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Why acid anhydrides more reactive than amides?
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Melanie Jiang
Why acid anhydrides more reactive than amides?
The atom attached to the carboxyl group of acid amides is an electron donor, which decreases the electrophilicity of the carboxyl carbon, which is attacked during the hydrolysis of the amide. In a carboxylic acid anhydride, the atom bound to the carboxylic carbon is an oxygen which in turn is bound to another carboxylic carbon. The latter are electrophilic, which only serves to increase the electrophilicity of either carboxylic carbon. This renders it more susceptible to attack by a moderate to weak nucleophile like the oxygen in water, or a stronger one like an amine or ammonia itself. Other electrophiles, like halogens or phosphate, also increase the electrophilicity of the carboxyl carbon. The acyl phosphates, it should be noted, are mixed organic-inorganic anhydrides, since the phosphate is a salt of phosphoric acid.
The atom attached to the carboxyl group of acid amides is an electron donor, which decreases the electrophilicity of the carboxyl carbon, which is attacked during the hydrolysis of the amide. In a carboxylic acid anhydride, the atom bound to the carboxylic carbon is an oxygen which in turn is bound to another carboxylic carbon. The latter are electrophilic, which only serves to increase the electrophilicity of either carboxylic carbon. This renders it more susceptible to attack by a moderate to weak nucleophile like the oxygen in water, or a stronger one like an amine or ammonia itself. Other electrophiles, like halogens or phosphate, also increase the electrophilicity of the carboxyl carbon. The acyl phosphates, it should be noted, are mixed organic-inorganic anhydrides, since the phosphate is a salt of phosphoric acid.
Acid anhydride is less resonance stabalised than amides because ,
First of all, the resonance in acid anhydride is splited into two carbonyl groups. And secondly, nitrogen in amide is a better e- donor as compared to Oxygen in acid anhydride because oxygen is more electronegative than nitrogen. So, acid anhydride will be less stable, thus more reactive than amides.
Acid anhydride is less resonance stabalised than amides because ,
First of all, the resonance in acid anhydride is splited into two carbonyl groups. And secondly, nitrogen in amide is a better e- donor as compared to Oxygen in acid anhydride because oxygen is more electronegative than nitrogen. So, acid anhydride will be less stable, thus more reactive than amides.
The atom attached to the carboxyl group of acid amides is an electron donor, which decreases the electrophilicity of the carboxyl carbon, which is attacked during the hydrolysis of the amide. In a carboxylic acid anhydride, the atom bound to the carboxylic carbon is an oxygen which in turn is bound to another carboxylic carbon. The latter are electrophilic, which only serves to increase the electrophilicity of either carboxylic carbon. This renders it more susceptible to attack by a moderate to weak nucleophile like the oxygen in water, or a stronger one like an amine or ammonia itself. Other electrophiles, like halogens or phosphate, also increase the electrophilicity of the carboxyl carbon. The acyl phosphates, it should be noted, are mixed organic-inorganic anhydrides, since the phosphate is a salt of phosphoric acid.
The atom attached to the carboxyl group of acid amides is an electron donor, which decreases the electrophilicity of the carboxyl carbon, which is attacked during the hydrolysis of the amide. In a carboxylic acid anhydride, the atom bound to the carboxylic carbon is an oxygen which in turn is bound to another carboxylic carbon. The latter are electrophilic, which only serves to increase the electrophilicity of either carboxylic carbon. This renders it more susceptible to attack by a moderate to weak nucleophile like the oxygen in water, or a stronger one like an amine or ammonia itself. Other electrophiles, like halogens or phosphate, also increase the electrophilicity of the carboxyl carbon. The acyl phosphates, it should be noted, are mixed organic-inorganic anhydrides, since the phosphate is a salt of phosphoric acid.
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Acid anhydride is less resonance stabalised than amides because ,
First of all, the resonance in acid anhydride is splited into two carbonyl groups. And secondly, nitrogen in amide is a better e- donor as compared to Oxygen in acid anhydride because oxygen is more electronegative than nitrogen. So, acid anhydride will be less stable, thus more reactive than amides.
Acid anhydride:
Acid anhydride is less resonance stabalised than amides because ,
First of all, the resonance in acid anhydride is splited into two carbonyl groups. And secondly, nitrogen in amide is a better e- donor as compared to Oxygen in acid anhydride because oxygen is more electronegative than nitrogen. So, acid anhydride will be less stable, thus more reactive than amides.
Acid anhydride:
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