Synthesis,characterization, and application of oligomer‐type‐based phosphites

Organic alkyl and aryl phosphites are effective antioxidants and photostabilizers with applications in a wide range of polymers. The primary role of phosphites is to decompose hydroperoxide. However, aryl phosphites are also capable of reacting as antioxidants by affecting the kinetics. In particular, oligomer‐type phosphites have a greater effect on polymer degradation because of their high compatibility, reactivity, and solubility with almost all polymers. Generally, phosphites are sensitive to hydrolysis. In order to overcome this hydrolytic sensitivity in phosphites, a novel hydrolytically stable oligomeric phosphite incorporating a sterically hindered aromatic alcohol (2,4‐di‐tert‐butyl‐6‐methylphenol) that gives hydrolytic stability to the phosphite was synthesized and characterized, and its performance as an antioxidant for polypropylene was investigated. J. VINYL ADDIT. TECHNOL., 22:146–155, 2016. © 2014 Society of Plastics Engineers     

Additive interactions in the stabilization of film grade high-density polyethylene. Part I: Stabilization and influence of zinc stearate during melt processing

The melt stabilization activity of some of the most commercially significant phenolic antioxidants and phosphites (alone and in combination), without and with zinc stearate, was studied in high-density polyethylene (HDPE) produced by Phillips catalyst technology. Multiple pass extrusion experiments were used to degrade the polymer melt progressively. The effect of stabilizers was assessed via melt flow rate (MFR) and yellowness index (YI) measurements conducted as a function of the number of passes. The level of the phenolic antioxidant remaining after each extrusion was determined by high-performance liquid chromatography (HPLC). Phenolic antioxidants and phosphites both improved the melt stability of the polymer in terms of elt viscosity retention; the influence of zinc stearate was found to be almost insignificant. However, phosphites and zinc stearate decreased the discoloration caused by the phenolic antioxidants. A correlation was found between the melt stabilization performance of phosphites and their hydroperoxide decomposition efficiency determind via a model hydroperoxide compound. Steric and electronic effects associated with the phosphorus atom influenced the reactivity towards hydroperoxides. Furthermore, high hydrolytic stability did not automatically result in lower efficiency. Besides phosphite molecular structure, stabilization activity was also influenced by the structure of the primary phenolic antioxidant and the presence of zinc stearate.     

Synthesis,characterization, and application of a hydrolytically stable liquid phosphite

Organic alkyl and aryl phosphites are effective antioxidants and photostabilizers with applications in a wide range of polymers. The primary role of phosphites is to decompose hydroperoxide. However, aryl phosphites are also capable of reacting as antioxidants by negatively affecting the kinetics. In particular, liquid phosphites have a greater effect on polymer degradation because of their high compatibility, reactivity, and solubility with almost all polymers, but they are sensitive to hydrolysis. In order to overcome this hydrolytic sensitivity in liquid phosphites, a novel hydrolytically stable liquid phosphite incorporating a sterically hindered aromatic alcohol (2,4‐di‐tert‐butyl‐6‐methylphenol) that gives hydrolytic stability to the phosphite was synthesized and characterized, and its performance as an antioxidant for polypropylene was investigated. J. VINYL ADDIT. TECHNOL., 22:163–168, 2016. © 2014 Society of Plastics Engineers     

Improvement of melt stability and degradation efficiency of poly (lactic acid) by using phosphite

Concurrent improvement of melt processing stability and degradation efficiency of poly(lactic acid) (PLA) is still a challenge for the industry. This article presents the use of phosphites: tris(nonylphenyl) phosphite (TNPP) and tris (2,4-di-tert-butylphenyl) phosphite (TDBP), to control the thermal stabilization, mechanical performance, and hydrolytic degradation ability of the compressed PLA films. The hydrolysis process is followed as a function of time at 45, 60, and 75°C. During melt extrusion, both phosphites function as a processing aid, besides acting as a chain extender stabilizing the PLA molecular weight. The phosphite structure plays a crucial role over crystallinity and water absorption, in controlling the hydrolytic degradation of PLA. The application of TNPP significantly catalyzes the hydrolysis of PLA, which is the initial step of the biodegradation process. The optimum amount of TNPP for best hydrolytic degradation efficiency and thermal stabilization of PLA is 0.5 wt%. The excessive TNPP loadings cause a drastic drop in PLA molecular weight and, as a consequence, a reduction of flexural strength. The reactions between PLA and phosphite molecules are discussed.     

Performance and antioxidant activity of phenol/phosphite antioxidants in synergistic blends in the thermal and photooxidation of high‐density polyethylene (HDPE) film: Influence of zinc stearate

The influence of zinc stearate (ZnSt) on the thermal and photochemical stabilities of phenolic antioxidant/phosphite combinations has been determined in HDPE by using FTIR analysis. The results show that while under thermal aging the effects are generally antagonistic, under photooxidation the effects are synergistic. The interactions appear to be dominated by the role of complex formation between the phosphites and ZnSt. Such interactions would remove the hydroperoxide effectiveness of the phosphite in thermal oxidation, while under light they could cause stabilization. Derivative UV and FTIR analysis on pre‐melt blends of the additives in solution shows evidence for strong complexation for the phosphite antioxidants. Other acid scavengers such as hydrotalcite and calcium stearate also appear to influence the behavior of phenolic antioxidants in thermal oxidation. The antagonistic effect of zinc stearate was also confirmed following a single pass in an extruder, where for all formulations there was a greater reduction in MFI associated with crosslinking.     

Contribution to the study of mechanism of stabilizing action of esters of phosphorous acid

The rate of the reaction of a series of phosphites with cyclohexene hydroperoxide and cyclohexene peroxy radicals was studied. The results of the measurements were compared with the stabilization efficiency of the same compounds in isotactic and in atactic polypropylene at 160°C and 120°C respectively and during the course of atmospheric ageing. It was found the reverse relation between the stabilization efficiency and the reaction constants of the reaction of phosphites with hydroperoxides. The main stabilization reaction of the phosphorous stabilizers seems to be the reaction of phosphites or of their decomposition products with radicals. The possibility of splitting off of free phenol from phosphites as a result of the reaction of the esters with hydroperoxide groups was checked.     

Phosphororganische Antioxidantien. III. Kinetik und Mechanismus der Cumylhydroperoxidzersetzung durch cyclische Phosphite

Organophosphorus Antioxidants. III. Kinetics and Mechanism of the Decomposition of Cumyl Hydroperoxide by Cyclic Phosphites The reaction mechanism of cyclic esters of phosphorous acids I to VIII with cumyl hydroperoxide has been studied kinetically by means of ³¹P n.m.r. spectroscopy, high performance liquid chromatography and iodometric titration. The five-membered cyclic phosphites ( I and II ) react with cumyl hydroperoxide to give the corresponding phosphates ( AI and AII ) and cumyl alcohol. With more hydroperoxide or water they form the open chain phosphate esters ( BI and BII ) which decompose cumyl hydroperoxide catalytically giving phenol and acetone. Higher membered cyclic phosphites ( III to VIII ) react with cumyl hydroperoxide to give the corresponding phosphates and alcohol only. The mode of reaction depends on the hydrolysis behaviour of the cyclic phosphates ( AI to A VIII ). Only fivemembered cyclic phosphites which give easily hydrolyzable phosphates are able to decompose cumyl hydroperoxide catalytically. The nature of the exocyclic group in the phosphites has no influence on this behaviour. The kinetic parameters of the separate reaction steps are given. The ionic mechanism of hydroperoxide decomposition is accompanied by a homolytic one.     

Design of Ionic Phosphites for Catalytic Hydrocyanation Reaction of 3‐Pentenenitrile in Ionic Liquids†

The synthesis and characterization of a novel class of ionic phosphites bearing either a single cationic group obtained by quaternization of aminophosphites or three cationic groups prepared by reaction of phosphorus trichloride with imidazolium phenols are reported. The catalytic hydrocyanation reaction of 3‐pentenenitrile (3PN) into adiponitrile has been performed in the presence of Ni(0) with ionic phosphite ligands, and a Lewis acid in biphasic ionic liquid/organic solvent system. The screening of several original cationic phosphites was performed and the experimental conditions were optimized for the tri‐cationic phosphite tris‐4‐[(2,3‐dimethylimidazol‐1‐yl)methyl]phenyl phosphite tris[bis(trifluoromethylsulfonyl)amide]. It is possible to obtain performance similar to molecular systems and the catalyst and the Lewis acid were immobilized in the ionic phase.     

Organophosphorus antioxidants action mechanisms and new trends

Phosphite and phosphonite esters can act as antioxidants by three basic mechanisms depending on their structure, the nature of the substrate to be stabilized and the reaction conditions. All phosph(on)ites are hydroperoxide-decomposing secondary antioxidants. Their efficiency in hydroperoxide reduction decreases in the order phosphonites > alkylphosphites > arylphosphites > hindered arylphosphites. Five-membered cyclic phosphites are capable of decomposing hydroperoxides catalytically due to the formation of acidic hydrogen phosphates by hydrolysis and peroxidolysis in the course of reaction. Hindered aryl phosphites can act as chain-breaking primary antioxidants being substituted by alkoxyl radicals and releasing hindered aryloxyl radicals which terminate the radical chain oxidation. At ambient temperatures, the chain-breaking antioxidant activity of aryl phosphites is lower than that of hindered phenols, because the rate of their reaction with peroxyl radicals and their stoichiometric inhibition factors are lower than those of phenols. In oxidizing media at medium temperatures, however, hydrolysis of aryl phosph(on)ites takes place giving hydrogen phosph(on)ites and phenols which are effective chain-breaking antioxidants. 2,2,6,6-Tetramethyl- and 1,2,2,6,6-Pentamethylpiperidinyl phosphites and phosphonites (HALS-phosph(on)ites) surpass many common phosphites, phenols and HALS compounds as stabilizers in the thermo- and photo-oxidation of polymers. Their superior efficiency is probably due to an intramolecular synergistic action of the HALS and the phosph(on)ite moieties of their molecules.     

Organophosphorus compounds. XXI. The Reaction of Alkyl Phosphites with 10-Methyleneanthrone and 10-Arylideneanthrones

The reaction of triethyl and trimethyl phosphites with 10-methyleneanthrone 1a , 10-benzylideneanthrone 1b , 10-(p-chlorobenzylidene)anthrone 1c , 10-(p-methoxybenzylidene)anthrone 1d and 10-(diphenylmethylene)anthrone 1e , has been investigated. Depending on the experimental conditions, reaction of 1a with triethyl phosphite gives diethyl (10-ethoxy-9-anthryl)methylphosphonate 3a and/or the spiroanthrone 8a , whereas, with trimethyl phosphite, dimethyl [(9, 10-dihydro-10-oxo-9-anthryl)methyl]phosphonate 11a is formed. Compound 1b on reaction with trimethyl phosphite yields dimethyl [α-(9,10-dihydro-10-oxo-9-anthryl) benzyl]phosphonate 11b . Reaction of 1c with triethyl phosphite and trimethyl phosphite gives rise to diethyl [p-chloro-α-(10-ethoxy-9-anthryl)benzyl]phosphonate 3c and dimethyl [p-chloro-α-(9,10-dihydro-10-oxo-9-anthryl)benzyl]phosphonate 11c respectively. Compounds 1d and 1e did not react with alkyl phosphites. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results.     

Effect of alkyl group on the chain extension of phosphites in polylactide

Polylactide (PLA), which is synthesized from natural resources and can degrade easier, possesses high mechanical strength, so it is a reasonable substitute for petroleum‐based plastics. Phosphites can increase the stability of PLA through chain extension with the hydroxyl and carboxyl groups simultaneously. But there are few reports on the structural effects of phosphites on the chain extension of PLA. In this article, three kinds of phosphites with different amounts of aryl and alkyl groups were used as chain extenders in PLA and were compared in detail. The molecular weights, complex viscosities, and storage moduli of virgin PLA and PLA stabilized by three different phosphites were characterized by gel permeation chromatography and rheometry. The results show that the presence of alkyl groups is not beneficial for chain extension, as the more alkyl groups there are, the worse the chain extension is. Regarding the three phosphite chain extenders added to PLA—triphenylphosphite (TPP), diphenylisooctylphosphite (PTC), and phenyldiisooctylphosphite (PDOP)—the number of alkyl groups in them can be ranked as follows: PDOP > PTC > TPP. Since PDOP had the most alkyl groups, the chain extension of PDOP was the weakest. In addition, the product, which was formed due to the chain extension of PLA and TPP, had some plastication, thus enabling PLA to move more freely and making it easier to process. J. VINYL ADDIT. TECHNOL., 25:144–148, 2019. © 2018 Society of Plastics Engineers     

Phosphite ester compositions for PVC compounds

The activity of various structural classes of liquid organophosphite esters has been examined in flexible PVC applications. Blends of the most active phosphites have been developed as alternative heat stabilizers for PVC. These new phosphite mixtures eliminate the dependence of compounders upon mixed-metal stabilizer systems based on heavy metals such as barium and cadmium. Static oven aging tests showed the superior performance of these blends compared to that of traditional mixed-metal stabilizers.     

我国亚磷酸酯类抗氧剂的合成与应用研究进展

简要介绍了亚磷酸类抗氧剂的作用机理，重点介绍了近年来我国亚磷酸酯类抗氧剂的合成及应用进展，最后指出了亚磷酸酯类抗氧剂今后的研究方向。     

Free radical addition of dialkyl phosphites to N,N-disubstituted amides of unsaturated fatty acids and screening of the products for antimicrobial activity

Free radical addition of dibutyl phosphites to terminal and internal double bonds of monounsaturated amides was attained in high yield. The reaction was initiated by irradiation using Cobalt-60. Attempts to add diphenyl phosphite to the unsaturated amides failed with the amides being recovered unchanged. Similar attempts to add dialkyl phosphites to N-linoleoylmorpholine resulted in products that were deficient in phosphorus. Screening for antimicrobial activity againstEscherichia coli, Trichosporon capitatum, Trichoderma viride andCandida lipolytica indicated that terminal addition products may be more active than the internal addition products, with the former strongly inhibiting the growth of all four test organisms. Presented at the AOCS Meeting, Los Angeles, April 1972. ARS, USDA.     

Synthesis and antioxidative properties of novel multifunctional stabilizers

New multifunctional stabilizers containing hindered amino, phosphite, and in some cases also free phenolic moieties have been synthesized starting from tris(diethylamino)phosphine. Some of them proved to be efficient stabilizers for model hydrocarbons and for polypropylene during processing, thermo‐, and photooxidation. Various sterically hindered phenols, amines (HAS), and phosphites have been modified by the reaction with isophorone diisocyanate (IPDI) to get new multifunctional stabilizers for polymers. The synthesized products have been investigated regarding their thermal and antioxidative behavior. The novel urethane stabilizers are, depending during the polymer processing to release the antioxidatively active parent phenols.     

Enantioselective hydroformylation of olefins catalyzed by rhodium(I) complexes of chiral phosphine–phosphite ligands

Using Rh(I) complexes of chiral phosphine–phosphites, hydroformylation of such a variety of olefins as aryl–substituted, alkyl–substituted, and heteroatom–substituted ones proceeded in high enantioselectivity. A trigonal bipyramidal RhH(CO)₂(phosphine–phosphite) complex is suggested as the active species, in which the hydride and the phosphite moiety are located at the apical positions. This revised version was published online in June 2006 with corrections to the Cover Date.     

The preparation and performance of “Cage” diphosphites as secondary antioxidants in the stabilization of polyolefins

“Cage” diphosphites, a new family of phosphorus antioxidants, are discussed in regard to their preparation, properties, and effectiveness in polyolefins, particularly, with phenolic stabilizers, in respect to their ability to control melt flow and color during processing. These trivalent phosphorus compounds have two different types of phosphite functionalities in their structure. One phosphorus is part of an eight membered (1,3,2-dioxaphosphocine) ring system while the other is part of a tricyclic cage of carbon and oxygen atoms. This structures can contribute to improved hydrolytic stability over rather similar aryloxy-alkoxy phosphites and show competitive stabilization effectiveness in the processing of polyolefins. The possible modes of formation and of hydrolysis are discussed.     

Additive interactions in the stabilization of film grade high-density polyethylene. Part II: Stabilization during long-term service

In the second part of this study, the performance of phenol/phosphite/zinc stearate packages and the contribution of each additive to the long-term thermal stabilization and photostabilization were evaluated in high-density polyethylene produced by using Phillips catalyst technology. Infrared spectroscopy, ultraviolet spectroscopy, and yellowness index measurements were used to establish the performance of the different additive packages. The HPLC analysis of dichloromethane extracts of the polymer was carried out after melt processing in order to determine the amount of phenolic antioxidant remaining in the samples. The long-term thermal stabilization was dependent only upon the phenolic antioxidant concentration, whereas both phenolic antioxidants and phosphites contributed directly to photostabilization. Zinc stearate did not show any significant influence on the stabilization under either thermooxidative or photooxidative conditions.     

Antioxidation and mechanism of phosphites including the free phenolic hydroxyl group in polypropylene

Inhibiting the degradation of polypropylene (PP) in melt processing and usage is an important issue in the plastic industry. It is becoming more and more urgent to increase the antioxidation of phosphites alone while maintaining the water resistance. In this study, one phosphite antioxidant, named bis‐2,2′‐methyl‐4,6‐di‐tert‐butylphenyl phosphite (BM46TBPP), which contains a water‐resistant inner ring and a free phenolic hydroxyl group together, was synthesized. Then, antioxidation in PP was characterized with multiple extrusions and oxidation induction times (OITs). Finally, the hydrogen‐donating ability of this antioxidant was tested with 2,2‐diphenyl‐1‐picrylhydrazyl radical colorimetry to explain the antioxidation mechanism. The results show that the phosphite BM46TBPP displays better antioxidation than tris(2,4‐di‐tert‐butylphenyl) phosphite (Irgafos 168) in melt processing and OIT testing. Furthermore, the priority of this antioxidant was more obvious when it was used in the presence of oxygen, so the antioxidant even made the PP stabilized by it alone show a longer OIT value than the PP stabilized by the complex system including Irgafos 168 and 2,4‐di‐tert‐butylphenol because there was a free phenolic hydroxyl group in the BM46TBPP antioxidant molecule and the hydroxyl group made the antioxidant show intermolecular synergistic antioxidation through hydrogen donation to radicals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44696.     

High‐performance phosphite stabilizer

The initial rates of air oxidation of eight aromatic phosphites were measured at 200°C in hydrocarbon solvents. The phosphites were oxidized to the corresponding phosphates, and, in every case, a small amount of the corresponding substituted phenol was also detected. The phenolic compounds likely arose from hydrolysis of the phosphites by water generated during oxidation. In general, alkyl substitution caused a decrease in the rate of oxidation. Phosphite 7 [bis(2,4‐dicumylphenyl) pentaerythritol diphosphite] and, to a lesser extent, phosphite 6 [bis(2,6‐di‐t‐butyl‐4‐methylphenyl) pentaerythritol diphosphite] had a combination of high rate of oxidation and good resistance towards hydrolysis in the bulk state, a combination that is not usual with most commercially available phosphites (1).