bomb40 - 30-11-2008 at 02:48
Hi,everyone,I haven't to this forum for a long time,I miss
you very much!
Now I have a problem!
These days I do a reaction which is the reduction of o-chrolophenyl-P-benzoquinone to corresponding phenol
by Sodium hydrosulfite.
The reaction was done at room temperature , and was monitored by TLC，it seems the reaction was very fast.
I have a problem, the product shouldn't be soluble in water, but the product I obtained can dissolve in water easily.
The TM had been sulfonated?
Anyone can tell me why, and how can I do this reaction?
Manythanks
Outer - 30-11-2008 at 05:14
What phenol? Do you mean the reduction to corresponding hydroquinone?
bomb40 - 30-11-2008 at 07:33
Yes,thanks!
not_important - 30-11-2008 at 08:39
Kinetics and mechanism of the addition of sulfite to p-benzoquinone
J. Org. Chem. 51(11), 1981-1985.
http://pubs.acs.org/doi/abs/10.1021/jo00361a008
Klute - 30-11-2008 at 08:46
You might want to try dithionite, the usual zinc/acid will surely dechlorinate? Maybe in the cold and for a short time?
Nicodem - 1-12-2008 at 00:42
"Sodium hydrosulfite" is just an archaic term for sodium dithionite.
para-Benzoquinones cleanly reduce to hydroquinones with Na2S2O4, I never heard of any side reaction like sulfonation, etc.
What para-benzoquinone were you reducing? (assuming with "P" you actually mean p)
"o-chrolophenyl-P-benzoquinone" is not a chemical name, actually it means nothing. Do you mean 2-(2-chlorophenyl)-para-benzoquinone
or what else?
Outer - 1-12-2008 at 09:22
It is known that Na2SO3 can easuly sulfonate quinones. It may be useful to reduct your quinone by SO2, or by other agents (for example, NaBH4).
[Edited on 1-12-2008 by Outer]
Klute - 1-12-2008 at 09:47
Hum, I overlooked the "hydro"... NaBH4 is indeed a good idea. SO2 will surely cause sulfonation in aqueuse medium, no? Or do you mean in a aprotic
solvent?
I think dithionite is no where as nucleophilic as the sulfite anion as to add to the double bond like Nicodem said. Your problem might be comming from
somewhere else.. did you make the quinone yourself?
un0me2 - 16-7-2010 at 22:38
Use dithionite - it is available in sachets at my local supermarket (nb it is used in dyeing - it removes excess dye from cloth, think about that
& you'll work out where to find it).
There is a nice Patent that describes the manufacture of sodium dithionite (aka sodium hydrosulfite) from aluminium metal (activated by a little HCl) into which
SO2 is passed. The aluminium dithionite/hydrosulfite is converted to the sodium salt by the addition of NaOH to
precipitate the aluminium hydroxide.
Shits all over using Zn, Al is a whole lot easier to find.