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All Physics Chemistry Botany Zoology

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Products of the following reaction

CH₃C $\equiv$ C.CH₂CH₃ $\to_{(ii) hydrolysis}^{(i) O_{3}}$ ... are

CH₃CHO + CH₃CH₂CHO

CH₃COOH + CH₃COCH₃

CH₃COOH + HOOC.CH₂CH₃

CH₃COOH + CO₂

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Explanation

The given reaction is the ozonolysis of 2-butyne, followed by hydrolysis of the ozonide intermediate. The products of this reaction are acetic acid (CH3COOH) and propanoic acid (HOOC.CH2CH3). The ozonide first forms, which then undergoes hydrolysis to give these two carboxylic acids.

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Which alkene on ozonolysis gives CH₃CH₂CHO and CH₃COCH₃?

CH₃CH₂CH=C $<_{{CH}_{3}}^{{CH}_{3}}$

CH₃CH₂CH=CHCH₂CH₃

CH₃CH₂CH=CHCH₃

${CH}_{3} - \underset{|}{C} = {CHCH}_{3} {CH}_{3}$

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Explanation

The alkene that will give acetaldehyde (CH3CHO) and acetone (CH3COCH3) on ozonolysis is 2-methylpropene (CH3CH=C(CH3)2). Ozonolysis cleaves the carbon-carbon double bond, and the resulting ozonide undergoes hydrolysis to give the two carbonyl compounds mentioned.

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Benzoic acid gives benzene on being heated with X and phenol gives benzene on being heated with Y. Therefore, X and Y are respectively

sodalime and copper

Zn dust and NaOH

Cu and sodalime

sodalime and zinc dust

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Which one of the following on oxidation gives a ketone?

primary alcohol

secondary alcohol

tertiary alcohol

All of these

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Explanation

(b) Ketones can be prepared by the oxidation of secondary alcohols by using oxidising agent such as K₂Cr₂O₇/H₂SO_4.

${}_{H_{3} C}^{H_{3} C}> CHOH$ + [O] $\to$ ${}_{H_{3} C}^{H_{3} C}>$ C=O + H₂O

2 $°$ alcohol Dimethyl ketone

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A carbonyl compound reacts with hydrogen cyanide to form cyanohydrin which on hydrolysis forms a racemic mixture of $α$ -hydroxy acid. The carbonyl compound is

acetaldehyde

acetone

diethyl ketone

formaldehyde

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Explanation

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The product formed in aldol condensation is

a beta-hydroxy acid

a beta-hydroxy aldehyde or a beta-hydroxy ketone

an alpha-hydroxy aldehyde or ketone

an alpha, beta unsaturated ester

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Explanation

In the aldol condensation reaction, two aldehydes or a ketone and an aldehyde undergo nucleophilic addition followed by dehydration to form a Î²-hydroxy aldehyde or a Î²-hydroxy ketone respectively. Therefore, the product formed is a Î²-hydroxy aldehyde or a Î²-hydroxy ketone.

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Consider the following reaction,

Phenol $\overset{Zn - dust}{\to}$ X $\to_{Anhy . {AlCl}_{3}}^{{CH}_{3} Cl}$ Y $\overset{Alk . {KMnO}_{4}}{\to}$ Z

The product Z is

toluene

benzaldehyde

benzoic acid

benzene

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Explanation

The given reaction sequence involves the dehydroxylation of phenol to benzene using Zn dust, followed by chlorination of benzene with anhydrous AlCl3 to form chlorobenzene, and finally oxidation of chlorobenzene with alkaline KMnO4 to give benzoic acid.

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Reduction of aldehydes and ketones into hydrocarbons using zinc amalgam and conc. HCl is called

Clemmenson reduction

Cope reduction

Dow reduction

Wolff-Kishner reduction

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Explanation

(a) Clemmensen reduction Aldehydes and ketones are reduced to the corresponding alkanes by means of amalgamated zinc and HCl.

>C=O + 4[H] $\overset{Zn - Hg / HCl}{\to}$ >CH₂ + H₂O

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Aldol condensation will not take place in

HCHO

${CH}_{3} CHO$

${CH}_{3} {COCH}_{3}$

${CH}_{3} {CH}_{2} CHO$

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Explanation

(a) Aldol condensation in aldehydes is due to presence of $α$ -hydrogen atoms. Those aldehydes which does not have $α$ -hydrogen atom like HCHO, does not give aldol condensation reaction.

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The -OH group of an alcohol or the -COOH group of a carboxylic acid can be replaced by -Cl using

phosphorus pentachloride

hypochlorous acid

chlorine

hydrochloric acid

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Explanation

(a) The -OH group of alcohol or the -COOH group of a carboxylic acid is replaced by -Cl using phosphorus pentachloride (i.e. PCl₅)

ROH + PCl₅ $\to$ RCl + POCl₃ + HCl

Alcohol

RCOOH + PCl₅ $\to$ RCOCl + POCl₃ + HCl

Acid

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