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Tsjerk
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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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Erm ... you might want to wait for verification from more knowledgeable members, cos I might be wrong
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RustyShackleford
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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.
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Bedlasky
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I think that cobalt salt is Co(III) violurate.
6-methyl-quinoline violurate look really nice.
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RustyShackleford
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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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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]
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RustyShackleford
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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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| 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?
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Boffis
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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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Did some aminoguanidine violurate using the violuric acid RustyShackleford sent me.
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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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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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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Diachrynic
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| 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.
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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]
we apologize for the inconvenience
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TheMrbunGee
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| 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.
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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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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
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valeg96
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This is the Rb salt. It slowly hydrates on air and turns blue like the K salt.
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Tsjerk
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Nice! So now only lithium left for the alkali metals?
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RustyShackleford
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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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Here it is.
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h0lx
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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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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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vano
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Where did you buy this acid? Its salt's have very nice colours.
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RustyShackleford
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| 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.
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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vano
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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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| 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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