Explanation
With Br2 water, phenol gives 2,4,6- tribromophenol
The facts that–I-effect of the –NO2 group and greater resonance stabilization of the p-nitrophenoxide ion are correct.
Due to greater electron-withdrawing effect of NO2 group or Cl-atom,nitrophenols are stronger acids than p-chlorophenol. Out of nitrophenols, p-nitrophenol is the strongest acid.
OsO4 is used for cis-hydroxylation of olefins.
Among isomeric alcohols, the surface area decreases from 1º → 2º → 3º alcohols and hence the boiling points decrease in the same order, i.e.1º >2º >3º.
Esters react with Grignard reagents to form 30 alcohols.
Phenoxide ion is stabilized through delocalization.
I-Propanol and 2-propanol in presence of Cu/Δ undergodehydrohydrogenation to give acetal dehyde and acetone respectively whichcan be distinguished by Fehiling solution since acetaldehydereduce whileacetone does not reduce Fehling solution In contrast with alk. KMnO4 of acidic K2Cr2O7, I-propanol will first givepropionic acid while 2-propanol will first give acetone and then on furtheroxidation will give acetic acid. Both these acids cannot be distinguished byFehling solution. Option (d) is incorrect since conc. H2SO4 does not bringabout oxidation of alcohols.
The reaction of phenols with benzoyl chloride in presence of aq.NaOH is called Schotten Baumann reaction.
p-Nitrophenol (III) > Phenol (I) > p-Cresol (II)
Try Your Self
Ethanol (CH3CH2OH), ethanol (CH3CHO) and 2-propanol (CH3)2 CHOH, allcontain the grouping CH3CHOH- and hence give +ve iodoform test
o- and p-Nitrophenols are stronger acids than m-nitrophenol.As a result,phenols (a) and (c) are stronger acids than (b) and (d). In (c), the NO2 groupsis flanked by two CH3 groups which push the NO2 group out of the plane ofthe benzene ring. As a result of this steric hindrance, the electronwithdrawing resonance effect of the nitro group will be reduced and hencethe acidic character of the phenol will decrease.Therefore, phenol (a) is thestrongest acid.
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