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Olive oil and KOH

CHRIS25 - 7-4-2014 at 02:19

Would someone be kind enough to explain to me what I am looking at please?
I have mixed 100g virgin olive oil with 20g KOH in 44.5mLs de-ionized water. This is for the first of two processes to extract oleic acid.
I see three distinct layers in this beaker which holds 150mLs soln and is 5cm depth total. I do not understand these layers nor which one contains the potassium oleate?

Bottom layer is 1cm depth and is a nice clear orange
Middle layer is 0.5cm deep and is a creamy off-white precipitate
top layer is 3.5cm depth and is a non-transparent milky orange.

This is my first ever experiment with fatty acids and touching organic chemistry which I am ignorant about despite having done some preparatory reading. So thankyou for your help.

deltaH - 7-4-2014 at 02:40

I have never prepared potassium soaps from olive oil, but usually when soap making, I blend the hydroxide solution with the oil with a blender until it starts to thicken (known in soap making as trace). At this point you can pour it out into a tub to allow it to react further. When you hit trace, usually the soap sets into a off white mass pretty quickly in my experience.

Not sure why you are seeing layers at this stage... maybe you're not blending it? It's essential to blend it until it starts to thicken because the potassium hydroxide solution will not want to mix with the oil, but by blending you get miniscule droplets of it forming in suspension which greatly increases the surface area for reaction between the two phases and allows the reaction to start causing it to stiffen up and lock the micro-droplets in place.

Just how long one needs to blend varies widely and depends mainly on the temperature of the blend, the type of oil and the concentration of the caustic solution and nature of the blender, but don't be surprised if it takes a few minutes. Don't leave it unattended though when blending because when it starts to thicken at trace, it will thicken rapidly thereafter that can burn out a blender if you don't turn it off!

In the hot method of making soap (fastest method), one can leave the soap in a slow cooker for a few hours to react further/completely after achieving trace using a blender, in the cold method it takes much longer (sometimes days).

A handheld blender works very nicely for reaching trace... but be warned, wear old clothes, rubber gloves and eye goggles and work outside because of the possibility of spatter of very caustic, viscous and sometimes hot material that burns like hell! Bad caustic burns are very painful and take long to heal.

In cold soap making, the soap is usually cured for several weeks after cutting into blocks, but this is not necessary in your case as you would probably not mind the presence of small amounts of potassium hydroxide as you will be neutralising/acidifying everything with HCl afterwards anyhow to get your oleic acid.

Finally, if you're wondering what trace looks like, it's kind of the consistency of soft margarine.

Hell I'm probably going into way to much detail here, my apologies if so!

[Edited on 7-4-2014 by deltaH]

CHRIS25 - 7-4-2014 at 03:21

Oh, no I did not blend it, just stirred it two or three times and then sat down. Thought that the potassium oleate would be there to filter off - simply did not understand this at all. thankyou for your help, so I presume that once I have blended it I need to wait a few weeks before mixing with the acid? Or can I begin the second phase after blending, which seems logical at this moment but I could be wrong?

deltaH - 7-4-2014 at 03:26

At trace, the saponification reaction has only just started (hence the name). Thereafter you have two choices, if you're in a hurry, pop it in a slow cooker and leave it for a few hours (several?). When it's done, you should have a solid mass of off white soap (colour varies depending on oils used so don't worry if this looks slightly beige or whatever, the point is it should resemble a solid mass of... well soap

The second choice is the 'cold method' which entails pouring out the trace soap into a mould, waiting overnight for it to set, then cutting it into blocks and waiting a few days for saponification to complete at room temperature.

If you intend using your soap for bathing (you may well want to when you start making these), please do leave it for several weeks to cure once cut into soap sized blocks and placed on a rack. This is to ensure that small amounts of potassium hydroxide remaining react with CO₂ to make potassium carbonate and also to dry the block. Else you will have a very harsh soap that will wrinkly your skin quickly and even burn/peel it!

Whatever the case, do not proceed to stage two until you have a hard mass of soap, either by using a slow cooker or letting the blocks sit for a few days in the cold method.

[Edited on 7-4-2014 by deltaH]

CHRIS25 - 7-4-2014 at 03:40

Ok then Thankyou very much. I only need to do this for oleic acid and not for bathing, I used ratios of KOH to olive oil allowing a 3% more KOH, which is not recommended for soap making, they usually say a bout 5% less than the SAP chart calculations, anyway, I thank you for your help here.

deltaH - 7-4-2014 at 03:45

My pleasure CHRIS25. Please post some pics of your stage one, I'm curious to see what a potassium olive oil soap looks like. Also, a photo of the trace stage may be useful for others attempting the same. BTW, olive oil soaps are also known as Castile soap after the region in Spain where they were origionally made.

[Edited on 7-4-2014 by deltaH]

CHRIS25 - 7-4-2014 at 04:30

Glad to be of some use. This is literally a minute after blending. Will post image after 24 hours. should add I blended till the top layer looked like speckles were dripping from the blender blade, this took about 6 minutes at top speed.

[Edited on 7-4-2014 by CHRIS25]

deltaH - 7-4-2014 at 05:13

Thanks! You're on your way...

It's hard to tell from the photo, but it looks like you're still a little shy of a good trace, but if it's firming up homogeneously, then you're set (excuse the pun).

If you're going the cold route, I'd wait a few days before doing your stage two just to ensure saponification has run it's course, but you should have a firm block by tomorrow already.

[Edited on 7-4-2014 by deltaH]

macckone - 7-4-2014 at 05:23

One note is that potassium based soaps are usually liquid. It generally won't set like a sodium based soap. Since you are trying to separate the raw acid, then you should really use the sodium hydroxide because the potassium base soap won't separate the glycerine like sodium hydroxide will. You can separate it but it will be difficult.

*added link*
ps. The following link is a good tutorial on liquid soap. Notice there is no step for separating the glycerine. You need a solid soap for that although in theory you can separate the glycerine in practice it isn't practical. Once you have pure soap then you would back titrate with acid to give the oleic acid.
http://chickensintheroad.com/house/crafts/how-to-make-liquid...

[Edited on 7-4-2014 by macckone]

deltaH - 7-4-2014 at 05:36

macckone, when making liquid potassium soaps, does one not nevertheless need to add quite a bit of water to make it liquid as I recall? I think the amounts op used should result in a firmish soap.

Secondly, the residual glycerine should not be a problem, because in stage two, he's going to dissolve this up in hydrochloric acid and the glycerine 'should' simply go in the aqueous phase together with the water and KCl.

If the potassium soap doesn't come out rock hard, that's a bonus because he still needs to dissolve it into the acid in phase two of his process.

[Edited on 7-4-2014 by deltaH]

CHRIS25 - 7-4-2014 at 05:41

Thankyou Nicola, it is already firm. macckone, the tutorial is very well presented. A good link. I take your point about Sodium and Potassium and actually only chose the potassium hydroxide because it is lab grade, whereas my sodium hydroxide is commercial. That was the only reason, but I take your point if I have to do this again which I probably will.

deltaH - 7-4-2014 at 05:47

Best of luck CHRIS25 and keep the photos coming, I love them!

CHRIS25 - 7-4-2014 at 06:35

Quote: Originally posted by deltaH

Best of luck CHRIS25 and keep the photos coming, I love them!

Well you are going to love this one, any hard to remove stains?
After two hours it had eaten away at my otherwise very strong plastic container.

also read a whole list of plastics with names I can not pronounce that are resistant to KOH plus a whole list that are not resistant. But now it's eating its way through a new york pizza box! Time for damage control.

[Edited on 7-4-2014 by CHRIS25]

HoH - 7-4-2014 at 11:45

Generally speaking, KOH is the hydroxide for liquid castile soap. NaOH is used for making bar soap.

A good recipe for organic liquid castile soap (I made 2 gallons of the stuff last week).

-In a stone or glass pot, 6oz of Vegetable glycerine is heated to 200f at which point 3oz of KOH is stirred in. An exothermic reaction occurs and 95% of the KOH goes into solution.

-In a separate pot, 13oz of olive oil, 1.5oz of coconut oil, 1.5oz of castor oil, and whatever essential oil you choose for fragrance (roughly 15g-28g worth) is added and heated to form a homogenous solution.

-With a blender in hand, the olivel/coconut/castor oil mix is added to the vegetable glycerine/KOH mix and both of these phases are intimately mixed and heated and then allowed to cool until a solid concentrate is formed. This concentrate needs to be mixed with 2 parts water. Apply heat to ensure complete dilution of the concentrate into the H2O.

-Bottle and age for at least a week allowing the liquid soap to cure.

This makes a very high quality liquid castile soap that is suitable for washing your face and your privates.

CHRIS25 - 7-4-2014 at 12:23

Kind of you to take the trouble to tell me this. 2 gallons? wow someone needs cleaning. Anyway I am synthesizing oleic acid and will be using NaOH as already suggested. If you see no more images up here that means I bought the darn stuff...but stubborness and desire to learn invigorates my determination to make it.

macckone - 7-4-2014 at 12:40

Use high density polyethylene or stainless steel for a container.
The stainless steel is a better choice as it is practically impervious
to hydroxides while polyethylene will eventually be damaged.
Your mileage may with other plastics as you discovered.
For the acid stage polyethylene or glass is pretty much the only
way to go. Glass is also usable for the soap stage but will
be damaged by the hydroxide if it sits too long.
As for separating the soap from the glycerine, it depends on
how pure of a product you want. Using HCl will cause some
glycerine to partially return to the ester form so you won't have
pure oleic acid. Good luck with your damage control.

deltaH - 7-4-2014 at 12:42

CHRIS25, put your soap in a polypropylene or polyethylene tub asap, they are marked PP or PE respectively.

Yeah many plastics are not resistant to strongly caustic agents, especially anything that is designed to be biodegradible. Polyesters, for example, have exactly the same type of bonds as in your oil, and they too can easily be saponified just like your oil

Well done with stubbornly perservering, chemistry is annoying that way! Come on, we want to see you win!

**********************************************
macckone, op will be using it to prepare ferrofluid, so I doubt small amounts of reformed fatty esters would cause any problems.

CHRIS25, if you like, we could advise you how to remove this glycerine and purify your soap using a 'salting out' technique. You only need a piece of cheese cloth and table salt to do this.

BTW, you also mentioned earier that you didn't want to use the commercial lye you had because of purity concerns as opposed to the KOH you had which was 'lab grade'. I wouldn't worry about this too much, commercial lye is usually quite pure and significantly cheaper.

[Edited on 8-4-2014 by deltaH]

CHRIS25 - 8-4-2014 at 05:49

Hallo, well second attempt using NaOH failed. It quite literally did not trace after 45 minutes of mixing, compare this with 10 minutes yesterday. Anyway after carefully checking calculations and backtracking the only thing I could think of was the fact that I used the last 91grams of olive oil from the bottle and this was 'dregs' so to speak. It was a slightly different colour, did not flow easily and seem divided into two products when I noticed it; a creamy globular precipitate surrounded by a bit of 'clearish' oil, not the same flowing consistency as yesterday, I did not think that this would matter, but I suppose that must have been the reason. There is a sale on this saturday with extra virgin oil (yes I have read about the huge world wide corruption in the olive oil trade fooling even the big supermarkets) but nevertheless I will but a few big bottles and check the exp date has at least two years and if it is in a dark bottle, best I can do. So postponement until saturday. Two things, yes I might as well go the full way and do the salting out technique, another thing to learn is always good. Also macckone mentioned back titrate. Now this was naturally the only thing I was unsure about, How to know How much HCl to use, and at 12M or dilute? Since this is not a reaction that I am used to in terms of inorganic stoiochemetry I am afraid I need some advice on this.

So:

C60H104O6 (920g/mol) + NaOH (40g/mol) = C18H2O2Na (320)

C18H2ONa + HCl (36g/mol) = C18H34O2 (283g/mol)

Using 12g NaOH and 91g olive oil in 31mLs H2O (Using SAP value of 0.1353)

Assuming my maths is correct then NaOH concentration is here is at 7.3M and contains 0.3 moles.

And the First part of the reaction runs thus:

10.12g (0.11 moles) + 12.3g (0.3 moles) = 31.6g (0.098 moles

Now of course this is confounded by glycerine and other fatty acids and therefore in practise is undoubtedly bizarre, but this is how I have been trying to control and get things organised. But naturally gives me no indication about how much HCl to use to get the final product.

deltaH - 8-4-2014 at 06:55

Hiya CHRIS25, olive oil is a sluggish oil for saponification because of it's relatively low saponification value. May I suggest that you warm the oil before blending to speed things up (c.a. 60C?), that should help.

Purifying soap with a salting out technique is fairly easy, though each soap is somewhat different and I can only give you a general guideline. Dissolve your potassium soap in boiling water. I don't know exactly how much you will need. Usually, some soap won't dissolve, this is normal, so don't just keep adding tons of water to try to get it all to dissolve. There is always some un-saponifiable matter in oil as well as low solubility long saturated fatty acid soaps. I normally just fish this out as it tends to clump together and float on the top.

Then to salt out, wait to cool down (but shouldn't set again, if so add a little more water). Then add about a quarter of the weight of the water you used as table salt and stir for a while. You should form masses of soap again, but this time as granules. This is because soap is only sparingly soluble in water and as an organic compound, it separates when adding large amounts of an ionic solute. When all's done, filter through cheese cloth and squeeze as much of the liquid out as possible by twisting the cheese cloth like a tourniquet. You should be left with a lighter lump of soap in the cloth. Squeeze tightly!

Almost all the glycerine will now be in the water salt phase and you should have a mass of purified olive soap in your cloth. You can use this mass for your next acidification stage.

[Edited on 8-4-2014 by deltaH]

CHRIS25 - 8-4-2014 at 09:02

Absolutely you may suggest...Will do that Saturday and then sunday will upload the images. Thankyou for that salting out technique, I will do that as well. You have been most helpful and I appreciate this. googling this yields a wealth of information I have never heard of, thankyou.

[Edited on 8-4-2014 by CHRIS25]

CHRIS25 - 12-4-2014 at 09:37

Five Hours and still waiting...................

Etaoin Shrdlu - 12-4-2014 at 10:11

Is the NaOH actually NaOH? Is it cut with something? I don't see why it would be as it's an extremely common extremely cheap commodity chemical, but you really shouldn't be having any problems here as long as you're mixing. You do generally need to keep mixing for the soap to trace properly. Heat helps as well. You can use it to finish things off within a day instead of letting the soap sit at room temperature for weeks.

Does the solution of NaOH/water heat up significantly when you make it up? If not there's definitely some problem with the chemical.

Can I ask the source of olive oil and NaOH? I'll try this on a small scale once I get back home and see if I wind up having similar problems, but I don't recall anything of the sort the last time I made olive oil soap (admittedly many years ago). I don't think the problem is with the olive oil since you got it to trace properly with KOH...

deltaH - 12-4-2014 at 10:29

Wow CHRIS25, you really know how to persevere! This doesn't seem right at all though, I agree with Etaoin Shrdlu, something is really amiss, probably with your NaOH? If your NaOH has been exposed to the atmosphere due to poor sealing or some such, then it would have converted to washing soda which is sodium carbonate and that would not saponify the oil.

The NaOH should have the appearance of semi-transluscent flakes or pearls (usually little beads but sometimes larger). It should not be a mass of white completely transparent or otherwise wet looking crystals, nor should it be completely white powder, but rather semitransparent 'waxy' looking solids.

Please confirm this and Etaoin's question about the heating when dissolving the lye in water and we should be able to help you debunk this. He is quite right, sodium hydroxide (lye) heats up a hell of a lot when added to water, usually causing it to steam at the concentrations one prepares for soap.

Be sure that your tub is sodium hydroxide, sometimes named 'caustic soda' on commercial tubs and not sodium carbonate, sometimes marked 'washing soda'. I once made the mistake of accidentally taking the wrong tub of a brand that were side by side, but quickly noticed my mistake after opening it, see my appearance description above.

[Edited on 12-4-2014 by deltaH]

CHRIS25 - 12-4-2014 at 11:16

Hi Guys. Ok, Firstly I can assure you that the caustic soda is NaOH, Dry and kept tight. It is flowing balls! And yes, I used according to SAP figures 40grams (just happens to be 1mole) in 94mLs distilled water (very very hot) and that was mixed with 300grams olive oil. This oil is Primadonna from Spain, and is extra virgin. Though the chances are 90/10 that it is not extra virgin and even mixed with sunflower oil, you simply can not tell anymore. Secondly I have used this to titrate other things and everything adds up and I have just used it to make sodium sulphate with theoretical yields matching actual yields within a 5% error margin. I have just poured all the Soap into silicon dishes and covered for the night, it did get thicker, but not 'gooey' thick, it did look traced after one hour of posting the image. If it is not traced I would imagine that I will wake up to oil floating on top of a yellow mush tomorrow morning?

I still do not know how to measure out the correct amount of HCl, i presume to put a fairly concentrated amount in until I see a precipitate, since oleic acid is insoluble in water, I suppose I had better use a fairly dilute soln HCl maybe just 1M?

deltaH - 12-4-2014 at 14:27

I'm truly amazed! Normally when making olive oil soaps, one always blends the olive oil with other fats that contain more medium chain triglycerides... now I know why... the long chain fatty acids simply saponify too slowly on their own under mild conditions it would seem.

I will ask you a funny question now: do you have a pool shop near you or a decent pool section at a hardware store or supermarket? If so, have a look at the algaecide products, specifically one for black algae (usually labelled as such). Then have a look at the active ingredients, see if you can find one that says it's based on something called dimethyldidecylammonium chloride or a similar name to this without other ingredients beside water. I will explain to you further how you could use this to possibly speed up your reaction greatly, employing it as a phase transfer catalyst, but only if you can find this OTC in Ireland as we can in South Africa.

As for the concentration of the acid you would use, experiment, 1M should be a good start I would guess.

[Edited on 12-4-2014 by deltaH]

CHRIS25 - 12-4-2014 at 14:56

Wow. I will definitely find some reading about this, very interesting. Thanks. I will visit a shop that I know and rummage, and will let you know if I find anything, naturally.

[Edited on 12-4-2014 by CHRIS25]

deltaH - 12-4-2014 at 15:12

Phase transfer catalysis is very interesting indeed. Normally chemicals like tetrabutylammonium chloride are used, but it's not the only substance that works, many other quaternary ammonium salts work, the dimethyldidecylammonium chloride is simply one I happened to notice in an OTC product and so easy for amateur chemists to get their hands on.

The way it's suppose to work is that it forms dimethyldidecylammonium hydroxide in the presence of concentrated NaOH, but the quaternary ammonium salt is quiet lipophillic, that is to say oil loving, and so dissolves in the oil phase pulling in the hydroxide ion as it goes where it can saponify the triglyceride forming dimethyldidecylammonium oleate and glycerine. The phase transfer catalyst then shuttles the oleate ion back to the aqeous phase where the sodium hydroxide solution sits and there exchanges this for another hydroxide ion and forms sodium oleate in turn and so the catalytic cycle completes, on and on and on.

Long story short, adding a small amount of a fairly concentrated dimethyldidecylammonium chloride solution to your soapmaking mix should speed things up... in theory

You will have a small amount of contaminant by way of the phase transfer catalyst, but this should not be a problem for you intended application of ferrofluids.

General Tip: MSDS's of products are often great sources to find out the rough concentration and composition of ingredients on commercial products that may otherwise not report much on the bottle. Not always the case, but often so.

[Edited on 13-4-2014 by deltaH]

Etaoin Shrdlu - 12-4-2014 at 17:22

I just tried this with 1.533 g of NaOH (Elemental Scientific), 15.33 g purified water (my RODI unit), and 11.53 g extra virgin olive oil (local grocery, Piggly Wiggly brand), mixture heated on stovetop at ~60°C with occasional very thorough mixing. It was at trace within 30 minutes even with the overabundance of water which tends to goof things up. Are you heating yours at all?

CHRIS25 - 12-4-2014 at 23:28

Some quick reading about this suggests that the soap making industry does not use PTC, and yet I did find references where it was being used. The long and short of the impression that I got was that when used the reason given was mostly 'speed' and 'better yield' . Etaoin, Hi, The problem is most likely the quality, and I did heat it up at the beginning, but never kept it warm. Even cold it should not have taken this long I imagine, besides I would never have learned about PTC's. Maybe you should try your same product cold? If it takes only say 1 1/2 hours then we know I have an oil suspect of being corrupted either purposefully or not.. Also ""and 11.53 g extra virgin olive oil"" I am sure that the amount you used has an effect on time- I was using 300grams. The other day I did it with KOH and a different olive oil, that took only 15 minutes. (100grams).

[Edited on 13-4-2014 by CHRIS25]

[Edited on 13-4-2014 by CHRIS25]

deltaH - 12-4-2014 at 23:42

If we assume the rule of thumb that for every 10C, the rate of this reaction doubles, then if Etaoin traced in 30 minutes at 60C, CHRIS should hit trace at 20C in 8h

This sluggishness also suggests that one has to be careful to make sure that the reaction runs to completion ultimately. I would definitely suggest that you don't use a cold method of making soap for this one unless you plan to age your bars for weeks!

Slow cookers work well if you have one, alternatively you can try an oven warmer. You would want to aim to keep the soap at about 80C for several hours after getting it to trace. Don't go too hot or the glycerine may decompose to foul smelling and toxic byproducts.

Alternatively, you can try a phase transfer catalyst if you can find a suitable compound OTC. But honestly, it just looks like you need some patience and elevated temperatures.

CHRIS25 - 13-4-2014 at 00:12

Ok Nicola, thanks. A learning curve in all this. But appreciations are on their way to the sunny tip of africa, although they might evaporate a bit along the way.

Fan oven seems good to consider, but will pop to the shop this morning when it opens. After 12 hours covered the soap has thickened but I can still slide my finger into it quite easily. Thanks to Etaoin macckone and HOH who have contributed.

CHRIS25 - 13-4-2014 at 03:38

As I suspected and expected here in the land of sheep and goats, this major outlet has majority of its fungal and algal mixtures in spanish and german, although some ingredients in English, none of them the Didecyl Dimethyl Ammonium Chloride, most of them have a butyl in their name, and certainly no ammonium chloride. Anyway no matter. I can get 500mLs for 18 euros which is 50%. I presume this is perfect since it comes from a Lab supplier. Is the 50% ok?

deltaH - 13-4-2014 at 04:00

Can't think why not, but only experimenting can confirm. Also if you're gonna go the non-OTC route, you may be well advised to search the literature online for recommended phase transfer catalysts specifically for saponification (ideally also of long chain triglycerides). In this case, I'd be shocked if it's not been extensively published and practiced already.

As for the thanks, no need, always a pleasure if I can be helpful.

[Edited on 13-4-2014 by deltaH]

CHRIS25 - 13-4-2014 at 09:31

I suppose as a last note I started reading everything I could about this product and saponification using quartenary ammonium compounds. After 2 days I am exhausted. I could not find a single document that mentions Didecyl dimethyl ammonium chloride in relation to any saponification process. The only recurring thing was this product as a disinfectant to be diluted and put into many hundreds of cleaning products. The only references to saponification I found were with DD ammonium bromide. But all of these were heavily analytical pdfs that were really way above my understanding. Practically all the research led me to references to general quartenary ammonium compounds with analysis on all sorts of fatty acids. Too much for me to understand. So Hot method next time and more patience. Or I might just bloody well buy the oleic acid, and I feel very defeated right now. Thanks though, I have learned quite a lot.

deltaH - 13-4-2014 at 11:18

Don't worry CHRIS25, when you're tackling problems like this, it can be tough when one is not following a known recipe (appologies if this sounds patronising, it's not meant as such). It's normal to feel overwhelmed and dishearted, but when you have success, you will be equally elated! May I suggest you take a step back and switch off from this for a while, I do this often and it helps to avoid a burn out with a particular set of challenging experiments.

Quote:

The only references to saponification I found were with DD ammonium bromide.

This sounds very good, the anion in this case shouldn't matter much. Can you attach that reference for us all to see please?

Don't feel defeated and make no mistake, what you are trying to do is admirable!

[Edited on 13-4-2014 by deltaH]

CHRIS25 - 13-4-2014 at 13:27

Yep I will certainly try again. In the meantime here were the two references, as vague as they seem to me. If they are completely off the beaten track then please forgive me, I have no knowledge of organic chemistry and have little idea about what was being written. However, I am setting myself the task to understand anionic and cationic surfactants and non polar and polar heads and tails - you get the idea, But I already have a question and it is bugging me, having learned about this so far, I can not understand why citric acid is listed as a surfactant especially with ferro fluid when quite clearly by definition it does not appear at all to qualify as a surfactant. If you do know, simple language to begin with thanks ever so much, if you do not know (I know you are a chemical engineer though) then I will post this as a separate question.

http://www.ncbi.nlm.nih.gov/pubmed/11441600 (in the abstract)

http://www.google.st/patents/WO2010047705A1?cl=en (Second column claim number 4)

deltaH - 15-4-2014 at 04:08

I think I can answer your citric acid question...

While the term surfactant is commonly used to refer to soaps by most of us, they use it in a more specific way here because what they mean is that the citric acid acts on the surface of the nano particles by adsorbing onto them and modifying its surface charge so that the particles repel each other and form a stable colloidal solution. In this sense, it is a 'surface acting agent', but not in the sense you and I may commonly know or refer to the term surfactant, yet this is nevertheless correct.

The theory behind this is somewhat complex and has to due with surface charge and zeta potentials.

A very big problem in preparing colloidal solutions, that is to say a suspension of very small particles that are stable and remains dispersed, is to prevent the microscopic particles in the suspension from sticking together forming larger particles and ultimately settling out.

Surfactants play an essential role in stabilizing these particles and keeping them dispersed, in fact, in this context, they are often referred to as dispersants.

Thanks for the articles:

The second one is of no use, it's about inorganic ammonium salts, phase transfer catalysts make use of organic ammonium salts, something called quaternary ammonium salts in organic chemistry.

In that sense, the first article looks promising. While we are not very interested in the ultrasound (assume you don't own an ultrasonic bath), the articles does investigate the use of a few phase transfer catalysts to speed up the kinetics of saponification. It would be useful to consider their findings, I suggest you politely request this article in the publications section.

[Edited on 15-4-2014 by deltaH]

CHRIS25 - 15-4-2014 at 06:01

I am doing quite a lot of investigation into fatty acids, it's proving to be an unexpected area of interesting reading for me. I have even mapped out the stoichiometry for all these reactions, something I could not do a few days ago and one of my previous posts with this now seems embarrassing in retrospect. Thankyou for responding to the citric acid.

The olive oil soap has hardened after three days, no residues or oils since I took a 19gram sample and it looked perfect, the ph is certainly above 11 still. Anyway I placed it in a 3M solution of HCl (Lab Grade SG 1.18), absolutely nothing happened, the soap just floated there quite happily even after breaking it up. No dissolving, no precipitation, the acid had no effect. I am assuming then that I must wait some weeks for the PH to drop to at least a 9 or 9.5. before the acid will break up the soap and the H+ ions from the Acid are able to take over where the Na+ ions were?

As for the first article I have no authority to ask this, especially since I do not know anything about what I am asking to be submitted, would people in the organic chemistry dept be interested do you think?

deltaH - 15-4-2014 at 10:37

Quote:

...absolutely nothing happened, the soap just floated there quite happily even after breaking it up. No dissolving, no precipitation, the acid had no effect.

I think your castile soap is so hellishly insoluble that it's struggling to react/exchange ions with the HCl because it needs to go into solution first. Don't forget, the salting out principle doesn't only apply to salt in solution, a fairly concentrated solution of HCl is just as ionic as a salt solution because HCl dissociates fully in water by this reaction:

HCl(aq) + H₂O(l) => H₃O⁺(aq) + Cl^-(aq)

So, what you might be seeing is the same thing as if you tried to dissolve a lump of your soap in 3M salt solution... it won't budge.

What I can suggest is to first try and dissolve as much of your soap as you can in clean boiling water, see how much goes in... hopefully it's usable amounts. Then fish out what doesn't dissolve and while hot, pour that soap solution in into your HCl solution while stirring quickly. The ion exchange reaction should be very fast and hopefully you will get your free fatty acid separating out. You may need to wait some time for the separation to take effect and get two layers, you may just see milkiness at first because the droplets are too fine, hopefully they coalesce... (cue ominous music)

As for the publications, I was talking about the sub forum here in SM reserved for that purpose, you need to request permission from Polverone though with a polite and short U2U message.

At any rate, if you got a hard bar after a few days, you're on your way, so no need to make it with a catalyst anymore.

Don't expect the pH to necessarily come down below 11, as I recall, you used a little excess lye. One can normally see this as it forms a powdery layer around the bar after some time as sodium carbonate effloresces.

[Edited on 15-4-2014 by deltaH]

CHRIS25 - 16-4-2014 at 05:04

Finally!
Total amount soap made from 300g Olive oil = 419.2g
30.9g soap needed 200mLs de-ionized water to dissolve
Required 60mLs 6M HCl to precipitate Oleic acid (though 20mLs extra added to ensure everything was done)
Crude Oleic acid precipitated whilst wet 34g ( sticky and gooey )

Out of the chemicals that I have CaSO4, MgSO4 or Anhydrous NaSO4 would be suitable desicants.

Looking at images of Oleic acid on the web at least my colour is consistent. But could not find any anhydrous images.

Just been doing some calculations based on:
HCl + C18H33NaO2 = C18H34O2
Converting everything I did stoichiometry wise I find that I used:
0.1 mole Acid + 0.1 mole olive oil gave me 0.098 mole oleic
which confirms the above amounts dissolved but the yield is far far less than expected, (unless someone spots an error in my thinking)

Order of Images:
Well it was the only mold I could find
Dissolving
Filtered solution
Precipitation
Left over did not dissolve
Crude oleic acid - I hope

[Edited on 16-4-2014 by CHRIS25]

[Edited on 16-4-2014 by CHRIS25]

deltaH - 16-4-2014 at 07:12

Nice photos CHRIS and well done! I was surprised to see that the product was a solid.

One question... what is the saturated fat content of the olive oil you used (you can find it on the label of bottle)?

If I understood you correctly, your yields are excellent, although they still probbably contain a lot of acified water in between the gooey mass.

It should melt when you heat it... does it?

Quote:

Just been doing some calculations based on:
HCl + C18H33NaO2 = C18H34O2
Converting everything I did stoichiometry wise I find that I used:
0.1 mole Acid + 0.1 mole olive oil gave me 0.098 mole oleic
which confirms the above amounts dissolved but the yield is far far less than expected, (unless someone spots an error in my thinking)

I think you left out the NaCl on the RHS of your equation. Also, do you not mean 0.1 mole sodium oleate, instead of 0.1 mole olive oil?

Finally, by my back-of-the-envelope calculation, you only needed about 20ml 6M HCl (with a little excess) to exchange 32g sodium oleate (assuming your soap is sodium oleate... close enough

)

[Edited on 16-4-2014 by deltaH]

CHRIS25 - 16-4-2014 at 07:42

Hallo, Firstly it melted within 25 seconds of entering luke warm water (in a beaker of course). The solid had the consistency of extemely thick hand cream (if there is such a thing). Now it has melted it looks like melted ice cream. It can be poured albeit very slowly, though i boiled it for a second or two and saw separation of water and what appeared to be a miniscule amount of oil?. I shall dry it with MgSO4 in a homemade desicator.

Yield? 1 mole HCl reacts with 1 mole sodium Oleate to give 1 mole oleic acid. Yep I missed my own pat on the back, wow.

The contents on the olive oil are:
saturated = 13.7g per 100mLs
monounsaturated = 71.1g (The oleic is here)
polyunsaturated = 6.4g

Right now I get it I will have to adjust all my calculations because this means that there was 213g theoretically in my 300g of oil used. Am interested to see how it dries.

deltaH - 16-4-2014 at 07:48

Yes, you can certainly pat yourself on the back, yields appear to be excellent, though they are crude yields.

The reason I asked about saturated fatty acids is because they melt at a much higher temperature, 60-70C depending on chain length. Their presence would raise the m.p. of your crude oleic acid and could explain in part, the firmness of the product, though you say the melting point is nevertheless quite low... which is good.

WELL DONE AGAIN!

[Edited on 16-4-2014 by deltaH]

CHRIS25 - 16-4-2014 at 08:07

well thanks nicola, and I did not know about having to melt it first. though I was aware of the meting point. what is m.p.? Yes the meting point was literally luke warm water, I did not take a temp reading. though I will be doing next batch with extra precision. if possible in a kitchen, and will purify the soap next time round with the salting out technique. Thanks so much for all your help, the learning process is far less stressful when you get someone, such as yourself, giving little nudges in the right direction, then I can target the research and understanding more efficiently.

""""Also, do you not mean 0.1 mole sodium oleate, instead of 0.1 mole olive oil""""? Yes I did sorry.

[Edited on 16-4-2014 by CHRIS25]

deltaH - 16-4-2014 at 08:15

Always a pleasure CHRIS and yes m.p is an abreviation for melting point.

CHRIS25 - 16-4-2014 at 08:20

Quote: Originally posted by deltaH

Always a pleasure CHRIS and yes m.p is an abreviation for melting point.

CHRIS25 - 17-4-2014 at 02:24

After 24 hours the off-white crude oleic acid had simply begun to turn into the same viscosity as a soft hand cream. It was supposed to crystalize at room temperature after melting it, then placing it in a desicator with anhydrous MgSO4. Nothing, and the MgSO4 had not absorbed any visible moisture.

So this morning I placed it in my home made hot chamber with MgSO4, it started to melt again but the MgSO4 absorbed nothing. I switched to Sodium Sulphate and within 10 minutes that became full of moisture, after just 30 minutes the crude Oleic acid melted into surprisingly a very clear liquid. In the photo below, however, there are clearly two separations, the outer layer is completely clear and free of 'debris'? and gravitated towards the centre you see an oily, globular clear mass.

Please could someone perhaps enlighten me about what is happening. My only thoughts are that the clear liquid on the outside is the pure oleic, and the inner mass is a mixture of other fatty acids and the globular pieces are glycerol.

Important I forgot to add that the PH registered between 6 and 7 with universal litmus, so I used a comparitor strip and the Ph was below 6.8, meaning that the Ph is definitely between a minimum 6 and maximum 6.8.

[Edited on 17-4-2014 by CHRIS25]

deltaH - 17-4-2014 at 02:47

You should use a narrower container so that you can properly seperate your two layers by decantation. I would suggest adding a few drops of each layer to clean water and observe what happens. I doubt though that there is any glycerol left in there. It could be that one of your layers is aqueous and the other the free fatty acid or more likely perhaps, one is free fatty acids and the other triglycerides (oil). The simple experiment I suggested should help in determining which.

[Edited on 17-4-2014 by deltaH]

CHRIS25 - 17-4-2014 at 05:42

Thanks for responding so quickly. I went away for two hours and left the mass at room temperature. When I returned it had separated into a whitish-light yellow crystaline and a clear liquid on top (not what it was when I first melted it, I believe now my melting was too quick and too high perhaps). I poured away the liquid into de-ionized water and it dissolved meaning that the liquid was polar, the sight of the liquid going into de-ionized water was the same effect and thing you see when you pour concentrated HCl into water, there is that appearance of something mixing then complete clarity again, please forgive the amateur way of explaining, once I fully understand everything I see I can then experiment and refine the procedures. I also tasted it, it was palatable and a bit sweet, I don't make a habit of tasting chemicals in the absence of analytical know-how, but I reasoned that this had to be water after all with a little bit of something in it.

[Edited on 17-4-2014 by CHRIS25]

deltaH - 17-4-2014 at 05:50

Yup, sweet and palatable sounds like glycerol. The optical effect of adding to water is also typical.

[Edited on 17-4-2014 by deltaH]

CHRIS25 - 17-4-2014 at 11:31

Hopefully last question then not to bother you again. I read from wikpedia that oleic is an oily lard like substance. I see a couple of commercial sites where it is sold as a liquid. So my question is how do they store oleic acid as a liquid, I just dissolved some in ethanol, but is this good for my purposes, for example when asked to use 5mLs, if I mix stoichiometric amounts with ethanol to get a correct solution? Or keep it in the fridge, as is at the moment where it is hard, and melt the mLs that I require? Sorry about these basic questions, but reading and studying the theory behind fatty acids and structures unfortunately does not help me with the practical issue at this moment in time. Thanks.

[Edited on 17-4-2014 by CHRIS25]

[Edited on 17-4-2014 by CHRIS25]

deltaH - 17-4-2014 at 12:13

I enjoy discussing experimental problems, so DO bother again.

You can work out the weight of 5ml oleic acid from it's liquid density and then simply cut and weigh that from your semi-solid. The solid will dissolve in your parrafin when you add it. If you're following a ferrofluid procedure, then best not to change it if you can, for this reason I wouldn't recommend alcoholic solutions, unless the recipe calls for it.

As for the liquid commercial products, I think they are much purer and so melt close to their literature value (13-14C). It should only be lard like if stored cold!

Remember your product contain appreciable amounts of both polyunsaturated fatty acids as well as saturated ones. That really messes up the phase behaviour, probaby why you don't get a hard lard like phase when cold nor melting promptly above 14C.

[Edited on 17-4-2014 by deltaH]

CHRIS25 - 17-4-2014 at 12:34

Yes ok I understand. Unfortunately I posted a new thread regarding this paraffin problem I have. It is in the beginners section because I felt, as a beginner, i should not really continue in the organic section where I think mostly very intelligent people reside asking very intelligent questions

. I would not mind if you could, when moments allow, take a look for me.

deltaH - 17-4-2014 at 12:51

I have tons of threads in beginners too. Also, many of these 'intelligent' questions have nothing to do with intelligence

I'll try to contribute as soon as I can, just a little swamped with so many things of late!

CHRIS25 - 17-4-2014 at 13:05

Thankyou

Oleic acid

CHRIS25 - 25-5-2014 at 12:18

Is my Oleic acid able to be purified via a simple distillation? I can only seem to discover that it can't due to the presence of other polyunsaturated fatty acids. But these commercial papers are dealing with complex stuff so I am not sure whether this applies to my humble conglomeration.

gdflp - 25-5-2014 at 16:36

That would depend on how good your hot plate is. Oleic acid boils at 360°C so it would require a long time to heat up to temperature to distill it, basically it's similar to sulfuric acid in the fact that it's nonvolatile. That's just assuming that your oleic acid is pure, I'm not sure about azeotropes or other fatty acids.

UnintentionalChaos - 25-5-2014 at 19:21

Quote: Originally posted by CHRIS25

Is my Oleic acid able to be purified via a simple distillation?

Very unlikely. That is a very high temperature. Methyl oleate would be a better intermediate and I still wouldn't try without at least aspirator strength vacuum. For ferrofluid, I wouldn't bother at all. The crude mix of fatty acids should be quite sufficient as a surfactant.

I now make soap as a small business...would you guys like me to throw together a quick writeup on how to go from olive oil to mixed fatty acids in 2 hours, tops?

In return, does anyone have a reliable ferrofluid writeup? I have seen a lot of preparations that vary pretty widely and am not sure which would work best.

[Edited on 5-26-14 by UnintentionalChaos]

CHRIS25 - 25-5-2014 at 21:34

Thankyou that was it. Unintentional chaos: have you seen this: http://www.youtube.com/watch?v=kPwIeoMFjJE I have seen a lot of rubbish but this is professionally presented and involves making everything.