Biomass Conversion Products as Steel Corrosion Inhibitors

By-products formed in the conversion of vegetable biomass (multicomponent tar) were studied in comparison with the target products of the process (5-hydroxymethylfurfural, 2,5-diformylfuran) as inhibitors of corrosion of low-carbon steel in sulfuric acid at temperatures of 25-90°C. The gravimetric method was used to determine the inhibiting effect of additives. All these additives exhibit medium protective effects in an acid medium, with the degree of protection in 1 M sulfuric acid at room temperature exceeding 80%. The potentiody-namic polarization method was used to determine the influence exerted by the additives on partial reactions of the corrosion process. It was shown that the tar and 2,5-diformylfuran behave as additives of the cathodic type, and 5-hydroxymethylfurfural, as that of a mixed type. Temperature-kinetic calculations were used to determine the mechanism of action of the inhibitors. The corrosion process occurs in the presence of additives predominantly under the kinetic control.

     

Structural and Optical Properties of Zn1‐xMgxO Prepared by Calcination of ZnO + Mg(OH)2 after Hydro Micro Mechanical Activation

Zn_1‐xMg_xO microcrystals are produced in the 0.15 ≤ x ≤ 1 composition range by calcination of ZnO + Mg(OH)₂ after hydro micro mechanical activation according to the patent WO2018065735A1. The structural properties of the samples have revealed the cohabitation of wurtzite and rock‐salt phases for x values ranging from 0.15 up to 0.6 with a clear increase of the proportion of cubic phase with x. A single cubic phase is observed in the range 0.66 ≤ x < 1. From the purity of these samples produced at very low cost, it is expected that they will be used as precursors for growth of advanced light emitters integrated into an already existing process as they exhibit exceptionally efficient (and robust with T) light emission in the ultraviolet region.     

Structure and Transformations of 1-Alkyladamantane Radical-Cations

The structure of the radical-cations of 1-alkyladamantanes (alkyl = Me, Et, i-Pr, t-Bu) was investigated by computational methods (BLYP and MP2) in 6-316* basis set. It was shown that the adiabatic ionization potentials decrease significantly in this series. The competition between C—H and C—C fragmentation of the radical-cations was investigated both theoretically and experimentally in the presence of outer-sphere and electrophilic oxidants.     

H-coupled electron transfer in alkane C-h activations with halogen electrophiles

The mechanisms for the reactions of isobutane and adamantane with polyhalogen electrophiles (HHal(2)(+), Hal(3)(+), Hal(5)(+), and Hal(7)(+), Hal = Cl, Br, or I) were studied computationally at the MP2 and B3LYP levels of theory with the 6-31G (C, H, Cl, Br) and 3-21G (I) basis sets, as well as experimentally for adamantane halogenations in Br(2), Br(2)/HBr, and I(+)Cl(-)/CCl(4). The transition structures for the activation step display almost linear C...H...Hal interactions and are characterized by significant charge transfer to the electrophile; the hydrocarbon moieties resemble the respective radical cation structures. The regiospecificities for polar halogenations of the 3-degree C-H bonds of adamantane, the high experimental kinetic isotope effects (k(H)/k(D) = 3-4), the rate accelerations in the presence of Lewis and proton (HBr) acids, and the high kinetic orders for halogen (7.5 for Br(2)) can only be understood in terms of an H-coupled electron-transfer mechanism. The three centered-two electron (3c-2e) electrophilic mechanistic concept based on the attack of the electrophile on a C-H bond does not apply; electrophilic 3c-2e interactions dominate the C-H activations only with nonoxidizing electrophiles such as carbocations. This was shown by a comparative computational analysis of the electrophilic and H-coupled electron-transfer activation mechanisms for the isobutane reaction with an ambident electrophile, the allyl cation, at the above levels of theory.     

Synthesis of 2-ethynylaziridines

2-Ethynyl-substituted aziridines were obtained by the reaction of acetylenic -amino and -azido alcohols with triphenylphosphine and carbon tetrachloride in the presence of triethylamine. The cycloaddition of carbenes and diazomethane to an acetylenic imine was investigated. 2-Ethynylaziridines were obtained in the case of carbonylalkoxycarbenes. The regioselectivity of the cycloaddition of carbenes to an acetylenic imine is demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 656–661, May, 1982.     

Steroid compounds of marine sponges. VIII. 24-Isopropyl-5α-cholest-22-ene-2β,3α,6α-triol trisulfate — A new steroid identified in the spongeTrachyopsis halichondrioides

A new sulfated steroid triol has been identified in extracts of the spongeTrachyopsis halichondrioides and its structure has been established as 24-isopropyl-5-cholest-22-ene-2,3,6-triol trisulfate. The possibility has been shown for the first time of the existence of identical side chains for free sterols and trisulfated steroids.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 111–115, January February, 1986.     

Synthesis of reversible carbon dioxide absorber based on hydrated zirconium oxide,intended for concentration and removal of CO<Subscript>2</Subscript> in habitable closed objects

Carbon dioxide absorber based on hydrated zirconium oxide was synthesized with ammonium carbonate and hydrogen peroxide. The effect of the molar ratio between ammonium carbonate and hydrogen peroxide on the sorption characteristics of the absorber was examined. The structural-sorption properties of the absorber were analyzed. It was shown tat the absorber has a high absorption capacity for CO₂.     

A Stable Crystalline Triarylphosphine Oxide Radical Anion

Triarylphosphine oxides (Ar₃P=O) are being intensely studied as electron‐accepting (n‐type) materials. Despite the widespread application of these compounds as electron conductors, experimental data regarding the structural and electronic properties of their negatively charged states remain scarce owing to their propensity for follow‐up chemistry. Herein, a carefully designed triarylphosphine oxide scaffold is disclosed that comprises sterically demanding spirofluorenyl moieties to shield the central phosphoryl (P=O) moiety. This compound undergoes chemical one‐electron reduction to afford an exceptionally stable radical anion, which was isolated and characterized by X‐ray crystallography for the very first time. The experimental data, corroborated by computational studies, shall allow for the construction of phosphine oxide materials with enhanced stability.