ III.

Pyridiminum chloro-chromate $(PCC)$ is specific for the conversion.

Water adds directly to the more reactive alkene in presence of a strongly acidic catalyst forming alcohols. Addition occurs according to Markonikov's rule.

$3$-methyl pentanol-$3$ will be dehydrated most readily since it produces tertiary carbonium ion as intermediate.

Alcohol and ether are isomer with each other. So, with same molecular formula we can make ether as well as alcohol.

For ex,

With molecular formula C₂H₆O

(1) $\,\,\,$ alcohol will be CH₃CH₂ OH

(2) $\,\,\,$ ether will be CH₃ $-$ O $-$ CH₃

In Alcohol there is hydrogen bond and in Ether there is Van der walls force of attraction.

We know that H bond is stronger bond than van der walls force of attraction as the atoms of alcohol are strongly attached with each other by hydrogen bonding so tendency of vaporization of alcohol is less compared to ether.

In alcohol inter-molecular hydrogen bonding look like this -

The dehydration of alcohol to form alkene occurs in following three step. Step $(1)$ is initiation step.