curiouschemist82
Member
Hello Soap Making Forum!
This is my first post on the site (although I have been lurking in the shadows for some time now lol). I should start by saying what an excellent resource this site is for soap makers, with such detailed content and expert opinions. Great work everyone!![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
I am a bit of a Newb when it comes to soapmaking (I have been making soap for my family and friends for about a year now). However I am not a Newb when it comes to chemistry. I have a Masters degree in Pharmaceutical Science and a PhD in Organometallic Chemistry and have worked in the chemical industry for years now. I therefore feel somewhat qualified to make the following critique of soapmaking methods (despite being a Newbie soapmaker):
This post concerns the "New" method of making soap from KOH and glycerol (as featured on the Soaping 101 Youtube video and mentioned quite a bit on this site - heralded as a much more convenient method for making liquid soap - and of course it is more convenient).
I find this method interesting on an academic level. Although I am sure that the product which is made by this method creates a very nice 'soap', I have reason to believe that this product is not truly 'soap' (or at least not the "natural soap" that has been made for hundreds of years). Rather than producing a mixture of potassium salts of fatty acids and glycerol, I think this method actually produces a complex mixture of mono- and di-glycerides.
Now bear with me. I am not saying there is anything wrong with the method. I know alot of very well respected soapmakers use this method and the last thing I want to do here is annoy anyone on my very first post on SMF, rather I am just asking a question about the actual chemical composition of the soap made by this new 'glycerin method'.
I have been doing some pondering... Which lead to some scribbling... I know most of you guys aren't chemists and I apologise to everyone for the technical nature of this post, but it is, I'm afraid, unavoidable. I have attached my scribbles for anyone on here who might be chemically inclined.
So, the point I am making is this: when you combine KOH and glycerol and heat up the mixture, you see bubbles. These bubbles are actually water boiling off - water that has been produced by the reaction between KOH and glycerol (the bubbles must be water because glycerol itself has a much higher boiling point - 290 oC). This initial reaction involves KOH acting as a base and 'deprotonating' the glycerol to form a potassium alkoxide species and water.
Now for the fun part: when the KOH/glycerol mixture is combined with the plant oils, it is the potassium alkoxide species that actually reacts with the triglycerides in the oil! "Who cares?" I hear you cry...
Well, I *think* that this will lead to a substantially different mixture of products compared to the 'old', 'cooking for four hours', method. The old method produces potassium salts of fatty acids and glycerol. This new method would, I reckon, produce a complicated mixture of mono- and di-glycerides by a process known as "transesterfication".
So I could sum up this post by saying that the old method is a process of saponification, while the new 'glycerin' method is largely transesterfication reactions.
Now mono- and di-glycerides do make good emulsifying agents and could therefore be used as soap, but *technically* they are not the good, ole fashioned, natural soaps that the hardcore soap enthusiasts love so much...
The files I have attached are very much a simplified representation of what may be going on in the KOH/glycerol reaction. I would love to discuss this further with anyone who is interested because there are several topics which I have not touched upon including; the fate of the alkoxide species formed in this process (which are very reactive and, I assume, are quenched by some of the more acidic unsaponifiable components) and the possibility of the formation of potentially dangerous degradation products of glycerol in that initial step (depending very much on how hot that KOH/glycerol mixture gets). I suppose the 'soap' produced in this new method should be considered safe, because we would know about it by now if it wasn't! But this would certainly be a relevant concern for anyone planning on taking this product to market as it is not technically 'natural' soap (i.e. not composed of potassium salts of fatty acids) and should not be labelled as such.
Phew! Apologies for the long post, but to a chemistry geek like me, these issues matter! lol
I personally will be sticking to the old method of making liquid soap. I do hope I haven't offended absolutely everyone. Of course everything I have said here is just the opinion of a humble chemist and we could confirm or deny all this pretty easily by conducting a full chemical analysis on the 'soap' made using the 'glycerin method'... Correction, the analysis would by horribly complicated, but HPLC, for instance, would certainly be able to highlight the different product distributions (or confirm if they are identical and I am spectacularly wrong in all of my assumptions lol).
Happy soaping folks!
This is my first post on the site (although I have been lurking in the shadows for some time now lol). I should start by saying what an excellent resource this site is for soap makers, with such detailed content and expert opinions. Great work everyone!
I am a bit of a Newb when it comes to soapmaking (I have been making soap for my family and friends for about a year now). However I am not a Newb when it comes to chemistry. I have a Masters degree in Pharmaceutical Science and a PhD in Organometallic Chemistry and have worked in the chemical industry for years now. I therefore feel somewhat qualified to make the following critique of soapmaking methods (despite being a Newbie soapmaker):
This post concerns the "New" method of making soap from KOH and glycerol (as featured on the Soaping 101 Youtube video and mentioned quite a bit on this site - heralded as a much more convenient method for making liquid soap - and of course it is more convenient).
I find this method interesting on an academic level. Although I am sure that the product which is made by this method creates a very nice 'soap', I have reason to believe that this product is not truly 'soap' (or at least not the "natural soap" that has been made for hundreds of years). Rather than producing a mixture of potassium salts of fatty acids and glycerol, I think this method actually produces a complex mixture of mono- and di-glycerides.
Now bear with me. I am not saying there is anything wrong with the method. I know alot of very well respected soapmakers use this method and the last thing I want to do here is annoy anyone on my very first post on SMF, rather I am just asking a question about the actual chemical composition of the soap made by this new 'glycerin method'.
I have been doing some pondering... Which lead to some scribbling... I know most of you guys aren't chemists and I apologise to everyone for the technical nature of this post, but it is, I'm afraid, unavoidable. I have attached my scribbles for anyone on here who might be chemically inclined.
So, the point I am making is this: when you combine KOH and glycerol and heat up the mixture, you see bubbles. These bubbles are actually water boiling off - water that has been produced by the reaction between KOH and glycerol (the bubbles must be water because glycerol itself has a much higher boiling point - 290 oC). This initial reaction involves KOH acting as a base and 'deprotonating' the glycerol to form a potassium alkoxide species and water.
Now for the fun part: when the KOH/glycerol mixture is combined with the plant oils, it is the potassium alkoxide species that actually reacts with the triglycerides in the oil! "Who cares?" I hear you cry...
Well, I *think* that this will lead to a substantially different mixture of products compared to the 'old', 'cooking for four hours', method. The old method produces potassium salts of fatty acids and glycerol. This new method would, I reckon, produce a complicated mixture of mono- and di-glycerides by a process known as "transesterfication".
So I could sum up this post by saying that the old method is a process of saponification, while the new 'glycerin' method is largely transesterfication reactions.
Now mono- and di-glycerides do make good emulsifying agents and could therefore be used as soap, but *technically* they are not the good, ole fashioned, natural soaps that the hardcore soap enthusiasts love so much...
The files I have attached are very much a simplified representation of what may be going on in the KOH/glycerol reaction. I would love to discuss this further with anyone who is interested because there are several topics which I have not touched upon including; the fate of the alkoxide species formed in this process (which are very reactive and, I assume, are quenched by some of the more acidic unsaponifiable components) and the possibility of the formation of potentially dangerous degradation products of glycerol in that initial step (depending very much on how hot that KOH/glycerol mixture gets). I suppose the 'soap' produced in this new method should be considered safe, because we would know about it by now if it wasn't! But this would certainly be a relevant concern for anyone planning on taking this product to market as it is not technically 'natural' soap (i.e. not composed of potassium salts of fatty acids) and should not be labelled as such.
Phew! Apologies for the long post, but to a chemistry geek like me, these issues matter! lol
I personally will be sticking to the old method of making liquid soap. I do hope I haven't offended absolutely everyone. Of course everything I have said here is just the opinion of a humble chemist and we could confirm or deny all this pretty easily by conducting a full chemical analysis on the 'soap' made using the 'glycerin method'... Correction, the analysis would by horribly complicated, but HPLC, for instance, would certainly be able to highlight the different product distributions (or confirm if they are identical and I am spectacularly wrong in all of my assumptions lol).
Happy soaping folks!
![traditional KOH method.jpg traditional KOH method.jpg](https://cdn.imagearchive.com/soapmakingforum/data/attach/20/20045-traditional-KOH-method.jpg)
![New KOH method.jpg New KOH method.jpg](https://cdn.imagearchive.com/soapmakingforum/data/attach/20/20046-New-KOH-method.jpg)