Thiocarbanates ?

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May 27, 2002
Ocala, Florida
Schaeffers uses a form of dithiocarbamate. Now, I'm not even close to a chemist and maybe Mr MolaKule can be of assistance as he seems to have a good resource on chemical composistions. [Smile] Where did you see the one you're asking about and how is it applied? in the oil already or as an additive?
Bob, It was in the "Maxlife Base Oil" thread that I read this: (The Pennzoil High Mileage Oil has the Thiocarbanate in it at a rate of 145ppm. Not much, but I guess it is a buffer.) Was just curious is all. I am guessing this is a form of Moly?
Good Question: A thiocarbonate describes a molecular link, in this case it is a three-carbon link. In organic chemistry, various prefixes describe the number of atoms linked or atoms involved in the makeup of the total molecule. For example, ZDDP is dialkyldithiophosphate, describing the fact that for a ZDDP molecule, it is composed of two (di) alkyl-like atoms and two-groups (di) of three (thio) phosphorus atoms. The zinc is an alyli whereas the phosphorus is acidic. The particular grouping makes up a salt, called ZDDP. There is another form of zinc-type additive which involves the carbonates or carbomates, and is called ZDTC. Generally, BOTH zinc type additives are used in lubricants as a "multifunctional" additive, or chemical: 1. As a friction modifier. 2. As an Oxidation Inhibitor, 3. An Extreme Pressure, antiwear, 4. Metal deactivators. MoDTC is (Moly Dithiocarbonate) is often used as an additive and works as per items 1 and 3. So the di-thio-carbonates or carbomates are used in many additives as a way of describing the atomic linkage for a particular molecule. So have no fear, they are the Good guys.
Well, I'm mostly with Mola. But since my background is BioChem, I feel obliged to make a small (but rather important) correction: "tri" is the organic chemistry term for 3. [Smile] "thio" is the organic chemistry term for a sulfur-containing compound, and typically it's a sulfide (-SH) Here's the importance of the Sulfide: Proteins have what are referred to in 4 structure levels. The primary is the amino acid sequence (as defined by the RNA it was produced by). This is basically due to TRUE chemical bonding (called a covalent bond, or in this case biochemists call it a peptide bond). The secondary structure is from localized rope folding due to the chemical properties of the amino acids which happen to be next to, or nearby, each other. These are interactions that cause spiraling or pleated sheets due mostly to polar/non-polar interactions. So how does this protein crap relate to oil? keep reading: The third and final structure for some proteins (single chain proteins) is due to large interactions between secondary structures. Big deal right? well, some proteins, like Insulin and Hemoglobin have di-sulfide bonds that assist with this tertiary folding. The disulfide bonds are SO strong, that they are nearly True chemical bonds (covalent bonding). Here's the benefit... by "cross-bracing" a single chain-molecule the density of molecule increases, as does it's heat stability. If you've ever heard of the rare bacteria that live in 200*F+ hot springs, you now know how they manage to hold together without ripping apart. The disulfide bonds are strong enough to keep the proteins from denaturing (unfolding and becoming functionally useless) under very high heats. Having an oil with properly designed sulfide groups could promote this disulfide bond in basic environments (acidic environments can make disulfide bonds break though). So why not just use longer chains (a heavier oil) and forget all this "temporary bond crap? well, Since the bonds aren't covalent, they will give way (i.e. sheer) much sooner than the molecules true bonds do. Allowing this "temporary" bond to sheer and re-form may give an oil a heavier operating density/viscosity, with some resistance to long-term sheering (since the viscosity will reform quickly, in the right environment). But that's just speculation on my part. [Smile] If you want to get into phosphate chemistry, boy can we crack open the biochem books! That's the whole basis of chemical energy-transport in your body (some of it is pretty crazy). Congrads, you've just been briefed on BioChem 401. [Smile] [ June 26, 2002, 12:07 AM: Message edited by: Steve in Seattle ]
So Thiocarbanate is a term describing the chemical bonding and not the actual chemical? As this is what schaeffers 10w30 shows Molybdenum Trialkyldithiocarbamate Assuming that the base additive reffered to here is the molybdenum and the other is describing the atomic linkage for this additive? If yes then that means that thiocarbanate is not moly in itself correct but the description of the linkage for what ever additive used? Sorry for being so ignorant and really appreciate you both for this basic 101 chemistry.
And to think I used to enjoy chemistry. [Eek!] I ll have to wait until the other 3/4 of my brain wakes up so I can figure out a small clue of what has been discussed. [I dont know] Keep it up guys, we appreciate it [Patriot] Thanks Bob- [Embarrassed] . I used the "edit feature" to add this. [Happy] [ June 24, 2002, 07:20 AM: Message edited by: Al ]
Steve, Good molecular explanation. I was attempting to keep the discussion at a low-level with regard to additives. I didn't want to get into divalent and monovalent bonds, etc. Bob, I think what Scheaffer's may be using is called (using the full name), "Molybdenum di-2-ethylhexyldithiocarbamate." It comes in two versions, MoDTC and MoDTP. The MoDTC is 4.1% (by weight) moly, while the MoDTP is 8.2% moly with 12.3% sulfur and 5.5% phosphorus. The "thiocarbamate" describes the elemental atomic linkages between the carbon at the end of the chain and the two sulphur atoms branching off the ends. Moly, like like most metallic salts, (such as ZDDP) form a surface layer of an organometallic layer which reduces boundary layer friction.
Has anybody told Mr. Scott about this? Perhaps he could use this approach to hold the Enterprise’s dilithium crystals together.... Great information guys! Thanks! [freaknout]
Originally posted by BOBISTHEOILGUY: So Thiocarbanate is a term describing the chemical bonding and not the actual chemical?
no, thiocarbonate would indicate a sulfer-containing molecule, and a carbonate group as well. This really doesn't do a whole lot for the oil by itself, but the PRESENCE of such branches on the oil molecules allows for the formation of disulfide bonds (in basic environments) which I discussed earlier.
As this is what schaeffers 10w30 shows Molybdenum Trialkyldithiocarbamate
carbamate is similar to carbonate, with a few minor differences. I could dig out a fairly good structural formula for you, but its not what's important here. Molybdenum is actualy a pure element (Mo) and can be found as anything from a nutral atom to +6 ion state. In the schafers example above, the Mo ion would be in the center, while the 3 alkyl groups and 2 thiocarbamate groups each bond to it as metal-alkaloid. It's the positive ion state that sets up a basic environment by removing protons from other componants. I'd bet the sulfer groups are forming a disulfide bond (although just the name itself won't give us the structure as is).
Assuming that the base additive reffered to here is the molybdenum and the other is describing the atomic linkage for this additive?
No, the other stuff tells you what chemical groups are involved in the molecule, just like the Molybdeum name does. Knowing HOW they bind is the study of organic chemistry. Don't sweat getting this all down, it's really not even close to chem 101. Metal alkiloids is more of a Organic Chem 240 level. Science majors (and a few minors) only. [Smile] [ June 26, 2002, 12:07 AM: Message edited by: Steve in Seattle ]
If you look at the structure of the "Molybdenum di-2-ethylhexyldithiocarbamate" dithiocarbonate part graphically, at the end of the chain is a triangle (hence thio): a carbon atom sits at the western most point of the triangle, while a double-bonded sulfur atom sits at the northeast point, and a single bonded sulfur atom sits at the southeast point. I don't know if that is better than "dilithium" crystals or not. We may have to wait for the next installment of "Star Trek." [Big Grin] [Off Topic!]
Originally posted by MolaKule: If you look at ... dithiocarbonate part graphically, at the end of the chain is a triangle (hence thio): a carbon atom sits at the western most point of the triangle, while a double-bonded sulfur atom sits at the northeast point, and a single bonded sulfur atom sits at the southeast point.
Yep, but its the sulfer that makes it thio, not "the triangle". Carbonate would have oxygen atoms in those spots, Thiocarbonate replaces them with sulfer. What you're describing above is actully the reason its called Carbonate. the alpha carbon is double bonded to a Sulfer/Oxygen atom, and single bonded to another oxygen atom, that dpending on the pH condition of the compound, can either be an ion or an oxide/sulfide group (OH or SH). Calcium Carbonate: CaCO2 ---> Ca+ [CO2]- Calcium Thiocarbonate: CaCS2 ---> Ca+ [CS2]- Trust me, between acing [Wink] O-Chem, tutoring students, and being a Professor's Lab Assistant... I've had to decipher some pretty crazy names. One reagent my prof ordered through Sigma was over 100 letters long. Once we had broke it down chemically, we found it came in 32 enatiomeres (geometric variations) only 16 or so that could be synthesized by man. [Smile] (O Chemists are WAY behind the abilities of nature when it comes to selecting enantiomer products) Organic nominclature uses thio when ever a sulfer atom replaces an oxygen atom in a known chemical group. Biochem respects the same observation. Not sure what else to tell you. Tri=three. [Smile] [ June 26, 2002, 02:32 AM: Message edited by: Steve in Seattle ]
I find this quite interesting even though a lot of this is up there over my head with the enterprise but I still think I've learned some good stuff here. Will it be usefull for me? who knows, but it's something that I've wondered about. So, let's step this back a couple of steps... I'm sure this isn't a simple analogy but here goes anyway. This chemical structure appears to be structuring the atomic/molecular levels of the complete additive(among other things), therefor, creating a chemical atomic linkage bond will that create an affinity to metal (or on my level of terms, does it attract to metal surfaces due to this structure?) Or should I say it's the different levels of di vs tri that makes a determination of atomic level attraction if that is the case? (I sure hope I'm not sounding stupid because of my ignorance, if so, just tell me and I'll give up trying to make sense of all this [Big Grin] )
On a related subject. I have beeen told by some reasonablely reputable individuals, and have read some tech bulletins from Exxon that PAO's and Esters tend to cling to metals better than Petroleum base stocks. due to their polar nature. This would help protect protect surfaces more effectively (Exxon claims) and is supposedly one of the factors involved in less oil consumption. It appears that syns seal more effectively around piston scraper rings. True or not true?? And if true would Esters or PAO's be equally effective??
your jumping the gun Al. [Frown] , my line of questioning was moving to that after establishing the attraction(or non) of additives to the surface. As I am seeing this, The surface can only hold additives but to layer the additives with a base oil on top of it(attracted not just coating it) then it would defeat the purpose of the additives as a barrier lube(among other things). The main purpose of the base oil is to carry those additives in suspension and replenish any and all sacrificial additives and that would not work if the base oil itself was polorized to the metal coating the surface. That is why it is so important for the oil to maintain its base properties as it is the critical portion that delievers these additives, and if the base oil was to burn off, or increase in viscosity it would fail in maintaining in delievery of the additives. This would be true in respect to the Mo as I know it is attracted to the surface and its only means for getting there would be the base oil, and if it had to fight the base oil for the spot on the surface, how could you ensure you are getting the use of the mo? I got to admit Al, You're quick as I suspect you knew what I was doing. [Razz]
Actually, you're both right. The coulombic (electrostatic) attraction is what makes them work. Esters, being highly polar, do have affinity for metal and sludge. This is why ester-based synths (>10% by weight) usually show cleaner engines and lower scuffing, better boundary lubrication, etc. However, if the additive has greater coulombic affinity than does the ester, a layer of organometallic film will be deposited on the metal via the base carrier as well. I surmise that Mobil's new Supersyn is using their newly developed esters to provide boundary friction modification (reduction) along with a powerful antioxidant (used in jet engine's, BTW) to make up for the reduced ZDDP (if any). A 2001 paper in LE pretty much spelled out this newly developed ester. One of the trends I've noticed is that technical paper disclosures precede new formulation announcements by one to two years.
Thanks Molakule. Bob- you're probably giving me to much credit. I know we had this discusion once at Edmunds (which has degenerated). I really hadn't thought so far as to question whether the base oil would compete with the anti-wear additive. [Smile] Later Al
Holy Moly [Eek!] This kind of talk is why I could barely pass the minimum chemistry requirments. I was much more in to Physics, statics, dynamics, etc. At least I think I have found a place to buy my next pocket protector. [Wink] Don
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