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Why is (i) 2,2 dimethyl-propanoic acid is slightly weaker, but phenyl-ethanoic acid is slightly stronger than ethanoic acid. (ii) In diphenylamine, acidic rather than basic character predominates?
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Laurie Keller
Why is (i) 2,2 dimethyl-propanoic acid is slightly weaker, but phenyl-ethanoic acid is slightly stronger than ethanoic acid. (ii) In diphenylamine, acidic rather than basic character predominates?
2,2 dimethyl-propanoic acid has two methyl groups that are electron donating. There is slightly more negative charge on the COOH group, it holds to on the proton more tightly. The opposite is true for phenylacetic acid, the benzene ring is slightly electron withdrawing, since the anion is stabilized by mesomeric effects (the charge is distributed over the shared pi-orbitals of the ring). It gives off the proton more easily. However this effect is diminished by the presence of the methylene (CH2) group in the middle.
In diphenylamine there are two phenyl rings, which are electron withdrawing. That makes it easier to deprotonate and harder to be protonated as compared to unsubstituted ammonia.
2,2 dimethyl-propanoic acid has two methyl groups that are electron donating. There is slightly more negative charge on the COOH group, it holds to on the proton more tightly. The opposite is true for phenylacetic acid, the benzene ring is slightly electron withdrawing, since the anion is stabilized by mesomeric effects (the charge is distributed over the shared pi-orbitals of the ring). It gives off the proton more easily. However this effect is diminished by the presence of the methylene (CH2) group in the middle.
In diphenylamine there are two phenyl rings, which are electron withdrawing. That makes it easier to deprotonate and harder to be protonated as compared to unsubstituted ammonia.
2,2 dimethyl-propanoic acid has two methyl groups that are electron donating. There is slightly more negative charge on the COOH group, it holds to on the proton more tightly. The opposite is true for phenylacetic acid, the benzene ring is slightly electron withdrawing, since the anion is stabilized by mesomeric effects (the charge is distributed over the shared pi-orbitals of the ring). It gives off the proton more easily. However this effect is diminished by the presence of the methylene (CH2) group in the middle.
In diphenylamine there are two phenyl rings, which are electron withdrawing. That makes it easier to deprotonate and harder to be protonated as compared to unsubstituted ammonia.
2,2 dimethyl-propanoic acid has two methyl groups that are electron donating. There is slightly more negative charge on the COOH group, it holds to on the proton more tightly. The opposite is true for phenylacetic acid, the benzene ring is slightly electron withdrawing, since the anion is stabilized by mesomeric effects (the charge is distributed over the shared pi-orbitals of the ring). It gives off the proton more easily. However this effect is diminished by the presence of the methylene (CH2) group in the middle.
In diphenylamine there are two phenyl rings, which are electron withdrawing. That makes it easier to deprotonate and harder to be protonated as compared to unsubstituted ammonia.
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Acidity is depends on the pka value ,as the pka value of ethanol is 15.2 than methanol 4.7 .So the ethanoic acid is stronger than methanoic.
Acidity is depends on the pka value ,as the pka value of ethanol is 15.2 than methanol 4.7 .So the ethanoic acid is stronger than methanoic.
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