Which of the following is an appropriate set of reactants for the preparation of l-methoxy-4- nitrobenzene and why?
Assertion (A): Phenols give o-nitrophenol and p-nitrophenol on nitration with cone. HNO3 and H2SO4 mixture.
Reason (R): -OH group in phenol is o-,p-directing.
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.
Which of the following are used to convert RCHO into RCH2OH?
(a) H2/Pd
(b) LiAlH4
(c) NaBH4
(d) Reaction with RMgX followed by hydrolysis
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
When phenol is treated with bromine water, white precipitate is obtained. Give the structure and the name of the compound formed.
Name the enzymes and write the reactions involved in the preparation of ethanol from sucrose by fermentation.
Explain why is OH group in phenols more strongly held as compared to OH group in alcohols.
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.
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.
Predict the major product of acid catalysed dehydration of
(i) 1-nicthylcyclohcxanoland
(ii) butan-1-ol
Give two reactions that show the acidic nature of phenol. Compare its acidity with that of ethanol.
Name the reagents used in the following reactions:
(i)Oxidation of a primary alcohol to carboxylic acid.
(ii)Oxidation of a primary alcohol to aldehyde.
(iii)Brominationofphenolto2,4,6-tribromophenol
(iv)Benzyl alcohol to benzoic acid.
(v)Dehydration of propan-2-oI to propene.
(vi)Butan-2-one to butan-2-oL .
Write the names of reagents and equations for the preparation of the following ethers by Williamson's synthesis:
(i)1-Propoxypropane
(ii)Ethoxybenzene
(iii)2-Methoxy-2-methylpropane
(iv)1-Methoxyethane
Write the equation of the reaction of hydrogen iodide with (i)1-propoxypropane (ii)methoxybenzene, and (iii)benzyl ethyl ether
Alcohols react with active metals, e.g., Na, K, etc., to give corresponding alkoxides. Write down the decreasing order or reactivity of sodium metal towards primary, secondary and tertiary alcohols.
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?
Assertion (A): Like bromination of benzene, bromination of phenol is also carried out in the presence of Lewis acid.
Reason (R): Lewis acid polarizes the bromine molecule.
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.
While separating a mixture of ortho and para nitrophenols by steam distillation, name the isomer which will be steam volatile. Give reason.
Explain the fact that in aryl alkyl ethers (i) the alkoxy group activates the benzene ring towards electrophilic substitution and (ii) it directs the incoming substituents to ortho and para positions in benzene ring.
When 3-methylbutant 2-ol is treated with HBr, the following reaction takes place:
Give a mechanism for this reaction.
(Hint: The secondary carbocation formed in step II rearranges to a more stable tertiary carbocation by a hydride ion shift from 3rd carbon atom.)
Arrange water, ethanol and, phenol in increasing order of acidity and give reason for your answer.
Which of the following reagents can be used to oxidize primary alcohols to aldehydes?
(a) CrO3 in anhydrous medium
(b) KMnO4 in acidic medium
(c) Pyridinium chlorochromate
(d) Heat in the presence of Cu at 573 K
Write the structures of the isomers of alcohols with molecular formula C4H10O. Which one of these isomers exhibits optical activity?
