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In Gegenwart seines Titansalzes läßt sich Brenzcatechin sowie das 4‐Methylderivat (Ib) bei 100‐150°C und 16 at mit hoher Ausbeute zu 3‐mono‐ bzw. 3,6‐disubstituierten Produkten alkylieren.

A novel class of biologically active substances was created. These are hybrid macromolecu lar antioxidants (HMAO) based on hydrophilic polymers with chemically grafted sterically hindered phenols with different structural parameters. The antiradical activities of HMAO were assessed in reactions with 2,2 diphenyl 1 picrylhydrazyl and the corresponding sodium sulfonate in various solvents. The mechanism that explains the substantially enhanced activi ties of HMAO in water was proposed. The state of HMAO in solutions was studied by viscosim etry and photon correlation spectroscopy. HMAO were assayed in biological models.

Hybrid macromolecular antioxidants based on hydrophilic polymers with chemically grafted sterically hindered phenol fragments in aqueous solution exhibited considerably higher antiradical activity than that typical of compositions consisting of a polymer and low-molecular phenol analogs. The activity of the examined antioxidants is determined mainly by formation of supramolecular structures in solution, as well as by the position of the phenolic fragment inside or outside hydrate shell. An important structural factor is the size of the spacer connecting the redox-active phenol ring with the polymer. R = H, SO 3 Na.Synthesis of hybrid compounds containing functionally different fragments in a single structure is one of the most promising lines in the design of antioxidants of new generation for biology and medicine. Advantages of hybrid structures may be enhanced antioxidant efficiency, the possibility for its targeted delivery in a biosystem to be protected, controllable solubility, and reduced toxicity.Up to now, methods have been developed for chemical modification of hydrophilic bio-and synthetic polymers with derivatives of sterically hindered phenols. As a result, macromolecular antioxidants (conjugates) were obtained, which were characterized by different structural parameters: molecular weight (M) of the base polymer, concentration of phenol fragments in the polymeric chain (γ, mol %), and nature of the polymer-antioxidant linker [1][2][3][4]. Such polymers as dextran (I), hydroxyethyl starch (II), polyethylene glycol (III), and polyvinyl alcohol (IV) and functionalized derivatives of sterically hindered phenols, capable of forming covalent bonds with hydroxy groups in a polymer, β-(4-hydroxy-3,5-di-tert-butyl)-phenylpropionic acid A, 4-hydroxy-3,5-di-tert-butylcinnamic acid B, α-methyl-(4-hydroxy-3,5-di-tertbutyl)phenylacetic acid C, and derivatives of 4-hydroxy-3,5-di-tert-butylbenzyl alcohol D and 2-hydroxy-3,5-di-tert-butylbenzyl alcohol E, were used as co-reagents (Table 1). The amount of sterically hindered phenol fragments attached to a polymer was determined by UV spectrophotometry (by measuring the absorption intensity of the aromatic chromophore).The activity of macromolecular antioxidants in comparison with low-molecular analogs was estimated by measuring the rate constants for their reactions with

Application of ethanol to the synthesis of 1,3-dioxolanes by the condensation of carbonyl compounds with vicinal diols results in a high yield of the reaction product and considerably reduces the duration of the process. It is assumed that the effect of the ethanol is caused by the adduct formation with carbonyl compounds (hemiacetals) which behave as active intermediates of the condensation. A cyclic ketal of acetone with glycerol obtained with the help of ethanol was used as a basis component in the synthesis of a series of ketals substituting diol or carbonyl components by transketalyzation mechanism proceeding without water liberation.Cyclic ketals and acetals (1,3-dioxolanes), condensation products of carbonyl compounds with vicinal di-or polyols, are used in practice as semiproducts and auxiliary substances in the synthesis of polymers, rubber goods and paint-and lacquer materials, perfumes and cosmetics. Recently they attracted additional interest due to the possibility of application in the petrol for improving the octane characteristics, increasing the phase stability of the alcohol-containing gasoline, and decreasing the toxicity of the exhaust gases [1]. The most detailed studies of cyclic ketals as fuel components included the ketals based on glycerol, ethylene glycol and lower ketones (acetone, methyl ethyl ketone, cyclohexanone.The main source of glycerol is the processing of fats and oils, in particular, the production of biologic diesel oil from plant triglycerides, mainly from the colza oil. The growing scale of this production surpasses the demand for crude glycerol that frequently is forcedly regarded as waste. New way of glycerol utilization in the framework of the same production as biodiesel would improve the economy of the process and approach it to the modern ecologic standards. This goal requires a development of new approach to the synthesis of cyclic ketals (1,3-dioxolanes) from glycerol and the other di-and polyols.The dilos condensation with carbonyl compounds providing 1,3-dioxolanes is an acid-catalyzed equilibrium process that can be shifted to the side of the reaction products by the elimination of the formed water. OH OH OH + R 2 CO Catalyst O O OH + R 1 R 2 H 2 O I _ IIIR 1 = R 2 = Me (I); R 1 = Me, R 2 = Et (II); R 1 ,R 2 = (CH 2 ) 5 (III); catalyst H 2 SO 4 , HCl, TsOH etc.Ketones as a rule form with water azeotropic mixtures, therefore the elimination of water can be performed by azeotropic drying. The water content in the mixture with acetone does not exceed fractions of a percent, therefore the azeotropic elimination of water requires in this case a prolonged boiling of the reaction mixture (~40 h) [2]. The chemical binding of water seems more effi cient. In the system glycerol-acetone-Ac 2 O 4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane (I) formed in 93% yield at boiling the reaction mixture over 3 h. The catalyst formed in situ (AcOH) does not require the neutralization for it can be removed by distillation. However therewith along-

Reaction of 2,4-di-tert-butylphenol with urotropin in conditions of Duff reaction takes an abnormal route and instead of the expected di-tert-butylsalicylaldehyde provides a mixture of N-substituted 3,5-di-tertbutyl-2-hydroxybenzylamines and redox conjugate benzoxazines containing mostly 6,8-di-tert-butyl-3-(3,5-ditert-butyl-2-hydroxybenzyl)- 2H-3,4-dihydrobenz[e] [1,3]oxazine. A solvolysis of an individual benzoxazine in the system HO(CH 2 ) 2 OHH 2 OHCl affords di(3,5-di-tert-butyl-2-hydroxybenzyl)amine, and in AcOH 3,5-di-tertbutylsalicilaldehyde. A mechanism of Duff reaction was suggested involving the formation of a benzoxazine intermediate.Duff reaction consisting in treating phenols with urotropin at elevated temperature in ethylene glycol or glycerol in the presence of H 3 BO 3 underlies one of the most convenient preparation methods for ortho-hydroxysubstituted aromatic aldehydes [1]. Its mechanism and the reason of the high regioselectivity are poorly understood. Presumably the overall process involves a phenol aminomethylation with iminomethane (CH 2 =NH) arising through the thermal decomposition of the urotropin, the oxidation of aminophenol with urotropin to give imine followed by its hydrolysis [2]. 2+ W%X , 2+ W%X ,, &+ 1 + %2 &+2 W%X W%X W%X 2+ W%X &+ 1&+ W%X 2+ W%X &+ 1 &+ ,,, ,9 >+@ >+@ W%X W%X 1 2 &+ W%X W%X 1 2 & 2+ W%X %XW + 9, 9In the course of the study of Duff reaction with 2,4-di-tert-butylphenol (I) under standard conditions we found that the expected 3,5-di-tert-butyl-2-hydroxybenzaldehyde (II) was not a single or the main reaction product. Its yield did not exceed 2%. The chromatographic analysis of the reaction products revealed and afforded in a preparative overall yield of around 80% two redox conjugate couples of compounds: 2,4-(di-tert-butyl)-6-dimethylaminomethylphenol (III), N-methyl-bis(3,5-ditert-butyl-2-hydroxybenzyl)amine (IV), and the corresponding substituted benzoxazines V and VI.

Macromolecular esters were synthesized from carboxy-substituted derivatives of spatially hindered phenols and hydrophilic polymers: dextran, hydroxyethylated starch, poly(ethylene glycols) of various molecular weight. The hybrid macromolecular antioxidants signifi cantly surpass in antiradical and antioxidant activity the low molecular weight analogs of the hindered phenols.This is indicative of the changed mechanism of the redoxprocesses in water and of the governing role therein of the supramolecular hydrated structures formed by the solvation of polymer molecules in water environment.

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