Chemistry Can Sulphonated Neatsfoot Oil Be Made Using Turkish Red Oil Method?

[Oyster farmer]

Homework Statement

Trying to figure out how to combine sulphuric acid and neatsfoot oil for tanning leather

Relevant Equations

Is it just get 1 Mol of sulphuric acid and 1 Mol of neatsfoot oil and mix together?

I am thinking a Mol to Mol ratio is what is needed. Is this correct?

 

[sysprog]

No, it's not that simple, and I think that it's too dangerous to mess with strong H2SO4 if you aren't already prepared with basic safety-related procedural information. Also, I'm not a Mentor/Moderator here on PF, but I think that this question doesn't belong in a homework sub-forum. Were you assigned leather-tanning protocols as homework, or do you have a leather-tanning idea in mind?

 

[Oyster farmer]

No, it's not that simple, and I think that it's too dangerous to mess with strong H2SO4 if you aren't already prepared with basic safety-related procedural information. Also, I'm not a Mentor/Moderator here on PF, but I think that this question doesn't belong in a homework sub-forum. Were you assigned leather-tanning protocols as homework, or do you have a leather-tanning idea in mind?

I already tan leather and hides. I like to use sulphonated neatsfoot oil as part of the process. I try to make as many of the ingredients myself as possible. The soap I use in this process is home made out of potash and rendered raccoon fat. There are many commercially produced tanning oils available. I want to make my own. I also laundry soap from deer tallow and NaOH which I have in crystal form. Maybe this isn't home work per say but this is work I do at home. Is there a more appropriate group in this forum?

 

[sysprog]

I already tan leather and hides. I like to use sulphonated neatsfoot oil as part of the process. I try to make as many of the ingredients myself as possible. The soap I use in this process is home made out of potash and rendered raccoon fat. There are many commercially produced tanning oils available. I want to make my own. I also laundry soap from deer tallow and NaOH which I have in crystal form. Maybe this isn't home work per say but this is work I do at home. Is there a more appropriate group in this forum?

Soap was and is often made from animal-derived lipids and NaOH, aka lye, aka caustic soda. I like plant-based lipids in soaps, but I like other soaps, too.

We're on the internet, specifically on the Physics Forums, and although I'm not commissioned to say anything on behalf of the Physics Forums, in trying to be responsible as a member, I have to say that when responding to a post regarding a potentially dangerous substance, such as H2SO4, I deem it appropriate to exercise caution in what I say.

Your question about whether a mole of lipids in 1:1 ratio to a mole of H2SO4 was appropriate for neatsfoot oil tanning, raised a bit of an alarm for me, not only because it suggested to me that you might be mis-modeling the reactions (I don't believe that there's really such a thing as a molecule of neatsfoot oil), but also because we as members, yourself included, have a responsibilty to not misdirect other members and other readership, especially when discussing potentially dangerous things.

 

[symbolipoint]

@Oyster farmer,
Chemical engineering and True manufacturing is not the same as "making my own soap". Sulphonation is something that a qualified and equipped chemical engineer would do.

 

[Borek]

For some general hints try to google for Wennström Sulphonated Oils - a bit dated (1927) but if the ideas presented there worked 100 years ago, they didn't stop to work now.

 

[Oyster farmer]

Soap was and is often made from animal-derived lipids and NaOH, aka lye, aka caustic soda. I like plant-based lipids in soaps, but I like other soaps, too.

We're on the internet, specifically on the Physics Forums, and although I'm not commissioned to say anything on behalf of the Physics Forums, in trying to be responsible as a member, I have to say that when responding to a post regarding a potentially dangerous substance, such as H2SO4, I deem it appropriate to exercise caution in what I say.

Your question about whether a mole of lipids in 1:1 ratio to a mole of H2SO4 was appropriate for neatsfoot oil tanning, raised a bit of an alarm for me, not only because it suggested to me that you might be mis-modeling the reactions (I don't believe that there's really such a thing as a molecule of neatsfoot oil), but also because we as members, yourself included, have a responsibilty to not misdirect other members and other readership, especially when discussing potentially dangerous things.

Thank you! I am not sure there is such a thing as a molecule of neatsfoot oil either. I am going to use a molecule of beef tallow as a substitute because, well, they both come from cows and that's the best I can do. I am not a chemist. I have a BS in Psych, neuroscience option, so I had general chemistry and o- Chem. I accept this using H2SO4 had potential to cause catastrophic injury. I am going to read literature related to safely handling such materials as a safety refresher course. Safety is very, very important. I have been using aluminum sulfate as my tanning agent. Once I remove the hide from the tanning solution I rinse it, stretch it, apply a thin layer of soft soap (this would be the KOH soap), and when that is absorbed, rub in the sulphonated neatsfoot oil and break the hide or pelt as it is drying. Results are good! I felled a large white oak in my backyard for milling into boards this spring. I am removing and drying the bark to dry and try veg tanning with the hides and pelts I get this winter. I do this because I want 100% biodegradable, locally sourced, petroleum free cold weather clothing.

 

[TeethWhitener]

As much as I hate to side with the chemophobes, this is one synthesis you're probably better off leaving to the professionals. The main reason is, even if you're assiduous with regard to safety, you likely won't get a usable product if you don't know any chemistry. It's kind of like saying "If I have enough metal parts, I can build a car." Maybe, but it's far more likely that you'll end up with a pile of trash. An expensive pile of trash, at that.

From a basic chemistry standpoint, it's important to note that a mole of sulfuric acid in a 1 M solution is not the same as a mole of pure sulfuric acid. They will react very differently. The aqueous sulfuric acid will probably partially de-esterify the fat and do little else. The pure sulfuric acid will give a crude sulfonic acid product (along with a lot of other crud). Most of the industrial syntheses that I was able to find use oleum or sulfur trioxide directly, since the presence of excess water tends to break down long chain aliphatic sulfonates. Sulfur trioxide is tough to work with outside of an industrial setting, since it's a very corrosive and reactive gas. On top of that, you'd have to worry about neutralizing your product (again, in a non-aqueous manner). From what I found, this generally entails use of an alcoholic solution of lye.

So you have issues of safety, product stability, and neutralization that are pretty complex to contend with, and that chemical plants can handle in bulk much more cheaply than you can manage at a boutique scale. It's probably best just to buy the oil, even if a gallon is a few hundred dollars.

 

[jim mcnamara]

For clarity - neatsfoot oil is a mixture of several different fatty acids as triglycerides. So, there is no such thing as one single molecular weight of neatsfoot oil. Neatsfoot oil is rendered from the ankles of cattle, just like the name says.
I think "neat" is an archaic word for cow. Somebody please correct me if I'm wrong.

 

[sysprog]

Thank you! I am not sure there is such a thing as a molecule of neatsfoot oil either.

I'm confident that there isn't $-$ neatsfoot oil is a mix of lipids:

Neats-foot oil contains the following fatty acids: oleic (67%), palmitic (17%), palmitoleic (9%), stearic (3%), myristic (1%), myristoleic (1%) arachidonic, and clupanodonic.​

(G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 527)​

 

[jim mcnamara]

They are present as triglycerides, all. Glycerine molecule esterified with 3 separate fatty acids. All three the same, or possibly "mixes". $H_2SO_4$ will likely break down the glycerine esterification first. So, @TeethWhitener nailed it earlier.

 

[chemisttree]

SO3 is preferred. See for example…

 

[DrDu]

Interesting project. I would not use tallow but rather some cheap olive oil which has a more similar spectrum of fatty acids as compared to neatsfoot oil. This gives you a type of turkish red oil. Sulphonation definitely will work with concentrated sulphuric acid. It is extremely important to cool the reaction mixture so that temperature does not rise above 25 to max 40 deg Celsius.
Apparently, with neatsfoot oil, there is a tendency that the reaction mixture heats up again even after addition of acid has ended.

From Heinrich Walland, Kenntnis der Bleich-, Wasch- und Appreturmittel, 1925:

"Aus Rizinusöl kann das Türkischrotöl auf folgende Weise hergestellt werden. In das Öl wird konzentrierte Schwefelsäure, bis zu 30% auf das Gewicht des Öles, in dünnem Strahl sehr langsam, am besten bei gleichzeitiger Kühlung eingerührt. wobei die Temperatur nicht mehr als 40 Grad betragen darf (ein Geruch nach Schwefeldioxyd solI mcht auftreten). Nach 24stündigem Stehen wird die sirupartige Masse zunächst mit kalk· und eisenfreiem Wasser und dann, um eine Abspaltung der gebundenen Schwefelsäure zu verhindern, zweimal mit einer Glaubersalz Lösung gewaschen. Dadurch werden die überschüssige freie Säure sowie das abge spaltene Glyzerin entfernt. Schliesslich wird das sulfonierte Öl mit Wasser emulgiert und mit Soda oder Ammoniak, auch mit beiden, neutralisiert. Die angeführten Arbeiten können, wie dies in manchen Textilbetrieben geschieht, in einem Holzbottich durchgeführt werden; bei der fabrikmässigen Herstellung bedient man sich eiserner, jedoch verbleiter Rührwerke."

here my translation:
"From castor oil, turkisch red oil can be obtained in the following manner: Concentrated sulphuric acid (up to 30% of the weight of the oil) is added under continuous stirring in thin stream very slowly, best with a simultaneous cooling. The temperature must not rise to to more than 40 degrees (a smell of sulphur dioxide should not be notable). After standing for 24 hours, the syrup like mass will first be washed with lime and iron free water and then, to prevent cleavage of bound sulphuric acid, two times with Na2SO4 solution. In this way, free acid and the cleaved glycerine are removed. Finally, the sulphonated oil is emulgated in water and neutralized with soda, ammonia or both. The work can be done, as is done in some textile industries, in wooden tubs; In factories, one uses rather stirrers made from leaded iron".

I think this is doable. I would start with no more than 300 ml of oil and 45 ml of concentrated sulphuric acid, use a flask made from laboratory glass and use an ice bath to keep temperature below 25 degrees, adding the acid in small batches. If everything works out, including the washing steps, you might scale up. Controlling the temperature becomes the more critical the larger the batch size. Lab coat, closed shoes, googles and one way nitrile gloves may be sufficient, when working with smaller quantities of acid.