Help me understand the use of Sodium Lactate

LBussy said:

Can you elaborate? I've read people using it but not tried it myself - nor am I really sure WTH it's supposed to do.

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Like others have now mentioned....it's the difference of dry poorly made mashed potatoes and freshly cooked pudding. Lumpy and thick vs. smooth and creamy.

Before I used it regularly my finished HP mixture was hard to put in the molds without some air pockets against the sides and bottom. I did a lot of pushing down and banging, but with the sodium lactate addition it glides right into the molds and is easier to scoop all of it out of the crock pot with minimal loss to clinging to the sides etc.

http://www.soapmakingforum.com//www.pinterest.com/pin/create/extension/

Does it seem ironic to anyone else that a lot of people get into making soap so they can use a product with less "chemicals", and we end up adding many of them back in?

Don't get me wrong, I'm not a chemophobe ... I just find it ... well, ironic.

For me the difference is a man-made version of a natural chemical (lye, for example) verses chemicals that don't actually exist outside of that which man makes. Let's be honest, there is no such thing as a natural pommace OO as it is solvent extracted. From that basis things like sodium lactate, sodium citrate and so on have a different place than polymonomanmadeparabenoxide

The Efficacious Gentleman said:

For me the difference is a man-made version of a natural chemical (lye, for example) verses chemicals that don't actually exist outside of that which man makes. Let's be honest, there is no such thing as a natural pommace OO as it is solvent extracted. From that basis things like sodium lactate, sodium citrate and so on have a different place than polymonomanmadeparabenoxide

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I think using these chemicals forces us to learn about them. Since we are adding them, and we do so armed with an understanding of what they are and do, we feel better about it.

So now that we are talking about SL ... anyone elver used Potassium Lactate? They both seem to be metallic salts resulting from the neutralization of lactic acid. One might surmise that it would be possible to make at home with lactic acid and lye ... or similar to Sodium Citrate, by adding the acid directly to the mix and accounting for the lye consumption.

The Efficacious Gentleman said:

For me the difference is a man-made version of a natural chemical (lye, for example) verses chemicals that don't actually exist outside of that which man makes. Let's be honest, there is no such thing as a natural pommace OO as it is solvent extracted. From that basis things like sodium lactate, sodium citrate and so on have a different place than polymonomanmadeparabenoxide

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Okay....I have to take a moment to say that I first did my best to pronounce this...and then laughed out loud...for a very long time. Still giggling a bit.....

"... One might surmise that it would be possible to make at home with lactic acid and lye..."

Yes, you surmise most correctly! Only problem -- where to find the lactic acid. Citric acid is pretty easy to find, even in grocery and hardware stores, so I'm willing to mess with turning it into sodium citrate. On the other hand, I've never seen lactic acid in a grocery store aisle. If I have to order lactic acid from Lotioncrafter or other chemical supplier, I figure I might as well buy the sodium lactate, unless I have some other use for lactic acid besides turning it into sodium lactate. Maybe I'm missing something???

It's not in a pure form, but additives like buttermilk would have a decent amount of lactic acid. (I happened to catch a factoid somewhere that buttermilk has one of the highest lactic acid contents.)

DeeAnna said:

Yes, you surmise most correctly! Only problem -- where to find the lactic acid.

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Seems like I have a lot of crossover chemicals/gear in my hobbies. LA is regularly used by Home Brewers to adjust the pH of the mash. I have tons.

The Efficacious Gentleman said:

polymonomanmadeparabenoxide

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Being that it's still April Fools day, I am almost tempted to start a thread to inquire where one might be able to purchase such a thing, or if anyone has used it in their soap. :razz:


IrishLass

We have a homebrew store in the local area -- I'll have to investigate.

DeeAnna said:

"... One might surmise that it would be possible to make at home with lactic acid and lye..."

Yes, you surmise most correctly! Only problem -- where to find the lactic acid. Citric acid is pretty easy to find, even in grocery and hardware stores, so I'm willing to mess with turning it into sodium citrate. On the other hand, I've never seen lactic acid in a grocery store aisle. If I have to order lactic acid from Lotioncrafter or other chemical supplier, I figure I might as well buy the sodium lactate, unless I have some other use for lactic acid besides turning it into sodium lactate. Maybe I'm missing something???

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And what is the amount of Lye that is needed to make sodium lactate out of lactic acid? I can find sodium lactate solution 60% and lactic acid but the acid must be cheaper (will learn tomorrow) .

I'm thinking of using SL instead of salt, along with sodium citrate, 1-2% sugar and part of the liquid with beer in a castile soap or in a low amount of CO/PKO recipe. Are all the above additives will create a full lather product, or a soap failure because I am using too many additives?

ngian said:

And what is the amount of Lye that is needed to make sodium lactate out of lactic acid? I can find sodium lactate solution 60% and lactic acid but the acid must be cheaper (will learn tomorrow) .

I'm thinking of using SL instead of salt, along with sodium citrate, 1-2% sugar and part of the liquid with beer in a castile soap or in a low amount of CO/PKO recipe. Are all the above additives will create a full lather product, or a soap failure because I am using too many additives?

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If my math is right (and DeeAnna will tell me if it's not):

NaOH + C3H6O3 -> NaC3H5O3 + H2O or
KOH + C3H6O3 -> KC3H5O3 + H2O

So:
1g of Lactic acid neutralizes 0.44g of NaOH and creates 1.24g Sodium Lactate
1g of Lactic acid neutralizes 0.62g of KOH and creates 1.42g Potassium Lactate


Which means if you want:
1g of Sodium Lactate you need to add 0.81g of Lactic Acid and 0.35g of NaOH
1g of Potassium Lactate you need to add 0.70g of Lactic Acid and 0.44g KOH

I think.

ETA: DeeAnna if you read this my math balances for that one but the closest I can get for Sodium Citrate is:

9(NaOH) + 3(C6H8O7) -> 3(Na3C6H5O7) + 7(H2O) + O2

... which misses balancing by .43% for some reason I can't figure out. Rounding errors maybe?

LBussy said:

So:
1g of Lactic acid neutralizes 0.44g of NaOH and creates 1.24g Sodium Lactate
1g of Lactic acid neutralizes 0.62g of KOH and creates 1.42g Potassium Lactate

Which means if you want:
1g of Sodium Lactate you need to add 0.81g of Lactic Acid and 0.35g of NaOH
1g of Potassium Lactate you need to add 0.70g of Lactic Acid and 0.44g KOH

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I should probably also add that anhydrous lactic acid is likely not going to be seen outside of a chem lab. You can buy 88% pretty easily. So with 88% Lactic Acid we are more around:
1g of 88% Lactic acid neutralizes 0.39g of NaOH and creates 1.09g Sodium Lactate
1g of 88% Lactic acid neutralizes 0.55g of KOH and creates 1.25g Potassium Lactate

Which means if you want:
1g of Sodium Lactate you need to add 0.92g of 88% Lactic Acid and 0.35g of NaOH
1g of Potassium Lactate you need to add 0.80g of 88% Lactic Acid and 0.44g of KOH

BUT ... remember KOH is often 90% so ... to get 1g of Potassium Lactate you need to add 0.80g of 88% Lactic Acid and 0.49g of 90% KOH

Yeah, that's enough math for tonight.

ngian said:

And what is the amount of Lye that is needed to make sodium lactate out of lactic acid? I can find sodium lactate solution 60% and lactic acid but the acid must be cheaper (will learn tomorrow) .

I'm thinking of using SL instead of salt, along with sodium citrate, 1-2% sugar and part of the liquid with beer in a castile soap or in a low amount of CO/PKO recipe. Are all the above additives will create a full lather product, or a soap failure because I am using too many additives?

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As the acid question is covered (very well, if I might add) pending confirmation, I will say that the additives you use certainly can increase lather, but I'm not sure if any can create lather. There is a difference, as Castile is notorious for lathering badly and the additives can improve that, but only within the confines of what they have available to them. So it should indeed improve the lather, but whether or not you get to a type of lather that you are looking for...........possibly. But it will certainly need a good long cure (maybe 6 months) cure regardless.

Finally got to looking at your numbers, Lee. They look fine -- kudos to you!

You asked:
"...DeeAnna if you read this my math balances for that one but the closest I can get for Sodium Citrate is:
9(NaOH) + 3(C6H8O7) -> 3(Na3C6H5O7) + 7(H2O) + O2
... which misses balancing by .43% for some reason I can't figure out. Rounding errors maybe?..."

Isn't the stoichiometry more like this:

3(NaOH) + C6H8O7 ->
3(Na+) + 3(OH-) + (C6H5O7---) + 3(H+) ->
Na3C6H5O7 + 3(H2O)

3 moles NaOH + 1 mole citric acid -> 1 mole trisodium citrate + 3 moles water

DeeAnna said:

Isn't the stoichiometry more like this:

3(NaOH) + C6H8O7 ->
3(Na+) + 3(OH-) + (C6H5O7---) + 3(H+) ->
Na3C6H5O7 + 3(H2O)

3 moles NaOH + 1 mole citric acid -> 1 mole trisodium citrate + 3 moles water

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It is! Taking the intermediate step of the dissociated ions made it a little less cluttered for me. Not quite sure how I missed it but it definitely works now.

Good! Glad that helped, Lee. I thought including that middle equation might clarify things a bit for you.

Another thing that is helpful to me (but I know might be absolute greek to many) is to rewrite the basic formula for citric acid ... C6H8O7 ... in a way that shows more about its structure. Rewritten, the formula looks like this ... C3H4OH-(COOH)3 ... The three "COOH" sections are the "carboxyl" groups that gives citric acid its acidic nature. The "H's" in the chemical equations in my post above are the H's that come off the acidic COOH parts of the molecule. Since there are three COOH's, there are three H's to play with.

What's cool about citric acid is there are THREE of those little carboxyl critters and thus three H's, which is why you don't need much citric acid to do a job compared with the other "weak" acids sometimes used in soaping, such as vinegar (acetic acid).

Acetic acid's basic formula is C2H4O2. Rewritten to highlight its acidic nature, the formula for acetic acid looks like this ... CH3-COOH ... See how there's only one carboxyl group? You can get only one H from the acidic COOH to play with.

Okay that makes sense ... acetic acid (methanecarboxylic acid) is a carboxyl and an alkane (I guess that's where the "methane" part comes from?) where lactic acid has the three carboxyl groups and is sort of a triple "strength" acid compared to acetic. So that's why you need ~20% more lye to neutralize a given mass of citric acid versus lactic.

Now the big question: Since both R-lactate and R-citrate have one molecule of their associated metal and R-lactate has 56% of the molar mass of R-citrate, that implies by mass, using R-citrate would require 43% more to achieve the same thing? (or did I get that backwards?)

And then examining the chelating effect of each: Sodium, Potassium, Calcium and Magnesium are the alkali metals at play here. Potassium and Calcium are in the same period where Sodium and Magnesium are in the same period. Generally, elements within a period go from most to least reactive; calcium and magnesium being alkali-earth metals, each have one more proton than it's partner in the period. How then does the salt preferentially associate with the less reactive metal? And then also considering those periods, will a potassium salt more freely chelate calcium and the sodium more freely chelate the magnesium?

And does THAT mean we might consider the makeup of the tap water when choosing between potassium and sodium salts?

And at what point should we have removed this from the "Beginner" forum?

Lee -- Your questions are stretching my little brain cells pretty good, so, yeah, this has definitely moved out of the beginner forum.

First, here's a definition of chelation:

"...Chelation (a word derived from the Greek word “chela”—a claw) is based on the simple fact that two or more attractive forces acting simultaneously on a metal atom are stronger than only one. A chelating agent is a molecule which contains at least two groups of polarity opposite to that of the atom it is wanted to remove, in such a sterical position as to fit the size of that atom, thus exerting a double or multiple pull on it...." Source: A Textbook on EDTA Chelation Therapy: Second Edition, by Elmer M. Cranton, 2001.

One point to take from this definition is that a chelator is a molecule (or ion) that can bond with a metallic atom in two or more places. Each individual fastening point might be relatively weak, but since the chelator is can form two or more bonds, it can create a firm overall connection with the metal.

Another point is the geometry of the connection has to be favorable for the bond to form. The chelator due to its geometry can wrap itself around the metallic atom -- nestling the metal within its bosom, so to speak. One mental picture I get of this is how a baseball nestles into a catcher's glove. The shape of the pocket in the glove is just right to hold the ball securely without a lot of pressure or effort.

***

"...How then does the salt preferentially associate with the less reactive metal? And then also considering those periods, will a potassium salt more freely chelate calcium and the sodium more freely chelate the magnesium?..."

I am not certain, but I don't think in this case that it's the citrate salts are doing the chelating -- it's the citrate ions. The "hard water" metals are ions with two positive charges (typically Ca++ and Mg++). A citrate ion has three "claws", each with a negative charge. The multiple connections between the citrate ion and the Mg or Ca ion are key to creating a relatively strong bond.

Now think about how citrate forms a bond with sodium or potassium. The citrate can make only one point of connection with a K or Na ion, because these ions have only one positive charge -- K+ or Na+. This single point of connection means citrate can't act as a chelator for these ions. Because K and Na have a strong ionic nature, the bond is more subject to being broken -- in effect, K and Na don't form strong covalent bonds; they can be quite happy as ions rather than stay bonded to other atoms.

There's my non-expert explanation of the difference.

***

Your general thoughts about the periodic table have merit, but the reactivity of any given set of atoms is more complicated than how you describe it.

The ability of atoms to donate and/or accept electrons, the geometry of the atoms/ions within a given chemical mix, the size of the electron cloud around each atom, the nature of the bonds between atoms, etc. -- all these factors enter into the chemical shenanigans going on at any given moment.

Speaking very generally, atoms on the far left side of the table are electron donors, and those on the far right are electron acceptors (not counting the extreme right column that contains the noble gases). Some atoms more-or-less in the middle (carbon for example) can walk either side of the street, depending on the circumstances.

As you go down any column or from left to right in any row, the atoms have increasingly larger electron clouds. A larger electron cloud means the outer electrons of an atom are further away from the nucleus and are more likely to form weak bonds with other molecules and ions.

Since you asked your question, Lee, I got curious about EDTA's role as a chelator in soap, since EDTA is also used in soap to reduce the chance of rancidity (aka DOS) and reduce scum formation. The product that we use in soap is tetrasodium EDTA -- this is basically the four-sodium salt of the acid, just as trisodium citrate is the three-sodium salt of citric acid.

"...[EDTA's] usefulness arises because of its role as a hexadentate ("six-toothed") ligand and chelating agent, i.e., its ability to "sequester" metal ions such as Ca2+ and Fe3+. After being bound by EDTA, metal ions remain in solution but exhibit diminished reactivity..." Source: Wikipedia, http://en.wikipedia.org/wiki/Ethylenediaminetetraacetic_acid

Wowser ... and I thought citrate's three claws were interesting ... but EDTA has six! The basic formula of EDTA is C10H16N2O8, but if you rearrange the formula to show the acidic nature of EDTA, the formula looks like this -- C6N2H12-(COOH)4.

When EDTA is in solution, it becomes a chelator in two ways. First, the four acidic carboxyl (COOH) groups each lose a hydrogen ion (H+). That creates four negatively-charged claws. This is exactly the same as what citric acid does to create its three claws.

The two nitrogen atoms (N) buried in EDTA's structure create the remaining two claws. These claws are a little different. The nitrogen atoms -- called "amines" -- each have unattached electrons that are looking for something to do. Like bored teens running around on Saturday night, they join forces with the four acidic claws and gang up on an unsuspecting metal ion.

The poor calcium or magnesium or iron ion (Ca++ or Mg++ or Fe+++, etc.) never has a chance. The EDTA molecule envelops the metal ion on all sides and locks it in place with its claws.

Arrrrrrrrr!!!! Chemical piracy at its best! :twisted: