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Vargouille
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I believe that it is due to the release of gases trapped in the filtrate. The movement of the liquid is part of what releases the trapped gases, akin
to how shaking a soda bottle results in foaming. While mentioning soda, recall that putting mentos in soda releases the gases because they provide
nucleation sites. The filter paper or frit on your funnel will do the same thing, to a greater or lesser extent, and the application of vacuum aids
the movement of the gases out of the filtrate. These gases carry some of the liquid along for a short while, making the foam.
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Hexavalent
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Why foam, though, as opposed to simply bubbling out?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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learningChem
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I tried the canizzaro reaction on ~23 grams of formalin (allegedly 40%) - I distilled ~3.6g methanol out of it and got a sludge of crystals which I'm
not yet sure how to work up. I guess it can be done but yields are not going to be too good...
I'm not sure if I can buy formic acid here - I thought the local nazis had banned it for peasants like me, but now I'm not sure - I'll have to check
again.
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Vargouille
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The lack of formation of large bubbles is likely jointly caused by a low amount of atmospheric gases trapped in common filtrates (as opposed to
carbonated beverages) and the relatively rapidity of nucleation. The speed of most filtrations means that smaller bubbles don't have the time to
coalesce into larger ones.
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Bronstein
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Does anyone know where to find the melting point for 2,4-dimethoxyphenethylamine hydrochloride? I can't seem to find it anywhere. I have looked in the
printed version of Beilstein, Combined chemical dictionary and The shulgin index, and searched google. I have found some articles where they make
2,4-dimethoxyphenethylamine, but none of them isolate it as the hydrochloride.
The only thing I can seem to find is the melting point of the picrate, the hydrogenoxalate and the boiling point for the freebase.
[Edited on 8-1-2013 by Bronstein]
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Nicodem
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Beilstein gives these two references for the mp of the hydrochloride:
mp 149-150 °C, Bailey et al., Journal - Association of Official Analytical Chemists 1974, 57, 70.
mp 159 °C, Kappe, Armstrong, Journal of Medicinal Chemistry 1965, 8, 368-372.
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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)
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learningChem
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How does MnO2 oxidize toluene to benzaldehyde? Do the O atoms from the Mn oxide go to the toluene or is the oxide a catalyst of sorts?
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Simbani
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New Question:
Is it possible to ball-mill silicon powder (starting with, say 100mµ)? I mean this stuff is quite hard (6,5 vs. 2,75 for Al) and I have no clue on
the grindability in a (steel vessel) ballmill.
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Hexavalent
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Quote: Originally posted by learningChem  | | How does MnO2 oxidize toluene to benzaldehyde? Do the O atoms from the Mn oxide go to the toluene or is the oxide a catalyst of sorts?
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The oxidation of toluene is usually done using KMnO4, which could produce benzaldehyde in theory, but would be exceptionally difficult to
control: for this reason, this concept usually produces benzoic acid and manganese dioxide.
Perhaps this is what you mean?
[Edited on 10-1-2013 by Hexavalent]
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learningChem
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Hexavalent,
Toluene can be converted into benzaldehyde using MnO2. See for instance
http://www.google.com/patents/US613460
Reaction of toluene and MnO2 in ~60% sulphuric acid --> benzaldehyde. My question is : where does the O come from - what happens to the MnO2?
-------
I'll put this in the benzaldehyde sticky thread too...
[Edited on 10-1-2013 by learningChem]
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barley81
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MnO2 (Mn IV) + 4H+ + 2e- ---> Mn2+ + 2H2O
Manganese dioxide is converted into manganese II sulfate.
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learningChem
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Ahh - thanks barley81
What about the 'common' equation? Something like this?
MnO2 + H2SO4 + Ph-CH3 --> MnSO4 + Ph-CHO + H2O + H2
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Vargouille
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Oh, here I was thinking you were looking for the reaction mechanism.
The balanced ionic equation, unless I've made an egregious error, is:
2MnO2 + 4H+ + PhCH3 -> PhCHO + 2Mn+2 + 3H2O
[Edited on 11-1-2013 by Vargouille]
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learningChem
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2MnO2 + 2H2SO4 + PhCH3 --> PhCHO + 2MnSO4 + 3H2O
?
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Vargouille
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Yup. Only difference is that the sulfate is ignored because it doesn't take part in the reaction.
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bahamuth
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Was wondering if anyone here know where or how I might be able to do a "bulk" search of CAS numbers?
I have a long list of CAS numbers that I need the names for, and I would like to just feed them into a database search and get a text file out or
similar.
I know ChemACX can do it but haven't been able to access their site today..
Any sufficiently advanced technology is indistinguishable from magic.
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mr.crow
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| Quote: Originally posted by bahamuth | Was wondering if anyone here know where or how I might be able to do a "bulk" search of CAS numbers?
I have a long list of CAS numbers that I need the names for, and I would like to just feed them into a database search and get a text file out or
similar.
I know ChemACX can do it but haven't been able to access their site today.. |
Is this for that ebay auction? I just cut-n-pasted them all from a spreadsheet into the sigma aldrich website! Its quite picked over already 
Double, double toil and trouble; Fire burn, and caldron bubble
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bahamuth
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| Quote: Originally posted by mr.crow | | Quote: Originally posted by bahamuth | Was wondering if anyone here know where or how I might be able to do a "bulk" search of CAS numbers?
I have a long list of CAS numbers that I need the names for, and I would like to just feed them into a database search and get a text file out or
similar.
I know ChemACX can do it but haven't been able to access their site today.. |
Is this for that ebay auction? I just cut-n-pasted them all from a spreadsheet into the sigma aldrich website! Its quite picked over already |
Got me there. But I am looking for unusual stuff, molecular biology stuff in unopened containers. Mostly buffer reagents and the like.
Saw that auction a very long time ago but only recently got my hands on some money to procure some of the stuff I need.
Anyways, did a bulk search with a trial ChemACX and opened the resulting exported file in ChemBioFinder Ultra to browse both the names and the
structures.
Btw, how did you manage to bulk interrogate all those CAS numbers at Sigma A, or did you input one and one.....?
Any sufficiently advanced technology is indistinguishable from magic.
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mr.crow
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Just Ctrl-C, Ctrl-V! I tired to write a scraper program in Python but it needs cookies or something to work.
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kingkey24
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How do I gain access to the reference section forum?
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ScienceSquirrel
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Send a U2U message to Polverone requesting access.
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Hexavalent
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Units for hygroscopy?
Is there a unit for measuring/quantifying the hygroscopy of a compound? Perhaps something like moles(water)/minute?
[Edited on 30-1-2013 by Hexavalent]
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Vargouille
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Apparently there is a source (Lang's Handbook of Chemistry) that states the hygroscopy of certain compounds in terms of grams water per gram of
material. There is also the concept of a "critical relative humidity", which describes the relative humidity below which a compound will not absorb
water from the air.
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Eddygp
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Should copper powder react with fluorescein?
there may be bugs in gfind
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Vargouille
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I can't imagine that it would, at least, not on a reasonable timeline. Copper isn't likely to even bat an eye at the ketone, ether, or alcohol
moieties, and the carboxyl group isn't likely to do much except in the presence of atmospheric oxygen. Even then, fluorescein's pKa is only 6.4, so
the reaction would be quite slow.
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