CHCl3 and CCl4 Prep Overview

Sorry about not being sufficiently clear. I read the thread, but the methods presented do not seem like easy methods. The method with CH3OH and HCl seems the easiest one, but there is the effect of back-reaction and I have bad experience with that kind of reactions (crappy yield, messy, hard to isolate). Probably my bad experience tells more about me and my organic chemistry skills, than about the reaction though

Would it be better to add CH3OH to concentrated sulphuric acid and adding some NaCl? Then there is dry HCl. Or does this result in formation of (extremely toxic) methyl sulfate?

Sauron,

The predominent reason cited that CW weapons were not used more extensively and/or operationally, in the PTO was due to volatility and the susceptibility of existing protective equipment to compromise through humidity/sweat transfer. The increased lethality of such agents (predominantly Mustard & Lewisite) also came as a shock to the volunteer's who participated in the trials (predominantly UK, US & Aust, conducted in Nth Queensland) as did the inneffectiveness of the protective equipment supplied for that purpose.

The overview of a book, 'Keen as Mustard' appears second in this link:

http://www.awm.gov.au/journal/j32/bookreviews.htm

Here is another look at the events:

http://www.opcw.org/synthesis/html/s7/p20.html

These show that playing with chemical weapons and the agents used therein, in tropical climates (which I'd imagine would include Thailand?) can have extremely different results and outcomes than would be expected in cooler climates.

PS Nitrates caused more deaths than any other chemical (although the actual cause of death probably could have been more directly attributable to Fe or Pb) during WWI. Germany did not use chemical weapons again in WWII as the prevailing winds were counterproductive (as they found in WWI). The only true chemical weapon used in quantity in WWII was WP (actually misnamed - called WP because the smoke is white, the actual phosphorus used in shells is RP, WP is far too difficult to store safely). Of side interest, the Geneva conventions prohibits the use of proximity (time) fuses on WP rounds, this despite the fact that the fuckers fit on the pointy end of the shell!!! This is because the shells are made to the standard pattern design and use the same case as the HE shells, on which the proximity fuse is designed to fit (interchangeable with the standard instant (HE-Q)/delay (HE-D) fuses normally found on shells straight out of the box).

As an addition (post-edit) is it possible to get this article:

http://www3.interscience.wiley.com/cgi-bin/summary/117873144...

It deals with, inter alia, thiocyanuric acid - as a derivative of cyanuric acid - I'd be interested to see how this occurs.

[Edited on 4-4-2008 by LSD25]

Civility? Do you speak it?

Sauron,

If you suggest that CWC type agents are of some use to you in a tropical climate - I'm fucked if I see any reason why I shouldn't point out the problems with that approach. I am on shaky ground here, 'cos of the fact that Sauron is involved and I'm just gunna get slapped down, so I'll shut the fuck up NOW

What, who me? What? Never...

Next thing you'll be suggesting I'm sarcastic

Iodine is indeed an excellent Lewis acid for certain reactions, perhaps just because it so mild as to prevent certain side reactions that would otherwise occur with such strong acids like AlCl3 (for example, direct chlorination of AcCl to CCl4 ).

But otherwise acyl chlorides enolize so easily that for monochlorination you don't even need any iodine or other acid catalysts. However, if you will want to use TCCA for alpha-perchlorination of AcCl you will probably have to add an acid catalyst to get it go to CCl3COCl at some acceptable conditions, but only experiments can tell.

The mention of PCl3 as a chlorinating reagent is probably a mistake. PCl5 is the reagent used in such HVZ reactions as a replacement for Cl2 (PCl3 is generally not an oxidant). We'll see what the original references say.

Well, yes in theory (read: on paper) the reaction should work even on plain acid due to the equilibrium:
RCOOH + X₂ <=> RCOOX + HX

However halogens dissociate very badly in carboxylic acids and the above equilibrium is way to the left. Using a sodium salt of the carboxylic acid would help moving the equilibrium more toward the right by lowering [HX] by neutralization (that is, by introduction of another equilibrium: RCOO^- + HX <=> RCOOH + X^-. Yet the [RCOOX] would still be too low for a rapid conversion to RX without side reactions prevailing (for example, when the decarboxylation takes too much time most of the formed RX will succumb to the nucleophilic substitution with RCOO^- forming the RCOOR ester). Using a silver salt is optimal since it quantitatively and rapidly forms RCOOX due to the AgX precipitate forcing the equilibrium quantitatively to the right (and still you often end up with low yields).
Surely one could try to use the free acid and exploit the above equilibrium even if far to the left by instead working on making the next step faster:
RCOOX <=> [RCOO* + X*] <=> [R* + CO₂ + X*] => RX + CO₂

Yet that requires irradiation with UV light and I can only guess what other side reaction would such a treatment promote (one for example, is the above thread talked about radical alpha-halogenation of carboxylic acids – the alternative to the HVZ reaction yielding the same products).

I checked if the Hunsdiecker reaction can be used in preparing alkyl chlorides and indeed it can be. However, mind that using silver carboxylates only works with X₂. Here you can not just substitute TCCA instead of Cl₂ since then you ruin the reaction by not having the AgCl precipitation to drive the reaction. TCCA can only work in methods developed for N-chlorosuccinimide (NCS) if you can find one such (and if there exist I bet they are substrate specific rather than general).

PS: Though this is still somewhat on thread topic it is only barely so and with the potential of straying away given it has little relevance for CCl4 or CHCl3 production, so I suggest you open a thread dedicated to the "Hunsdiecker-Borodin-the rest" reaction if you are really interested in it. Surely several members would appreciate if you compile whatever information you have.