The Alkylating Properties of Alkyl Thiophosphates

Hilgetag, Günter; Teichmann, Herbert

doi:10.1002/anie.196509141

Cited by 50 publications

(14 citation statements)

References 84 publications

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“…At temperatures ranging from 403 to 503 K depending on the alkyl groups present, ZnDTPs, being very strong alkylating agents [28][29][30][31][32], undergo a nucleophilic attack at the P-O-R group, which is often followed by an autocatalytic realkylation (Step 1 in Scheme 1b). After that, the negative charge migrates from the oxygen to the sulfur atom (Step 2 in Scheme 1b).…”

Section: Proposed Reaction Mechanismmentioning

confidence: 99%

“…Hilgetag and Teichman have accurately described the chemical behavior of organophosphates and organothiophosphates, pointing out that the key chemical feature of these compounds is their strong alkylating power [28,29]. All the chemical reactions could be explained on the basis of Pearson's acid-basis concept [30][31][32], according to which oxygen is a ''hard base'' and reacts preferentially with ''hard acids,'' such as protons, ''A'' metals (alkali metal cations, alkaline earth metal cations, and light transition metal cations in high oxidation states), carbonyl carbon and phosphoryl phosphorus.…”

Section: Introductionmentioning

confidence: 98%

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Reactivity of Triphenyl Phosphorothionate in Lubricant Oil Solution

2009

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Investigating the thermo-oxidative reactivity of anti-wear additives in lubricant oil solution at high temperature can significantly contribute to an understanding of the mechanism of thermal film and tribofilm formation on metal surfaces. In this study, the reactivity of triphenyl phosphorothionate (TPPT) in lubricant oil solution at high temperature (423 and 473 K) has been studied by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The results show that the TPPT molecule was highly thermally stable and did not completely decompose in oil solution even upon heating at 423 K for 168 h and at 473 K for 72 h. The degradation of the TPPT molecule, which turned out to be a first-order reaction, started taking place after 6 h at both temperatures, leading to the breakage of the P=S bond with the formation of triphenyl phosphate. During these heating experiments, no oil-insoluble compounds were detected. The oxidation of the base oil as a result of the prolonged heating demonstrated that the TPPT molecule did not effectively act as oxidation inhibitor.

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Section: Proposed Reaction Mechanismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Reactivity of Triphenyl Phosphorothionate in Lubricant Oil Solution

2009

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“…A plausible mcclranisni for the deconiposition is presented here, based upon the observed end-products and intermediates and on tlie well-established chemistry available in tlie literature for tl~iol)hospliate esters. 'I'he two major principles involved in the chemistry of thioplios~~liate esters are extensively discussed in two review articles ( 8 ) , (9). T h e principle reactivity of such cornpounds is as Ibllows:…”

Section: The Mechanism Of Zinc Dialkyldithiophosphate Decompositionmentioning

confidence: 99%

The Chemistry of the Thermal Degradation of Zinc Dialkyldithiophosphate Additives

Jones

Coy

1981

A S L E Transactions

135

124

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“…Hilgetag and Teichmann [14,15] described the chemical behaviour of pure organophosphates and organothiophosphates, focusing, in particular, on the difference in the nucleophilic reactivities of the phosphoryl and thiophosphoryl groups. The key chemical feature of these classes of compounds is their strong alkylating power.…”

Section: Introductionmentioning

confidence: 99%

Substituent Effect on the Reactivity of Alkylated Triphenyl Phosphorothionates in Oil Solution in the Presence of Iron Particles

2010

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The effect of the substituent attached to the phenyl rings on the reactivity of alkylated triphenyl phosphorothionates (t-butyl TPPT (b-TPPT) and p-nonyl TPPT (n-TPPT)) in oil solution at high temperature (423 and 473 K) was investigated by means of Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The FT-IR and NMR results show that the alkylated TPPTs were highly thermally stable and did not completely decompose in oil, even upon heating at 423 K for 168 h and at 473 K for 72 h, with and without steel filings and iron particles (both metallic iron and iron oxide particles). The reaction of alkylated TPPTs was found to start with the scission of the P=S bond to yield alkylated triphenyl phosphate. The kinetics of the thermooxidative reaction was slower when steel filings and iron particles were added to the oil solutions during the heating experiments. The reactivity of the unsubstituted molecule (TPPT) was higher than that of alkylated TPPTs at 423 K, while at 473 K TPPT and n-TPPT were more reactive than b-TPPT. In the case of the experiments performed at 473 K in the presence of steel filings or metallic iron or iron oxide particles, the reactivity of the alkylated TPPT molecules decreased with the length of the alkyl chain bound to the phenyl rings. The XPS results show that a reaction layer consisting of carbon, oxygen, phosphorus and iron was formed on the 100Cr6 steel filings immersed for 72 h in oil solutions containing alkylated TPPTs and heated at 473 K. Sulphur was neither detected on the surface nor in the composition vs depth profile. During the heating experiments, the base oil (PAO) was oxidized. At 423 K, the alkylated TPPTs had a strong antioxidant effect, which was found to be more pronounced upon increasing the length of the alkyl chain bound to the phenyl rings. At 473 K, the TPPTs did not inhibit the oxidation of the base oil as effectively as at 423 K.Keywords Thermo-oxidative degradation Á t-butyl triphenyl phosphorothionate (b-TPPT) Á Irgalube Ò 232 Á p-nonyl triphenyl phosphorothionate (n-TPPT) Á Irgalube Ò 211 Á Ashless anti-wear additives Á Low-SAPS additives Á FT-IR Á NMR Á XPS Á Iron particles 1 Introduction

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The Alkylating Properties of Alkyl Thiophosphates

Cited by 50 publications

References 84 publications

Reactivity of Triphenyl Phosphorothionate in Lubricant Oil Solution

Reactivity of Triphenyl Phosphorothionate in Lubricant Oil Solution

The Chemistry of the Thermal Degradation of Zinc Dialkyldithiophosphate Additives

Substituent Effect on the Reactivity of Alkylated Triphenyl Phosphorothionates in Oil Solution in the Presence of Iron Particles

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