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Nicodem
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| Quote: | Originally posted by starman
| Quote: | Originally posted by raiden
Does anybody have any info regarding sesamol to piperonal/safrole?
Cheers. |
Your serious? Phenolic group to unsaturated allyl group.Well some of the members may be knowledgable
enough to come up with that in a home lab,although the robustness of the MD grouping to survive would be suspect. |
Aryl triflates can be used in the Heck and Sonogashira couplings (quite possibly also for the Neigishi and Kumada couplings, but I'm not sure).
Obviously 1,3-benzodioxol-5-yl triflate can be prepared from sesamol just like any other phenyl triflate. It is only a question of choosing a proper
substrate to couple this triflate with, so that the cleavage/modification to safrol or piperonal is possible in a simple way. However, anybody who
bothered checking the price of sesamol and the reagents required will realize it is a pretty stupid idea to use such a route for preparing a substrate
such as piperonal which is relatively cheap and/or can be prepared by much simpler means.
…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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Jor
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I have 3 containers of zinc chloride here. They are supposed to be all anhydrous. One is still sealed, 250g p.A Merck. Two are from an eBay supplier,
who repacks his chems. Now, Im donating one of the containers from eBay supplier to another hobby chemist in uni. But I'm not really sure if the stuff
from eBay is really anhydrous. It does not fume, does not react with room temperature water, and does look crystaline. When dropped into heated water
in a test tube, it bubbles vigorously, but maybe this is just because the water is already above the boiling point, but can't boil due to the smooth
test tube.
I do not want to open the Merck container, it's still sealed, and it would reduce the quality.
Is there any way to quickly determine whether it's anhydrous or not, with a 100% certain outcome?
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Klute
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You could try dissolving it in a aprotic solvent such dioxane or toluene (not sur eof the solubilities though). I guess if it's sufficently hydrated,
it will not dissolve at all where as the anhydrous would be soluble (just a guess though).
I think anhydrous ZnCl2 is a cristallin solid anyway, so that should be a criteria for judging it's water content. Try heating a small sample in a
tube with a flamme, and see if water condenses on the sides (even if you ahev decomposition to the oxychlorie or similar)
or just throw some SOCl2 onto it, as for oxalic acid 
EDIT:
BTW, I would build myself a cheap dry box, and repack the ZnCl2 in small 2-10g containers as to not waste the whole container after opening it a few
times. A sealed dry box is very easy to build, and is really practical to weigh/handle moisture sensitive products with no concern (I even use it for
NaBH4 etc because it's easy to use and make your reagents last longer).
use some CaCl2 or NaOH (depending on the sensibility of the reagent) to dry the box for a few hours (I just leave 200-300g CaCl2 in it at all times),
with your containers spatula etc inside, and then do your repackaging/weighing safely.
I can post a pic of the dry box if you want, cost me under 10e to make, and a couple hours work.
[Edited on 30-9-2008 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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Jor
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Yes sure, post a picture, that'd be nice  . I was thinking of building some sort
of dry box before, my idea was a small box, with CaCl2 in it, the leave the spatula and container of chemical in the box for few hours, then open the
container with gloves integrated in the box (like a glovebox, but then much more simple).
I will try dissolving it in some solvent. I have at hand methanol, ethanol, acetone, benzene, DCM, ethyl acetate, Ligroin (high boiling hydrocarbons),
diethyl ether, GAA.
I think the hydrate will dissolve in methanol, ethanol and GAA, but I will try AcOEt, DCM, and acetone. Benzene I'm not so sure, I rather only use it
when my hood is finally done.
I don't have toluene :O. Well I do have 'Thinner' but it other crap as well like xylenes. Dioxane, I don't see a single reason why I would ever buy
that stuff, Ive hardly ever yet seen a synthesis involving it. Besides it probably carcinogenic.
SOCl2. Well I could try that in a few days when my thionyl chloride arrives. But still ZnCl2 will always contain SOME water, so there will be a
reaction anyway.
[Edited on 30-9-2008 by Jor]
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DJF90
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Pictures are always good. What materials did you build it from? And what did you used to seal the joints?
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Klute
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I used a cheap transparent platic box, some PVC tubing, some washing gloves, and silicon to seal all the connection. The lid/box seal was improved by
applying a layer of "elastic" silicon , and letting it dry without the lid on, so that when the lid is on the silicon is pressed down and the box is
sealed properly.
I will post some pictures in the Tour my lab thread.
\"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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Jor
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Ok, I'm quite convenient that it is anhydrous ZnCl2 now.
-Heating in a test tube results is melting, and a slightly yellow liquid is formed. The temperature in the tube is far above 100C, I think at least
200C (used alcohol burner, with absolute alcohol technical grade as the fuel). No fumes or condensing water are observed whatsoever.
Adding water after the liquid has solidified results in complete dissolution and formation of clear liquid.
-Adding about 100mg of the material to 2mL p.a. Acros acetone (wich is thus very dry, so hardly any formation of possible hydrate). Solid completely
dissolves and forms clear solution wich appears a little turbid but if you look good it is completely clear.
-Adding 2mL of very pure diethyl ether to about 100mg results in partial dissolution, however most of the ZnCl2 does not dissolve.
http://www.acros.be/DesktopModules/Acros_Search_Results/Acro...
It should be soluble in ether, however it is not mentioned how much dissolves.
Based of the 1st experiment I assume I have the anhydrous material. Im not sure if hydrated zinc chloride dissolves in acetone, so the 1nd is unsure.
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Klute
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Has anyone used sodium isopropoxide in IPA for b-ketoester alkylations (AcAcOEt to be precise)? Or do you see any reasons why it would work as well as
EtONA/EtOH? I would prefer using IPA to ethanol, as it is less of a pain to dry than the latter (and I have anhydrous IPA, but only 96% EtOH at hand).
Or could I just stick to acetone/K2CO3, using quite reactive benzyl halides?
\"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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Panache
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Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
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I can't remember if the pKa of organic acids that are solids at RT is quoted at their melting point or is it some standard solution of, thats the
first question.
Secondly if someone could bash out for me how much of an excess of malic acid over sodium propionate i would require to effectively completely
protonate all of the propionate. I must go and buy a scientific calculator, i started using the log tables in the crc but quickly decided fuck that. I
will love you forever.
Relevant data,
Malic acid, MW=134, pKa1=3.4, pKa2=5.13
Propanoic acid,MW=74, pKa=4.88, inverse log is the dissocation constant for sodium propionate.
If it turns out too great an excess could you quickly check the numbers for
citric acid,
MW=192 pKa1=3.15, pKa2=4.77, pKa3=6.40,
this may be a better option.
Loving you in advance!!!! Thanks!!!!
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Nicodem
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Panache, the pKa of solid acids has nothing to do with their state when pure. All pKa values are always reported for a specific solvent since the
acidity is highly dependent on solvent. If no solvent is reported then it is assumed the pKa value stands for a water solution as the standard
solvent.
The pKa stands for the negative decadic logarithm of the (de)protonation equilibrium constant. So, if you need the equilibrium equation of a mixture
of an acid (malic acid) and base (propionate anions) in water solution, it is simply the difference of the two constants "deloged". Unfortunately
malic acid has two pKa values which complicates things a lot and you will need someone with some knowledge in mathematics to solve the problem (I'm
clueless when it comes to mathematics). You could ignore the pKa2 of malic acid if c(malic acid)>>c(propionate), but this would be a source of
(potentially big) error:
Ka1(malic acid) = -([malonate][H3O+] / [malic acid])
Ka(propionic acid) = -([propionate][H3O+] / [propionic acid])
K = [malonate][propionic acid] / [malic acid][propionate] = 10^(pKa(propionic acid)-pKa1(malic acid)) = 30.2
So an quimolar mixture of malic acid and propionate would consist of a malonate : malic acid = propionic acid : propionate in a ratio of ~30 (when
ignoring the pKa2 of malic acid). The ratio would be even slightly higher when not ignoring the pKa2. Obviously it is not possible to fully protonate
the propionate to form only propionic acid since this would require an infinite concentration of malic acid. Therefore, essentially the answer to your
question is that it is impossible to completely protonate the propionate anion using malic acid, but you can reach an approximately 97% protonation
just by mixing your propionate with an equivalent molar amount of malic acid.
| Quote: | Originally posted by Klute
Has anyone used sodium isopropoxide in IPA for b-ketoester alkylations (AcAcOEt to be precise)? Or do you see any reasons why it would work as well as
EtONA/EtOH? I would prefer using IPA to ethanol, as it is less of a pain to dry than the latter (and I have anhydrous IPA, but only 96% EtOH at hand).
Or could I just stick to acetone/K2CO3, using quite reactive benzyl halides? |
I have used both NaOH/EtOH, NaOEt/MeOH, NaOEt/MeOH/PhMe for C-benzylating ethyl acetoacetate or diethyl malonate (the reason why I did not used EtOH
as solvent, like usually done, was because I had no absolute ethanol). NaOH/EtOH worked well on ethyl acetate even when the ethanol used was 96% (but
fails miserably on diethyl malonate). NaOEt/MeOH gives poor yields (I don't remember if I used it for the acetylacetate or malonate), perhaps due to
the low reflux temperature. A mixture of MeOH/PhMe with a longer reflux worked a better. This is from memory - I should check my lab notes to be sure.
But in essence I think isopropanol will work just fine, though you might end up with some transesterification (which I guess is irrelevant since you
will probably hydrolyse/decarboxylate your product anyway).
K2CO3/acetone is unlikely to work.
…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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Klute
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Well, I have an old patent (US 1 094 417) where AcAcOEt is C-benzylated with 4-MeOBnCl in moderate yields (~50%) using acetone and K2CO3, but they
don't specify the amount of K2CO3 used and reflux for 12h...
But indeed i better stick to more conventional reaction conditons.
If you find you notes or remember more details, I'd love to hear them.
I have solid NaOMe and NaH, so might try the methoxid'e in MeOH and toluene at first, and then jump to NaH/IPA if it doresn work as well as I would
like it to. Thanks for tips.
\"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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12AX7
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| Quote: | Originally posted by Panache
I must go and buy a scientific calculator |
Windows+R
"calc"
<ENTER>
View, Scientific
Tim
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solo
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In a reduction amination reaction when the ketone isn't soluble in methanol but soluble in ethylacetate, and ethyl acetate has a solubility of
8.3gr/100ml H2O ...my question is can the reaction be run in this solvent as a transition solvent without running the risk of any side
reactions.............solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Klute
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What reducting agent will be used? NaBH4? catalytic hydrogenation?
Will the amine be used anhydrous or as an aqueous solution? have you tested the solubility of the ketone in other alcohols, like IPA or even EtOH?
\"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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solo
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The reducing agent ill be through Pd/C via catalytic hydrogenation and the amine will be in water....will try the iso propanol alcohol, however since
ethylacetate is soluble in alcohol and there is some solubility of water in ethyl acetate and in alcohol It may be enough to allow the reaction to go
forward.....solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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querjek
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I was reading this the other day:
http://orgsyn.org/orgsyn/prep.asp?prep=cv4p0866
And was hoping to find anything more about the same/similar reactions on aldehydation of aromatic rings; I've tried numerous Google searches and
searches here but haven't come up with anything (and I can't find the fourth reference in that article, which is supposed to be the original
procedure).
Also, can anyone tell me why/under what conditions phenols polymerize?
Thanks!
it's all about chemistry.
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12AX7
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The word is "formylation".
Interesting synthesis, a bit perplexing. I suppose the glycerol is a polar solvent to help deal with the ammonia and substitution? An odd choice as
a solvent, it's often quite reactive. Maybe that's part of the reason it turns black. I don't get the boric acid, and just about enough is added to
take up the ammonia, but ammonia still bubbles out of it (that must be a foamy mess!). The tight temperatures and exothermy looks tricky as hell to
get to work first time. Maybe even second time.
The textbook addition consists of aromatic substitution, which in analogy to any other acylation, means using formyl chloride, CHOCl, which doesn't
exist in a bottle so is created in situ using formylating agents.
Phenol polymerizes under conditions of formaldahyde, for instance. That makes bakelite. Methylene bridges substitute the ring at the ortho/para
positions, eliminating H2O. This is the most connective reaction (a potential of three links per phenol -- now that's a rigid plastic), but others
take place, such as monosubstitution (leaving a -CH2OH on a ring) and linking the hydroxyls and even some ether bridges.
Phenols in general? Depends. Phenols in general are strongly activated at the ortho/para locations, so unless substituents are blocking those
positions, whatever can happen, will. Even if blocked, the substituents might be reasonable substrate, carbonyls (at or adjecent to the ring) for
instance. Benzylic carbons are somewhat acidic as is.
Tim
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Klute
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Better look at Mg methoxide/paraformaldehdye formylation of phenols, the conditions are much less ahrsh and the reaction is very selective and high
yielding with sufficently activated substrates. There a thread on this in the Prepublication forum
\"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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Nicodem
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| Quote: | Originally posted by querjek
I was reading this the other day:
http://orgsyn.org/orgsyn/prep.asp?prep=cv4p0866
And was hoping to find anything more about the same/similar reactions on aldehydation of aromatic rings; I've tried numerous Google searches and
searches here but haven't come up with anything (and I can't find the fourth reference in that article, which is supposed to be the original
procedure). |
You probably did not use the correct search terms. Actually it is obvious you did not, since you call the reaction "aldehydation". The reaction is a
formylation and is called the Duff reaction. The electrophile is the protonated hexamine and the intermediate the same as in the Sommelet reaction (the N-benzyl-hexaminium
cation). The original version used glyceroboric acid as catalyst (made in situ from glycerol and boric acid), but the new or so called modified Duff
reaction uses carboxylic acids as both solvent and catalyst. It only work on reactive phenols. There are versions using AcOH or mixtures of
HCOOH/AcOH, while the use of trifluoroacetic acid allows for the formylation of even less nucleophilic aromatic systems than phenols.
| Quote: | | Also, can anyone tell me why/under what conditions phenols polymerize? |
Simple phenols do not polymerize unless they have a polymerizable double bond or other such functional groups. They can polymerize by condensation
with some electrophiles like formaldehyde, glyoxal, etc. In such case the intermediate o,p-hydroxybenzyl alcohols condense with other phenolic
moieties (via acid catalysed Friedel-Crafts benzylation) yielding a crossed polymer. The classical such polymer is bakelite which can be prepared by condensing phenol with formaldehyde under acidic conditions (for example using H2SO4 as catalyst).
…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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solo
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In a recent experiment with aldehyde rearrangement the conversion to the desired ketone results in a thick emulsion which has all the properties of a
polymerized failed reaction......during the process all the experimental instructions were followed ....however after the reaction and prior to the
distillation of the ketone from the non polar solution containing the ketone the mixture was washed with both brine solution and a carbonate solution
....which in fact might have just contributed to the polymerization of the unreacted aldehyde as all was fine till the last wash with plain water
where all the solution turn to milk.....left alone for two days at which time the non polar has separated from the water and of course once the non
polar was distilled off at 25mm the remaining material refused to give forth the ketone at the indicated temp at 25mmm and only a honey
remained.......so is it possible that the aldehyde might have gone through some base catalyzed aldol condensation which would polymerize the
material........
| Quote: | | These oxygen containing compounds,particularly acetaldehyde, will undergo polymerization in the presence ofthe basic wash or scrubbing conditions.
|
..................source,
US Patent 5160425 - Method of inhibiting formation of fouling materials during basic washing of hydrocarbons contaminated with oxygen compounds
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Klute
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But if the workup described a basic wash, the compound can't be that sensible? Perhaps alot of unreacted aldehdye was left for what ever reason, and a
aldol was caused by the washes, but I'm surprised it would happen so quick.. Maybe using a very dilute, cold NaHCO3 wash next time might minimze
things. But I don't think that wash is responsible for the faimure of the reaction, i guess it's something to to with the recation conditiosn properly
spoken off.
\"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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solo
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| Quote: | Originally posted by Klute
But if the workup described a basic wash, the compound can't be that sensible? Perhaps alot of unreacted aldehdye was left for what ever reason, and a
aldol was caused by the washes, but I'm surprised it would happen so quick.. Maybe using a very dilute, cold NaHCO3 wash next time might minimze
things. But I don't think that wash is responsible for the faimure of the reaction, i guess it's something to to with the recation conditiosn properly
spoken off. |
....
......the original russian study never mentioned any washes it's the later efforts reported where they go into the washes many with similar failures
while others has success....will try the reaction without the wash as all the temps were carefully monitored....Danilov's rearrangement has been
tried by many with only two reported success stories ....one with the wash and the other without , at lest it wasn't mentioned....the material does
have the ketone scent but it's chained up in a monster polymer that won't let go ....may also try to cross the barrier with the material in
ethylacetate and adding the bisulfite in alcohol and water, to see if it can pull it out......solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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ssdd
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How large must a molecule containing an amine in the form of an HCL salt be to not be soluble in water.
I know as a general rule most HCl salts of amines are soluble in water, but when does the molecule become to large if at all? Are there any exceptions
to the above rule?
-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
http://deepnorth.info/ |
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Klute
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I don't have the precise examples in head, but yes I am sure some HCl salts are sparingly soluble, or even not at all. I will try to find some
examples. I think it has soemthing to do with the gloabl polarity of the molecule and stearic hindrance of the ammonium function, and the size
obviously. I don't know if there is a universal rule though.
\"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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kclo4
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I am unable to find a synthesis for Benzoic acid from Toluene via KMnO4.
I imagine its just add a solution of KMnO4 to Toluene and reflux/stir a lot, or something like that, but I'd rather take the guess work out of it do
something that works.
Do I add an excess of toluene or just stoichiometric amounts, etc?
3 C6H4CH3 + 2 KMnO4 + KOH = 3 C6H4COOK + 2 MnO2 + H2O
Is its reaction, right?
[Edited on 5-10-2008 by kclo4]
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