CaptainMolo
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Xysyl chloride as a protecting group? Substitute for Tosyl Chloride.
Hello everyone, I was thinking about something yesterday and I wanted to run it by the great minds here at the forums because google searching has
lead me pretty much nowhere on this particular query.
I want to know if I can use the Xylene moiety as a substitute for the Toluene moiety in Tosyl Chloride, creating a compound I've dubbed for lack of a
better term Xysyl Chloride (Xylenesulfonyl Chloride). I want to have access to protection groups, but toluene is somewhat hard to acquire in my area
in an economical and facile manner.
I could distill it from various cleaning/stripping agents, but I would like to avoid this. It's time consuming and not very economical or ecologically
sound.
Toluene only differs from Xylene by one methyl group, so I figure that Xylene most likely has some similar properties in terms of reactivity and such.
Has anyone tried to use this as a protecting group for sensitive reactions? Also if I wanted to pioneer and try this out, is there any good reaction
anyone can think of that is relatively easy to carry out to demonstrate the protection/deprotection of a functional group in question?
I checked eBay and one can purchase Tosyl Chloride at around 500g for $40 USD. This seems a bit high for me, because I try not to spend more than $50
or so per month on this hobby. Xylene on the other hand can be had at the hardware store for around $15 for a gallon. Just a guess but that would most
likely make far more than 500g of Xysyl Chloride.
Any help, suggestions, links to reading material, figuratively anything at all would be greatly appreciated.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. - Albert Einstein
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Boffis
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Its not the price of the hydrocarbon that is your problem its the chlorosulphonic acid you require. Expensive and difficult to obtain.
Or you could go via the lower yielding dry sulphonic acid /or sulphonate salt + phosphorus pentachloride or similar but none of these is easily
obtained or easily prepared in quantity and $40 for 500g is a really good price.
I have a small quantity of 2,4,6-trimethylbenzenesulphonyl chloride that I acquired along with some other chemicals a few years ago so I don't see why
you couldn't use a xylene derivative apart from accessibility. How are you planning to convert your Xylene sulphonic acid into the chloride?
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CaptainMolo
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I don't have the foggiest idea. I don't actually know the ins and outs of how to make Tosyl Chloride in the first place, I mainly wanted to know if
that extra methyl group would bugger up Xylene's potential protective qualities. I may be thinking too hard about this though. I don't actually know a
lot about the mechanics of Tosylate protection.
I think I understand that it's to provide a functional group that's harder for a specific reagent to attack, therefore favoring attack at the target
location, and that it's relatively easy to reverse later to get your target compound. Aside from that basic understanding, I thought there would maybe
be more going on, like the benzene ring on toluene would be preferable to the benzene ring with the extra methyl on Xylene, in terms of reactivity.
Phosphorus Pentachloride is going to be tough for me to get my hands on, pretty much any reactive Phosphorus compound is severely regulated in the
USA.
If you say that price is good for the 500g of Tosyl Chloride, I'm going to defer to your better judgement / experience and buy it when I get the
chance.
That being said, I still think it might be interesting to explore this idea further. If I started by making Xylenesulfonic Acid, would it be as simple
as reacting Xylene and Sulfuric Acid, perhaps at reflux with a drying agent present? This is probably way too simplistic, but perhaps this
Xylenesulfonic Acid could be reacted with elemental chlorine gas, via a gas generator and bubbling it through the liquid? I wonder if one might be
able to photocatalize that reaction similar to toluene and chlorine in the benzyl chloride synthesis. That's probably apples to oranges, but I imagine
that reaction needing a kick somewhere.
Another idea might be to react the two in the gas phase right before a condenser in a convergent system of some kind.
I'm honestly shooting in the dark, I don't have enough experience to say with confidence what direction that should go yet.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. - Albert Einstein
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myristicinaldehyde
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This might help you http://orgsyn.org/demo.aspx?prep=CV7P0508
Chlorination of a sulfonic acid with straight chlorine is, to my knowledge, impossible. Aliphatic sulfonyl chlorides are easier to make: http://www.sciencemadness.org/talk/viewthread.php?tid=9921&a... but it isn't tosyl by far.
If we don't study the mistakes of the future we're doomed to repeat them for the first time.
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clearly_not_atara
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If you can buy 500g of TsCl, it should last you for many months, so it shouldn't destroy your budget. You can make sulfonyl chlorides but there are no
easy ways to do so, really.
If you chlorinate the rxn product of ethyl bromide with sodium thiosulfate by dissolving it in acetic acid and passing Cl2 gas through, you can make
small amounts of ethanesulfonyl chloride, but it's unlikely you're going to buy all of these precursors -- bromide, H2SO4, sodium thiosulfate,
chlorine, acetic acid, and hydrochloric acid -- and build a chlorination apparatus all for under $40.
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CaptainMolo
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All very good points, thank you all for the advice. I will read those articles/threads and crack out the old Vogel organic chem book and see what I
can think up.
I do however have Acetic Acid, Hydrochloric Acid, and H2SO4 already. I wanted to get some Sodium Bromide to have around for bromine anyway, and also
some Sodium Thiosulfate for a variety of reasons, one of which is to get rid of iodine if necessary.
I have a decent selection of glassware and tubing at my disposal, actually thinking more about it, a chlorination apparatus would probably be pretty
easy to set up for me.
Atara: The route you're describing to get to Ethanesulfonyl Chloride sounds interesting. I wonder if it would be viable to brominate Xylene and then
follow up with the Thiosulfate and Cl2 as described.
I'm definitely going to buy my TsCl, but at this point the Xysyl Chloride thing is interesting and I want to pursue it for purely academic curiosity.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. - Albert Einstein
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BezeneBoy
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Sounds good
Your idea sounds pretty good;
The likely reason why we use toluene instead of benzene in the first place is because its easier to produce, and cheaper to produce;
For us normies though, toluene is hard to get nowadays and Xylene would offer the replacement, only gotta watch out over sterric hindrance if you
chose p-xylene as you have a methyl group always next to your acid group; but doubt it will be an issue
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