Phosphite phenolic

Most oxidation inhibitors today are either amines, phenols, or phosphites. Phenols were suggested as early as 1870 to combat aging. Amines are now used more than phenols in elastomers. Combinations are often used for heat. 

Phenol, p-nonyl-. See p-Nonyl phenol Phenol, nonyl-, phosphite (3 1). See Tris (nonylphenyl) phosphite Phenol, octyl. See Octylphenol Phenol, pentachloro-. See Pentachlorophenol Phenol, pentachloro-, potassium salt. See Potassium pentachlorphenate Phenol, o-phenyl, potassium deriv.. See Potassium o-phenylphenate... 

As stabilisers are often used in combination interactions are possible. ESR studies in the liquid state have been used to elucidate such interactions, e.g. with HALS/phenol mixtures it is possible to obtain information about the interactions between nitroxyl radicals and phenols, nitroxide radicals and phenoxy radicals, between phosphites, nitroxyl and phenoxy radicals in phosphite/phenol and phosphite/HALS mixtures. The results are useful for optimisation of additive formulations. 

Organic compounds (e.g., polyoles, epoxy compounds) and Co-stabilizers (e.g., phosphites, phenols, di- and tri-ketones, amino crotonates) [560]. 

Several bifunctional, autosynergist molecules were synthesized as Phenol/HAS, UV absorbers/HAS, HAS/phosphites, phenol thioethers, such as ... 

It can be used satisfactorily in combination with other stabilizers, for example other light stabilizers, phosphites, phenolic antioxidants, and their combinations. Its use in combination with a UV absorber such as 2(2 -hydroxy-3, 5 -di-/cr/-butylphenyl)-5-chloro-... 

Function 3 affects performance as determined by the chemistry of alkylate, carboxyl, sulfonyl, phenolic, phosphate, pyrophosphate, and phosphite groups. 

Oxidation of LLDPE starts at temperatures above 150°C. This reaction produces hydroxyl and carboxyl groups in polymer molecules as well as low molecular weight compounds such as water, aldehydes, ketones, and alcohols. Oxidation reactions can occur during LLDPE pelletization and processing to protect molten resins from oxygen attack during these operations, antioxidants (radical inhibitors) must be used. These antioxidants (qv) are added to LLDPE resins in concentrations of 0.1—0.5 wt %, and maybe naphthyl amines or phenylenediamines, substituted phenols, quinones, and alkyl phosphites (4), although inhibitors based on hindered phenols are preferred. 

Both thermooxidation and photooxidation of polyolefins can be prevented by using the same antioxidants as those employed for the stabilization of polypropylene, ie, alkylated phenols, polyphenols, thioesters, and organic phosphites in the amount of 0.2—0.5% (22,25). 

When the phenol reactant is 2,4-di-/ f2 -butylphenol, a phosphite ester with greater hydrolytic stabiUty is produced. 

Antioxidant Types. Commercially available antioxidants may be divided into three general classes secondary amines, phenolics, and phosphites. 

The hydrolysis of phosphites is retarded by the addition of a small amount of a base such as triethanolamine. A more effective approach is the use of hindered phenols for esterification. Relatively good resistance to hydrolysis is shown by two esters derived from hindered phenols tris(2,4-di-/ / butylphenyl)phosphite [31570-04-4] (25) and tetrakis(2,4-di-/ /f-butylphenyl)4,4 -biphenylenediphosphonite [38613-77-3] (26). The hindered fluorophosphite [118337-09-0] (27) has excellent resistance to hydrolysis. 

Me3Si)2NH, Me3SiCl, Pyr, 20°, 5 min, 100% yield. ROH is a carbohydrate. Hexamethyldisilazane (HMDS) is one of the most common sily-lating agents and readily silylates alcohols, acids, amines, thiols, phenols, hydroxamic acids, amides, thioamides, sulfonamides, phosphoric amides, phosphites, hydrazines, and enolizable ketones. It works best in the presence of a catalyst such as X-NH-Y, where at least one of the group X or Y is electron-withdrawing. ... 

In addition to stabilisers, antioxidants and ultra-violent absorbers may also be added to PVC compounds. Amongst antioxidants, trisnonyl phenyl phosphite, mentioned previously, is interesting in that it appears to have additional functions such as a solubiliser or chelator for PVC insoluble metal chlorides formed by reaction of PVC degradation products with metal stabilisers. Since oxidation is both a degradation reaction in its own right and may also accelerate the rate of dehydrochlorination, the use of antioxidants can be beneficial. In addition to the phenyl phosphites, hindered phenols such as octadecyl 3-(3,5-di-tcrt-butyl-4-hydroxyphenyI)propionate and 2,4,6-tris (2,5-di-rcrt-butyl-4-hydroxybenzyl)-1,3,5-trimethylbenzene may be used. 

When two antioxidants are used together, a synergistic improvement in activity usually results. Synergism can arise from three combinations (1) homosynergism — two chemically similar antioxidants (for instance, two hindered phenols) (2) autosynergism — two different antioxidants functions that are present in the same molecule (3) heterosynergism — the cooperative effect between mechanistically different classes of antioxidants, such as the combined effect of primary and secondary antioxidants. Thus, combinations of phenols and phosphites are widely used to stabilize synthetic rubbers. 

Bis(2,2,2-trifluoroethyl)]phosphite can be used to prepaie esters of phos phorous acid by a transestenfication reaction with alcohols and phenols [750] (equation 78)... 

Phenols give triaryl phosphites P(OAr)3 directly ai " -160 and these react with phosphorous acid to give diaryl phosphonates ... 

Synergism can also arise from cooperative effects between mechanistically different classes of antioxidants, e.g., the chain breaking antioxidants and peroxide decomposers (heterosynergism) [42]. For example, the synergism between hindered phenols (CB—D) and phosphites or sulphides (PD) is particularly important in thermal oxidation (Table 2). Similarly, effective synergism is achieved between metal dithiolates (PD) and UV-ab-sorbers (e.g., UV 531), as well as between HALS and UV-absorbers, (Table 3). 

Sulfonic esters are most frequently prepared by treatment of the corresponding halides with alcohols in the presence of a base. The method is much used for the conversion of alcohols to tosylates, brosylates, and similar sulfonic esters. Both R and R may be alkyl or aryl. The base is often pyridine, which functions as a nucleophilic catalyst, as in the similar alcoholysis of carboxylic acyl halides (10-21). Primary alcohols react the most rapidly, and it is often possible to sulfonate selectively a primary OH group in a molecule that also contains secondary or tertiary OH groups. The reaction with sulfonamides has been much less frequently used and is limited to N,N-disubstituted sulfonamides that is, R" may not be hydrogen. However, within these limits it is a useful reaction. The nucleophile in this case is actually R 0 . However, R" may be hydrogen (as well as alkyl) if the nucleophile is a phenol, so that the product is RS020Ar. Acidic catalysts are used in this case. Sulfonic acids have been converted directly to sulfonates by treatment with triethyl or trimethyl orthoformate HC(OR)3, without catalyst or solvent and with a trialkyl phosphite P(OR)3. ... 

When excess amounts of the HHT of phenyl glycinate 42 were used with diphenyl phosphite, the preferred product was the novel cyclic derivative 45 (2). Presumably, ring-opening of the HHT produced intermediate 43 first, which lost an equivalent of glycinate formaldimine to give 44. The proximity of the activated phenyl carboxylate ester to the N-H in 44 presumably promoted intramolecular cyclization to 45 with loss of phenol (2). 

The formation and reaction of peroxyl radicals derived by reaction of tervalent phosphorus compounds with oxygen have attracted interest. Photolysis of trialkyl phosphites in oxygenated solutions of aromatic hydrocarbons gives phenols. " Phosphorus trichloride reacts with 1,2-dichloroethylene, in the presence of oxygen, to give (17). It is tempting to suggest that both reactions occur via similar intermediates, e.g. (15) and (16). 

SRNl substitution include ketone enolates,183 ester enolates,184 amide enolates,185 2,4-pentanedione dianion,186 pentadienyl and indenyl carbanions,187 phenolates,188 diethyl phosphite anion,189 phosphides,190 and thiolates.191 The reactions are frequently initiated by light, which promotes the initiating electron transfer. As for other radical chain processes, the reaction is sensitive to substances that can intercept the propagation intermediates. 

Kellum [115] has described a class-selective oxidation chemistry procedure for the quantitative determination of secondary antioxidants in extracts of PE and PP with great precision (better than 1 %). Diorgano sulfides and tertiary phosphites can be quantitatively oxidised with /-chloropcroxybenzoic acid to the corresponding sulfones and phosphates with no interference from other stabilisers or additives. Hindered phenols, benzophenones, triazoles, fatty acid amides, and stearate... 

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