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Nicodem
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Yes indeed. 
I'm not going to claim any color for p-benzoquinone since it is a "cameleon" compound, however the p-benzoquinone*hydroquinone complex has a defined
color, some kind of metalic dark blue. I remember a thread from another forum where there was a huge discussion on p-benzoquinone color. All kind of
colors were proposed (including your yellow one) and at the end all gave up. If you got a yellow product it does not mean much since making it by a
different published method or from another batch of hydroquinone would give a different color. For example, in our lab we have some technical grade
p-benzoquinone which is brown or almost black and some p.a. quality that is some kind of a weird color in between dark yellow and dark green.
Madandcrazy or whatever nickname you now have, you should stop posting misinformation like that bullshit about "dipicric acid". I don't know why you
do these things, but please keep in mind that some members might actually believe in all your fantasy compounds and procedures, which is irresponsible
from your part.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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YT2095
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well since I`m reasonably new to Organic chem, I find it quite amazing that the different properties of what at face value in empirical formula looks
like 3 identical chemicals, Hydroquinone, resorscinol and pyrocatechol, are in fact so very different when it comes to the actual material itself. all
by althering the positions of the OH from 2 3 or 4.
I`ve trien the pyrocatechol in Iodine water, there was little in way of a reaction at first, but left to stand for a week, there is now a deep purple
(KMnO4 purple) stain on the inside of the tube where the liquid rests, the actual liquid itself is a purple/brown and no where near as deep in color
as the stain, there`s also a Very distinct smell to it also, not at all unpleasant but very hard to describe, it`s sweetish and mildly resembles
wintogreen(sp) ester?
it in no way behaved the same way as the hydroquinone did,
I certainly have much more learning to do, as this is a perfectly Fascinatinfg area of chem!
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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woelen
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| Quote: | Originally posted by chromium
Btw this was Nicodem who described properties of quinone incorrectly. |
Good that you pointed out that one. My apologies towards Mason_Grand_ANNdrews.
As far as the color of p-benzoquinine is concerned, I have understood that it really is yellow, but all kinds of brown/green tinges can appear, due to
impurities. The material is very prone to oxidation or decomposition and then it forms all kinds of highly colored compounds. It is a little like
aniline, or p-aminophenol, which are colorless, resp. white, when very pure, but in practice these are brown due to all kinds of oxidized species,
which are formed on contact with air.
@YT2095: Yes, the three dihydroxybenzenes are quite different, but resorcinol, the meta-form, is much more different than the other two. The other two
can be oxidized very easily, due to their ability to form quinone-structures, while this is not possible with resorcinol. The latter compound hence is
much more stable on storage and also in solution.
If you want really weird things, then try reacting the catechol with chromium compounds in alkaline medium (e.g. chrome alum). You'll get really
beautiful colors, ranging from deep red, to bright oranges, but also blacks. Try the same with iron and copper salts. These compounds form MANY highly
colored complexes with most transition metals. I have tried almost all combinations of Cu(2+), Fe(3+), VO(2+), Ni(2+), Cr(3+) and Co(2+) with
hydroquinine and catechol in neutral and in alkaline solutions. Try it and be amazed by all these beautiful colors you obtain!
The chemistry behind all these things is amazingly complex. It is a combination of complex formation, redox reaction, and condensation of smaller
molecules/ions to larger ones. Unfortunately, most of these are riddles to me, but the experimental outcomes are quite nice.
Most beautiful though is mixing a neutral solution of hydroquinone with a slightly acidified solution of ferric chloride or ferric sulfate and then
adding a small amount of H2O2 and letting it stand. A 3D network of very thin metallic looking glittering wires and needles will be formed, which
really looks amazing.
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YT2095
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| Quote: | Originally posted by woelen
mixing a neutral solution of hydroquinone with a slightly acidified solution of ferric chloride or ferric sulfate and then adding a small amount of
H2O2 and letting it stand. A 3D network of very thin metallic looking glittering wires and needles will be formed, which really looks amazing.
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I just tried that, it went Brown/black almost instantly and got very Hot!? 
FeSO4 disolved in water then a droplet of sulphuric acid added.
then in another tube the HQ dissolved in water.
I mixed the 2 and there was no reaction, I then added a few drops of H2O2 and then it changed.
but I`ll let it stand a while and see what happens next.
my test tube rack holds 100 test tubes, so I still have plenty of room left to do other things whilst I wait
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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Marvin
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"but also blacks"
Is black really a colour, or is it just too much of something else?
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YT2095
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I think In my case with that last reaction it`s just Very bark brown with a hint of black, HQ seems such a delicate chemical and is very easily
destroyed in what seems like Carbonised burned sugar looking liquid crap 
well at least in My (possibly clumsy) hands it does *sigh*
the pyrocatechol seems alot more stable and will take quite a bit of punishment before it craps out.
nevermind, I`ll get the hang of it eventualy!
caramel anyone? 
[Edited on 19-7-2006 by YT2095]
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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Mason_Grand_ANNdrews
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Exuse me, you are right, some of my posts was not correct in the topic and i would give any comnents to the dipicric acid synthesis. I guess that will
attach importance
similar the bipheny synthesis when it will work. 3-methylphenol is nitrated to 3-methyl-2,4,6-trinitrophenol and than dissolved in methylene chloride
and methanol ratio 1/5, the solution is heated to 50-60 °C, a solution of 5% sodium hypochlorite and 2% NaOH is added to the mix and the dipicric
acid is obtained by vaporizing the CH2Cl2/methanol. I don`t know the result contains some remainders of sodium picrate wich have formed ? I guess the
way of 3-bromo-2,4,6-trinitrophenol to dipicric acid is more complex. Exuse me that this reply is staying in this topic, it will not meant worse.
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