benzaldehyde reduces tollen reagent but not fehling solution . why ?
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Answered by
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Fehiling's solution is an alkaline solution of copper sulphate containing sodium potassium tartarate.
When Fehling's solution is added to a aldehyde, it gives out a red precipitate. This red precipitate is nothing but cupprous oxide.
Normally, when Fehling's solution is added to say, acetaldehyde, it gives acetic acid and cupprous oxide.
CH3-CHO + 2CuO -----------> CH3-COOH + Cu2O
But when benzaldehyde is added, it rapidly converts into benzyl alcohol and sodium benzoate because of the presence of alkali(Cannizzro's Reaction) . Here, there is no formation of cupprous oxide to give out a red precipitate.
When Fehling's solution is added to a aldehyde, it gives out a red precipitate. This red precipitate is nothing but cupprous oxide.
Normally, when Fehling's solution is added to say, acetaldehyde, it gives acetic acid and cupprous oxide.
CH3-CHO + 2CuO -----------> CH3-COOH + Cu2O
But when benzaldehyde is added, it rapidly converts into benzyl alcohol and sodium benzoate because of the presence of alkali(Cannizzro's Reaction) . Here, there is no formation of cupprous oxide to give out a red precipitate.
Answered by
7
Explanation:
In benzaldehyde the bond between C-H is very strong due to less polarity, and Fehling's solution can't reduce it as it is weaker reducing agent than tollen's agent, so benzaldehyde reduces tollen's but not feelings..
Hope u understand
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