Somebody was asking about availability of R-11. I'm still working on that - basically, the one refrigeration expert I know here is so busy I can't get hold of him.
I've dug up info on synthesis of the methane-derivative (single-carbon) halocarbon refrigerants. According to Karrer's comprehensive book on Organic Chemistry (4th English Edition, Elsevier, 1950), they are synthesized from carbon tetrachloride. "Carbon tetrachloride, on treatment with hydrogen fluoride and antimony pentachloride gives CCl3F [R-11] and CCl2F2 [R-12] which are used as refrigerants." He doesn't mention CClF3 (R-13), but it seems logical to expect some of that to be produced, too. The products have very different boiling points, so they can presumably be separated by fractional distillation. By the way, I've finally figured out what the designations mean. The first digit is the number of carbons, the second the number of fluorine atoms. Where does carbon tet. come from? It can be synthesized from carbon disulfide and chlorine in the presence of a halogen carrier (e.g. antimony pentachloride, aluminum chloride, iodine...): CS2 + 3 Cl2 --> CCl4 + S2Cl2, or by reaction with sulphur monochloride in the presence of a catalyst (iron, ferric chloride or "other metals" - Karrer) CS2 + 2 S2Cl2 --> CCl4 + 6S Note that the second synthesis path consumes sulphur monochloride, which is a product in the first reaction. Presumably the two processes could be combined to give an overall reaction: CS2 + 2 Cl2 --> CCl4 + 2S And no doubt you're wondering where carbon disulfide comes from. Well, Karrer says: "Carbon disulphide...is prepared by passing sulphur vapour over heated coke (800-900 deg)." I included the carbon disulfide and carbon tet. syntheses only for completeness. Both are widely used industrial solvents, unavailable for years to consumers because of the Nanny State, but still available to industry. I will try to get more details of the R-xx synthesis - how much of each reagent, what temperature, is the pentachloride consumed, is free chlorine produced, etc. Marc de Piolenc Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Please do NOT send "unsubscribe" messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
