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woelen
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thionyl chloride and alcohols
I mixed some methanol with thionyl chloride and this gives a very violent reaction, in which copious amounts of HCl are evolved. I did an experiment,
with 1 ml of methanol and 0.5 ml or so of thionyl chloride and mixing these. A lot of gas is produced and I immediately loosely stoppered the test
tube. After the reaction stopped, I put the test tube under water and removed the stopper. AT ONCE, the test tube is filled with water for almost
100%, only a small bubble of gas remained. So, the gas must almost be 100% HCl. This is in agreement with the following:
http://www.lambdasyn.org/synfiles/dimethylsulfit.htm
I, however, had the impression that thionyl chloride also can be used for chlorinating compound with hydroxyl groups, e.g.
ROH + SOCl2 --> RCl + SO2 + HCl
Is this reaction possible? I would like to make some CH3Cl from methanol. Can SOCl2 be used for this purpose, under some different reaction
conditions? I know of other methods of making CH3Cl, but they are not really easy.
The wiki on thionyl chloride mentions the chlorination of alcohols as a possible reaction:
http://en.wikipedia.org/wiki/Thionyl_chloride#Organic_chemis...
Is this wiki-page wrong?
[Edited on 30-5-08 by woelen]
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Formatik
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There's some information in Beil about making CH3Cl from MeOH.
Beilstein 1, 144
Beilstein supl. 1, 33
Beilstein references
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Fleaker
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Thionyl chloride will chlorinate alcohols into their alkyl halides. I don't think methanol is an exception--you will have methyl chloride, HCl and of
course SO2 produced. I think the methyl chloride all boiled away during the initial violence of the reaction.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Klute
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But he would have obtained some SO2 afetr dissolving the HCl in water, no?
I think alcohol which form less stable carbocations, like methanol, can not be deplaced by the Cl- anion once the thionyl chloride has added to the
oxygen, without further heating...
I guess the formation of the dialkyl sulfite is limited to methanol and other short primary alcohols.
This is only speculation though.
Woelen, can you not substitute MeBr for MeCl? The former cna be esaily genearted with methanol, alkali bromides and H2SO4/H3PO4 as Painkilla
demonstrated... Or do you specifically need MeCl?
\"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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chemrox
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I need an alkyl chloride too. One not commercially available from the usual suspects. The bromide is resistant to the reaction being planned. I
am considering two approaches; DMF/TCC complex, a la DeLuca, looks promising, @Sauron (see thread) and the classical, ZnCl2/HCl method. Both should
work. The first more efficient than the second. SOCl2 would work too but I don't want to use it when the other methods are available and the SOCl2
might be needed for something else.
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Sauron
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Thionyl chloride and methanol in stoichiometric quantities will give MeCl, SO2 and HCl.
All of these are gases at STP. What did you expect?
Methanol was simply not a very good choice of substrate.
Try this with, say, cyclohexanol, and run the reaction with a stoichiometric equivalent of pyridine or TEA or doethylaniline to trap the HCl, and you
will get cyclohexyl chloride in decent yield.
Vogel has some examples of alcohol to alkyl chloride preps with SOCl2.
Running the reaction in the cold will moderate reaction rate and make things tamer.
If you want to make MeCl, use methanol and TCT and reflux at about 15 C under the bp of the methanol. Use a Dewar condenser to collect the MeCl and
store it in a stainless steel sample bomb (pressure vessel.)
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Nicodem
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In the Organikum, a typical practical chemistry book, the authors claim that: "With thionyl chloride there exist two different possibilities: in any
case the ester (R-O-SO-Cl) forms first, which in presence of pyridine reacts with the chloride ion leading to an inversion of configuration, but in
the absence of pyridine an 'internal nucleophilic substitution' occurs (S<sub>N</sub>i) which leads to a product retaining the original
configuration." (my translation)
So chances are that it is possible to prepare MeCl with SOCl2 even without using pyridine or other bases. However, whenever I was using SOCl2 to form
alkyl chlorides from primary alcohols I always added an equivalent of pyridine and left the reaction run at room temperature in CH2Cl2 until TLC
indicated more or less complete conversion. That is also the most common procedure you can found in numerous papers, so I don't have any experience
using any alternative method in absence of pyridine.
Woelen, your experiment with the absorption of reaction gases in water does not demonstrate that no MeCl formed since according to one of the
Beilstein abstracts Schockwave provided above, methyl chloride forms a clathrate with water (though under pressure and lower temperature), so it could
be relatively soluble in water. In fact its MSDS claims it is soluble up to 0.5g per 100ml water and surely there could have been no more than a few
milligrams in your test tube.
PS: According to SciFinder, supposedly J. Chem. Soc., 1963, 1059-1064 (DOI: 10.1039/JR9630001059) describes the reaction of methanol with SOCl2 to form MeCl, but unfortunately my access to RSC is malfunctioning today
so I can not check or post the paper.
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Polverone
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Here's JR9630001059, though it appears to not actually report results for methanol + thionyl chloride.
PGP Key and corresponding e-mail address
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S.C. Wack
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Dimethyl sulfite is not the only possible product, methyl chlorosulfite aka methyl chlorosulfinate is possible when there is less than a 2:1 ratio.
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garage chemist
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In Vanino, there is a preparation of MeCl that says that MeCl gas can be conveniently stored by dissolving it into methanol, in which it is very
soluble.
When this solution is then dripped into water, the MeCl escapes under fizzing since its solubility in water is very low. This way, a steady stream of
gaseous MeCl can be generated.
So woelen, if you want to find out whether your reaction makes any MeCl you have to add your reaction mix to water and see if there is fizzing from
MeCl.
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Nicodem
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I suspected that SciFinder entry to be erroneous as there was also another abstract using SOCl2 that also lead to a paper where alcohols other than
methanol were actually used. Until I get access to Beilstein I wont be able to find any useful references where this method is tried on methanol.
However, I thought about it and considered what if MeOSOCl in methanol (without pyridine) reacts faster with methanol rather than the chloride ion?
This would explain the procedure for preparing dimethylsulfite. On the contrary, in CH2Cl2 using stoichiometric amount of MeOH and SOCl2 with pyridine
the concentration of pyridine hydrochloride is higher than the residues of unreacted MeOH so that all MeOSOCl reacts with the chloride ions rather
than forming the dimethyl sulfite. At least that is the only way I can currently explain this anomaly.
So, Woelen, could you try again using the standard procedure (with or without pyridine) and dichloromethane as solvent? MeCl is surely highly soluble
in dichloromethane, thus a washing with 1M NaOH(aq) should remove all unreacted SOCl2, SO2 and HCl, followed by 1M HCl(aq) to remove pyridine. However
I'm unsure on how could you prove that MeCl formed without analytical instruments in an amateur setting or without derivatization. If it is present
the solution will start boiling bellow the bp of dichoromethane, but this is no definitive proof.
…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)
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woelen
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I had a near-accident when mixing triethylamine and thionyl chloride  . These
two react insanely violently with each other.
The idea was to make a dilute solution of SOCl2 in triethylamine and let this react with cyclohexanol. I added 0.5 ml of thionyl chloride to 2 ml of
triethylamine and the stuff almost exploded . The contents of the testtube
became black and part of the triethylamine is charred. I also obtained a black plume of smoke (presumably carbon I think). Before I added the
thionylchloride, I saw white smoke, but that was what I expected (HCl and SO2, formed in the humid air give white solid triethylamine hydrochloride
and sulfite), but as soon as the liquid SOCl2 touched the liquid triethylamine the contents was blown out of the test tube, there was a lot of
crackling noise and a black plume of smoke came out of the test tube. Luckily, the test tube was not pointed towards me.
I skipped the experiment with cyclohexanol, I first need a method of moderating the reaction. triethylamine apparently is not the moderator of choice.
Right now, I'll think about moderation of reactions with inert solvents. Could the method, proposed by Nicodem be done with ligroin (bp range 60 ...
90 C)? I expect CH3Cl to be very soluble in ligroin as well, and it is easy to see whether there is CH3Cl in the ligroin or not.
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Nicodem
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| Quote: | Originally posted by woelen
I had a near-accident when mixing triethylamine and thionyl chloride . These
two react insanely violently with each other. |
That's what you get if you play solventless with thionyl chloride!  Good you
were not hurt, but rather be careful with this stuff. It reacts violently with a lot of stuff. Except for preparing acyl chlorides from carboxylic
acids it is nearly always used in solutions, generaly in chloroform or dichloromethane, and with cooling.
As for using ligroin instead od CH2Cl2, I just set the reaction and while I was at it, I did not add any pyridine out of curiosity on what will
happen. I do not have ligroin, so I mixed 20ml n-heptane with 30ml petroleum ether (bp 40-60°C). I guess this mixture is quite close to
ligroin by properties. To 50ml of this solvent stirring in a flask was added 2.03ml methanol (50mmol). It took some time, but it finaly dissolved in a
clear homogenous mixture. To this mixture stirring in a cold water bath was then added dropwise a solution of 4.4ml SOCl2 (60mmol) in 10ml petroleum
ether. Not much happened. Some HCl is forming as expected, indicated by checking the exhaust gases with a moist pH paper. I will let it stir for a day
or two and then check the presence and ratios of MeCl, MeOH, MeOSOCl, (MeO)2SO, etc. via HNMR (the alkanes have all signals bellow 1.5 ppm, so it
should be possible to scan the reaction mixture in CDCl3).
…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)
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Klute
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Nice!
At least we will be sorted out as to what happens during the reaction with SOCl2 and methanol! Thank you for your time Nicodem.
\"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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Sauron
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Well, all that about inversion vs retention of configuration only applies to secondary alcohols, and then only in cases where a chiral center can
result (R1 does not equal R2),
There are other reagents that will give MeCl from methanol, most of them will also spit out HCl, but few also SO2. That makes for a somewhat more
straightforward isolation process of the methyl chloride, as the HCl is easily scrubbed away, leaving the MeCl to be condensed.
TCT is one such. As I mentioned upthread somewhere, just refluxing TCT in MeOH at about 15 C under the bp of MeOH will work just fine. Excess MeOH
serves as solvent. Yields are good, on order of 50-60%.
A better procedure is to employ the TCT/DMF complex and react that with methanol in DCM at room temperature, the yield is near quantitative. I believe
I have posted papers on both of these reactions previously.
Sic gorgeamus a los subjectatus nunc.
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woelen
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I have read quite a few reactions with TCT, but unfortunately I don't have it and I have still not found a source for this. I do have a lot of special
chems, but this particular one is hard to find (at least for me). Maybe someone who reads this thread could tell me a source of TCT in the EU?
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kmno4
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Something interesting to read:
A Study of the Reaction of Alcohols with Thionyl Chloride
William E. Bissinger, Frederick E. Kung
J. Am. Chem. Soc.; 1947; 69(9); 2158-2163.
and
Factors in the formation of isomerically and optically pure alkyl halides. Part X. Reactions of saturated aliphatic alcohols with thionyl
chloride
J. Chem. Soc., Perkin Trans. 1, 1976, 104 - 108
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Sauron
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@woelen, I buy my TCT (cyanuric chloride) from Acros in Belgium. One of the main manufacturers is Lonza in Italy. The prime manufacturers are usually
ion the HCN business because TCT is a downstream product via cyanogen chloride. The companies in question make things like malononitrile,
chlorosulfonyl isocyanate etc. Lonza I believe sells TCT (CC) in 20 Kg sacks or drums. Acros, Merck etc. probably just repack it rather than produce
it themselves.
Where I am I can import TCT no problem but thionyl chloride is a no no.
It is possible to prepare TCT in the lab by a modification of the industrial method but this is highly dangerous. The safer method is to chlorinate
methyl thiocyanate. TCT crystallizes out of the mixture that forms in good yield. Continued chlorination of the supernatant liquor eventually gives
CCl4. Do note that the intermediate mixture is toxic and highly obnoxious, containing perchloromethyl mercaptan and thiophosgene and sulfur
chlorides. But this is still safer than mucking around with neat HCN and ClCN.
Sic gorgeamus a los subjectatus nunc.
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woelen
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Can you buy from Acros, as a private individual? I personally have very bad experience with the big chemical companies, they only sell to companies
and research labs from universities and so on. I have all my chems from 'less official' suppliers, e.g. from eBay, or from hobby supplies, who sell to
individuals. But such sources usually have a limited range of chemicals (e.g. only pyro stuff, or only common organics).
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Klute
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Without wanting to go too offt opic, try localdistributors, they will ahev most acros, alfa aesar, Fluka etc etc products. I buy all my chems from my
local glassblower, the cheapest are often from Panreac a spanish manufacturer, very close to where I live (south of France).
Try to see if there are any local companies that might reatisl chemicals, and contact them. Obviosuly, at first I would go and ask about other things
that PCl5, chlorosulfonic acid or even TCT, and then work my way up once there's a good relathionship going on.
How did you get your thionyl chloride? Surely not on ebay or similar? pardon my curiosity.
\"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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Sauron
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I also buy through the local Acros distributor and sometimes through another Thai company who buy from same distributor. I also deal with them rather
than Merck's local office. There is a local agent for Fluka and Aldrich, although Aldrich is usually ridiculously costly due to Hazmat bullshit not
imposed by European vendors. There are also local agents here for Panreac, Ajax and Carlo Erba.
No agent here for Alfa.
Sic gorgeamus a los subjectatus nunc.
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Klute
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Localpanreac agent in Thailand? I'm impressed! i didn't think it was such abig company. I thought it didn't go further than western europe. Good news
then. Although slightly overpriced in some instance, I have always been very satisfied by their purity and the speed in which the products are
delivered from the plant in Spain to my distributor. It's just a pity that speciality reagents are not pacakged in less than 100-250g, sometimes
500-1000g.
But this is totally OT. Sorry.
EDIT: I just checked, Panreac doesn't seem to sell TCT. Maybe they cna have some on demand, though.
Woelen, are you trying to make MeCl with SOCl2 for academical purposes, or because you need the reagent for a subsequent reaction? I would rather try
the MeBr route in the latter case.
[Edited on 3-6-2008 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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Nicodem
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| Quote: | Originally posted by Nicodem
As for using ligroin instead od CH2Cl2, I just set the reaction and while I was at it, I did not add any pyridine out of curiosity on what will
happen. I do not have ligroin, so I mixed 20ml n-heptane with 30ml petroleum ether (bp 40-60°C). I guess this mixture is quite close to
ligroin by properties. To 50ml of this solvent stirring in a flask was added 2.03ml methanol (50mmol). It took some time, but it finaly dissolved in a
clear homogenous mixture. To this mixture stirring in a cold water bath was then added dropwise a solution of 4.4ml SOCl2 (60mmol) in 10ml petroleum
ether. Not much happened. Some HCl is forming as expected, indicated by checking the exhaust gases with a moist pH paper. I will let it stir for a day
or two and then check the presence and ratios of MeCl, MeOH, MeOSOCl, (MeO)2SO, etc. via HNMR (the alkanes have all signals bellow 1.5 ppm, so it
should be possible to scan the reaction mixture in CDCl3). |
Here are the results…
After letting the reaction mixture stand for two days, 0.2ml were taken for an H NMR analysis in CDCl<sub>3</sub>. There were only traces
of methanol left and only very little methyl chloride formed. The main products are the sulfite esters. Unfortunately I was not able to obtain the H
NMR spectra of methyl chlorosulfite (MeOSOCl) in the literature, but I would lean toward assigning the singlet at 4.05 ppm to this product. In such
case this is the main product and the composition of products in the mixture is:
MeOSOCl (?): 100
(MeO)<sub>2</sub>SO : 33.4
MeCl : 3.7
MeOH : 0.5
<sub> (experimental error not included)</sub>
So I would tend to conclude that this method does not work in the absence of pyridine, though there still is a remote chance that the reaction does
perform differently in dichloromethane and that the absence of S<sub>N</sub>i reaction is due to the very hydrophobic environment of the
solvent used. Or perhaps it is just this specific case of methanol simply not working in this reaction.
…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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Thank you for posting the spectrum, very interesting.
What could be worth a try is doing the reaction in DCM, taking a sample of H NMR, then adding pyridine/triethylamine and retaking a sample. Maybe the
amine will promote direct decomposition of the sulfites, or maybe it needs to be present before introduction of the thionyl chloride for the chloride
to be produced.
\"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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I agree that it would be interesting, but unfortunately I don't have the time for these experiments. I'm currently flooded with work and I did the
above experiment just out of curiosity, as well as for its potential application since a solution of MeCl in an inert, nonpolar solvent could be
useful to me (it is commercially available in gas bottles though).
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