Zinc dialkyldithiophosphate,

Lubricants, Fuels, and Petroleum. The adipate and azelate diesters of through alcohols, as weU as those of tridecyl alcohol, are used as synthetic lubricants, hydrauHc fluids, and brake fluids. Phosphate esters are utilized as industrial and aviation functional fluids and to a smaH extent as additives in other lubricants. A number of alcohols, particularly the Cg materials, are employed to produce zinc dialkyldithiophosphates as lubricant antiwear additives. A smaH amount is used to make viscosity index improvers for lubricating oils. 2-Ethylhexyl nitrate [24247-96-7] serves as a cetane improver for diesel fuels and hexanol is used as an additive to fuel oil or other fuels (57). Various enhanced oil recovery processes utilize formulations containing hexanol or heptanol to displace oil from underground reservoirs (58) the alcohols and derivatives are also used as defoamers in oil production. 

Some commercially important isobutyl derivatives include isobutyl acetate, employed as a replacement solvent for -butyl acetate zinc dialkyldithiophosphate (ZDPP) lube oil additives isobutyl acrylate [106-62-8] and methacrylate [97-86-9] monomers isobutylamines and amino resins (qv). 

Eleven zinc dialkyldithiophosphates (ZDDPs) in lubricating oil additives were separated by NPLC [723] eight ZDDPs were separated on an ODS column... 

Zinc dialkyldithiophosphates (ZDDPs), which act as antiwear additives in lubricating oils and were postulated to exist in various molecular forms (monomer, dimer or neutral form, and basic form), were studied by multi-edge (Zn K-, P K- and S K-) XAS for structural assessment [311]. Grazing incidence absorption spectroscopy measurements have provided evidence for breakdown of the ZDDP molecule following its adsorption on to a steel substrate surface [312]. XANES and CEMS were used to study the interaction of per-fluoropolyalkyl ether (PFPAE) additives with Fe-based alloys [313],... 

Reactive FFs can only be applied to a few specific cases for which they have been developed, such as the hydrocarbon systems discussed in the first part of this section. For other systems, describing tribochemical reactions requires the use of quantum chemical methods. In recent studies, such methods have been applied to investigate the behavior of zinc phosphates (ZPs) in response to high pressures. ZPs form the basis of anti-wear films derived from zinc dialkyldithiophosphates (ZDDPs), which are additives that have... 

Review of the Lubrication of Metallic Surfaces by Zinc Dialkyldithiophosphates. 

Inhibition of Oxidation. Several antioxidants were tested in chloroprene at 45°C. Those which can be classified as mainly suppressors of initiation (I), because of their ability to destroy hydroperoxides—namely, zinc dialkyldithiophosphates, zince dialkyldithiocarbamates, triphenyl-phosphine, and the like—had no inhibiting effect at the 100-p.p.m. level. 

Zinc Dialkyldithiophosphate Zinc Chloride Zinc Chromate Zinc Chromate Zinc Acetate... 

Most lubricating oils for engine use contain additives designed to improve such properties as lubricity, detergency, oxidation resistance, and viscosity. The additives contain elements that could be potentially harmful to catalysts. Table I lists these elements and their typical concentration in lubrication oils of 1973. The first three elements are combined usually in one compound, zinc dialkyldithiophosphate. Thus, before combustion, sulfur and phosphorus in oil are in a different chemical state than the same elements are in fuel. Little is known whether combustion nullifies these differences partially or fully. Some data, to be discussed subsequently, are available on the separate poisoning effects of these elements as derived either from the fuel or from the oil. 

Most commercial engine oils contain the antiwear agent zinc dialkyldithiophosphate (ZDP). The effect of phosphorus derived from oil is of particular concern when the poison concentration in the fuel is very low. One should keep in mind that the ZDP additive contains within its own chemical formula a potential scavenger for phosphorus, i.e., zinc. Other potential scavengers which form stable phosphates, such as alkaline earth metals, are also present in the commercial oil additive package. ... 

Lubricant additives (Ashless dispersant A and B, Zinc dialkyldithiophosphate) TT A (Ward et ah, 2002b)... 

The rearrangement of zinc dialkyldithiophosphate initiated by a double alkyl group migration from oxygen atoms to sulfur atoms (Fuller et al., 1998 Jones and Coy, 1981 Varlot et al., 2000), is believed to be the result of the following reaction mechanism (equation 1.2) ... 

Zinc dialkyldithiophosphates (ZDDPs) function mainly as antioxidants and antiwear additives. Molecules of ZDDPs adsorb on metal surface to participate in surface tribofilm formation under conditions of boundary lubrication. The solid tribofilms are formed at the metal surface to protect even under conditions of coarse contact under load (Bom et al., 1992). 

Mixtures of metallic detergents, such as phenates, sulfonates, phosphonates, and salicylates with ashless dispersants such as succinimides and benzylamine, together with zinc dialkyldithiophosphate (ZDDP), can lead to new effects. The possible interactions between these main additives used in lubricating formulations when dissolved/dispersed in hydrocarbon media are shown in Fig. 2.8 together with an indication of the intensity of those respective interactions. 

Fig. 2.9. Intermolecular interaction between dispersants (succinimides) and zinc dialkyldithiophosphates (ZDDPs)...

II) Zinc dialkyldithiophosphates as multifunctional additives in lubrication formulations... 

The antiwear and antioxidant additive, zinc dialkyldithiophosphate, is a key ingredient in the great majority of engine oil formulations, and other lubricant applications such as hydraulic fluids and gear oils. The ZDDP-derived tribochemical films have been studied by a number of laboratories, but their mode... 

Fig. 2.11. Solubilization mechanism of zinc dialkyldithiophosphate molecules (ZDDP) by soft-core reverse micelles (RMs)...

ZDDPs are formed by the reaction of phosphorus pentasulfide (P2S5) dimer with alcohol (ROH) or phenol (dithiophosphoric acid ester formation), followed by reaction with zinc powder or zinc oxide or with zinc chloride and sodium hydroxide solutions (see below). The various types of ZDDPs differing in R-group structures are shown in Table 2.6 (SAE, 1983 Yamaguchi et al., 1966). Scheme of the formation of zinc dialkyldithiophosphate, ZDDP ... 

Dithiophosphoric acid ester Zinc dialkyldithiophosphate (monomeric)... 

Oxidative degradation test ISOT. The oxidative stability of RMs of borates and carbonates with sulfonates and salicylates were evaluated in the presence of ZDDP. The concentration of secondary type zinc dialkyldithiophosphate was 1 wt% and that of the detergents was 2.2 wt% in SAE 10 mineral oil. Table 3.8 shows the results (Inoue, 1993). 

Table 3.8. Oxidation stability of mutifunctional additives (carbonate-sulfonate and borate-sulfonate RMs) in the presence of zinc dialkyldithiophosphate in SAE 10 mineral oil. Initial oxidation (In) time (min) and the remaining oxidation (Re) time (min) after 100 hrs oxidative degradation (ISOT) test8...

Table 4.2. Chemical characterization of tribochemical and thermal films generated from zinc dialkyldithiophosphates (ZDDPs) using (P) L-edge and (S) L-edge XANES spectroscopy (Fuller et al., 1997)...

Zinc dialkyldithiophosphate ZDDP A linkage isomer (LI-ZDDP) of ZDDP... 

The tribochemical film produces two major bands, one centered between 1130 cm"1 and 1185 cm"1 and one centered at 620 cm"1. Amorphous ortho- and pyrophosphate were prepared and their spectra seem to be consistent with the spectra of the tribochemical films. The films had two broad major bands consistent with the phosphorus-oxygen bonds. This indicates that the tribochemical film was not composed of phosphate glasses as expected, but rather predominantly amorphous orthophosphate or pyrophosphate formed by thermooxidative decomposition of zinc dialkyldithiophosphate. These groups may be connected by the metal cations. 

Phosphorus is present in zinc dialkyldithiophosphate and deactivate platinum catalysts in engine exhaust systems. Using zinc, antimony and oxothiomolybdate dialkyl-dithiocarbamate (MoDTC) complexes alone or in combination with other lubricating oil additives appears to solve this problem. Antimony complexes are used also as extreme pressure agents while molybdenum ones as friction modifier additives (Hill et al., 1994). Analyses of Zn(dtc)2 decomposition using the thermogravimetric method, flash vacuum pyrolysis, and four-ball machine... 

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