Stelios, I am not sure I understand what you are saying. I am not saying it wrong, just that I don't follow it. Bob Allen's comment on the water content would definitely cause an apparent difference between the two. I mainly doubt that the positive ion would have an effect on the saponifaction because as far I knew it is the hydroxide ion that initiates saponification and the metal just hung around to balance the charge.
Andy On Fri, 14 Jan 2005 19:24:57 +0200, Stelios Terzakis <[EMAIL PROTECTED]> wrote: > > > Sorry for my mistake there is not indeed any K-Oor Na-O bond, but the > organic mechanism of saponification could suggest an interaction of K+ or > Na+ with the charged oxygen in the intermediate (thus stabilisation of the > intermediate). It is not so easy to say if it hasn't an effect...Anyway KOH > works better for me now. It depends also on what oil you use, costs and on > many other things. > > Step 1: > The hydroxide nucleophiles attacks at the electrophilic C of the ester > C=O, breaking the p bond and creating the tetrahedral intermediate. > > Step 2: > The intermediate collapses, reforming the C=O > results in the loss of the leaving group the alkoxide, RO-, leading to > the carboxylic acid. > > Step 3: > An acid / base reaction. A very rapid equilibrium where the alkoxide, > RO- functions as a base deprotonating the carboxylic acid, RCO2H, (an > acidic work up would allow the carboxylic acid to be obtained from the > reaction). > > > ----- Original Message ----- > From: "bob allen" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Friday, January 14, 2005 6:13 PM > Subject: Re: [Biofuel] Kaliumhydroxide. > > > Let me take a shot at this, even though inorganic chemistry is not my > > forte. > > > > <INORGANIC> Both KOH and NaOH are strong bases, meaning they ionize > > completely in water to metal cations and hydroxide anions. Hence the > > K-OH or Na-OH bond is ionic. In a sense you may say that one is more > > polar on the basis of the fact that Potassium is more electropositive than > > Sodium (K is below Na in the periodic chart) . This means that the > > difference in the Pauling electongativities of Potassium and Oxygen is > > greater than for the Sodium oxygen pair. </INORGANIC> > > > > All that having been said, I don't think that there is any difference in > > degrees of saponification EXCEPT for the fact that commercial NaOH > > contains about 15 per cent water, where as KOH can be had with less than > > 8 per cent water. Without that excess water in the system there will be > > little saponification. That is why you need to be sure and remove as much > > water as possible from WVO before doing the transesterifcation with > > alcohol. > > > > > > > > > > Andrew Cunningham wrote: > > > >>I would like to get a copy of those article. Can you explain what you > >>mean by the K-O bond being more polar? I didn't think that there were > >>any K-O bonds left once the KOH is dissolved (reacted) with the > >>methanol creating methoxide since that acid-bace reaction is quite > >>complete. > >> > >>Andy > >> > >> > > -- > > > > ------------------------------------------------------------------ > > Bob > > /ozarker.org/bob > > ------------------------------------------------------------------ > > ----------------------------------------------------------------- > > The modern conservative is engaged in one of Man's oldest exercises > > in moral philosophy; that is, the search for a superior moral > > justification for selfishness > > -------------------------------------------------------------------- > > --- > > [This E-mail scanned for viruses by Declude Virus] > > > > _______________________________________________ > > Biofuel mailing list > > [EMAIL PROTECTED] > > http://wwia.org/mailman/listinfo.cgi/biofuel > > > > Biofuel at Journey to Forever: > > http://journeytoforever.org/biofuel.html > > > > Biofuel archives at Infoarchive.net (searchable): > > http://infoarchive.net/sgroup/biofuel/ > > > _______________________________________________ > Biofuel mailing list > [EMAIL PROTECTED] > http://wwia.org/mailman/listinfo.cgi/biofuel > > Biofuel at Journey to Forever: > http://journeytoforever.org/biofuel.html > > Biofuel archives at Infoarchive.net (searchable): > http://infoarchive.net/sgroup/biofuel/ > > _______________________________________________ Biofuel mailing list [EMAIL PROTECTED] http://wwia.org/mailman/listinfo.cgi/biofuel Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuel archives at Infoarchive.net (searchable): http://infoarchive.net/sgroup/biofuel/
