08-17-03 06:06
No 454031
(Edited)
Anyone have some links as to the molar ratio's of potassium permangante to methanol required for 100% conversion? Also, the PH that it should be acidified to would help. Would one acidify the methanol then add the permanganate then distill, or form a solution of acidified water and add permanganate, then combine, and distill?
(Chief Bee)
08-17-03 23:26
No 454180
It won't work, the formaldehyde will be further oxidized to formic acid, among other things.
If you UTFSE you'll see that this reaction has already been tried (with formic acid as the desired product), and the results were not especially great: Post 98271 (ChemHack: "Re: formic acid easy from methanol", Chemistry Discourse)
(Stranger)
08-19-03 11:24
No 454499
Okay. What about a weaker oxidiser, like chlorine gas bubbled through it or something. Any suggestions? Or is there some other way formaldehyde can be obtained from methanol? What about the use of silver catalysts? Could a silver catalyst oxidation be done without needing massive temperatures?
(Hive Bee)
08-20-03 01:27
No 454585
Prepd commercially by catalytic vapor phase oxidation of methanol using air as the oxidizing agent and heated silver, copper, alumina, or coke as
catalysts. Process using molybdenum iron oxide catalyst: Allyn et al., U.S. pat. 2,812,309 (1957) and U.S. pat. 2,849,492 (1958 to Reichhold Chem.). Prepn of stable formaldehyde by heating low molecular polyoxymethylenes with P2O5: Ger. pat. 1,070,611 (1959 to BASF). Mfg processes: Faith, Keyes Clark's Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds. (Wiley-Interscience, New York, 4th ed., 1975) pp 422-429. Prepn of semicarbazone: M. Pomerantz et al., J. Org. Chem. 47, 2217 (1982).
Though it's not a watched precursor...
-mnm
(Stranger)
08-20-03 12:04
No 454679
thanks, i knew the metal catalyst ones, guess ill stick to em :)
(Hive Bee)
08-20-03 13:35
No 454688
How about using the Pfitzner-Moffatt oxidation method?
Pfitzner-Moffatt (http://themerckindex.chemfinder.com/The
It is a mild oxidation method, that will oxidize primary and seconday alcohols to their corresponding aldehyde/ketone. DCC is somewhat more expensive than just buying formaldehyde, but the method is quite practical, as it runs at room temperature under mild conditions.
If formaldehyde is hard to get, maybe DMSO and DCC are also a little to exotic. But the method is quite useable for many sensitive compounds in general synthetic chemistry.
Regards
Bandil
Size doesn't matter, it's the sound you make when hitting the ground after smoking it, that matters!