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Picric-A
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I find west condensers are better for reflux whilst liebig's are better for distillations.
When distilling with a West the solvent gets stuck in the bulbs and needs to be inverted at the end which gets annoying...
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kclo4
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isn't the difference between as west and a Liebig the amount of water they hold for cooling?
Picric-A, It sounds like you are thinking of a Allihn Condenser. Your not supposed to use those for distillations.
The most practical length depends on what you are using it for, such as the boiling point of the chemical you are using and the temperature of the
water you are using it for. So this question is hard to answer since we don't know what you are dealing with.
Personally, I wish I had bought a 400mm Liebig instead of my 200mm Liebig, but it works well enough for what i use it for that I haven't bought a
400mm yet.
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chief
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Mixing HMnO4 and HClO3 : What to expect ?? Do those 2 mix and co-exist, or gives it trouble, poison and explosion ? Some HCl would also be present,
from the Chlorate-impurities ...
Plan would be: Ba(MnO4)2 + Ba(ClO3)2 + H2SO4(dilute); maybe instead of the Ba-compounds the sodium-versions ...
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S.C. Wack
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I have a couple Wests with small bulbs at each end, but this only affects the condenser water.
This is the acetylene article that goes with the DOI link that I posted earlier.
Attachment: jacs_43_2071_1921.pdf (739kB)
This file has been downloaded 937 times
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mechem
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PRESSURE IN A SEALED VESSEL PROBLEM
IF 1-LITER OF WATER IS HEATED TO 300 DEG-C INSIDE A 2-LITER CAPACITY SEALED VESSEL WHAT PRESSURE WOULD IT REACH INSIDE THE VESSEL.
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solo
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This should have been posted in the short question thread........solo
Gas Law
PV = nRT
\ P is the absolute pressure of the gas,
\ V is the volume of the gas,
\ n is the number of moles of gas,
\ R is the universal gas constant,
\ T is the absolute temperature.
........see,
http://en.wikipedia.org/wiki/Ideal_gas_law
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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crazyboy
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I mixed about 15mls acetone with 15mls 98% sulfuric acid then it was stirred gently and after 3 minutes 20mls water was added after a few minutes a
strong minty/alcoholic odor different from acetone or sulfuric acid was evident. Any idea what this is?
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kclo4
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I'm not to sure what it is but H2SO4 catalysis acetone to condense, eventually forming Mesitylene, and probably some other stuff. http://en.wikipedia.org/wiki/Mesitylene
Oh! isn't Phorone formed by the condensation of acetone? If so, I bet it could be that or something similar.
http://en.wikipedia.org/wiki/Phorone
I think that would be fun to make!
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Formatik
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Mixing acetone with H2SO4 under cooling is said to form single-basic "mesitylsulfuric acid" C3H5.SO3H (apparently 1,3-propane sultone, or
3-hydroxy-1-propanesulfonic acid gamma-sultone) mentioned in Hlasiwetz, J. 1856, 487. Sultone is the only empirical formula I've been able to find
that matches up to that given above. It could be a mesitylsulfonic acid perhaps.
According to the article below, 1,3-propane sultone is genotoxic, directly alkylating and carcinogenic. http://linkinghub.elsevier.com/retrieve/pii/S037842740400083...
Kane (P. 44, 479) mentions mixing without cooling of 2 vol. acetone with 1 vol. H2SO4 gives mesitylsulfuric acid of the formula C6H10O.H2SO4, the
double basic. Using 1 vol. acetone and 2 vols H2SO4 forms "Hypermesitylsulfuric acid", C3H6O.H2SO4.
Distilling acetone with conc. H2SO4 is known to form 1,3,5-trimethylbenzene C9H12 aka mesitylene, as 3 H2O is removed. As by-products are: propylene,
1,2,3,5-tetramethylbenzene, phorone, mesityl oxide, acetic acid and a hydrocarbon C15H20 (Bp. 280 to 282 deg) and an oil which boils at 183-5 deg.
with the formula of C14H22O (Orndorff, Young, Am. 15, 255). The references are from Beilstein.
[Edited on 13-10-2008 by Formatik]
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n_oromarr
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Quick question about palladium on carbon (pd/c)
Hello everyone. This looks to be a really great website.
I was reading Vogels and in the section on palladium/carbon preparation it mentions that the activated carbon is suspended in 10% nitric acid while
heating to prepare it.
I thought this was interesting.
As we all know, HN03 is sometimes difficult for some of us to get.
I was wondering if another acid would work, such as HCL or H2SO4?
Thanks for any info you can offer up.
Norman
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Picric-A
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I plan on distilling some ether. up till now i ave always used crude methods of distilling which never condense all (involving heating a flask full of
ether and passing vapours into a test tube submurged in ice)
Now i have proper quickfit apparatus i plan on distilling with that however i see a problem. the water comming out the tap will be too warm to
condense the vapours properly...
What can i use to pump cold water around the condenser?
would some aquarium pump work and if so could someone please reccomend a fairly cheao one to me?
How cold can these things actually go? as in, could i pump liquids at -5 degrees C around it or wouldnt it work?
Thanks,
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Panache
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| Quote: | Originally posted by Picric-A
I plan on distilling some ether. up till now i ave always used crude methods of distilling which never condense all (involving heating a flask full of
ether and passing vapours into a test tube submurged in ice)
Now i have proper quickfit apparatus i plan on distilling with that however i see a problem. the water comming out the tap will be too warm to
condense the vapours properly...
What can i use to pump cold water around the condenser?
would some aquarium pump work and if so could someone please reccomend a fairly cheao one to me?
How cold can these things actually go? as in, could i pump liquids at -5 degrees C around it or wouldnt it work?
Thanks, |
pond pumps from your local hardware for around $10 in a bucket of ice water works fine, however possible problems you may encounter are
1) if your bucket is on the ground, your condenser on the bench or higher, these cheap pumps may not have the 'head' of pressure to run, simply raise
the bucket higher
2)if you're using an ether condenser these pumps can run then at only very low flow rates because of the back pressure from the thin internally coiled
condenser, in this case you may have to see how it goes, ether does not require much cooling/unit vol vapour and if your condenser is longish you will
be fine. If its a jacketed condenser this point is irrelevant
3)the pumps have a tendency to chew out their impellers from time to time, in australia there are two brands with 3 year replacement warranties, buy
these if you have them, but maintenance-wise just take the thing apart between uses to check for entangled things in the impeller it will affect it's
already pathetic capacity. I have had them at -10 without a fuss before, using a alcohol/water mix, most of them are acrylate construction and any
decent solvent will turn it into the blob really quickly, so keep your water water.
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kalacrow
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Oxidation of Eugenol ref
Does anyone have a ref to the actual procedure to oxidize eugenol to vanillin, as used in the good 'ol days to make synthetic vanillin?
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solo
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EUGENOL (allyl guaiacol, eugenic acid), C10H1202,anodoriferous principle; it is the chief constituent of oil of cloves, and occurs in many other
essential oils. It can be synthetically prepared by the reduction of coniferyl alcohol, (HO) (CH 3 O) C6H3 CH :CH CH20H, which occurs in combination
with glucose in the glucoside coniferin, C16H2208. It is a colourless oil boiling at 247° C., and having a spicy odour. On oxidation with potassium
permanganate it gives homovanillin, vanillin, &c.; with chromic acid in acetic acid solution it is converted into carbon dioxide and acetic acid,
whilst nitric acid oxidizes it to oxalic acid. By the action of alkalis it is converted into iso-eugenol, which on oxidation yields vanillin, the
odorous principle of vanilla. This transformation of allyl phenols into propenyl phenols is very general (see Ber., 1889, 22, p. 2747; 1890, 23, p.
862). Alkali fusion of eugenol gives protocatechuic acid. The amount of eugenol in oil of cloves can be estimated by acetylation, in presence of
pyridine (A. Verley and Fr. Baelsing, Ber., 1901, 34, p. 3359). Chavibetol, an isomer of eugenol, occurs in the ethereal oil obtained from Piper
betle. The structural relations are: nOCH OH / OH 3 f IOCH3 ./11 ?? CHICH:CHa CI I:CH CH3 Eugenol. Iso eugenol
..........source,
http://www.1911encyclopedia.org/Eugenol
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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kalacrow
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Thanks.. I have that ref 
What I am looking for is an account of the lab or industrial process to successfully oxidize eugenol to vanillin in high yield, with all particular
conditions and procedures If someone could post a journal ref or synthesis account, that would be very appreciated!
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Panache
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| Quote: | Originally posted by solo
EUGENOL (allyl guaiacol, eugenic acid), C10H1202,anodoriferous principle; i On oxidation with potassium permanganate it gives homovanillin, vanillin,
&c.; ...... By the action of alkalis it is converted into iso-eugenol, which on oxidation yields vanillin, the odorous principle of vanilla.
........
http://www.1911encyclopedia.org/Eugenol |
the answers are there, just in the wrong order
an aside from the same quote
'....Alkali fusion of eugenol gives protocatechuic acid...'
Yeah right!! what in 0.0003% yield. I did remember reading years ago about a NaOH/ALCl3 melt (~180C) to which eugenol was dripping into to
demethylate, that sounded like awesome fun. Apparently this melt was a common way of demethylating aryl ethers back when the first depression seemed
like it could never happen....
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solo
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REFERENCES
Ber., 1889, 22, p. 2747; 1890, 23, p. 862
A. Verley and Fr. Baelsing, Ber., 1901, 34, p. 3359
http://ifile.it/sr68jlu
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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kalacrow
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Oof. Thanks! I'll have to do some cutting and pasting... 
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sonogashira
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Improving yield for ester ---> amide
With a sterically hindered (or otherwise unreactive) ester ---> amide conversion is there any catalysts etc. that can be added to the conc. NH3 to
improve yield?
[Edited on 19-10-2008 by sonogashira]
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Klute
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DMAP is said to be very effective, it works very well for b-ketoesters, yielding the amides with no enamine formation. There is an article on the
subject in the ref forum (pdf )
Otherwise I think basic catalyst are the most suited, such as sodium methoxide, tertiary amines (pyridine: here), etc.
Cyanide anion seems to be usefull too:
Cyanide as an Efficient and Mild Catalyst in the Aminolysis of Esters
Thomas Hogberg et al.
J. Org. Chem.;; 52(10), 2033-2036 (1987)
DOI: 10.1021/jo00386a025
Abstract:
Cyanide anion was found to be a versatile catalyst in the aminolysis of nonactivated esters. A comparative
study on various catalysts, including (dimethylamino)pyridine, 2-hydroxypyridine, imidazole, and sodium cyanide,
in the ammonolysis of ethyl (S)-l-ethyl-2-pyrrolidinecarboxylat(1e ) in methanol showed sodium cyanide to be
the superior catalyst. Furthermore, the reaction was completely stereoconservative; i.e., less than 1% racemization
occurred. Cyanide ion also proved to be an efficient catalyst in the transesterification with the solvent. Comparative
studies on 1, ethyl benzoate (4), ethyl 3-phenylpropionate (51, and ethyl phenoxyacetate (6) in aminolysis with
ammonia, methylamine, and dimethylamine in methanol showed cyanide to be a general catalyst. The reactivity
order for various esters was found to be MeNHz > NHS > Me2NH.
Apaprently, some modified zeolites can also be used (but who really uses them?!) Acylation of amines by aminolysis of esters over H-ZSM-5 catalyst
[Edited on 20-10-2008 by Klute]
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
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sonogashira
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Thanks klute that looks like a really interesting paper. I can only see the first page but it looks like they use NH3 in methanol. I wonder if the
cyanide can be added to an aqueous solution instead?... probably not so well : /
[Edited on 20-10-2008 by sonogashira]
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Klute
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It might cause some hydrolysis I think, or at least perturb the equilibrium.. Depending on your substrate, I would gas the neat ester with dry NH3,
avoiding solvent. As they said transesterification can occur, so if your ester isn't the methyl or t-butyl, you could also dissolve your ester in
MeOh, add the catalyst, and then gas with NH3 until saturation: this way part of your ester will convert to the more recative methyl ester, and then
go through aminolysis. Dry NH3 is that much of a hassle at a small scale.
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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stoichiometric_steve
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Is there any other way to cleave a primary amide to the parent acid besides the use of Alcoholates, Hydroxides?
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Formatik
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What do aqua regia or NOCl and ethanol yield?
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Picric-A
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Formatik- most probably an explosion but otherwise i would guess if dilute eough the HNO3 may oxidise the EtOH to acetaldhyde or ethanoic acid...
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