Thiobisphenol

Plastics Additives. Many claims have been made for the use of nickel chemicals as additives to various resin systems. By far the most important appHcation is as uv-quenchers in polyolefins (173,174). Among the useful nickel complexes in these systems are dibutyldithiocarbamate nickel [13927-77-0], nickel thiobisphenolates, and nickel amide complexes of bisphenol sulfides (175). The nickel complex of... 

An insecticide intermediate, 4,4 -thiobisphenol [2664-63-3] is made from sulfur dichloride and phenol ... 

The other class of primary antioxidants are the phenols (hindered phenols, hindered bisphenols, hindered thiobisphenols, polyhydroxy phenols) (Fig. 34). Phenolic antioxidants are generally used when the discolouration of the amine antioxidants cannot be tolerated. Phenols may produce coloured reaction products (yellow, tan or pink) but the discolouration is significantly less than produced with amines. 

Recently, Liu et al. used DCDPS to prepare thiobisphenol S (TBPS) by hydrolysis.258 DTPS can be used to react with DCDPS in a dipolar aprotic solvent with K2C03 as the weak base at 165°C and high molecular weight can be obtained due to higher reactivity of TBPS compared with its BPS counterpart. 

Thermoplastic resins, self-reinforced, 26 Thermoplastics, preparation of, 257-258 Thermoplastic step-growth polymers, 3 Thermosetting polyester resins, 29-31 Thermosetting resins, 3-4, 19 Thermotropic compounds, 49 THF. See Tetrahydrofuran (THF) Thiobisphenol S (TBPS), 364 Thionyl chloride, 80 activation of, 111 3,3 -linked polymers, 480 Tin-amine coordination complex, 234 Tin compounds, 86, 232-233... 

Closely related behavior had previously been observed with the Cu complex 14, prepared from the corresponding thiobisphenol ligand (HL ) (Scheme 7) [158]. The species formed upon oxidation was proposed at the time to be a dinuclear diphenoxyl radical dication 15. The catalytic behav-... 

Thanks to proper stabilization, polypropylene has found outdoor applications as a low cost fiber and engineering material. Phenolic antioxidants, such as methylenebisphenol and thiobisphenol, are highly potent, nonvolatile, and solvent resistant but yellow on exposure to nitrogen oxides, always present in urban atmospheres. 2,6-Didodecyl-p-cresol and 2,6-dioctadecyl-p-cresol have been found as highly effective, nondiscoloring, and nonvolatile antioxidants. Lappin describes an economic process for the second product. 

Some of these groups are common units in high molecular weight phenolic antioxidants, such as the methylenebisphenol types and the thiobisphenol types, all of which are gas yellowing. 

Various polyesters derived from phosphorous or phosphoric acids were prepared. Efiicient polyphosphites were synthesised in the early 196(. Polyphosphite prepared from 152 and 4,4 -isopropylidenebis(cyclohexanol) was tested as a thermal stabilizer for PC [199] or as secondary AO for radiation sterilized EPM [200]. Built-in phosphites obtained by transesterification of triallcylphosphite with 4,4 -isopro-pylidenebisphenol or 4,4 -thiobisphenol possess antioxidant properties in polyolefins. Stabilizer containing phosphite moiety 153 was prepared from tris(2-hydroxy-ethyl)isocyanate, decyl alcohol and triphenylphosphite [201]. Various phosphites were derived firom polynuclear phenols or dihydric phenols. For example, a polycondensate prepared by reaction of phosphorus trichloride with 2,5-di-rert-butylhydroquinone was tested as heat and light stabilizer for PP [202], A linear polyester with a built-in phenolic moiety was synthesised from (2,6-di-tm-butyl-4-methylphenyl)bis(6-hydroxyhexyl)phosphite and dimethyl terephthalate [203]. 

Some polysulfides contain in the polymer backbone other groups besides -S-. A common type of group is oxycarbonyloxy, such as in the polymer resulting from the reaction of phosgene (chloroformyl chloride or carbonic acid dichloride) with 4,4 -thiobisphenol. This reaction can be considered a polycondensation and can be written as follows ... 

Sulphur interrupts the conjugation between phenolic nuclei. Therefore, unpaired electron is delocalized mostly over one phenolic nucleus in phenoxyls formed from 2,2 -thiobisphenols CLXVII23). Only about 15% of the density of unpaired electrons is delocalized to the sulphur of the sulphidic bridge. As a consequence, the stability... 

Phenolic sulphoxides and sulphones are formed in the transformation process of thiobisphenolic antioxidants (Chap. IV B). Sulphoxide restores the antioxidant capacity though to a lesser extent than that of sulphide266,267) while sulphone has no antioxidant properties. However, corresponding phenoxyls are formed from both these compounds22,260) they are less stable than phenoxyls from the starting sul-... 

The formation and reactivity of radicals formed from thiobisphenols can be the cause of further intermolecular processes which may be used in the modification of polymers. For example, it was shown in271 that di- and trithiobisphenols transfer chains in the polymerization of styrene and diene monomers. In this process, 2,2 -dithiobis(4-methyl-6-tert-butylphenol) was successfully bonded into the polymer chain. 

Important information about the transformation of thiobisphenols under the conditions of inhibited oxidation were obtained on the basis of product analysis of model reactions. The detailed investigation was carried out with 4,4 -thiobis(2-methyl-6-tert-butylphenol) (CLXVIIIa), which is among the most effective thiobis-phenolic antioxidants and tert-BuOOH was chosen as a simple model of polypropylene hydroperoxide. The reaction was followed at 20 °C in benzene solution and in the presence of the catalytic amount of Co(II)acetylacetonate272). Under these conditions, the phenolic antioxidant was attacked by both alkylperoxyls and hydro-... 

Some products of interaction of tert-BuOOH with thiobisphenol CLXVIIIa were probably formed according to these general reactions. From the reaction mixture, these were isolated272 4,4 -sulphinylbis(2-methyl-6-tert-butylphenol) CLXXXIIa and 4,4 -sulphonylbis(2-methyl-6-tert-butylphenol) CLXXXIIIa. 4-[(3-Methyl-5-tert-butyl-4-hydroxyphenylthio)-sulphonyl]-2-methyl-6-tert-butylphenol CLXXXVa is derived from dithiobisphenol CLXXIXa which belongs to primary products of transformation. The thiosulphinate CLXXXIVa which is less stable to thermal decomposition and oxidation is assumed as an intermediate. 

Separation of the reaction mixture after oxidation of CLXVIIIa was very difficult Semiquantitative data about the yields of individual transformation products of thiobisphenols CLXVIIIa may give an idea about the ratios of individual reactions which proceed simultaneously in one reaction mixture at ambient tempera-... 

The product study272) and the kinetic study261) form the experimental basis for the discussion of complex transformations of thiobisphenolic antioxidants. Their retardation effect in polypropylene after the induction period and the mechanism of formation of intermediates or products catalytically active in ROOH decomposition indicate the reactivity of both different centres in molecule and provide partial data for the discussion of intramolecular synergism of thiobisphenols5 57,258,26 ). 

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