gruns
(Stranger) 02-15-02 06:44 No 269996 |
Iron pentacarbonyl | Bookmark | ||||||
Howdy all, this is my first post, I hope I don't screw it up. Let me begin by saying that I am not a chemist, in fact I know next to nothing about chemistry. I do, however, know how to gather and collate information, and this is what I'm basing this post from. Anyway, I noticed in Rhodium's isomerization article the bit about using small amounts (~1g/200g olefin) of Iron Pentacarbonyl to isomerize olefins. I looked up that Fe(CO)5 and found the following: It's a spectacularly poisonous (causes cyanosis) viscous yellow liquid with an autoignition temp of 50C and a BP of 103C, if decomposed somewhere around 250C it leaves pure iron particles. It is produced commercially by exposing iron to carbon monoxide at 120C under a pressurized, inert atmosphere. Here's what I'm proposing, a method to isomerize small amounts (less than 200g) of olefin in good yield. *Gruns checks his notes* HCOONa --heat--> CO + NaOH (Alternately, formic acid can be added to sulfuric for the same effect, although there'd probably be a little water vapor in there somewhere.) Fe + 5CO --heat--> Fe(CO)5 (280mg Fe + 720mg CO --heat--> 1g Fe(CO)5) CO occupies 862ml/g at room temp/pressure (or so said a commercial supplier of CO, well, actually he said it was .862m3/kg[1]), so the functional limit for each reaction would be the size of the reaction vessel unless you have access to compressed CO. As I said previously, I am not a chemist, I do not yet know the method by which it works [not for lack of trying, I couldn't find a patent for this and I have yet to locate that chemistry journal mentioned in the isomerization text], so the data I work from is the empirical data from the text. Experiment: Under an inert atmosphere charge a 1l vessel capable of being pressurized to 30psi with CO (having a spgrav of .9676), throw in 280mg of iron powder and cap with a stopper allowing for later pressurization. (I realize this is an excess of CO, but as "Bob" always says, "Too much is always better than not enough.") On that, I'm sure that somewhere out there exists a stopper made just for this, but for the purposes of the ghetto, it seems like a one-holed stopper fitted with a bicycle-tube valve stem and held in place with some champagne cork wiring would do the trick. A champagne bottle would probably work well, I don't know what pressures a RBF is capable of handling. In any case, pressurize the container to "1 or 2 bars"[2], or 15-30psi with the inert gas and gently raise the temp to 120C with an oil bath. Once the conversion is complete, remove from heat and chill to as cold as you can goddamned get it, 'cos Fe(CO)5 is some NASTY STUFF, breathing the vapors can kill you, or so says every MSDS I've read concerning this chemical. Once cold, carefully depressurize, decork, add reagents and proceed with the isomerization as detailed by the aforementioned document, adjusted to use 1g of Fe(CO)5. Considerations, questions, requests: Would unreacted Fe affect the isomerization reaction? Would the CO react with the brass in the valve? How long would the isomerization take? Autoignition is only a concern if there's oxygen to burn with...right? Would CO2 work as the inert atmosphere? Nitrogen? Could someone post the full text of the ref in the isomerization text? Is Fe(CO)5 too dangerous to work with, even with the precautions I've listed? Okay, this is total speculation on my part, but, sodium formate decomposes into NaOH and CO upon heating, so, what if one were to place both iron powder and sodium formate into a vessel also containing an inert atmosphere, pressurize... maybe not mix them, but put them in different areas on the bottom of the vessel to heat separately, then the remaining NaOH would be there, ready to assist in the isomerization of the olefin. Unless of course, liquid Fe(CO)5 reacts with NaOH, in which case that wouldn't work. Fe(CO)5 has a lower vapor density than carbon dioxide. [1] - http://www.spectra-gases.com/PureGases/c [2] - http://www.angelfire.com/md/dmdventures/ Pertinent text of latter link, a site discussing the chemistry of using ores and such found on mars as construction materials/precursors for "ordinary" substances. **************************************** Iron Refinement 3Fe2O3 + 9CO +> 6Fe + 9CO2 leaving metallic Iron (((3Fe2O3 + CO +>2Fe3O4 + CO2))) (((Fe3O4 + CO +> 3FeO + CO2))) (((FeO + CO +> Fe + CO2))) Leaving metallic Iron would require some form of electromagnetic separator or rake to remove the Fe from the regolith. Carbonyl However, using Iron Carbonyl production, the Iron is drawn off as a carbonyl vapor. So actually, we do not need an electromagnet... unrefined regolith goes in (maybe sorted by particle size) the mix is heated to 120° C with CO and the pressure is raised a bar or two. The gas is drawn off leaving the SiO2, CaO, etc all as they were. The gas is depressurized and cooled with the Fe(CO)5 condensing out for our use!! Iron Carbonyl Production Fe + 5CO => Fe(CO)5 120° C liquid, vaporizes at modest pressures **************************************** Bonus time. US Patent: 3,091,641 While searching patents for iron pentacarbonyl, I came across a number of them using it as a catalyst for the production of tertiary amines from aliphatic ketones. *boom* I actually found a number of these, most of them under the unassuming title of "preparation of tertiary amines" and using a combination of ruthenium/rhodium/osmium etc carbonyls with iron pentacarbonyl as catalysts, but one of them listed only Fe(CO)5 and CO aside from the usual suspects. If indeed Fe(CO)5 is found safe and effective for the symptomatic treatment of 1-alkenes, it may well turn out to be a big pain in the ass for the suits if the same is true for this reaction. Here's some text to get you wet: The present invention relates o the preparation of tertiary amines and, more particularly, to the preparation of tertiary amines from a secondary amineand an aliphatic ketone by reaction with carbon monoxide and water in the presence of an iron carbonyl catalyst. The reaction can be represented by the following equation: H 0 | || R R" R-N-R' + R"-C-R'"+ CO ---> \ / N-CH + CO2 / \ R' R'" wherein R, R', R", and R'" each represents an alkyl group or an aralkyl group or a cycloalkyl group, the alkyl portion or group containing from 1 to 7 carbon atoms and wherein at least one of the R" and R'" groups is an alkyl group. It is preferred that the groups R, R', R", R'" represent lower alkyl groups containing from 1 to 4 carbon atoms. Unfortunately I can't post the entire text of the patent as it is only available in TIFF format and I don't have an OCR app handy. Please, please, rip this document apart. |
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