Alcohols, Phenols and Ethers
(I) 1,2-Dihydroxybenzene
(II) 1,3-Dihydroxybenzene
(III) 1,4-Dihydroxybenzene
(IV) Hydroxy benzene
The increasing order of boiling points of the above mentioned alcohols is
I $<$ II $<$ III $<$ IV
I $<$ II $<$ IV $<$ III
IV $<$ I $<$ II $<$ III
IV $<$ II $<$ I $<$ III
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.
In the following reaction
Identify X and Y.
Explanation:
When (1-methylcyclopentyl) methanol is treated with H$^+$ at high temperature, it is converted to 1-methyl-1-cyclohexene.
Therefore, X is 1-methyl-1-cyclohexene.
The mechanism for the same is represented below.
The H$^+$ on heating with (1-methylcyclopentyl) methanol get attached to O atom of hydroxy group, producing a positive charge on O atom. The elimination of water molecule results in the formation of primary carbocation, which undergoes ring expansion followed by elimination of proton yields product X.
The 1-methyl-1-cyclohexene undergoes ozonolysis followed by treatment with Zn/ CH$_3$COOH, it gives 6-oxoheptanal.
Therefore, compound Y is 6-oxoheptanal
Y on further undergoes aldol condensation reaction to form $\alpha$, $\beta$ unsaturated carbonyl compounds in presence of NaOH followed by heat.
Final Answer
Hints :
Ozonolysis of an unsaturated compound results in replacing double bonds with carbonyl group. The Zn in acetic acid is a reducing agent.
