chem問題一條 - Ans.fyi 參考答案

chem問題一條

2007-10-29 3:58 am

experiment:Identification of a carbonyl compound by preparing its derivatives

Q:If the melting point of the 2,4-dinitrophenylhydrazine is 156 ℃, suggest and explain what kinds of tests can be used to confirm whether the unknown compound is propanal or pentan-3-one.

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[匿名]

2007-10-29 4:58 am

✔ 最佳答案

You may carry out reactions that can only apply to aldehydes.
1. React with Tollen's reagent:
Mix Tollen's reagent [Ag(NH3)2OH] with the sample in a clean test tube. If the sample is an aldehyde, silver mirror will be formed on the test tube. No reaction for ketone.
2. Reaction with Fehling's reagent:
Mix Fehling's reagent [Cu2+/NH3 or Cu2+/NaOH] with the sample. Reddish-brown ppt formed indicates the sample is aliphatic aldehyde while there is no reaction with aromatic aldehyde and ketone.

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