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learningChem
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| Quote: | | Okay, boss. However don't expect to get much help with your attitude. |
God dammit. You don't get it sonny? None of the trolls here are or were interested in helping, to begin with.
They are interested in babbling their laughable moralistic nonsense.
| Quote: | | From the evidence here, my odds are that you're not all that interested in the science of this but are rather looking for one piece in some
get-rich-quick scheme |
ROFL
See, we have a 'scientist' who reads tea leaves...
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elementcollector1
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Quote: Originally posted by learningChem  | God dammit. You don't get it sonny? None of the trolls here are or were interested in helping, to begin with.
They are interested in babbling their laughable moralistic nonsense. |
So, you come onto our board, with no provocation, call a few of the respectable members here "trolls" (an ironic accusation, considering your
reputation for not being useful), and insult our procedures. Then, when called out for being one of the rudest k3wl's it has ever been my displeasure
to meet online, you call us trolls, and what's worse, you might just actually believe it.
I'm calling bullshit on this entire topic, due to OP rudeness, unhelpfulness, and unwillingness to work with the rest of the board.
Go find a board that agrees with you if you want to be agreed with.
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learningChem
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Like I told you EC, please stop spamming this thread.
You made it clear you have nothing to say regarding the oxidation of toluene. And you made it clearly you are just a biased troll playing fawkes
lapdog. You had your fun, now go troll somewhere else.
By the way, you piqued my interest with your dumb remark about fawkes post count, so I checked how many posts the learned, helpful fawkes made in the
benz. sticky thread? You know how many? Right. Ze ro. Interesting, ne?
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elementcollector1
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| Quote: Originally posted by learningChem | Like I told you EC, please stop spamming this thread.
You made it clear you have nothing to say regarding the oxidation of toluene. And you made it clearly you are just a biased troll playing fawkes
lapdog. You had your fun, now go troll somewhere else.
By the way, you piqued my interest with your dumb remark about fawkes post count, so I checked how many posts the learned, helpful fawkes made in the
benz. sticky thread? You know how many? Right. Ze ro. Interesting, ne? |
Alright, fine. You win, let's help you out a little. Even though I have the significant urge to "troll" by telling you how things work both in social
life and on the internet, let's go with this:
On pages 2, 3, 6 and 19 of the toluene-> Benzaldehyde thread there are writeups far more comprehensive than yours, using a variety of OTC and
specialized reagents, any one of which we can help you synthesize. Examples are manganese ammonium alum, sodium carbonate, sulfuric acid, and many
others. For a better perspective, visit the pages mentioned above.
What exactly are you trying to achieve with your workup? Do you want a larger yield of benzaldehyde, less work time / reagents involved, what?
I don't like to come across as a troll. In fact, I make it my business to be generally honest and at least somewhat fair. But I consider most of the
folks on here acquaintances, if not outright friends - and Nicodem and watson.fawkes are certainly not exceptions to that rule. So, when you came on
here insulting them for criticizing you, naturally I wasn't happy about it. Sorry if things got a little rude, I just don't like to see a bunch of
posts saying "You're a troll! No U!" and not contributing to the thread.
You're entirely right, by the way. I don't know anything about benzaldehyde, from preparations to uses. I'm more of an inorganic guy, and the MnO2
caught my eye first. 
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learningChem
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EC,
Thanks for your message. I take back the name-calling.
I tried the electrolitical methods to prepare both manganese persulfate (divided cell), and manganese amonium sulfate. But since I didn't measure how
much current was used, I wasn't sure about much oxidizer was created, and I wasn't sure about the rest of the stoichiometry either, etc.
Yes, there's more information on those oxidizers, but right now, I want to use MnO2.
| Quote: | | What exactly are you trying to achieve with your workup? Do you want a larger yield of benzaldehyde, less work time / reagents involved, what?
|
Well, the point of the work-up would be to isolate whatever benz. has been produced, I guess...? In this case I'm using 10g of toluene, so the max.
theoretical yield would be 0.8g benzaldehyde, if my math is correct...
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elementcollector1
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That would very likely be MnO2 hydrate, a brown 'mud' of sorts that's impossible to airdry completely.
Also, did you happen to see any pink manganese sulfate anywhere? That sulfuric acid should do its job quickly if MnO2 hydrate is present and not the
calcined, less reactive black powder. (Thought - reuse the MnO2 if you can, but just dry it, don't re-calcine it back to brown. It will be much more
reactive this way, but will contain some amount of water.)
EDIT: As to your theoretical yield, almost no procedure ever gets 100% theoretical yield. I usually see figures in the area of 10-20% if the synthesis
is difficult, and 50-80% if the synthesis is extremely well done.
If your goal is to isolate a reasonable quantity of benzaldehyde, I would suggest that you first calculate your % yield (actual/theoretical x 100%)
and then scale that up to the amount you'd like to obtain (as a calculated actual yield, not the theoretical).
[Edited on 15-2-2013 by elementcollector1]
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learningChem
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| Quote: | | Also, did you happen to see any pink manganese sulfate anywhere? |
After the reaction is done, all of the MnO2 is 'gone', and what's left is a light yellow precipitate. I'm guessing that is MnSO4. Also, part of the
MnSO4 must be dissolved in the water/acid layer.
The yellow color comes at least partially from some kind of condensation product(s) from the organic layer.
I've seen (light) pink manganese sulfate in my bottle of manganese sulfate monohydrate (store bought) =P - That's what I'm using as starting point
for the MnO2.
| Quote: | | If your goal is to isolate a reasonable quantity of benzaldehyde, I would suggest that you first calculate your % yield (actual/theoretical x 100%)
and then scale that up to the amount you'd like to obtain (as a calculated actual yield, not the theoretical |
.
Yes, but I still need to carry the reaction with a minimun of efficiency, which is something I apparently haven't managed to.
Also, I realize that the actual yield is going to be even smaller since the MnO2 is creating side products like benzoic acid, and whatever stuff is
coloring the reaction yellow.
But it's also true that the reaction uses a rather large excess of toluene, so if yield is calculated based on toluene, it's pretty low to start with
- and so perhaps it should be 'easy' to achieve' (though it doesn't seem to be...)
Anyway, all of the MnO2 is reacting in my tests, but it doesn't seem as if much benzaldehyde is being produced. I'm wondering now if it's possible for
most of the MnO2 to be reacting with the H2SO4 'directly', without affecting the toluene?
Also, I took a look again at this thread
https://sciencemadness.org/talk/viewthread.php?tid=6882
and I can't help but notice that Hilski never said what his yields were. He said he was 'hopping' for ~80% but didn't provide any hard data...
[Edited on 15-2-2013 by learningChem]
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elementcollector1
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The MnSO4 could be in the yellow precipitate, but the pure stuff is, as you said, pink - and some of it may as well be trapped in the water layer.
I think the MnO2 is reacting with the H2SO4, and is possibly used up before the toluene has a good chance to react.
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learningChem
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Actually, I have 'recycled' the yellow precipitate by dissolving it in water, and then adding Na2CO3 and precipitating a white non-water-soluble
substance that can't be anything but MnCO3.
-----
I've cleaned glass that was stained with MnO2 using concentraded H2SO4 (~90%) at room temperature. The MnO2 disappears and the acid turns pink in a
couple of minutes.
On the other hand, when I wanted to turn a couple of grams of MnO2 into MnSO4, I had to heat them in H2SO4 for hours - the acid was 90% and virtually
boiling.
I guess I need to run a test with only 3g MnO2, 23g H2SO4 65% and no toluene. Stir it for a couple of hours at 50C and see what happens.
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