Match the starting materials given in Column I with the products formed by these (Column II) in the reaction with HI.
(i —> d), (ii — » e), (iii —> b), (iv — » a)
(i) CH3 – O – CH3 is a symmetrical ether so the products are CH3I and CH2OH.
(ii) In (CH3)2CH – O – CH3 unsymmetrical ether, one alkyl group is primary while another is secondary. So, it follows SN 2mechanism. Thus, the halide ion attacks the smaller alkyl group and the products are
(iii) In this case, one of the alkyl group is tertiary and the other is primary. It follows SN 1 mechanism and halide ion attacks the tertiary alkyl group and the products are (CH3)3 C-I and CH3OH.
(iv) Here, the unsymmetrical ether is alkyl aryl ether. In this ether 0-CH3 bond is weaker than 0-C6H5bond which has partial double bond character due to resonance. So, the halide ion attacks on alkyl group and the products are C6H5-OH and CH3I.
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.
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.
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.
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
While separating a mixture of ortho and para nitrophenols by steam distillation, name the isomer which will be steam volatile. Give reason.
Explain how does the – OH group attached to a carbon of benzene ring activate it towards electrophilic substitution?
Arrange the following compounds in increasing order of acidity and give a suitable explanation:
Phenol, o-Nitrophenol, o-Cresol
Write the equation of the reaction of hydrogen iodide with (i)1-propoxypropane (ii)methoxybenzene, and (iii)benzyl ethyl ether
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.
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
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.
Write the structures of the isomers of alcohols with molecular formula C4H10O. Which one of these isomers exhibits optical activity?
Why is the reactivity of all three classes of alcohols with cone. HCl and ZnCl2 (Lucas reagent) different?
Match the starting materials given in Column I with the products formed by these (Column II) in the reaction with HI.
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.
Predict the major product of acid catalysed dehydration of
(i) 1-nicthylcyclohcxanoland
(ii) butan-1-ol
Which of the following is an appropriate set of reactants for the preparation of l-methoxy-4- nitrobenzene and why?
Alcohols are comparatively more soluble in water than hydrocarbons of comparable molecular masses. Explain this fact.
You are given benzene, cone. H2S04and NaOH. Write the equations for the preparation of phenol using these reagents.
Show how will you synthesise
(i)1 -phenylethanol from a suitable alkene.
(ii)cyclohexylmethanol using an alkyl halide by an SN2 reaction.
(iii) Pentan-l-ol using a suitable alkyl halide?
Illustrate with examples the limitations of Willamson synthesis for the preparation of certain types of ethers.
Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method.Give reason.
Phenol can be distinguished from ethanol by the reactions with ………….
(a) Br2/water (b) Na
(c) Neutral FeCl3 (d) All of these
