Dipole moment of phenol is smaller than that of methanol. Why?
In phendl, C – O bond is less polar due to electron withdrawing effect of benzene ring, whereas in methanol C – O bond is more polar due to electron releasing effect of—CH3 group. Hence, the dipole moment of phenol (1.54 D) is smaller than that of methanol (1.71 D).
Assertion (A): Boiling points of alcohols and ethers are high.
Reason (R): They can form intermolecular hydrogen bonding.
Assertion (A): Bond angle in ethers is slightly less than the tetrahedral angle. Reason (R): There is a repulsion between the two bulky (-R) groups.
Explain why is OH group in phenols more strongly held as compared to OH group in alcohols.
Assertion (A): Ethanol is a weaker acid than phenol.
Reason (R): Sodium ethoxide may be prepared by the reaction of ethanol with aqueous NaOH.
Explain a process in which a biocatalyst is used in industrial preparation of a compound known to you.
Name the enzymes and write the reactions involved in the preparation of ethanol from sucrose by fermentation.
Explain why alcohols and ethers of comparable molecular mass have different boiling points.
When phenol is treated with bromine water, white precipitate is obtained. Give the structure and the name of the compound formed.
Why is the reactivity of all three classes of alcohols with cone. HCl and ZnCl2 (Lucas reagent) different?
In Kolbe's reaction, instead of phenol, phenoxide ion is treated with carbon dioxide. Why?
Why is the C – O – H bond angle‘in alcohols slightly less than the tetrahedral angle whereas the C – O – C bond angle in ether is slightly greater?
Assertion (A): IUPAC name of the compound
Reason (R): In IUPAC nomenclature, ether is regarded as hydrocarbon derivative in which a hydrogen atom is replaced by -OR or -OAr group [where R = alkyl group and Ar = aryl group]
Write structures of the compounds whose IUPAC names are as follows:
(i)2-Methylbutan-2-ol
(ii)l-Phcnylpropan-2-ol
(iii)3,5-DimethyIhexane-l,3,5-triol
(iv)2,3-Dicthylphenol
(v)1-Ethoxypropane
(vi)2-Ethoxy-3-methylpentane
(vii) Cyclohexylmethanol
(viii) 3-Cyclohexylpcntan-3-ol
(ix)Cyclopcnt-3-en-l-ol
(x)4-ChIoro-3-ethylbutan-l-ol
Phenol can be distinguished from ethanol by the reactions with ………….
(a) Br2/water (b) Na
(c) Neutral FeCl3 (d) All of these
Give two reactions that show the acidic nature of phenol. Compare its acidity with that of ethanol.
Explain how does the – OH group attached to a carbon of benzene ring activate it towards electrophilic substitution?
Preparation of alcohols from alkenes involves the electrophilic attack on alkene carbon atom. Explain its mechanism.
Assertion (A): o-Nitrophenol is less soluble in water than the m- and p-isomers.
Reason (R): m-Nitrophenol and p-Nitrophenol exists as associated molecules.
You are given benzene, cone. H2S04and NaOH. Write the equations for the preparation of phenol using these reagents.
Explain the following with an example
(i) Kolbe's reaction (ii) Reimer – Tiemann reaction –
(iii) Williamson ether synthesis (iv) Unsymmetrical ether
Ortho and para nitrophenols are more acidic than phenol. Draw the resonance structures of the corresponding phenoxide ions.
(i) Draw the structures of all isomeric alcohols of molecular formula C5HI20 and give their IUPAC names.
(ii) Classify the isomers of alcohols in question (i)as primary, secondary and tertiary alcohols.
Give equations of the following reactions:
(i)Oxidation of propan-l-ol with alkaline KMnO4 solution.
(ii)Bromine in CS2 with phenol.
(iii)Dilute HNO3 acid with phehoL
(iv)Treating phenol with chloroform in presence of aqueous NaOH.
Mark the correct increasing order of reactivity of the following compounds with HBr/HCl.
Write the structures of the isomers of alcohols with molecular formula C4H10O. Which one of these isomers exhibits optical activity?
Assertion (A): p-Nitrophcnol is more acidic than phenol.
Reason (R): Nitro group helps in the stabilization of the phenoxide ion by dispersal of negative charge due to resonance.
Alcohols are comparatively more soluble in water than hydrocarbons of comparable molecular masses. Explain this fact.
How are the following conversions carried out?
(i) Propene —> Propan -2-ol
(ii) Benzyl chloride —> Benzyl alcohol
(iii) Ethyl magnesium chloride —> Propan-l-ol
(iv) Methyl magnesium bromide —> 2-Methylpropan-2-ol
