Metal complexes with ligands–organic phosphites as polyolefin antioxidants. I. Kinetics and mechanism of polyolefin and model hydrocarbon stabilization by organic phosphites

Pobedimskii, D. G.; Kirpichnikov, P. A.

doi:10.1002/pol.1980.170180304

Cited by 18 publications

(4 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The formation of Et 2 PO t Bu in reactions of 3 and 5 with Et 3 P indicates a similar pathway in these cases. It should be noted that t BuOO • is not involved in the reactions of 1 since this peroxyl radical is known to quantitatively oxidize (PhO) 3 P to the phosphate (PhO) 3 PO, which is not observed. t BuOO • in principle could be formed by Ti−O bond homolysis, as reported recently for Cp 2 Ti(TEMPO)(Cl) …”

Section: Discussionmentioning

confidence: 99%

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

2006

View full text Add to dashboard Cite

The titanium(IV) alkylperoxide complex Cp 2 Ti(OO t Bu)Cl (1) is formed on treatment of Cp 2 TiCl 2 with NaOO t Bu in THF at −20 °C. Treatment of 1 with AgOTf at −20 °C gives the triflate complex Cp 2 Ti(OO t Bu)OTf (2), which is rapidly converted to the bromide Cp 2 Ti(OO t Bu)Br (3) on addition of n Bu 4 NBr. The X-ray crystal structures of 1 and 3 both show η 1 -OO t Bu ligands. Complex 2 is stable only below −20 °C; 1 H, 13 C, and 19 F NMR spectra suggest that it also contains an η 1 -OO t Bu ligand. Removal of the chloride from 1 with [Ag(Et 2 O) 2 ]BAr' 4 (Ar' = 3,5-(CF 3 ) 2 C 6 H 3 )) yields the etherate complex [Cp 2 Ti(OO t Bu)(OEt 2 )]BAr' 4 (4). Again, coordination of a fourth ligand to the Ti center indicates an η 1 -OO t Bu ligand in 4. These peroxide complexes do not directly oxidize olefins or phosphines. For instance, the cationic etherate complex 4 reacts with excess Et 3 P simply by displacement of the ether to form [Cp 2 Ti(η 1 -OO t Bu)(Et 3 P)]BAr' 4 (5). Compounds 1-5 all decompose by O-O bond homolysis, based on trapping and computational studies. The lack of direct oxygen atom transfer reactivity is likely due to the η 1 coordination of the peroxide and the inability to adopt more reactive η 2 geometry. DFT calculations indicate that the steric bulk of the t Bu group inhibits formation of the hypothetical [Cp 2 Ti(η 2 -OO t Bu)] + species.

show abstract

Section: Discussionmentioning

confidence: 99%

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

2006

View full text Add to dashboard Cite

show abstract

“…* Calculated constants k7 of the interaction of styrene peroxy radicals with In, stoichiometric coefficients of this reaction, and Arrhenius parameters for k7 are listed in Table I (the curves are typical and therefore not pre~ented).~ It should be noted that values of f-k7, calculated for different initial concentrations of inhibitors [In], proved to be similar in value. This means that radicals from complex inhibitors do not participate in the reactions of the propagation of substrate oxidation chain; for example, for complex inhibitor Cusp2 at 45OC, concentrations mol/L we have the following values of f-k7: 1.8 X lo5 and 1.2 X lo5 L/mol s, respectively. Here it should be noted that the differences obtained in the value of fvk7 (30%) are within the limits of precise calculation according to the linearization method used.…”

Section: Ro; + Ro; + Productsmentioning

confidence: 99%

“…The choice of stable metal complexes of Cu (1) was made for a number of reasons. First, the Cu(1) ion forms stable complexes with organic phosphites that can be obtained as individual substances (their synthesis is simple5).…”

Section: Introductionmentioning

confidence: 99%

Metal complexes with ligands—organic phosphites as polyolefin antioxidants. III. Kinetics and mechanism of the inhibiting action of individual stable Cu(i)‐complexes with phosphites

Pobedimskii¹,

Kurashov²,

Kirpichnikov³

1983

J. Polym. Sci. Polym. Chem. Ed.

Self Cite

View full text Add to dashboard Cite

The general features of behavior of kinetically labile complexes (metal phosphite) revealed earlier 1,2 provide the basis for the prediction of the activity of a new class of oxidation inhibitors. These are individual, stable metal complexes with organic phosphites as main ligands. The remarkable feature of these complexes, as shown as in this article on Cu(I) complexes, is the significant increase in the stoichiometric coefficient of inhibition f due to the suppression of the additional chain consumption of phosphite in the complex. The study of the initiated oxidation of styrene and solid isotactic polypropylene has proved that the phosphite complexes with Cu(I) ion are more effective than free, noncoordinated phosphites; quantitative characteristics of the inhibiting action of these complexes have been calculated. It is proved that termination of oxidation kinetic chains on the inhibitor molecules includes oxidation of coordinated phosphite without changing the oxidation degree of the central ion of metal. During inhibition of the oxidation of the substrate with mixtures of phosphite complexes of Cu(I) and phosphites (in styrene) or with aromatic amines (in polypropylene), the phenomenon of nonadditive strengthening (synergism) was discovered and the mechanism and kinetic regularities of synergism were revealed. This investigation of the phosphite complexes of the ions of Cu(I) presents new opportunities for controlled stabilization of polymers in uncontrolled conditions.

show abstract

“…Reaction of 1 with P(OPh) 3 gives the phosphite t BuOP(OPh) 2 without any phosphate (PhO) 3 PO. Given the known reactivity of P(OPh) 3 with oxyl radicals (eq 5), this shows that peroxyl radicals are not present …”

mentioning

confidence: 97%

Oxygen−Oxygen Bond Homolysis in a Novel Titanium(IV) Alkylperoxide Complex, Cp₂Ti(OO^tBu)Cl

2002

View full text Add to dashboard Cite

Cp2TiCl2 reacts with NaOOtBu to form the new titanium peroxide complex, Cp2Ti(OOtBu)Cl (1), which has been characterized both in solution and in the solid state. This complex is surprisingly unreactive towards olefins and phosphines, as it does not directly transfer an oxygen atom. Instead, decomposition occurs via initial homolysis of the oxygen-oxygen bond, yielding a tert-butoxyl radical. Decomposition of 1 in the presence of phosphines yields either phosphine oxides (e.g., OPPh3) or phosphinites (e.g., tBuOPEt2), products that result from tBuO* + PR3. O-O bond homolysis is surprising because the Ti(IV) center is d0 and cannot be oxidized, where all previous clear examples of homolytic cleavage of metal peroxide complexes are facilitated by oxidation of the metal center.

show abstract

Metal complexes with ligands–organic phosphites as polyolefin antioxidants. I. Kinetics and mechanism of polyolefin and model hydrocarbon stabilization by organic phosphites

Cited by 18 publications

References 9 publications

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

Metal complexes with ligands—organic phosphites as polyolefin antioxidants. III. Kinetics and mechanism of the inhibiting action of individual stable Cu(i)‐complexes with phosphites

Oxygen−Oxygen Bond Homolysis in a Novel Titanium(IV) Alkylperoxide Complex, Cp₂Ti(OO^tBu)Cl

Contact Info

Product

Resources

About

Metal complexes with ligands–organic phosphites as polyolefin antioxidants. I. Kinetics and mechanism of polyolefin and model hydrocarbon stabilization by organic phosphites

Cited by 18 publications

References 9 publications

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp2TiIV(η1-OOtBu)L]+/0, L = Cl-, OTf-, Br-, OEt2, Et3P

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp2TiIV(η1-OOtBu)L]+/0, L = Cl-, OTf-, Br-, OEt2, Et3P

Metal complexes with ligands—organic phosphites as polyolefin antioxidants. III. Kinetics and mechanism of the inhibiting action of individual stable Cu(i)‐complexes with phosphites

Oxygen−Oxygen Bond Homolysis in a Novel Titanium(IV) Alkylperoxide Complex, Cp2Ti(OOtBu)Cl

Contact Info

Product

Resources

About

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

Oxygen−Oxygen Bond Homolysis in a Novel Titanium(IV) Alkylperoxide Complex, Cp₂Ti(OO^tBu)Cl