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Author: Subject: Benzoquinone (mono) oxime... ?
kmno4
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[*] posted on 15-8-2009 at 22:36
Benzoquinone (mono) oxime... ?


I am looking for informations about prepration of this compound
from benzoquinone and hydroxylamine [benzoquinone (mono) oxime is also known as 4-nitrosophenol]. Generally reaction takes place, brown-black suspension is obtained and black powder can be obtained from it. I do not like this colour (but this oxime is described elsewhere just as black powder), possibly this is adduct of oxime and its tautomer (nitroso form)... who knows. nevermind. So if anyone has any info about benzoquinone/hydroxylamine procedure, write here please.
Of course, if such a procedure really exists :P

ps. If it is needed/convenient - move this post to "The short questions thread".
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kmno4
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[*] posted on 23-8-2009 at 01:35


As I understand nobody has heard about this procedure.
In Annalen I have found another procedure for preparation this oxime by nitrosation of phenol.
Procedure is a little strange:
To 60g of PhOH (Phenol) in 1500 cm of H2O (Wasser), add 27g of NaOH (Aetznatron) and 54g of NaNO2 (Natriumnitrit), cool to 7-8 C and add 150g of H2SO4 (Schwefelsaure) in 400g of H2O .......
Does anybody see any sense in adding NaOH ?
Page with this procedure in attachment. It is in German - if somebody can translate it, please write translation here.
Maybe I mistake something ?
Thanks in advance.

Attachment: 7.pdf (53kB)
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kclo4
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[*] posted on 23-8-2009 at 01:45


perhaps it is to increase solubility of the phenol?



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Picric-A
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[*] posted on 23-8-2009 at 04:59


yes it is to make sodium phenolate which is highly water soluble, unlike phenol itself which is only 8.3g/100ml H2O @ 20deg.C
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DJF90
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[*] posted on 23-8-2009 at 05:17


I wouldnt jump to such strong conclusions - theres 1.5L of water in there, more than enough to solve the 60g of phenol added... But you are right about forming the phenoxide, which is needed/beneficial for the reaction. I'll draw a mechanism is necessary but should be simple enough to work out yourself.
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[*] posted on 23-8-2009 at 08:01


translated:

experimental part

methyl quinone oxime,

quinone oxime used for all preparations herein, was prepared as follows:

6O g phenole, 27 g NaOH and 54 g NaNO2 were dissolved in 1500 ccm of water and cooled to 7-8°C. To this, a solution 150 g H2SO4 in 400 mls of water was added. precipitated quinoneoxime was filtered after 2 h, washed with ice-water and cleaned by taking up in ether and treatment with animal charcoal in the cold. On evaporation of the etheral solution the quinoneoxime separates as yellowish needles, which, if dried qickly, can be stored without decomposition (yield 75-80%). To obtain Quinoneoxime, as well as its Chloro- and bromo-substituted products absolutely pure, they are best recrystallized from benzene or toluene. Quinoneoxime crystallizes in brownish needles from benzene. The needles do not darken under 124°C and will melt completely at 126°C.


Why do they title methylquinoneoxime and give its formula, when in the recipie there is made quinoneoxime?



[Edited on 23-8-2009 by behemoth]
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Formatik
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[*] posted on 23-8-2009 at 12:08
There's more to it than meets the eye


Quote: Originally posted by behemoth  
Why do they title methylquinoneoxime and give its formula, when in the recipie there is made quinoneoxime?


Because the paper continues onto the methyl quinone oxime part. Using that quinone oxime they prepare the silver salt and then use methyl iodide to get to the methyl quinone oxime.
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kmno4
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[*] posted on 23-8-2009 at 13:09


Thanks to behemoth for translation.
The cause of using NaOH is still not clear for me.....
Phenol is the weakest acid in this mixture and when you add H2SO4 you will get Na2SO4 and phenol from sodium phenolate solution. Phenolate anion should react first with H3O+, next reaction should be H2SO4 + NaNO2 -> HNO2.
I am going to make this with and without NaOH on 1/10 scale.
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Picric-A
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[*] posted on 23-8-2009 at 13:29


maybe adding te sodium ion the the alcohol group makes the phenolate group larger and so more para directing?
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DJF90
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[*] posted on 23-8-2009 at 13:39


There is no alcohol group. I know what you mean but you have to be careful with your terminology, others may not be so understanding. Like kmno4 says, the acid should react with the phenolate first, before forming any NO(+) so I am unsure as to its true purpose in the reaction. Perhaps it is to prevent the solution from being TOO acidic, hence facilitating the proton exchange needed for the tautomerisation?
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kmno4
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[*] posted on 24-8-2009 at 05:07


I have just made an experiment, without NaOH and in different proportions: 6g fenol/4,9g NaNO2/ 5g ~97% H2SO4/ ~150g H2O total, at ~0 C (ice bath), H2SO4 solution was adding during ~10 minutes on magnetic stirring. Generally no NOx giving off was observed.
Wet product is pale brown (looks like sparkling cacao powder), crystalline and weights ~8g. Some foto - later.

Dried product of reaction:


Amount: 4,4 g (56%).
Probably ~2 grams remain in 200 cm3 of filtrate/washing waters , but etheral extracts are strongly red colored, surely contaminated by some phenole matters.
Of course same oxime is not a goal in itself. It is a substrat for something else.
I do not like this 56% of impure oxime :mad:
As it is stated elsewhere, pure oxime is pale yellow.... :(



[Edited on 24-8-2009 by kmno4]
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[*] posted on 24-8-2009 at 09:08


Sounds like it may have worked. Product is brown as expected from the translation above, and once its dried you can take an accurate weight to work out the yield. But its looking good. Well done :)
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kmno4
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[*] posted on 27-8-2009 at 10:51


Run 2, with NaOH, 1/10 of amounts from cited article.
Yield: 66% and looks like oxime from previous run.
Seems that yield 75-80% is unreachable for me :mad:
Interesting thing: when acivated carbon is added to acetone solution of oxime, colour quickly turns from yellow-brown to clear green. On evaporation, brownish substance is collecting on walls of Petri dish.
Dioxane solution still remains yellowish when carbon is added.
On the picture - acetone solution , probably this is colour of mononitroso tautomer of the oxime.



[Edited on 27-8-2009 by kmno4]
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[*] posted on 30-8-2009 at 21:06


Acetone is not a good solvent to use with this compound as it can react to form benzoquinone and acetoneoxime.



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kmno4
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[*] posted on 1-9-2009 at 07:57


Quote: Originally posted by smuv  
Acetone is not a good solvent to use with this compound as it can react to form benzoquinone and acetoneoxime.

Yes, I thought about it, but benzoquinone in not formed even after 4 days in large excess of acetone. But after a few days also dioxane solution turn green.
I tried to reduce this oxime to 4-aminophenol by Na2S2O4 but I got something white, immediately turning black in the air, in acid it gave deeply violet colour :P
I hate phenols :mad:
Everything I make is black or strongly coloured, impossible to purify by crystallization...
F*ck
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[*] posted on 22-11-2013 at 17:05


I decided to repeat this nitrosation. After the lecture of several papers and few additional experiments, I came to few conclusions, the most important are:
phenol solution cannot be too concentrated
reaction mixture should be strongly acidic
nitrosation should be conducted at low temperatures
addition of phenol should be slow.

If these conditions are not fulfiled, the most possible product is brown tarry material. This "tar" is however soluble in water and possess phenolic character.
Complications rises from reactivity of phenol for coupling:

<img src="http://exchange.chemport.ru/index.php?mode=download&way=ind.PNG" alt="ind.PNG - 11kB" width="250px" border="0px" height="150px">

Nitrosation is a slow process, and when phenol accumulates in solution it is partialy converted to indophenol matters (and possibly also another compounds).

Experimental.

Solution_1: 5g of 95% H2SO4 in 50 g of water is placed in a flask and cooled, until some ice starts to collect.
Solution_2: 3g of phenol + 2,5g of NaNO2 in 50-60 g of water is chilled and placed in separatory funnel.

Flask with acid sol. is immersed in water-ice bath and placed on mag. stirrer.
To this, phenol solution is added, 1 drop per 5-10 seconds, total addition time 2-3 hours.
At the very begining nothing interesting happens. After some time, solution becomes yellow, next orange, and finally orange-red (similar to carrot). If the mixture becomes brown, mixture goes to WC (or similar place, hah). It indicates that phenol was added too quickly or temp. was too high.
When ~1/2 of phenol sol. is added, bright precipitate strat to collect in solution. It is the desired product, and if it is brown →WC.

When addition of phenol is finished (mixture must be still close to 273 k), the red mixture with solid deposit is fildered at once and collected solid washed with small (~10 g) of cold water in few portions. The solid is dried (~60°C) and weighted.
1,8g of nitrosophenol(or its oxime form) as a bright yellow-brown crystalline powder, stabe in air, is obtained, It is soluble in water, giving very intensive yellow colour. When base is added, solution becomes brown, when some acid is added intense yellow colour fades. It is soluble in toluene (but not very), and solution possess very weak yellow colour, even if larger amout of nitrosophenol is dissolved. Also its solubility in DCM is strongly limited.
Melting point is 138-139°C (two measurements), sharp but with decomposition (coal black powder after cooling).

To remaining red solution after filtration, ~20g of NaCl was added to precipitate more product.
Unfortunately, obtainded sediment was not so good looking as earlier one: darker and - if not washed with water - darkens in the air. Additional 0,5 g of (not very pure) nitrosophenol was obtained. Brown, but much less than in earlier (failed) experiments.
Washings are initially red, but in air they turn deeply red, brown and finally almost black.

On the picture, from left: main product (1,8g), second crop (0,5g) and a sample from earlier experiments (goes to WC after foto session)

<img src="http://exchange.chemport.ru/index.php?mode=download&way=set.JPG" alt="" width="280px" border="0px" height="150px">


Some literature for interested:

The chemistry of nitroso-compounds. Part II. The nitrosation of phenol and anisole
DOI: 10.1039/J29710000770
Nitrosation of phenols. Part I. 3-Chloro-4-nitrosophenol and its conversion into two isomeric chloroquinonemonoximes
DOI: 10.1039/CT9232302499
Nitrosation of Phenolic Compounds: Inhibition and Enhancement
DOI: 10.1021/jf981094n




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