Reactions of derivatives of phosphorylacetic acid hydrazides with 3,5-di-tert-butyl-4-hydroxybenzyl acetate

Abstract

To obtain new polyfunctional inhibitors of radical-chain oxidative processes, C- and N-benzylation of a number of phosphorylacetic acid hydrazide derivatives is realized in their reactions with 3,5-di-tert-butyl-4-hydroxybenzyl acetate. N-benzylation of mixtures of Z and E isomers of hydrazones of phosphorylacetic acid derivatives proceeds stereoselectively with the formation of only E_C=N isomers.     

Excited-state proton transfer of 3-hydroxybenzoic acid and 4-hydroxybenzoic acid

The excited-state proton transfer of 3-hydroxybenzoic acid and 4-hydroxybenzoic acid was studied by time-resolved laser-induced fluorescence spectroscopy with ultra-short laser pulses. The excited-state reactions were identified in aqueous media as a function of the pH value. Apart from the well-known inversion of the ordinary dissociation properties of these compounds, new species were found which exist only in the excited-state resulting from a temporal and reversible annihilation of the aromatic bond system. These species and their reaction mechanisms were detected by their absorption and fluorescence spectra.     

Synthesis of 3,5-di-tert-butyl-4-hydroxyphenylsulfanylmethyl-substituted tetramethylcalix[4]resorcinarenes

Russian Journal of Organic Chemistry -     

Reactions of 4-acylresorcinol derivatives with 3,5-di-tert-butyl-4-hydroxybenzyl acetate

Reactions of hydroxyphenylcarbonyl derivatives with 3,5-di-tert-butyl-4-hydroxybenzyl acetate under mild conditions gave novel functionalized diarylmethanes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1128–1133, July, 2006.     

Photostabilising action of Zn and Ni salts of 3,5-DI-t.-butyl-4-hydroxybenzoic acid in polypropylene

The photostabilising action of two metal chelates of the commercial antioxidant Shell acid (3,5-di-t.-butyl-4-hydroxybenzoic acid) viz. its zinc and nickel salts, is examined, using i.r. and derivative u.v.-visible spectroscopy and hydroperoxide analysis. The polymeric matrix was commercial polypropylene. The results show that both salts operate by inhibiting hydroperoxide formation during melt processing and thermo-oxidative conditions. The latter effect is attributed to a chain breaking donor mechanism which terminates, not alkylperoxyl, but macroalkyl radicals. Both salts are relatively efficient photostabilisers when compared with the parent antioxidant, probably because of their good photostability to both polychromatic and monochromatic radiation. The latter also shows that the nickel salt may also operate by scavenging alkoxyl and hydroxyl radicals during photo-oxidation. The addition of calcium stearate in conjunction with the salts produces some interesting effects which are explained in terms of metal exchange.     

Thermotropic copolyesters of 4-hydroxybenzoic acid

Copolyesters of 4-hydroxybenzoic acid were prepared by thermal polycondensation of 4-acetoxybenzoic acid with various acetylated comonomers, such as 4-mercaptobenzoic acid, 3-hydroxybenzoic acid, N-(4-carboxyphenyl)4-hydroxyphthalimide or hydroquinone in combination with 1,12-dodecane bistrimellitimide. The copolyesters were characterized by elemental analyses, inherent viscosities, ¹H- or ¹³C NMR spectroscopy, DSC-measurements, WAXS-measurements at temperatures between 25 and 425°C, microscopic observation, thermomechanical and thermogravimetrical analyses. Copolyesters containing 4-mercaptobenzoic acid or N-(4-carboxyphenyl)4-hydroxyphthalimide possess a reversible first order phase transition which represent a change of modifications and not a melting process. Both classes of copolyesters adopt the same kind of high temperature modification as poly(4-hydroxybenzoate), namely a pseudo-hexagonal chain packing. In contrast, copolyesters of 3-hydroxybenzoic acid or copoly(ester imide)s with aliphatic spacer containing more than 50% 4-hydroxybenzoic acid form a nematic phase over a broad temperature range. However, in the case of copolyesters derived from 3- and 4-hydroxybenzoic acid the homogeneous nematic melt is thermodynamically unstable and gradually turns into a heterogeneous more or less crystalline material with blocks of 4-hydroxybenzoate units.     

Protective role of butylated hydroxytoluene and certain carotenoids in photocarcinogenesis

Butylated hydroxytoluene (BHT) and certain carotenoid pigments have been found to inhibit photocarcinogenesis in animal models. In addition, BHT protects against UV-B-induced erythema and UV-B induction of ornithine decarboxylase. Studies on the photoprotective mechanism(s) of BHT suggested that changes in the physico-chemical properties of the keratin of the stratum corneum layer of skin occurred, leading to increases in UV absorption of that tissue. These changes might be exerted via the anti-radical action of BHT that retards oxidation and prevents cross-linking of the keratin chains, resulting in a diminution of UV-B radiation reaching potential target sites. The carotenoids beta-carotene, canthaxanthin and phytoene also inhibit UV-B carcinogenesis. beta-Carotene and canthaxanthin are excellent quenchers of singlet oxygen, and all three pigments can quench free radicals. beta-Carotene and canthaxanthin have been shown to quench singlet oxygen/free radical reactions in the skin of porphyric mice, and these two pigments as well as phytoene have been found to quench excited species formed on irradiation of mouse skin by UV-B.     

Reaction of alkyl splitting of 4-acetylamino-N-(3,5-di-tert-butyl-4-hydroxybenzyl)-benzenesulfonamide

Russian Journal of General Chemistry - Alkyl splitting of 4-acetylamino-N-(3,5-di-tert-butyl-4-hydroxybenzyl)benzenesulfonamide with alkali solution has been discovered, the reaction being uncommon...     

Molecular structures of 3-hydroxybenzoic acid and 4-hydroxybenzoic acid, obtained by gas-phase electron diffraction and theoretical calculations

The structures of 3-hydroxybenzoic acid and 4-hydroxybenzoic acid have been determined by gas-phase electron diffraction using results from quantum chemical calculations to inform the choice of restraints applied to some of the structural parameters. The results from the study presented here demonstrate that resonance hybrids are not as helpful in rationalizing the structures of 2-, 3-, and 4-hydroxybenzoic acids as are models based upon electrostatic effects.     

Condensation of certain selected 1-monoalkylisoindigo with 3,5-di-tert-butyl-4-hydroxybenzyl acetate

Russian Journal of General Chemistry -     

Synthesis and Antioxidative Properties of Bis(3,5-di-tert-butyl-4-hydroxyphenyl) Polysulfides

An efficient procedure was developed for preparing bis(3,5-di-tert-butyl-4-hydroxyphenyl) polysulfides in the presence of phenolic Mannich bases. The antioxidative activity of the resulting bis(polysulfides) in rubbers of various structures and in their vulcanizates was examined.     

Synthesis of 1-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-r-benzimidazoles

Reaction of 2,6-di-tert-butyl-1,4-benzoquinone with o-phenylendiamine gives 2,6-di-tert-butyl-1,4-benzoquinone-4-(N-o-aminophenyl)imine which reacts smoothly with heterocyclic, aromatic and aliphatic aldehydes to form (1-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-substituted benzimidazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 483–485, April, 1990.     

Selective synthesis of 4-hydroxybenzoic acid using immobilized cyclodextrin

-cyclodextrin immobilized with epichlorohydrin was used for the selective syntheses of 4-hydroxybenzoic acids from phenols and carbon tetrachloride in aqueous sodium hydroxide solutions. The selectivities were 100 %, and the yields were larger than 80 mole%. The immobilized catalysts were easily separated from the reaction mixture, and were repeatedly used without measurable decrease in the catalytic activity.     

Synthesis of hybrid compounds by benzylation of acylhydrazones with 3,5-di-tert-butyl-4-hydroxybenzyl acetate

Russian Chemical Bulletin - N-Benzylation of acylhydrazones of the hydroxybenzaldehyde series with 3,5-di-tert-butyl-4-hydroxybenzyl acetate was performed at room temperature in the absence of acid...     

Crystal and Molecular Structure of 2,4,6-Tris(3,5-di-tert-butyl-4-hydroxybenzyl)resorcinol

The structure of 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)resorcinol in the crystal is virtually identical to that of 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)mesitylene, which is an effective antioxidant.