Action mechanism of antioxidation and anticorrosion and molecular design for perfluoropolyether fluid additives (I) --Action mechanism of additive and property of donating-accepting electron

The combination energy and chemical adsorption energy of N-substituted perfluoropoly- alkyletherphenylamide (PFPEA) additive to perfluoropolyalkylether oxygen radical (RfO.) and to Fe atom have been calculated by quantum chemical methods. Structural characteristics, action mechanism, property of donating-accepting electron and substituent effect for antioxidant and anticorrosive additive are investigated. It is found that HOMO of the additives is a p-molecular orbital with lone pair electron of heteroatom. The HOMO of PFPEA additive reacts with LUMO of Fe atom to result in chemical adsorption. The LUMO of additive can interact with the SOMO of RfO. and accept electron of RfO. to form stable addition product. The additives have the property of donating-accepting electron. The electron-releasing group, particularly, the phenyl group, introduced to N atom of phenylamide can increase the combination energy and chemical adsorption energy, and enhance the antioxidant and anticorrosive efficiency. The research achievements can provide useful information for the designing of new antioxidant and anticorrosive additive. Based on the calculated results, antioxidant and anticorrosive efficiency can be predicted roughly as the following order: compounds III＞II＞I＞IV＞V.     

Action mechanism of antioxidation and anticorrosion and molecular design for perfluoropolyether fluid additives (II)

Three kinds of the antioxidation and anticorrosion additives from the N-substituted perfluoropolyalkylether phenylamide (PFPEA) were selected and synthesized. UV and IR spectral analyses were carried out, and strong absorption peaks of UV from benzene ring are about 240.7, 215.4 and 230.1 nm, respectively. The characteristic peaks of IR from the C=O are about 1713.9, 1712.2 and 1710.8 cm^-1, respectively. The antioxidant and anticorrosive property was tested for the three synthesized additives. The results show that the weight loss of lubrication oil can decrease by 1/7, 1/9 and 1/25 respectively after adding synthesized additives. The thermal decomposition temperature(T_D) in the presence of Al₂O₃ can increase by 19–22°C. From theoretic and experimental study it indicates that the PFPEAs with nitrogen heteroatom not only accepts electron from perfluoropolyalkylether oxygen radical (R_fO.) to form a stable adduct and to prevent RfO. decomposing further, but also donates electron to form chemical adsorption film and to protect metal from corrosion. These additives have shown the better property of the antioxidation and anticorrosion. An electron-releasing group, or phenyl group, introduced to the N-atom of this kind of compound can improve the antioxidant and anticorrosive efficiency of the additives.     

Action mechanism of antioxidation and anticorrosion and molecular design for perfluoropolyether fluid additives (I)

The combination energy and chemical adsorption energy of N-substituted perfluoropoly-alkyletherphenylamide (PFPEA) additive to perfluoropolyalkylether oxygen radical (R_fO.) and to Fe atom have been calculated by quantum chemical methods. Structural characteristics, action mechanism, property of donating-accepting electron and substituent effect for antioxidant and anticorrosive additive are investigated. It is found that HOMO of the additives is a π-molecular orbital with lone pair electron of heteroatom. The HOMO of PFPEA additive reacts with LUMO of Fe atom to result in chemical adsorption. The LUMO of additive can interact with the SOMO of R_fO. and accept electron of R_fO. to form stable addition product. The additives have the property of donating-accepting electron. The electron-releasing group, particularly, the phenyl group, introduced to N atom of phenylamide can increase the combination energy and chemical adsorption energy, and enhance the antioxidant and anticorrosive efficiency. The research achievements can provide useful information for the designing of new antioxidant and anticorrosive additive. Based on the calculated results, antioxidant and anticorrosive efficiency can be predicted roughly as the following order: compounds III>II>I>IV>V.     

The beauties of calorimetry An overview

This paper gives a short overview of direct and indirect calorimetric experiments to determine the heat production or at least the metabolic turnover of whole plants or their blossoms. A special emphasis is placed on thermogenic plants because of their high specific heat production rates equal to those of mammals or birds and sometimes even surpassing them.     

Award for service Professor Jean-Marie Lehn

Chronicle

Award for service Professor Jean-Marie Lehn     

Approaches to Carbocyclic Sialidase Inhibitors Invited Review

 The crucial role played by carbohydrates in many physiological processes has made this class of compounds an interesting target for drug design. Consequently mimicking carbohydrates has been one of the most rapidly growing fields in synthetic organic chemistry in recent years, and particularly intense focus has been devoted to sialic acids and sialic acid metabolizing enzymes, including sialidases. Inhibition of the latter enzyme from influenza virus can be regarded as one of the most successful examples of structure-based drug design and high affinity inhibitors based on neuraminic acid have been developed. There is an ongoing search for inhibitors with improved physicochemical properties and among them, carbocyclic systems, where the ring oxygen of the carbohydrate is replaced by carbon, have become the center of interest. This review intends to give a brief overview over the structures and synthetic approaches which surfaced in the last decade.     

DNA microarray synthesis by using PDMS molecular stamp (II) Oligonucleotide on-chip synthesis using PDMS stamp

Based on the standard phosphoramidites chemistry protocol, two oligonucleotides synthetic routes were studied by contact stamping reactants to a modified glass slide. Route A was a contact coupling reaction, in which a nucleoside monomer was transferred and coupled to reactive groups (OH) on a substrate by spreading the nucleoside activated with tetrazole on a polydimethylsiloxane (PDMS) stamp. Route B was a contact detritylation, in which one nucleoside was fixed on the desired synthesis regions where dimethoxytrityl (DMT) protecting groups on the 5’-hydroxyl of the support-bound nucleoside were removed by stamping trichloroacetic acid (TCA) distributed on features on a PDMS stamp. Experiments showed that the synthetic yield and the reaction speed of route A were higher than those of route B. It was shown that 20 mer oligonucleotide arrays immobilized on the glass slide were successfully synthesized using the PDMS stamps, and the coupling efficiency showed no difference between the PDMS stamping and the conventional synthesis methods.     

Molecular electronegativity in density functional theory(VIII) Charge polarization modes in a closed system

Based on the density functional theory and the atom-bond electronegativity equalization model (ABEEM), a method is proposed to construct the softness matrix and to obtain the electron population normal modes (PNMs) for a closed system. Using this method the information about the bond charge polarization in a molecule can be obtained easily. The test calculation shows that the PNM obtained by this method includes all the modes about the bond charge polarization explicitly. And the bond charge polarization mode characterized by the biggest eigenvalue, which is the softest one of all modes related with chemical bonds, can describe the charge polarization process in a molecule as exquisitely as the correspondingab initio method.     

Interactions of ammonium nitrate with different additives Thermodynamic analysis

In order to elucidate the influence of Ca and Mg carbonates with or without the presence of boron, manganese and copper compounds on the thermal stability of ammonium nitrate (AN), thermodynamic analysis of different reactions between AN and additives was carried out. Temperature dependency of Gibbs free energy changes ∆G _T and equilibrium composition of reaction products were calculated for a set of reactions using the HSC software. Main solid compounds that can form in the systems of AN and carbonates, were Ca(NO₃)₂ and Mg(NO₃)₂, Ca(OH)₂ and Mg(OH)₂, CaO₂ and MgO₂, CaO and MgO, and N-containing gaseous compounds NO, N₂O and NO₂. As a result of H₃BO₃, MnO₂ and CuSO₄ addition, the content of CuO, Cu₂O and MnO as solids and SO₂, SO₃ and HBO as gaseous reaction products reached the same level. Thereby, their equilibrium concentrations did not depend on the carbonate origin of CaCO₃, MgCO₃ or CaMg(CO₃)₂. Small amount of CuSO₄, H₃BO₃ or MnO₂ additive (0.01–0.05 mol) in the system, practically, did not influence the temperature dependencies of ∆G _T of the reactions between AN and CaCO₃ or CaMg(CO₃)₂. The influence of additives taken in the larger amount (0.5 mol) was evident and, depending on the additive and reaction, shifted their proceeding temperatures in either direction by more than 300–400 K.     

Low pressure phases Thermodynamic properties of the γ-aminobutyric acid

A metastable form of γ-aminobutyric acid has been prepared by sublimation under vacuum. A theoretical unary phase diagram has been deduce from experimental thermal analysis. Aqueous solution of γ-aminobutyric acid (Gaba) prepared from commercial product (monoclinic) does not cross blood–brain barrier after intra peritoneal administration to mice, hence it displays no anticonvulsion activity. Therefore, we developed a polymorphic form, the solution of which presents such activity. In the present paper the preparation and the physico-chemical properties are reported.     

Action mechanism of antioxidation and anticorrosion andmolecular design for perfiuoropolyether fluid additives (Ⅱ)Synthesis and measurement of N-substituted perfluoropolyalkylether phenyla-mide

Three kinds of the antioxidation and anticorrosion additives from the N-substituted per-fluoropolyalkylether phenylamide (PFPEA) were selected and synthesized. UV and IR spectralanalyses were carried out, and strong absorption peaks of UV from benzene ring are about 240.7,215.4 and 230.1 nm, respectively. The characteristic peaks of IR from the C==O are about 1713.9,1712.2 and 1710.8 cm-1, respectively. The antioxidant and anticorrosive property was tested forthe three synthesized additives. The results show that the weight loss of lubrication oil can de-crease by 1/7, 1/9 and 1/25 respectively after adding synthesized additives. The thermal decom-position temperature(TD) in the presence of Al2O3 can increase by 19-22℃. From theoretic andexperimental study it indicates that the PFPEAs with nitrogen heteroatom not only accepts electronfrom perfluoropolyalkylether oxygen radical (RfO.) to form a stable adduct and to prevent RfO. de-composing further, but also donates electron to form chemical adsorption film and to protect metalfrom corrosion. These additives have shown the better property of the antioxidation and anticorro-sion. An electron-releasing group, or phenyl group, introduced to the N-atom of this kind of com-pound can improve the antioxidant and anticorrosive efficiency of the additives.     

Trimethylsilyl-substituted diazoalkanes : I. Trimethylsilyldiazomethane

Trimethylsilyldiazomethane was prepared by the action of aqueous KOH on nitroso-N-(trimethylsilylmethyl)urea. The spectroscopic properties of this stable, greenish-yellow liquid which can be isolated by gas chromatography are discussed. Its reaction with acetic acid gives the expected CH₃CO₂CH₂SiMe₃ in addition to SiC cleavage products, CH₃CO₂CH₃ and CH₃CO₂SiMe₃. Products of the 1,3-dipolar addition of Me₃SiCHN₂ to activated olefins were not very stable, and only the adduct with acrylonitrile was isolated as a pure material Trimethylsilyldiazomethane undergoes Me₃SiCH transfer to olefins, giving trimethylsilyl-substituted cyclopropanes, in the presence of CuCI in benzene, but other products are formed as well. Thus such a reaction with cyciohexenegave anti-7-trimethylsilylnorcarane (65%), syn-7-trimethylsilylnorcarane (7%), cis- and trans-l,2-bis(trimethylsilyl)ethylene (9% and 13%, respectively), and an unidentified Me₃SiCH trimer (2.3%).