JJay
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Rooto Brand Drain Cleaner Is an Overrated Source of Sulfuric Acid
Many have probably seen Robert Bruce Thompson's YouTube video series where he tests Rooto brand drain cleaner and proclaims that it is suitable for
all uses but "critical quantitative work." If you haven't seen the series, you can watch it here: https://www.youtube.com/watch?v=-bweWvb0wws&t=14s
After several reactions that failed, had low yields, or had unexpected impurities, I started distilling my Rooto drain cleaner, and I have come to the
conclusion that Robert Bruce Thompson either had an unusually pure bottle of Rooto drain cleaner or was mistaken in this conclusion. I also question
the accuracy of his titration, which was carried out using substandard equipment despite the prominent display of a volumetric burette.
When Rooto brand drain cleaner is distilled to about 1/3 of its volume, it first darkens and then turns yellow, and a white precipitate forms:
This precipitate seems to dissolve slightly in concentrated sulfuric acid under strong heating and turns it yellow. Upon cooling, it precipitates out
and the yellow color disappears. I'm not really sure what it is, but I definitely don't want it in my sulfuric acid.
I question whether Rooto brand is really better than Liquid Fire and other drain cleaners that are cheaper and easier to find on shelves. It is
certainly not reagent grade and is likely considerably less pure than many technical grade sulfuric acid products. I advise against using it without
purification unless you are willing to tolerate relatively large amounts of impurities.
[Edited on 26-7-2017 by JJay]
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unionised
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Do you think that products like this have tight quality control systems that ensure that the product purity (or impurity) is consistent?
It's very likely that either he was lucky and got a bottle from a "good" batch or that you were unlucky and got a crappy one.
The only real conclusion here is
"You need to check".
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JJay
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I see little reason to believe that *any* bottle of Rooto brand sulfuric acid would not contain pickling agents to prevent it from dissolving iron
pipes.
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unionised
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Interesting.
What might those agents be?
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JJay
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There are a lot of them... one common one is Rhodamine B, but dihydroxybut-2-yne is used too. I remember seeing on a question/answer section of a
product page that it contained a piperazine based inhibitor, but the source was of dubious authority (though perhaps accurate). Most inhibitors would
be destroyed at the temperature of boiling sulfuric acid.
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j_sum1
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Sheesh JJay! That video is ages old. You don't suppose that there have been any changes in the product in the past few years?
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XeonTheMGPony
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well I got much the same resualts when distilling some clear crystals and some times white, I add in 200Ml of 35% peroxide to help things along to
burn off any organics.
So far seems to help with things, some times less peroxide I go by eye with the additions at 25ml an addition
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Magpie
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Thank you JJ for this valuable information. I often use Rooto for routine experiments but have not always got the expected yields or quality. I will
use a better grade from Duda Diesel from now on.
The single most important condition for a successful synthesis is good mixing - Nicodem
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unionised
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Quote: Originally posted by JJay  | | There are a lot of them... one common one is Rhodamine B, but dihydroxybut-2-yne is used too. I remember seeing on a question/answer section of a
product page that it contained a piperazine based inhibitor, but the source was of dubious authority (though perhaps accurate). Most inhibitors would
be destroyed at the temperature of boiling sulfuric acid. |
I may be wrong, but I think dihydroxybut-2-yne would be destroyed by concentrated sulphuric at the temperature of boiling acetaldehyde or ethylamine.
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JJay
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I don't know for sure what the inhibitor is. I would expect the concentration to vary somewhat but the additives/impurities wouldn't ordinarily be
changed without a label change.
I actually do expect that Rooto has some level of quality control in place.
A lot of hobbyists use Rooto drain cleaner as sulfuric acid with an expectation of purity. If you search the board, you can find several examples of
this.
[Edited on 26-7-2017 by JJay]
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G-Coupled
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I bought some Sulphuric Acid that is labelled as '96% w/w H2SO4' and sold as 'Drain Cleaner' and when it came, I saw that it had quite a deep
brown/green colouration to it - I phoned the company that sold it, and was told that they'd bought 2000L(!) of SA cheap which had been sitting in a
tank for years, and the owners wanted to dispose of it, do this company purchased it and is selling it as a drain cleaner. The manager couldn't tell
me what the colourant(s) could be - he thought it might have been something to do with it having been stored in tanks for so long.
I looked up how other people attempt to purify their H2SO4 and ended up adding a small amount of H2O2 to it and heating it until it fumed, and I now
have a smaller bottle of crystal-clear looking acid. I haven't titrated it to try and measure its purity, but it weighs what around 96% H2SO4 should.
I think that the colourants were additives to slow down metal erosion, but that's just my guess.
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Sulaiman
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| Quote: Originally posted by JJay | I would expect the concentration to vary somewhat but the additives/impurities wouldn't ordinarily be changed without a label change.
I actually do expect that Rooto has some level of quality control in place.
A lot of hobbyists use Rooto drain cleaner as sulfuric acid with an expectation of purity. |
I doubt that amateur chemists are a part of Rooto's marketing strategy 
I rather imagine that they would prefer a competitors product to be our choice, just in case of any negative P.R.
CAUTION : Hobby Chemist, not Professional or even Amateur
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ninhydric1
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Just wondering, which purification method do you guys prefer: the H2O2 method or the distillation method?
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XeonTheMGPony
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I use both, I add 35% peroxide at 25ml a shot till it goes clear under heat, then distill it. May just be me but I feel like I get better results when
both used.
Less nastier looking sludge in the end when both used Vs just distilling.
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