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 .
(i) Acidified potassium dichromate or neutral/ acidic/ alkaline potassium permanganate.
(ii)Pyridinium chlorochromate (PCC), (C5H5NH)+ ClCrO3– in CH2Cl2
or Pyridinium dichromate (PDC),[(C5H5NH)2]2+Cr2O72-in CH2Cl2
(iii)Aqueous bromine, i.e., Br2/H2O.
(iv)Acidified or alkaline potassium permanganate.
(v)85% H2S04 at 440 K.
(vi)Ni/H2 or NaBH4 or LiAlH4.
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.
Assertion (A): Phenol forms 2,4, 6-tribromophenol on treatment with Br2 in carbon disulphide at 273 K.
Reason (R): Bromine polarizes in carbon disulphide.
Write the structures of the isomers of alcohols with molecular formula C4H10O. Which one of these isomers exhibits optical activity?
Ethers can be prepared by Williamson's synthesis in which an alkyl halide is reacted with sodium alkoxide. Di-tert-butyl ether cannot be prepared by this method. Explain.
While separating a mixture of ortho and para nitrophenols by steam distillation, name the isomer which will be steam volatile. Give reason.
Match the starting materials given in Column I with the products formed by these (Column II) in the reaction with HI.
Explain how does the – OH group attached to a carbon of benzene ring activate it towards electrophilic substitution?
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
Explain the following with an example
(i) Kolbe's reaction (ii) Reimer – Tiemann reaction –
(iii) Williamson ether synthesis (iv) Unsymmetrical ether
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.
Give structures of the products you would expect when each of the following alcohol reacts with (a)HCl-ZnCl2 (b)HBrand (c) SOCl2
(i)Butan-1-ol
(ii)2-Methylbutan-2-ol
Arrange the following compounds in increasing order of acidity and give a suitable explanation:
Phenol, o-Nitrophenol, o-Cresol
Assertion (A): Boiling points of alcohols and ethers are high.
Reason (R): They can form intermolecular hydrogen bonding.
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.
Write the reactions of Williamson synthesis of 2-ethoxy-3-methylpentane starting from ethanol and 3-methylpentan-2-ol.
Alcohols are comparatively more soluble in water than hydrocarbons of comparable molecular masses. Explain this fact.
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
Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method.Give reason.
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
When phenol is treated with bromine water, white precipitate is obtained. Give the structure and the name of the compound formed.
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.
Explain why is OH group in phenols more strongly held as compared to OH group in alcohols.
Explain why alcohols and ethers of comparable molecular mass have different boiling points.
Arrange water, ethanol and, phenol in increasing order of acidity and give reason for your answer.
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): Ethanol is a weaker acid than phenol.
Reason (R): Sodium ethoxide may be prepared by the reaction of ethanol with aqueous NaOH.
Write the equations involved in the following reactions:
(i) Reimer-Tiemann reaction
(ii) Kolbe's reaction
