That brings up something for me that I was just wondering about (being a bucket chemist as well, and in fact a very ignorant one): what are the reactants in saponification? Is water a catalyst or a reactant there? Is there anything other than soap formed? What is the role of heat in saponification- is it a condition needed for saponification to take place?
Mark At 12:08 PM 8/6/2003 +0700, you wrote: >Hi Marc, > >*When is a catalyst not a catalyst?* > >If your catalyst is partly consumed in the reaction you are promoting then >it is not, by definition, a catalyst! (Hence your use of quotes I presume) > >In the case of methoxides, the problem is surely that they are consumed by >side reactions (notably with water and free fatty acids) which are all >reactions we would prefer not to promote. The methoxides in this case are >very definitely reactants and not catalysts! > >But surely you would agree that methyl oleate is methyl oleate is methyl >oleate no matter which catalyst or enzyme you use to produce it ? > >Current catalyst theory suggests that some catalysts also influence >reactions without necessarily forming any measurable intermediates. It is >supposed that they do this because their topographic surface ionic charge >can "line-up" suitable molecules in close proximity. Do such catalysts >"participate"? I dunno . . . . I'm just a humble bucket-chemist! But I do >take your point that it is unlikely that methoxide works without >"participating" in the transesterification reaction in some way. > >I'm curious about the possible specificity of catalysts in the >transesterification reaction: Are you perhaps suggesting that potassium >methoxide and sodium methoxide can produce a different range of esters from >the same oil? As I said, I have no experience with the use of potassium >hydroxide so your observations would be most welcome. > >Michael Allen >Thailand > >On Sat, 02 Aug 2003 11:16:43 +0800, Marc de Piolenc <[EMAIL PROTECTED]> >wrote: > > >> We don't use potassium hydroxide and I have no personal experience of > >> its > >> use. I'm sure there are other people who read this who can be of more > >> help. > >> However, you may have to explain what you mean by "good". Chemically, > >> the > >> various methyl esters of palm-oil should not be influenced by the choice > >> of > >> catalyst. Afterall, catalysts are not supposed to take place in a > >> reaction > >> are they? > > > > Not quite. Catalysts DO participate in reactions. What makes them > > catalysts (and not precursors or products) is that they are not > > consumed; instead, they are regenerated. Apparently, our "catalysts" ARE > > partially consumed. > > > > And it is not physically impossible for a reaction to show a preference > > for one catalyst over another. To take an extreme example, in organic > > chemistry some enzymes (organic catalysts) catalyze ONLY one reaction, > > and that reaction cannot even take place without its specific enzyme. > > > > Marc de Piolenc > > > > > > Biofuels at Journey to Forever > > http://journeytoforever.org/biofuel.html > > Biofuel at WebConX > > http://webconx.green-trust.org/2000/biofuel/biofuel.htm > > List messages are archived at the Info-Archive at NNYTech: > > http://archive.nnytech.net/ > > To unsubscribe from this group, send an email to: > > [EMAIL PROTECTED] > > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > > > > > > > > >-- >Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ > > > >Biofuels at Journey to Forever >http://journeytoforever.org/biofuel.html >Biofuel at WebConX >http://webconx.green-trust.org/2000/biofuel/biofuel.htm >List messages are archived at the Info-Archive at NNYTech: >http://archive.nnytech.net/ >To unsubscribe from this group, send an email to: >[EMAIL PROTECTED] > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ ------------------------ Yahoo! Groups Sponsor ---------------------~--> Rent DVDs from home. Over 14,500 titles. Free Shipping & No Late Fees. Try Netflix for FREE! http://us.click.yahoo.com/BVVfoB/hP.FAA/ySSFAA/9bTolB/TM ---------------------------------------------------------------------~-> Biofuels at Journey to Forever http://journeytoforever.org/biofuel.html Biofuel at WebConX http://webconx.green-trust.org/2000/biofuel/biofuel.htm List messages are archived at the Info-Archive at NNYTech: http://archive.nnytech.net/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
