Aldehydes, Ketones And Carboxylic Acids

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JEE Mains

Addition of grignard reagents to aldehydes and ketones

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1. Grignard reagents add to the carbonyl group to form an adduct which on hydrolysis yields an alcohol.
2.
The reaction produces a primary alcohol with methanal, a secondary alcohol with other aldehydes and tertiary alcohol with ketones.
Which one of the following reagents reacts with both acetaldehyde and acetone?
A
Fehlings solution
B
Grignard reagent
C
Schiffs reagent
D
Tollens reagent
The order of reactivity of Phenyl Magnesium Bromide with the following compounds is:
A
B
C
D
All react with the same rate
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Cross-aldol condensation reactions

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1. When aldol condensation is carried out between two different aldehydes and/or ketones, it is called Cross aldol condensation.
2. If both of the molecules contain -hydrogen atoms, a mixture of four products is obtained.
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Effect of substituents on the acid strength of aliphatic acids

1. Substituents affect the stability of the conjugate base and affecting the acidity of the carboxylic acids.
2. Electron withdrawing groups increase the acidity of carboxylic acids by stabilising the conjugate base through delocalisation of the negative charge by inductive and/or resonance effects.
3. Electron donating groups decrease the acidity of carboxylic acids by destabilising the conjugate base by inductive and/or resonance effects.
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JEE Advanced

Cross cannizzaro reactions

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If an aldehyde without any -hydrogen is made to react with formaldehyde in presence of a base to give sodium formate and an alcohol, it is called as Cross Cannizzaro reaction.
The correct statement about the synthesis of erythritol used in the preparation of PETN is:
A
The synthesis requires three aldol condensations and one Cannizzaro reaction
B
Alpha hydrogens of ethanol and methanol are involved in this reaction
C
The synthesis requires two aldol condensations and two Cannizzaro reactions
D
The synthesis requires four aldol condensations between methanol and ethanol
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Comparison of acidic strength of hydroxybenzoic acids

1. The acidic strength order of hydroxybenzoic acids is as follows:
hydroxybenzoic acid > hydroxybenzoic acid > hydroxybenzoic acid
2. acid is strongest due to H bonding with carboxylate ion, while acid is weakest due to the effect of group.
The correct order of acidity for the following compounds is:
A
I > II > III > IV
B
III > I > II > IV
C
III > IV > II > I
D
I > III > IV > II
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Haloform reaction

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1. Aldehydes and ketones having at least one methyl group linked to the carbonyl carbon atom are called Methyl ketones.
2. Methyl Ketones can be oxidized by sodium hypohalite to sodium salts of corresponding carboxylic acids having one carbon atom less than that of carbonyl compound.
3. The methyl group is converted to haloform. This oxidation does not affect a bond, if present in the molecule.
4. This reaction is used for detection of group or group.