Aldehydes Ketones and Carboxylic Acids Test

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Aldehydes Ketones and Carboxylic Acids Test - 53

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Weekly Quiz Competition

Question 1
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A carbonyl compound 'A' reacts with hydrogen cyanide to form a cyanohydrin 'B' which on hydrolysis gives an optically active alpha hydroxy acid 'C'. 'A' gives a positive iodoform test 'A', 'B' and 'C' are given by the set :-

A

B

C

D

Solution

The correct option is (B)
when a carbonyl compound react with HCN it forms cyanohydrin (B) ,the compound (A) must have two different valency which is only possible when the compound (A) is $$CH_3CHO$$
$$CH_3CHO$$ on reaction with HCN gives (B) $$C_2H5OCN$$ which on hydrolysis gives (C) $$C_2H5OCOOH$$.
Question 2
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Directions For Questions

Aldehyde, ketone, acid and acid derivatives contain $$>C = O$$ group. Aldehyde and ketones give nucleophilic addition reactions whereas acid and acid derivatives give nucleophilic addition followed by elimination reactions. Nucleophilic addition reactions followed by elimination of acid derivatives is known as acyl substitution reaction. This substitution reaction takes places by the formation of tetrahedral intermediate.

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Which of the following compounds has very poor leaving group?

A

B

C

D

Solution
Question 3
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Directions For Questions

Aldehyde, ketone, acid and acid derivatives contain $$>C = O$$ group. Aldehyde and ketones give nucleophilic addition reactions whereas acid and acid derivatives give nucleophilic addition followed by elimination reactions. Nucleophilic addition reactions followed by elimination of acid derivatives is known as acyl substitution reaction. This substitution reaction takes places by the formation of tetrahedral intermediate.

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For the given reaction, which of these is correct?

A
$$L$$ must be better leaving group than $$Nu$$

B
$$Nu^-$$ must be strong enough nucleophile to attack carbonyl carbon

C
Carbonyl carbon must be enough electrophilic to react with $$Nu^-$$

D
All of these

Solution
Question 4
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Directions For Questions

Aldehydes and ketones are amphoteric. Thus they can act both as acids and bases. Under acidic conditions, the carbon of the protonated carbonyl group is much more electrophilic, reacting even with weak nucleophilie. Carbonyl compound gives nucleophilic addition reaction. In this reaction the nucleophilic attack precedes the electrophilic attack.

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Which of these statements are correct ?

A
Carbonyl compound is amphoteric in character

B
Acid catalyst makes the carbonyl carbon more electrophilic

C
basic catalyst makes the nucleophilic attack more faster.

D
All of these

Solution

All the three statements are correct.
(A) Carbonyl compound is amphoteric in character. It can react with acids as well as bases.
(B) Acid catalyst makes the carbonyl carbon more electrophilic. The carbonyl oxygen is protonated which in turn withdraws electron density from carbonyl carbon atom.
(C) Basic catalyst makes the nucleophilic attack more faster.
Question 5
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Directions For Questions

Aldehydes and ketones are amphoteric. Thus they can act both as acids and bases. Under acidic conditions, the carbon of the protonated carbonyl group is much more electrophilic, reacting even with weak nucleophilie. Carbonyl compound gives nucleophilic addition reaction. In this reaction the nucleophilic attack precedes the electrophilic attack.

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Carbonyl compounds gives nucleophilic addtion with :

A
carbon nucleophile

B
oxygen nucleophile

C
Nitrogen nucleophile

D
All of these

Solution
Question 6
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Directions For Questions

Aldehydes and ketones are amphoteric. Thus they can act both as acids and bases. Under acidic conditions, the carbon of the protonated carbonyl group is much more electrophilic, reacting even with weak nucleophilie. Carbonyl compound gives nucleophilic addition reaction. In this reaction the nucleophilic attack precedes the electrophilic attack.

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Which of the statements are/is correct ?

A
The rate determining step of addition reaction is the addition of nucleophile.

B
The rate-determining step is addition of electrophile.

C
The reaction intermediate of the reaction is alkoxide ion.

D
Both (A) and (C)

Solution
Question 7
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Directions For Questions

Aldehyde and ketones are specially susceptible to nucleophile addition because carbonyl group $$>C=O$$ is polar (due to electronegativity different between carbon and oxygen). >$$\overset{\delta +}{C} - \overset{\delta-}{O}$$ Positive charge on carbon makes it reactive towards the nucleophile. This addition is catalysed by acid.
Reactivity of carbonyl compound towards nucleophilic addition increases with increase in the electron deficiency at carbonyl carbon. Thus, ($$-I.E.$$) group increase while ($$+I.E.$$) groups decrease the reactivity of carbonyl compound.

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Which of the following is most reactive to give nucleophilic addition ?

A
FCH$$_2$$CHO

B
ClCH$$_2$$CHO

C
BrCH$$_2$$CHO

D
ICH$$_2$$CHO
Question 8
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In this reaction: $$\displaystyle CH_{3}CHO+HCN \rightarrow CH_{3}CH(OH)CN \xrightarrow[] {H.OH}CH_{3}CH(OH)COOH$$, an asymmetric centre is generated. The acid obtained would be:

A
$$D$$ isomer

B
$$L$$ isomer

C
$$50\%$$ $$D$$ + $$50\%$$ $$L$$ isomer

D
$$20\%$$ $$D$$ + $$80\%$$ $$L$$ isomer

Solution
Question 9
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Directions For Questions

Aldehyde and ketones are specially susceptible to nucleophile addition because carbonyl group $$>C=O$$ is polar (due to electronegativity different between carbon and oxygen). >$$\overset{\delta +}{C} - \overset{\delta-}{O}$$ Positive charge on carbon makes it reactive towards the nucleophile. This addition is catalysed by acid.
Reactivity of carbonyl compound towards nucleophilic addition increases with increase in the electron deficiency at carbonyl carbon. Thus, ($$-I.E.$$) group increase while ($$+I.E.$$) groups decrease the reactivity of carbonyl compound.

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Carbonyl compounds show nucleophilic addition with :

A
HCN

B
NaHSO$$_3$$

C
(CH$$_3$$OH + HCl)

D
all of these

Solution
Question 10
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Directions For Questions

Aldehyde and ketones are specially susceptible to nucleophile addition because carbonyl group $$>C=O$$ is polar (due to electronegativity different between carbon and oxygen). >$$\overset{\delta +}{C} - \overset{\delta-}{O}$$ Positive charge on carbon makes it reactive towards the nucleophile. This addition is catalysed by acid.
Reactivity of carbonyl compound towards nucleophilic addition increases with increase in the electron deficiency at carbonyl carbon. Thus, ($$-I.E.$$) group increase while ($$+I.E.$$) groups decrease the reactivity of carbonyl compound.

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Which among the following carbonyl compound is most polar ?

A

B

C

D

Solution

Among 2- butanone, acetone, acetaldehyde and formaldehyde,
Formaldehyde is most polar.

Alkyl groups are electron releasing through +I effect.

As the number of alkyl groups increases, the +I effect increases and the polarity of carbonyl group decreases as the charge on carbonyl carbon decreases.

Option D is correct.