# Synthesis of oxalyl chloride that doesn't involve phosphorus

I have been synthesizing TCPO (bis(2,4,6-trichlorophenyl) oxalate) for chemiluminescent reactions, using 2,4,6-trichlorophenol and oxalyl chloride.

Since I am tired of paying for oxalyl chloride (and hazard class 3 shipping), I wish to find a synthetic route to produce my own stock.

The most common synthesis of oxalyl chloride uses oxalic acid and phosphorus pentachloride. This would reduce the cost, but is also problematic because phosphorus chlorides are considered to be drug precursor (21 CFR 1310.02), still too expensive, and hazardous to ship.

Can anyone recommend a synthetic route to oxalyl chloride that does not use phosphorus? Or an alternate (safer / easier / less expensive) route to TCPO?

• I believe you can try to find a route via transesterification. Excess of TCP heated with dialkyloxalate in presence of catalitic amound of strong base should give the desired product. The produced alcolohol should be distilled off to enforce the reaction. I highly discourage use of PCl5 or similar compounds outside a professional lab. – permeakra Jul 26 '15 at 14:44
• I would like to point out to you that TCP, or 2,4,6-trichlorophenol, is carcinogenic and I would not recommend using this. – LiamH Jul 29 '15 at 10:13
• @reluctantmathematician there are several notions of synthesis of acetyl chloride using $\ce{S2Cl2}$. This compound is not much better than $\ce{PCl5}$, but can be prepared from reasonably available and unregulated chlorine and sulfur (Chlorine can be obtained by reaction of hydrochloric acid and bleach, but it should be dried by bubbling through sulfuric acid). $\ce{S2Cl2}$ should work for oxalyl chloride as well. That said, I think that buying oxalyl chloride is preferable, and transesterification is even better. – permeakra Aug 3 '15 at 4:20
• T3P (n-propylphosphonic anhydride) is also another useful coupling agent for esters – Beerhunter Aug 3 '15 at 16:46

The likes of CDI or $\ce{Ac2O/DMAP}$ can react with your phenol when over-stoichiometric amounts are used.