Reaction Equation Help: Pentan 3 One + 2,4-Dinitrophenylhydrazine Formula

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Discussion Overview

The discussion revolves around the reaction equation for pentan-3-one and 2,4-dinitrophenylhydrazine, focusing on the chemistry involved, particularly the implications of the Wolff-Kishner reaction and Brady's test. Participants explore the nature of these reactions and their applications in identifying ketones and aldehydes.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant requests assistance in writing the reaction equation for pentan-3-one and 2,4-dinitrophenylhydrazine, expressing a lack of confidence in this area of chemistry.
  • Some participants suggest the Wolff-Kishner reaction as a relevant process but express uncertainty about its applicability to DNP derivatives.
  • Another participant clarifies that DNP-hydrazine is used to test for ketone carbonyls and mentions Brady's test, which results in a yellow or red precipitate.
  • There is a correction regarding Brady's test, emphasizing that it specifically involves the formation of the DNP derivative and not its further reduction to an alkane, which is associated with the Wolff-Kishner reduction.
  • Some participants note that the Wolff-Kishner reduction requires hydrazine and a strong base, distinguishing it from Brady's test.
  • One participant acknowledges a need for further research, referencing Wikipedia for additional information on the topic.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between the Wolff-Kishner reaction and Brady's test, with some clarifying that they are not the same. The discussion remains unresolved regarding the exact nature of the reaction equation and the applicability of the Wolff-Kishner reaction to the DNP derivative.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the reactions and the definitions of terms like "hydrazine" and "DNP derivative." The scope of the discussion is also restricted to the specific reactions mentioned without broader context.

newkidintownu
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Please can someone help me.

I need to write an equation for the reaction between pentan 3 one and 2,4-dinitrophenylhydrazine.

I am not very good with this area of chemistry so any help will be much appreciated.

Ta
 
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Last edited:
bomba923 said:
Hint: Wolff-Kishner

(Edit: this probably belongs in the Homework Help/Other Sciences forum)

The Wolff-Kishner reaction is the reduction that (typically) follows this reaction of a ketone with hydrazine (H2N2H2). I'm not sure it works on a DNP derivative, though. DNP derivatives are usually employed for melting point determinations.
 
chemisttree said:
The Wolff-Kishner reaction is the reduction that (typically) follows this reaction of a ketone with hydrazine (H2N2H2). I'm not sure it works on a DNP derivative, though. DNP derivatives are usually employed for melting point determinations.
DNP-hydrazine (from the OP) is used to test exclusively for the presence of ketone carbonyls within a molecule via the general Wolff-Kishner reduction. This procedure is known as Brady's Test, which is positive upon formation of a yellow or red precipitate (see Analyst, 1926, 51, 77 - 78, DOI: 10.1039/AN9265100077)
 
Last edited:
bomba923 said:
DNP-hydrazine (from the OP) is used to test exclusively for the presence of ketone carbonyls within a molecule via the general Wolff-Kishner reduction. This procedure is known as Brady's Test, which is positive upon formation of a yellow or red precipitate (see Analyst, 1926, 51, 77 - 78, DOI: 10.1039/AN9265100077)

That's almost correct. Brady's test is specifically the formation of the DNP derivative itself (both ketones and aldehydes)... not it's further reduction to the alkane if only hydrazine itself were used (Wolff-Kishner Reduction).

The Wolff-Kishner reduction is a specific reaction utilizing an aldehyde or ketone and hydrazine (NOT 2,4-DNP a different 'hydrazine') and a strong base to yield an alkane. Wolff-Kishner is NOT Brady's test. Some elements of the chemistry are similar, however.
 
chemisttree said:
That's almost correct. Brady's test is specifically the formation of the DNP derivative itself (both ketones and aldehydes)... not it's further reduction to the alkane if only hydrazine itself were used (Wolff-Kishner Reduction).

The Wolff-Kishner reduction is a specific reaction utilizing an aldehyde or ketone and hydrazine (NOT 2,4-DNP a different 'hydrazine') and a strong base to yield an alkane. Wolff-Kishner is NOT Brady's test. Some elements of the chemistry are similar, however.
Indeed--I should have first looked this up on Wikipedia!
http://en.wikipedia.org/wiki/2,4-Dinitrophenylhydrazine
(even at best, the most convenient reference for this concept)

--Accordingly, no reduction occurs but rather the precipitation of the DNP-derivative
itself and yes, aldehydes as well as ketones are detected by Brady's test
 
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