V. B. Vol’eva

New Opportunities for Duff Reaction

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-tert-butyl-2-hydroxybenzylamines and redox conjugate benzoxazines containing mostly 6,8-di-tert-butyl-3-(3,5-di-tert-butyl-2-hydroxybenzyl)-2H-3,4-dihydrobenz[e][1,3]oxazine. A solvolysis of an individual benzoxazine in the system HO(CH2)2OH-H2O-HCl affords di(3,5-di-tert-butyl-2-hydroxybenzyl)amine, and in AcOH 3,5-di-tert-butylsalicilaldehyde. A mechanism of Duff reaction was suggested involving the formation of a benzoxazine intermediate.

Synthesis of the components of engine fuels on the basis of renewable raw materials: Trends and prospects

The basic methods for obtaining the components of engine fuels using the most commonly encountered type of raw materials, i.e., biomass polysaccharides, are discussed. The emphasis is placed upon two groups of methods of the conversion of polysaccharides: the heat treatment of the biomass with the subsequent processing of the resulting biopetrol with the conversion into the components of fuels using a hydroprocess and the selective conversion of monosaccharides into compounds that are subsequently used as components of fuels (along with hydrocarbons). Data on the synthesis of a new class of high-octane components of alcohol-containing fuels, i.e., ketals derived from polyols such as glycerol and pentoses, are given. It is shown that the effective catalysts of this process are some zeolites and ion-exchange resins.

New approach to the synthesis of 1,3-dioxolanes

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.

Structural factors responsible for the activity of macromolecular phenolic antioxidants

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.

Photooxygenolysis of 3,6-di-tert-butyl-o-benzoquinone

The photolysis of 3,6-and 3,5-di-tert-butyl-o-benzoquinones in benzene (λ > 380 nm, inert atmosphere) involves decarbonylation of the compounds to furnish respectively 2,5-and 2,4-di-tert-butylcyclopentadienones. The 2,5-isomer is stable, and the 2,4-di-tert-butylcyclopentadienone suffers a conversion into a Diels-Alder adduct. The participation of oxygen inhibited the decarbonylation and changed the direction of the photolysis: Here the products of the 3,5-di-tert-butyl-o-benzoquinones conversion were a di-tert-butylmuconic anhydride and dipivalylethylene. It was concluded that a singlet oxygen was involved in the process which formed by a triplet-triplet annihilation at the interaction of 3O2 with a triplet-excited initial quinone.

ANTIBACTERIAL ACTIVITY OF SUBSTITUTED 1,3-DIOXOLANES

Cyclic ketals and acetals (1,3-dioxolanes) substituted at positions 2 and 4 of the dioxolane ring, prepared by condensation of glycerol and ethylene glycol with aldehydes and ketones, had antimicrobial activity against Gram-positive and Gram-negative bacteria. This activity, which may be associated with the antiradical activity of the study compounds and depended on their hydrophilic-hydrophobic balance, allows targeted variation in structural parameters for the creation of new active compounds. Cyclic ketals with high antimicrobial activity can be used as antiseptics for sterilization of working surfaces and instruments.

Alkylation of pyrocatechol in tert-butyl alcohol-sulfuric acid-benzene

Alkylation of pyrocatechol with tert-butyl alcohol in benzene in the presence of sulfuric acid gave 3,5-di-tert-butylbenzene-1,2-diol in a higher yield than in analogous reaction with tert-butyl alcohol. This result was rationalized by reduction of inhibitory effect of liberated water, formation of heterogeneous system, and occurrence of the alkylation process in nonpolar organic phase. Intermediate products were identified and found to undergo intra- and intermolecular tert-butyl group transfer with formation of more stable 3,5-di-tertbutylbenzene-1,2-diol. The formation of p-di-tert-butylbenzene indicated participation of benzene in crossalkylation processes.

Antiradical activity of dioxolane derivatives

Abstract1,3-Benzodioxoles synthesized by condensation of 3,6-di-tert-butylbenzene-1,2-diol with carbonyl compounds showed antiradical activity due to their ability to undergo one-electron oxidation with formation of stable radical cations. On this basis, the antiknock effect of their structural analogs, 1,3-dioxolanes derived from vicinal diols, was interpreted in terms of oxidation of these compounds with active radicals generated from fuel hydrocarbons to produce more stable radical or radical ion species, depending on the fuel composition. The formation of radical species was detected in model oxidation reactions of 2,2-dimethyl-1,3-dioxolane and 2,2-dimethyl-1,3-dioxolan-4-ylmethanol with radicals generated by photolysis of iron(III) chloride and benzoyl peroxide.

Synthesis and properties of macromolecular esters of carboxy-substituted derivatives of hindered phenols

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 significantly surpass in antiradical and antioxidant activity the low molecular weight analogs of the hindered phenols. This is indicative of the changed mechanism of the redox-processes in water and of the governing role therein of the supramolecular hydrated structures formed by the solvation of polymer molecules in water environment.

Urotropin synthesis of 3,5-di-tert-butylsalicylic acid derivatives

The stability of 3,5-di-tert-butylsalicylic aldehyde against oxidation is due to autoinhibiting of the chain process. However its oxidation into 3,5-di-tert-butylsalicylic acid was performed at the use of acetyl protection of the hydroxy group. In reaction of 6-bromo-2,4-di-tert-butylphenol with urotropin the formation was discovered of 3,5-di-tert-butylsalicylic acid, its nitrile and amide.