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Mailinmypocket
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[*] posted on 3-7-2013 at 13:57
Vanillin purity


I recently purchased some vanillin powder:

http://www.ebay.ca/itm/130667995612

Having done some experiments with it I am having some doubts on its purity... Several experiments state that vanillin is to be dissolved in acetic acid (3.08g/11ml GAA), this material does not dissolve completely and rather leaves behind some clear crystals that refuse to go into solution even after 30 mins stirring. Upon adding a bit of water they slowly dissolve. The material has an extremely strong vanilla smell and has a bitter, vanilla-like taste. Has anyone else had experience with this seller and their vanillin and/or have some tests that could prove the existence of sugars or sweeteners alongside the vanillin itself, should it be adulterated with sweeteners? I asked the seller if it was pure vanillin even after explaining these experiences and they confirmed that yes, it is pure vanillin. I remain doubtful. Thanks for any help!

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bfesser
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[*] posted on 3-7-2013 at 14:56


Sounds like you should recrystallize it a few times. As for the solvent, I've read that water works. However, your unknown contaminant dissolved upon addition of water, so that's a poor choice. Perhaps start by testing solubility with a hot low polarity solvent, and gradually increase polarity as needed until you find one or a mixture that dissolves primarily the <a href="http://en.wikipedia.org/wiki/Vanillin" target="_blank">vanillin</a> <img src="../scipics/_wiki.png" />. Vanillin is slightly soluble in water; soluble in benzene and <a href="http://en.wikipedia.org/wiki/Petroleum_ether" target="_blank">ligroin</a> <img src="../scipics/_wiki.png" />; and very soluble in ethanol, diethyl ether, and acetone.<sup>1</sup>

Glacial acetic acid should not dissociate appreciably until some water is added (no water to protonate forming <a href="https://en.wikipedia.org/wiki/Hydronium">hydronium cations</a> <img src="../scipics/_wiki.png" />;). Perhaps your contaminant was insoluble until it reacted with the acid after addition of water?

<strong>CH<sub>3</sub>COOH + H<sub>2</sub>O <img src="../scipics/_equil.png" /> CH<sub>3</sub>COO<sup>-</sup>(aq) + H</sub>3</sub>O<sup>+</sup>(aq)</strong>
p<em>K</em><sub>a</sub> = 4.756 (at 25&deg;C)<sup>1</sup>

Personally, I don't really trust most eBay sellers who sell bulk chemicals repacked in plastic baggies. I generally only buy sealed jars of reagents from known manufacturers. I definitely wouldn't <em>taste</em> any reagents purchased from eBay. Who can say what they <a href="http://en.wikipedia.org/wiki/Cutting_agent" target="_blank">cut</a> <img src="../scipics/_wiki.png" /> them with to maximize profit. Considering cost, your contaminant could be something as ubiquitous as NaCl&mdash;which is why you may wish to experiment with cold water to 'wash' out most of it.

Is there any chance you could spread out a small spatula of your vanillin on a watch glass or suitable background and give us a high resolution macro photo of the crystals?

1. <a href="http://en.wikipedia.org/wiki/CRC_Handbook_of_Chemistry_and_Physics" target="_blank"><em>CRC Handbook of Chemistry and Physics,</em> 89th ed.</a> <img src="../scipics/_wiki.png" />

[Sorry the editing took so long, I haven't gotten used to navigating this newfangled 89th ed. of the <em>CRC Handbook</em>&mdash;it's too easy! And I accidentally closed the tab after completing all of the editing once. :(]

[Edited on 7/9/13 by bfesser]




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Mailinmypocket
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[*] posted on 3-7-2013 at 16:42


Thanks for the info- I am going to try some solubility and recrystallization experiments tomorrow to figure out what exactly is going on here. Ligroin and ethanol will be the first two solvents and I'll go from there. I really think that there are granules of sugar in this stuff... After shaking it around on a glass plate there is a clear difference and clear crystals that look like sand are obvious, I attached some pictures but the iPhones' photo abilities are limited... Tasting is not the best idea of course but, what does pure vanillin taste like? I'm assuming it would have a strong scent but the flavor itself would not be sweet- right?

*edit* I have never had a bad experience buying from eBay for the most part... If this is some sugar/sweetener adulterated crap I won't be happy. Especially since I already left good feedback. Hopefully I can at the very least recrystallize something out of this, should worse come to worst*

Sellers response to inquiry:

"Dear mailinmypocket,

I see.We buy from our big supplier and that is what they said that its a pure vanillin.We are olny trading this product and never experience wit it.If you not happy with a product we of course can agree for a return."
image.jpg - 104kB image.jpg - 160kB

[Edited on 4-7-2013 by Mailinmypocket]
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bfesser
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[*] posted on 3-7-2013 at 17:05


Holy ████! That's definitely been adulterated with something. Salt is cheaper than sugar, so that was my guess, but either would look similar in these pictures. Use a magnifying glass. If it's <a href="http://en.wikipedia.org/wiki/Monoclinic_crystal_system" target="_blank">monoclinic</a> <img src="../scipics/_wiki.png" />(slanty), I'd guess sucrose. If it's <a href="http://en.wikipedia.org/wiki/Cubic_crystal_system" target="_blank">cubic</a> <img src="../scipics/_wiki.png" /> (right-angles), I'd guess sodium chloride. I'm still new to crystallography, so I could be utterly wrong. Becuase of the apparently irregular grain size of the contaminant, and the typical uses for vanillin, my money's now on sucrose. If either, try a wash with ice cold water before resorting to any other solvents.

[edit]
Let's hope they didn't fill your bag with bulk <a href="http://beprepared.com/imitation-vanilla-powder-2-5-can.html" target="_blank">imitation vanilla powder</a> <img src="../scipics/_ext.png" />:
Quote:
<strong>Ingredients:</strong> Maltodextrin, Sugar, Cornstarch, Natural and Artificial Vanilla Flavor, Dextrose, Tricalcium Phosphate.
I'm browsing through the <a href="http://www.ebay.ca/sch/minerals-water.ltd/m.html" target="_blank">items</a> <img src="../scipics/_ext.png" /> of the seller you purchased from. Not a bad selection.

[Edited on 7/9/13 by bfesser]




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[*] posted on 4-7-2013 at 03:28


I agree on the pics that that is not vanillin, vanillin has needle-like crystals when pure, and always small ones (as in thin), and the pure compound has a fluffy appearance due to the thin relatively long crystals.

The taste is very weak of vanilla, with a slight burning taste in the throat afterwards. No notable "tones" at all. I just tasted it from pharmaceutical grade stuff, though like 50 years old.




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Justin Blaise
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[*] posted on 4-7-2013 at 10:23


Perhaps you could crush up some of your original sample so that everything is a homogenous powder, then take a melting point. You can test how effective your recrystallization solvent is by comparing the melting point to that of the original sample.
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watson.fawkes
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[*] posted on 4-7-2013 at 10:35


Quote: Originally posted by Mailinmypocket  
We buy from our big supplier and that is what they said that its a pure vanillin.
You're in a position to insist on having them send you the name of the manufacturer, their trade name for it, and perhaps a snapshot of the label on the original container.
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Mailinmypocket
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[*] posted on 4-7-2013 at 11:02


I have requested that information from them for "health reasons" since it quite obviously is not pure vanillin, thanks for suggesting that. We will see what the response is. As far as the purity is concerned I am holding off on re-crystallizing and doing MP's etc since if this happens to be a mashup of 5+ components it isn't worth the trouble or waste of solvents/time. Too bad though- I was happy to have some vanillin... Once (or if...) I get a reply from the seller I will see if purifying is worth the time and effort...
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[*] posted on 4-7-2013 at 12:14


I bought some vanillin from this supplier last year and it was fine and many other chemicals too with no problem. It may just be an isolated incident.
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[*] posted on 4-7-2013 at 12:20


Quote: Originally posted by Scr0t  
I bought some vanillin from this supplier last year and it was fine and many other chemicals too with no problem. It may just be an isolated incident.


Did your vanillin have the same appearance? I've always trusted this seller but it seems like they may have dropped the ball on this stuff.
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[*] posted on 4-7-2013 at 12:20


Quote: Originally posted by Mailinmypocket  
I have requested that information from them for "health reasons" since it quite obviously is not pure vanillin, thanks for suggesting that.
You're welcome.

You know, regardless of how they sourced it, and whether they are corrupt or not, if the product isn't as labelled, they are the ones that are on the hook for shipping the wrong product. They probably don't want an incident report with eBay, so you have some power in this regard.
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[*] posted on 4-7-2013 at 12:33


Quote:
Did your vanillin have the same appearance? I've always trusted this seller but it seems like they may have dropped the ball on this stuff.

No, the stuff I had did not look like your picture. It looked like some the other vanillin from another source that I still had lying around.
I don't think this seller is corrupt, maybe their supplier has ripped them off this time, but they're still responsible as watson said.
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[*] posted on 4-7-2013 at 14:16


Well, after asking for a list of ingredients, manufacturer or label, the response was :

"Well.It is a food grade classified so certainly yes it will be great for use in kitchen.
- minerals-water.ltd"

Time to just cut the losses I think.
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[*] posted on 4-7-2013 at 14:40


Yes I thought you might get response like that, unless they test it they wont know if their supplier is being accurate.

Mislabeled things can really matter especially if they are labelled as "food grade", if they can't maintain sufficient quality control to identify the substance(s) they are selling then there is no guarantee that it's actually food grade.

There was another eBay supplier known as "mistral-ie" that a year or two ago mistakenly sold some NaNO2 marked as Sorbitol and some Italian woman died from consuming it.

As a result they withdrew selling things on eBay and they immediately removed the "food grade" claim from all their products.
They still have the websites but it's now downgraded where they have sold off most of their more interesting hobby Chems. in a clearance sale and are now focusing more on cleaning Chems.
Shame really.
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[*] posted on 4-7-2013 at 15:14


I buy food grade hdrogen peroxide from APC Pure.
I do a few basic tests on each batch as it comes in.
I use it as tank wash, it goes in to the tanks as a final sterilising non chlorine wash and it is rinsed out with sterile water.
All my chemicals and adjuncts come from large reputable suppliers eg Brupaks.
Ingredients are sourced from major suppliers with an excellent track record.
The malt comes from Warminster, the hops from Charles Faram, the yeast from Fermentis.
Exhaustive in house analysis is impossible on a craft scale.
I think I have done what I reasonably can.
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[*] posted on 4-7-2013 at 15:35


I bought 1kg of sodium percarbonate from minerals-water aka pure-domestic-chemistry some time ago.
It was a white powder that assayed volumetrically for 27.5% hydrogen peroxide.
I did not use it for anything and sold it to friend to use in her loo.
She hates chlorine based bleach and thought it was excellent at getting rid of toilet pongs.
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[*] posted on 5-7-2013 at 05:15


Quote: Originally posted by Mailinmypocket  
Time to just cut the losses I think.
File an eBay complaint as well for misrepresentation. These people, at best, are being irresponsible with their labeling.
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[*] posted on 5-7-2013 at 06:26


Quote: Originally posted by watson.fawkes  
Quote: Originally posted by Mailinmypocket  
Time to just cut the losses I think.
File an eBay complaint as well for misrepresentation. These people, at best, are being irresponsible with their labeling.


Since I never got a response in regards to giving me at the very least, the ingredients, I will be doing that. I ran a very crude test just now to see if I could recrystallize anything from it. About 5 heaping teaspoonfuls of this "vanillin" was added to 50ml of methanol, a turbid mixture resulted that had a yellow tint to it. This was decanted from the massive amount of what is obviously sugar and placed into a dish to evaporate. I'm not too impressed with the look of this shitty filtrate though, you can see in the image what it looks like. Also, note the amount of sugar left in the flask.


image.jpg - 70kB image.jpg - 71kB

[Edited on 5-7-2013 by Mailinmypocket]
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[*] posted on 5-7-2013 at 08:32


I purchased vanillin from the same supplier a few months ago, and it too was shipped in the same packaging as the OPs. Here are some shots of what I got;

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It has always worked properly in experiments, and readily dissolves in room-temperature ethanol to give a clear, colourless solution. It also dissolves readily in NaOH solution, to give a clear, yellow, solution.

I have also taken its melting point, and it melted at 81-82oC, which is very sharp and perfectly matches the literature values.


[Edited on 5-7-2013 by Hexavalent]




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[*] posted on 5-7-2013 at 09:11


Quote: Originally posted by Hexavalent  
I purchased vanillin from the same supplier a few months ago, and it too was shipped in the same packaging as the OPs. Here are some shots of what I got;




It has always worked properly in experiments, and readily dissolves in room-temperature ethanol to give a clear, colourless solution. It also dissolves readily in NaOH solution, to give a clear, yellow, solution.

I have also taken its melting point, and it melted at 81-82oC, which is very sharp and perfectly matches the literature values.


[Edited on 5-7-2013 by Hexavalent]


Thanks for that, it's obvious at this point that I was screwed ( not intentionally) by this seller. What a pity that I left good feedback before doing experiments with it. This stuff makes a yellow solution in alcohol, does not dissolve completely and the yellow portion is cloudy. I didn't even bother to take a MP with this dumb stuff.... I'm currently trying to figure out how to resolve this with the seller. They offered to have me send it back and then determine a refund amount but for the amount I paid, it seems rather ridiculous to go through all that trouble. I really didn't feel like buying it through my usual supplier since it is very expensive (buying through work = Aldrich pricing...100g is about 60$)
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[*] posted on 24-7-2013 at 09:16


Well, after threatening to open a dispute with eBay as they were not providing me with the composition of the said "vanillin" they refunded the purchase and let me keep it. I threw it away... Not going to start using it for cooking if I don't even know what's in it! Finally managed to get my hands on some proper vanillin, tested by MP, from an eBay seller called Triangle Chemical.


image.jpg - 101kB
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[*] posted on 24-7-2013 at 15:07


I am glad you straightened that out with the seller in a way. At least now he will recognize that the last shipment "vanillin" wont pass with all his costumers, and it has cost him a bit of money already, so I am sure they will be more thorough in the future about quality and proper labeling.

Glad you got what you where after too. I know it is a bummer to order something, wait and wait excitedly for it, only to have it be a disappointment. I have ordered on different occasions, and from different suppliers 2 30cm Graham condensers, and both times the inner coil was cracked or broken off, rendering it useless. I got a replacement in one instance, and a refund in the other. Both after sending pictures and jumping through hoops. Grrr.

[Edited on 24-7-2013 by Bot0nist]




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[*] posted on 30-4-2014 at 12:51


I also ordered vanillin from this seller, which was probably the same shit as Mailinmypocket got.
An m.p above 200C, and sugar looking crystals mixed with a tiny amount of actuall vanillin.

I will not order from this seller again!
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[*] posted on 30-4-2014 at 13:30


That was one of my biggest piss offs as far as chemical orders have ever went. Call it "vanilla sugar... Vanilla flavoring..." Don't say vanillin.. Sheesh.

Triangle chemical on eBay sold me some excellent vanillin though (see above)
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[*] posted on 30-4-2014 at 13:45


I agree, and apparently they now know that it isnt pure vanillin and they still havent changed the description. I will definately leave a negative feedback.

Thanks for the tip, i couldnt find the ebay store though, could you send a link? :)
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