Aldehydes ketones and carboxylic acids
Aldehydes ketones and carboxylic acids Lecture-3
Physical properties
Methanal ( H C H O ) (HCHO) ( H C H O ) [ ( H C H O ) n ] [(HCHO)_n] [( H C H O ) n ]
Ethanal C H 3 C H O CH_3CHO C H 3 C H O
The boiling points of aldehydes & ketones are higher than the hydrocarbon & either of similar molecular mass due to molecular interaction arising out of dipole-dipole interaction
Physical properties → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Physical properties
The boiling points of aldehydes & ketons are lower than alcohols of similar molecular masses due to absence of hydrogen bonding
Mol-mass - 55-60
C H 3 C H 2 C H 2 O H > C H 3 C H 2 C H O ≈ C H 3 C − C H 3 > C H 3 O C H 2 C H 3 > C H 3 C H 2 C H 2 C H 3 CH_3CH_2CH_2OH > CH_3CH_2CHO≈CH_3C-CH_3 > CH_3OCH_2CH_3 > CH_3CH_2CH_2CH_3 C H 3 C H 2 C H 2 O H > C H 3 C H 2 C H O ≈ C H 3 C − C H 3 > C H 3 OC H 2 C H 3 > C H 3 C H 2 C H 2 C H 3
Physical properties → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Physical properties
Lower aldehydes and ketones are soluble in water due to hydrogen bonding with water
As the size of substituent increases, the solubility decreases
Lower aldehydes have sharp pungent smell
The size increases, the smell becomes more fragnent
Physical properties → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuclear addition reaction
Reactivity : Aldehydes are more reactive than ketones
Steric : Two alkyl groups increases the bulkiness around carbonyl carbon
Electronic effect : Two alkyl groups decreases the eletrophilicity of carbonyl due to (+I) effect
Physical properties → \rightarrow → Nuclear addition reaction → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuclear addition reaction
Physical properties → \rightarrow → Nuclear addition reaction → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuclear addition reaction
(1) Hydrogen cyanide addition
Physical properties → \rightarrow → Nuclear addition reaction → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuceophilic addition reaction
Examples:
(2) Addition of sodium hydrogen sulphite ( N a H S O 3 ) (NaHSO_3) ( N a H S O 3 )
Position of the equilibrium
Right side for the aldehydes, to the left side for ketones due to steric reason
Physical properties → \rightarrow → → \rightarrow → Nuceophilic addition reaction → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuceophilic addition reaction
Examples:
(3) Addition of alcohols
Aldehydes react with one molecule of monohydric alcohol to provide monoalkoxy alcohol(hemiacetal)
Hemiacetal reacts further with molecule of monohydric alochol to generate dialkoxy compound (acetal)
Remove H 2 O H_2O H 2 O
Physical properties → \rightarrow → → \rightarrow → Nuceophilic addition reaction → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuceophilic addition reaction
Examples:
(3) Addition of alcohols
Ketones similarly react to provide hemiketal & ketal respectively
Physical properties → \rightarrow → → \rightarrow → Nuceophilic addition reaction → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuceophilic addition reaction
(4) Addition of grignard reagent (R’MgX)
Physical properties → \rightarrow → → \rightarrow → Nuceophilic addition reaction → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuceophilic addition reaction
Examples:
(5) Addition of ammonia & its derivatives
Physical properties → \rightarrow → → \rightarrow → Nuceophilic addition reaction → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuceophilic addition reaction
Physical properties → \rightarrow → → \rightarrow → Nuceophilic addition reaction → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Reduction reaction
Physical properties → \rightarrow → → \rightarrow → → \rightarrow → Reduction reaction → \rightarrow → → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Nuceophilic addition reaction
Conversion to hydrocarbons
Physical properties → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → Nuceophilic addition reaction → \rightarrow → → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Clemenson reduction
Alcohol do not give products in this condition
Physical properties → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → Clemenson reduction → \rightarrow →
Aldehydes ketones and carboxylic acids Lecture-3
Wolff-kishner reaction
Physical properties → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → → \rightarrow → Wolff-kishner reaction
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