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Nicodem
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The short questions thread (3)
The old thread has become too long so please continue here. Those who never received a proper reply in the old thread, please feel free to repost the
question.
| Quote: | This is a thread where you can post all those short questions you always wanted to ask but did not consider them worthy of a new thread. You can ask
amateur science related questions of all kind as long as you think they are simple enough to be answered by other forum members in a preferably single
post.
Consequently, self discipline in avoiding off topic replies is expected. |
…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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Nicodem
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Thread Topped
29-7-2010 at 23:49 |
Nicodem
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I guess this was one of the last unanswered questions in the last short questions thread. Having some experience with how cover designers think and
work, I would guess that being more or less clueless on the specific content of the book, he/she resorted to use stereotypes and therefore used a
stylised picture of Mount Sinai as a symbolism for spiritual revelation or cognitive illumination that the pop culture associates with the use of
psychedelics. It is just a guess, but when it comes to book covers you can be pretty sure they try to use stereotypes to have a major impact on the
potential book buyer.
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psychokinetic
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I was thinking similarly
Could also be a 'peak', as in 'peaking' and the obvious mountain 'peak'. (Along with a potential pronunciation of the book, 'peak-al').
“If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found
the object of his search.
I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.”
-Tesla
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Picric-A
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Does anybody know the best solvent for 4-Aminobenzoic acid?
I am looking to purify a load of PABA to get rid of the starch impurity so i want to dissolve as much 4-Aminobenzoic acid in as little solvent as
possible.
Thanks
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JohnWW
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It should be soluble in water, and in polar organic solvents such as acetone, diethyl ether, ethanol, isopropanol, tetrahydrofuran, dioxane, pyran,
etc.
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DJF90
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Where the hell did the starch come from?! Purification of Laboratory Chemicals says:
| Quote: |
p-Aminobenzoic acid [150-13-01] M 137.1, m.p. 187-188*C, pK1 2.45, pK2 4.85.
Purified by dissolving in 4-5% aqueous HCl at 50-60°C, decolorising with charcoal and carefully precipitating with 30% Na2CO3 to pH 3.5-4 in the
presence of ascorbic acid. It can be crystd from water, EtOH or EtOH/water
mixtures.
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Picric-A
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Quote: Originally posted by DJF90  | Where the hell did the starch come from?! Purification of Laboratory Chemicals says:
| Quote: |
p-Aminobenzoic acid [150-13-01] M 137.1, m.p. 187-188*C, pK1 2.45, pK2 4.85.
Purified by dissolving in 4-5% aqueous HCl at 50-60°C, decolorising with charcoal and carefully precipitating with 30% Na2CO3 to pH 3.5-4 in the
presence of ascorbic acid. It can be crystd from water, EtOH or EtOH/water
mixtures.
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As i said in my post.... i am purifying the 4-aminobenzoic acid from PABA vitamin supplements and so the starch is present as the filler i am
guessing. They were in caps so i meerly pulled the cap open and poured out the powder.
It is only very slightly soluble in water, 4.9g/kg so this is out. I think i will try EtOH or MeOH.
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solo
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Will the amine from alpha -trans-methylcinnamaldehyde produce stereoisomers of the l enantiomer or the d, or a recimic product of l-(+/-) , or
d-(+/-)....i"ve read from the links below , but still not clear to me......solo
http://en.wikipedia.org/wiki/Diastereomer
http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/ster...
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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turd
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Red/Yellow benzaldehyde?
Someone who is me tried to make 3,4,5-trimethoxybenzaldehyde from 5-bromo-vanillin. After Ullmann and methylation an oil was obtained which distilled
in a narrow range of 102-104°C - so far so good. But what was really strange: in the beginning of the distillation the distillate was a pale yellow
oil which then crystallized to a distinctly red solid. An absolutely weird sight, more so considering that usually it's the other way round: slightly
coloured oil giving colourless crystalls. Question: how comes?
My only explanation, although not very convincing, is that in the beginning of the distillation there was a small amount of polymeric stuff bumping
into the receiver. When crystallizing, the red impurity was concentrated on the outside of the crystals, making it much more visible than when mixed
with the liquid distillate.
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mewrox99
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NH4NO3 Odour?
Today was the first time using some AN I bought a month or so ago.
It claims to be Lab grade prills.
For some reason it seems to have a very slight unusual odor that one my friends was also able to notice.
Anyone have any clues what it could be (my guess is small amounts of NH3 or N2O)
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psychokinetic
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NH3 makes sense, mewrox99.
“If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found
the object of his search.
I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.”
-Tesla
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Nicodem
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You mean the product of reductive amination? The transformation of CHO into CH2NH2? That would give beta-methyl-cinnamylamine. This compound has no
chirality so it has no enantiomers (the -CHO is not a prochiral). It can have two diasteromers though, the E and Z isomers. However, which of the
isomers would be the main or sole product depends on the reaction conditions and the configuration of the starting compound. If the conditions are not
such as to cause E/Z-isomerization then the product will retain the same configuration around the C=C double bond. For example if you start with the E
diastereoisomer you end up with the E diastereoisomer of the product. But only if the reaction conditions are not such as to cause E/Z-isomerization,
either in the starting or ending compound.
Also, mind that some methods of reductive amination would also cause the reduction of the double bond. That double bond is also quite electrophilic so
it can also alkylate amines via the Michael reaction. In short, the reductive amination of that aldehyde is not trivial and only few methods apply.
…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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turd
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I guess that's the product solo is talking about? Evidently you would get the racemate, as it is not a diastereomer. The result would be the same for
the cis- and trans-isomers of the reactant.
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Picric-A
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This is probably a very trivial question but here we go;
How does one form formate (methanoate) esters?
I know conc H2SO4 reacts with conc formic acid producing carbon monoxides so i guess if one were to try make the ester the usual way (acid + alcohol +
conc H2SO4) you would just be left with a bunch of alcohol and CO. So how does one actually go about it? I would specifically like to make ethyl
formate (from conc formic acid and methylated spirit)
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Lambda-Eyde
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Any strong acid will catalyze the Fischer esterification reaction. You can use hydrochloric acid instead of sulfuric acid. Using a Dean-Stark trap or
a similar device will improve the yield.
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DJF90
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Formic acid is strong enough to catalyse its own esterification; no added catalyst is necessary.
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turd
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Why don't you use Google before asking, lazy bastard.
http://pubs.acs.org/doi/abs/10.1021/ed027p245
I cannot upload the PDF since it's larger than 2MB.
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Picric-A
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Wow calm down! Bit strong!
Thanks for all the proper informative responses.
Will refluxin formic acid and an excess of ethanol produce said ester? Seems very simple.
[Edited on 5-8-2010 by Picric-A]
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mnick12
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The yield of uncatalized n-propyl formate with 12hrs of reflux is said to be around 65%, so I would expect ethyl formate yields to be similair. Also
couldnt one use p-tsa as a catalyst? I have heard of it being used in some esterifications, and it does not have the same dehydrating properties
sulfuric acid has.
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panziandi
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I made methyl formate from formic acid (98%) and methanol. Just refluxed and then distilled the very volatile ester. That was a long time ago can't
find my notes.
In fact dehydration of formic acid would require a fair quantity of sulphuric acid, unlike the catalytic quantity used for esterification and
sulphuric acid diluted in formic acid doesn't dehydrate it, whereas formic acid diluted in sulphuric acid dehydrates on warming. But as we are saying,
catalysis is not required for the esterifcation of alcohols with formic acid, maybe zeolites or magnesium sulphate would help by removing water.
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gardenvariety
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@Nicodem: regarding the Pihkal cover, the mountain looks just as much (if not a bit more) like Mt Diablo, which Shulgin's house/lab overlooks.
For my own question, does metabisulfite hydrolyze into two bisulfite ions or one bisulfite ion and one SO2 molecule?
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Picric-A
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| Quote: Originally posted by panziandi | I made methyl formate from formic acid (98%) and methanol. Just refluxed and then distilled the very volatile ester. That was a long time ago can't
find my notes.
In fact dehydration of formic acid would require a fair quantity of sulphuric acid, unlike the catalytic quantity used for esterification and
sulphuric acid diluted in formic acid doesn't dehydrate it, whereas formic acid diluted in sulphuric acid dehydrates on warming. But as we are saying,
catalysis is not required for the esterifcation of alcohols with formic acid, maybe zeolites or magnesium sulphate would help by removing water.
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Thanks Panziandi, i will try making both the methyl and ethyl ester tommorow. Although maybe a bit trivial, i have 2.5L of formic acid and havnt realy
found a use for it. Also making an ester with such a low boiling point will be good tecnique practice.
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turd
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Apparently not strong enough. First of all you refused to search for yourself, and then instead of fetching the reference I posted detailing the
synthesis for students (J. Chem. Education), you continue the begging for being spoon fed. If that's not the behaviour of a lazy bastard, I
wonder what is.  Hint: the interesting part is not so much the catalyst but the
question whether your product forms azeotropes with the reactants and byproducts.
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Picric-A
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| Quote: Originally posted by turd |
Apparently not strong enough. First of all you refused to search for yourself, and then instead of fetching the reference I posted detailing the
synthesis for students (J. Chem. Education), you continue the begging for being spoon fed. If that's not the behaviour of a lazy bastard, I
wonder what is. Hint: the interesting part is not so much the catalyst but the
question whether your product forms azeotropes with the reactants and byproducts. |
I did not continue 'begging' to be spoon fed, i got my question answered and there was no need for you to lash out.
I have done research and yes i know methyl formate forms an azeotrope with both water and diethyl ether. The ether azeotrope boils at 31.5. Enough
research for you?!?! now back off.
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sakshaug007
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does anyone know if potassium iodide is very soluble in glacial acetic acid? i want to try an electrolysis experiment to obtain methyliodide. the
iodide shouldn't oxidize to iodine right? because acetic acid is a weak non-oxidizing acid correct?
thanks
"If everyone knew everything what would be the point?"
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