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Author: Subject: Violuric acid salts (fantastic colors and variety)
Tsjerk
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[*] posted on 23-12-2020 at 01:50


I don't think this would give colored complexes if 1,3-diethylvioluric acid was formed. The 1 and 3 positions are important in the different resonance structures, which are causing the different colors.

https://sci-hub.do/https://doi.org/10.1016/j.ccr.2014.01.002

The formula you posted does indicate it is 5,5-diethyl barbituric acid. Chemically there is not very much interesting to do with it.

[Edited on 23-12-2020 by Tsjerk]
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artemov
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[*] posted on 23-12-2020 at 02:12


Quote: Originally posted by Lion850  
Artemov thanks for the feedback. It will be returned to the source, no use to me then.



Erm ... you might want to wait for verification from more knowledgeable members, cos I might be wrong:P
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RustyShackleford
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[*] posted on 23-12-2020 at 10:08


Much requested cobalt violurate turned out to be quite bad, just brown.
6-methyl-quinoline turned out quite nice, light pink-red and acetone solution of it is a deep orange.

qqq.png - 4MB
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Bedlasky
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[*] posted on 23-12-2020 at 22:29


I think that cobalt salt is Co(III) violurate.

6-methyl-quinoline violurate look really nice.




If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

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RustyShackleford
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[*] posted on 24-12-2020 at 02:22


Quote: Originally posted by Bedlasky  
I think that cobalt salt is Co(III) violurate.

6-methyl-quinoline violurate look really nice.

What makes you think its Co(III)? i used Co(II)CO3 to make it but it may well have oxidized i guess.
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Bedlasky
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[*] posted on 24-12-2020 at 03:07


Brown colour isn't typicall for Co(II) salts. If some cobalt salt is brown, it have usually some higer oxidation state.

Some cobalt complexes (especially wtih N donor ligands) have tendency to get oxidized by aaerial oxygen quite easily. For example [Co(NH3)6]2+ is slowly oxidized by oxygen to [Co(NH3)6]3+. Or Co(OH)2 is slowly converted by oxygen in to CoO(OH). [Co(CN)6)]4- is oxidized even by water to [Co(CN)6]3-.

[Edited on 24-12-2020 by Bedlasky]




If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

"An old friend once told me something that gave me great comfort. Something he had read. He said that Mozart, Beethoven and Chopin never died. They simply became music." Dr. Robert Ford, Westworld
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RustyShackleford
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[*] posted on 24-12-2020 at 03:57


Quote: Originally posted by Bedlasky  
Brown colour isn't typicall for Co(II) salts. If some cobalt salt is brown, it have usually some higer oxidation state.

Some cobalt complexes (especially wtih N donor ligands) have tendency to get oxidized by aaerial oxygen quite easily. For example [Co(NH3)6]2+ is slowly oxidized by oxygen to [Co(NH3)6]3+. Or Co(OH)2 is slowly converted by oxygen in to CoO(OH). [Co(CN)6)]4- is oxidized even by water to [Co(CN)6]3-.

[Edited on 24-12-2020 by Bedlasky]

Seems very possible, how would i go about preventing the oxidation? seems a bit difficult since i need to heat the cobalt with the acid in water and then evaporate it dry.
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DraconicAcid
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[*] posted on 24-12-2020 at 03:57


Quote: Originally posted by Bedlasky  
Brown colour isn't typicall for Co(II) salts. If some cobalt salt is brown, it have usually some higer oxidation state.

Some cobalt complexes (especially wtih N donor ligands) have tendency to get oxidized by aaerial oxygen quite easily. For example [Co(NH3)6]2+ is slowly oxidized by oxygen to [Co(NH3)6]3+. Or Co(OH)2 is slowly converted by oxygen in to CoO(OH). [Co(CN)6)]4- is oxidized even by water to [Co(CN)6]3-.

[Edited on 24-12-2020 by Bedlasky]


Yeah, but you need strongly-splitting ligands to do that, and there's only two violurates per cobalt centre. I have my doubts.

Isn't [Co(NH3)6]2+ a rather dingy brown-yellow?




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[*] posted on 24-12-2020 at 10:56


Some transition metals form true complexes, Co2+ doesn't seem to form a sparingly soluble salt like Zn and Mn but the solution slowly turns deep orange which, given that some oxidizing agents accelarate its formation, is likely to be a Co3+ compound. It is likely to be a triple ligand complex and since its formation seems to be insensetive to the other ions present and Co3+ tends to form 6-fold complex and I suspect violuric acid is a bidentate ligand. The complex is orange and very soluble.

Fe2+ complex is deep indigo blue and very soluble while the Cu2+ complex is olive green and less soluble. I have seen a paper comparing the complexes of Fe and Al with violuric acid, the latter forms a three fold octohedral colourless complex.
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h0lx
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[*] posted on 29-12-2020 at 08:49


Did some aminoguanidine violurate using the violuric acid RustyShackleford sent me.
UYeaRE2.jpg - 894kB
I reacted
136mg (1mmol) aminoguanidine bicarbonate
and
175mg (1mmol) Violuric acid
in some warm dH2O and it precipitated out.
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TheMrbunGee
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[*] posted on 30-12-2020 at 09:56


Hey, Do You have alloxan procedure, You mentioned? Colors look amazing, could try alloxan route, since I have sample with no use.



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Boffis
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[*] posted on 30-12-2020 at 13:39


Alloxan reacts with 1 molar equivalence of hydroxylamine to give violuric acid. In practice a hydroxylamine salt and sodium hydroxide are usually used.
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[*] posted on 5-1-2021 at 02:31


Quote: Originally posted by TheMrbunGee  
Hey, Do You have alloxan procedure, You mentioned? Colors look amazing, could try alloxan route, since I have sample with no use.

I would try the improved procedure by Guinchard from 1899:

violuric_from_alloxane.png - 34kB

Quote:
Violuric acid (or rather, pseudovioluric acid)
For the preparation of violuric acid I recommend the following, more convenient and higher yielding modification of the impractical method by Ceresole;
20 g alloxane (1 mol weight) and 10 g hydroxylamine hydrochloride (1.5 mol weight) [translators note: this is not a 1:1.5 molar ratio, it is more a 1:1.1 molar ratio] are dissolved in 150 g of water and heated for 1 hour on the water bath, after cooling one obtains 12.5 g of pure violuric acid directly in glittering, almost colorless crystals and another 2 g from carefully evaporating the mother liquor.



[Edited on 5-1-2021 by Diachrynic]




we apologize for the inconvenience
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TheMrbunGee
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[*] posted on 5-1-2021 at 14:29


Quote: Originally posted by Diachrynic  
Quote: Originally posted by TheMrbunGee  
Hey, Do You have alloxan procedure, You mentioned? Colors look amazing, could try alloxan route, since I have sample with no use.

I would try the improved procedure by Guinchard from 1899:



Quote:
Violuric acid (or rather, pseudovioluric acid)
For the preparation of violuric acid I recommend the following, more convenient and higher yielding modification of the impractical method by Ceresole;
20 g alloxane (1 mol weight) and 10 g hydroxylamine hydrochloride (1.5 mol weight) [translators note: this is not a 1:1.5 molar ratio, it is more a 1:1.1 molar ratio] are dissolved in 150 g of water and heated for 1 hour on the water bath, after cooling one obtains 12.5 g of pure violuric acid directly in glittering, almost colorless crystals and another 2 g from carefully evaporating the mother liquor.



[Edited on 5-1-2021 by Diachrynic]



This looks more like a procedure, thanks, I will try it when I find a moment.




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RustyShackleford
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[*] posted on 9-1-2021 at 08:24


Today i have produced some more salts of violuric acid thanks to SM user Tsjerk.
The ceasium salt, like the potassium, forms a blue hydrate, a slight bit darker than the potassium. On dehydration it turns to a nice teal, while the potassium turns purple.
The nickel salt is quite crummy, its a dirty light green, significantly worse than copper which in comparison was a wonderful moss green
IMG_20210109_171337.jpg - 1.3MB
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valeg96
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[*] posted on 23-1-2021 at 10:54


This is the Rb salt. It slowly hydrates on air and turns blue like the K salt.

IMG_20210123_195350.jpg - 429kB





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Tsjerk
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[*] posted on 23-1-2021 at 12:00


Nice! So now only lithium left for the alkali metals?
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RustyShackleford
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[*] posted on 23-1-2021 at 13:20


Very nice! thank you for making it! Could you post a picture of the hydrated form also?
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valeg96
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[*] posted on 31-1-2021 at 03:31


Here it is.

IMG_20210131_123007.jpg - 364kB





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h0lx
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[*] posted on 7-2-2021 at 15:23


Ethanolaminium Violurate

here it is compared to the aminoguanidinium one:



[Edited on 7-2-2021 by h0lx]
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Housane
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[*] posted on 8-2-2021 at 03:52


What amazing colours, I want to try and make sum but I can't find any sodium nitrite over here as it is a restricted chemical, could it be substuted for any easier to obtain chemicals here in the UK?



Green QD's so far

Feel free to correct grammar or incorect knknowledge. We are all learning.
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[*] posted on 8-2-2021 at 11:28


Where did you buy this acid? Its salt's have very nice colours.



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RustyShackleford
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[*] posted on 8-2-2021 at 13:32


Quote: Originally posted by Housane  
What amazing colours, I want to try and make sum but I can't find any sodium nitrite over here as it is a restricted chemical, could it be substuted for any easier to obtain chemicals here in the UK?


Im afraid atleast from barbituric acid you will need nitrite, if you want another route you can go from diethylmalonate via sodium metal and hydroxylamine.

Quote: Originally posted by vano  
Where did you buy this acid? Its salt's have very nice colours.


I made it myself and have sent out a couple grams to several users on this forum. If you have an interesting new idea and are willing to pay a few bucks in shipping ill send you some too.
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[*] posted on 8-2-2021 at 14:24


I gladly tried the following metals. Scandium, cadmium, mercury 1 and 2, Gallium, indium, copper 1, samarium, silver, beryllium and others. Probably all is possible. Is it possible to send a parcel from your country to my country?



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RustyShackleford
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[*] posted on 8-2-2021 at 14:57


Quote: Originally posted by vano  
I gladly tried the following metals. Scandium, cadmium, mercury 1 and 2, Gallium, indium, copper 1, samarium, silver, beryllium and others. Probably all is possible. Is it possible to send a parcel from your country to my country?


Ill gladly send you some, i sent a PM
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