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All 2 posts Subject: Review: Sodium Dithionite Reductions Please login to post Down

Rhodium
(Chief Bee)
09-28-03 03:19
No 461416
User Picture       Review: Sodium Dithionite Reductions
(Rated as: excellent)

Very interesting review - Na₂S₂O₄ reduction of N-alkylpyridine salts to N-alkylpiperidines, reductive amination, and reduction of imine/oxime/azide/nitro functionalities to amines. The article is in French though...

Review: Sodium Dithionite Reductions in Organic Chemistry
O. Louis-André, G. Gelbard
Bull. Soc. Chim. France [4] 565-577 (1986) (https://www.rhodium.ws/pdf/dithionite.reduction.review.pdf)

Summary

Sodium dithionite, Na₂S₂O₄, is a low-cost reducing agent widely used in the paper and textile industry. In this review the inorganic properties are examined first: structural aspects, behaviour of aqueous solutions and redox properties. The use of sodium dithionite in organic chemistry concerns the reduction of several nitrogen functions: nitro, nitroso, N-oxide, azo, azide, imine, oxime, pyridinium. The reduction of aldehydes and ketones into the corresponding alcohols is also possible but the most interesting reaction is the exclusive 1,4-reduction of enones.

Chimimanie
(Hive Bee)
09-28-03 17:16
No 461485
User Picture       Yes, interesting

I had this paper for some time...

What is interesting is those reduction potential :

Dithionite at pH=10: -1.12V
Borohydride: -1.24V
Formamidine sulfinic acid (made from thiourea and H2O2) at pH=4-8: -1.5V

Which state that formamidine sulfinic acid has more reducing power than borohydride. Check also Post 455221 (Vitus_Verdegast: "thiourea dioxide", Chemistry Discourse)

Sadly dithionite is pretty insoluble in water, so polar solvent or PTC agent such as crown ether should be used, altough Ba had success with it from nitropropenes to oximes Post 427794 (Barium: "Nitrostyrenes to oximes with sodium dithionite", Novel Discourse).

A downside of dithionite is that according to this paper only quinonic oxymes gave amines by reduction, the aliphatic and aromatic oxymes gave only the ketone, in high yield.

The hydrolyse product is also obtained with nitriles, giving the amide and not the amine.

Dithionite is remarkably good for activated double bond reduction (in alpha of a ketone).

The uses above mentioned by Rhodium such has pyridinum (unsubstitued) to piperidine derivates could also be useful for our purpose.

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		Rhodium (Chief Bee) 09-28-03 03:19 No 461416				Review: Sodium Dithionite Reductions (Rated as: excellent)
						Very interesting review - Na₂S₂O₄ reduction of N-alkylpyridine salts to N-alkylpiperidines, reductive amination, and reduction of imine/oxime/azide/nitro functionalities to amines. The article is in French though... Review: Sodium Dithionite Reductions in Organic Chemistry O. Louis-André, G. Gelbard Bull. Soc. Chim. France [4] 565-577 (1986) (https://www.rhodium.ws/pdf/dithionite.reduction.review.pdf) Summary Sodium dithionite, Na₂S₂O₄, is a low-cost reducing agent widely used in the paper and textile industry. In this review the inorganic properties are examined first: structural aspects, behaviour of aqueous solutions and redox properties. The use of sodium dithionite in organic chemistry concerns the reduction of several nitrogen functions: nitro, nitroso, N-oxide, azo, azide, imine, oxime, pyridinium. The reduction of aldehydes and ketones into the corresponding alcohols is also possible but the most interesting reaction is the exclusive 1,4-reduction of enones.



		Chimimanie (Hive Bee) 09-28-03 17:16 No 461485				Yes, interesting
						I had this paper for some time... What is interesting is those reduction potential : Dithionite at pH=10: -1.12V Borohydride: -1.24V Formamidine sulfinic acid (made from thiourea and H2O2) at pH=4-8: -1.5V Which state that formamidine sulfinic acid has more reducing power than borohydride. Check also Post 455221 (Vitus_Verdegast: "thiourea dioxide", Chemistry Discourse) Sadly dithionite is pretty insoluble in water, so polar solvent or PTC agent such as crown ether should be used, altough Ba had success with it from nitropropenes to oximes Post 427794 (Barium: "Nitrostyrenes to oximes with sodium dithionite", Novel Discourse). A downside of dithionite is that according to this paper only quinonic oxymes gave amines by reduction, the aliphatic and aromatic oxymes gave only the ketone, in high yield. The hydrolyse product is also obtained with nitriles, giving the amide and not the amine. Dithionite is remarkably good for activated double bond reduction (in alpha of a ketone). The uses above mentioned by Rhodium such has pyridinum (unsubstitued) to piperidine derivates could also be useful for our purpose.

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