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Topic: Synthesis of Luminol  (Read 13331 times)

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Offline doublek1229

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Synthesis of Luminol
« on: March 12, 2010, 08:54:09 AM »
In our organic chemistry lab with synthesized luminol.  I understand the mechanism of the reaction, however I don't understand the purpose of triethylene glycol.  Why would the reaction of 3-Nitropthalic acid and hydrazine require triethylene glycol?  (It says it is "conveniently" carried out in a high boiling point solvent.  Also what does the Na2S2O4 do to the 5-Nitropthalhydrazide to convert it into luminol.  Thanks for any *delete me*

Offline sjb

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Re: Synthesis of Luminol
« Reply #1 on: March 12, 2010, 01:26:37 PM »
In our organic chemistry lab with synthesized luminol.  I understand the mechanism of the reaction, however I don't understand the purpose of triethylene glycol.  Why would the reaction of 3-Nitropthalic acid and hydrazine require triethylene glycol?  (It says it is "conveniently" carried out in a high boiling point solvent.  Also what does the Na2S2O4 do to the 5-Nitropthalhydrazide to convert it into luminol.  Thanks for any *delete me*

Why should any reaction require solvent?

What is the difference between 5-nitropthalhydrazide and luminol?

Offline Babcock_Hall

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Re: Synthesis of Luminol
« Reply #2 on: June 07, 2011, 01:06:07 PM »
In our organic chemistry lab with synthesized luminol.  I understand the mechanism of the reaction, however I don't understand the purpose of triethylene glycol.  Why would the reaction of 3-Nitropthalic acid and hydrazine require triethylene glycol?  (It says it is "conveniently" carried out in a high boiling point solvent.  Also what does the Na2S2O4 do to the 5-Nitropthalhydrazide to convert it into luminol.  Thanks for any *delete me*
The solvent is just there to control the temperature.  When a solvent is refluxing, it is at its boiling point.  I am not sure about the salt you mentioned.  Do you have a reference to the synthesis?

Offline TMS lover

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Re: Synthesis of Luminol
« Reply #3 on: June 18, 2011, 11:36:33 PM »
The reason DEG is used as a solvent is because the temperature the reaction is carried is very high, and as a result, a high boiling point solvent is required, so that while the reaction is being refluxed, the solvent still remains there and it is not fully evaporated.

Offline BobfromNC

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Re: Synthesis of Luminol
« Reply #4 on: June 22, 2011, 04:37:57 PM »
The TEG is just a solvent, other solvents should work, but that allows easy heating to high temps.   The Sodium Dithionate is a reducing agent, which reduces the 3-nitro group to a 3-amino group.  This could also be done with hydrogenation, tin or iron in HCl, or a variety of other reducing agents, but Sodium Diothionate is very safe and easy to use, with no heavy metals or major fire hazards.  I did that reaction many years back myself.   Gotta love glowing stuff.  Do you oxidize the luminol with NaFe(CN)6 and hydrogen peroxide?

Bob

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