Solvent Screening, Optimization and Kinetic Parameters of The Biocatalytic Epoxidation Reaction of Beta-Pinene Mediated by Novozym®435

Monoterpenes are secondary metabolites widely used in the flavors and fragrance industries and can have their structure altered to enhance their applicability, such as producing epoxides, which are used as synthetic blocks for pharmaceuticals. Epoxides are commonly synthesized by the use of inorganic acids as catalysts, although the acid medium induces epoxide degradation. To overcome these limitations biocatalysis is shown as an alternative, in view that lipases can perform the reaction in a non-acidic medium. Related to, this work aimed to perform the synthesis of beta-Pinene epoxide using Pseudozyma antarctica lipase B (Novozym®435) as biocatalyst and to determine the independent variables that influence the reaction using experimental design tools. Different solvent systems were evaluated for until 72 h, in reactions with molar ratio of 2:2:1 (beta-Pinene, octanoic acid, and urea-hydrogen peroxide - UHP) at 40°C, 250 rpm, and 10%(w/v) of the biocatalyst. Ethyl acetate showed higher conversion (40% in 24 h) into the product without the formation of by-products. The atom economy (AE) was determined using metrics of green chemistry and ethyl acetate proved to have a higher atom economy (67.8%), while the other solvents that used octanoic acid as an acyl donor had 41.3%. In the following reactions, ethyl acetate was maintained as the solvent, while the temperature, molar ratio, and the percentage of the biocatalyst were varied. The increase in the molar ratio (beta-Pinene:UHP, 1:1) and percentage of biocatalyst (20%w/v) resulted in 80% of the product after 3 hof reaction at 40°C. To evaluate the impact of each independent variable, an FFD was performed by varying temperature, molar ratio, stirring, and percentage of enzyme, in one level. All variables were statistically significant, with different rates of impact. Due to this, the same variables were maintained on the CCRD, varying in two levels. The conversion ranged from good to excellent (32 - 93%). The independent variables that influenced the direction were temperature > stirring > molar ratio. In conclusion, the combination of two different tools of experimental design provided the development of an optimized model for beta-Pinene epoxidation, achieving high yields within 3 h.

Analysis of the Effects of Food Additives on Porphyromonas gingivalis

This study aims to investigate six food additives (octanoic acid, decanoic acid, acesulfame K, aspartame, saccharin, and sucralose) used in foods for the elderly or people with dysphagia because of the effect of these food additives on Porphyromonas gingivalis (P. gingivalis), which is a keystone pathogen of periodontal diseases. The growth of P. gingivalis was inhibited by 5 mM octanoic acid, 1.25 mM decanoic acid, 1.25% acesulfame K, 0.0625% aspartame, 0.03125% saccharin, and 0.625% sucralose. In addition, these food additives showed bactericidal activity for planktonic P. gingivalis (5 mM octanoic acid, 5 mM decanoic acid, 0.25% aspartame, 0.25% saccharin, and 5% sucralose). Moreover, biofilm formation was inhibited by 10 mM octanoic acid, 10 mM decanoic acid, 10% acesulfame K, 0.35% aspartame, 0.5% saccharin, and 7.5% sucralose. Moreover, the same concentration of these food additives without aspartame killed P. gingivalis in the biofilm. Aspartame and sucralose did not show cytotoxicity to human cell lines at concentrations that affected P. gingivalis. These findings may be useful in clarifying the effects of food additives on periodontopathogenic bacteria.

Design of a Bench-Scale Tubular Reactor Similar to Plug Flow Reactor for Gas-Phase Kinetic Data Generation-Illustration with the Pyrolysis of Octanoic Acid

The material described in this article deals with waste conversion into energy vectors by pyrolysis, steam cracking, or oxidation of liquid biomass, carried out at small to medium scale. The design of a bench-scale experimental setup devoted to gas phase kinetic data generation in a tubular reactor under laminar regime close to plug flow is detailed based on a very simple approach. Validation of the designed bench-scale setup was successfully carried out within the context of octanoic acid pyrolysis by generating kinetic data with satisfactory measurement repeatability and material balances. The key to this positive result is that axial dispersion coefficient is much smaller in gas-phase than in liquid-phase, thus allowing the designed small sized tubular reactor to be close to the plug flow reactor. Such a feature of the axial dispersion coefficient is not well known by the wider public. Besides, octanoic acid was selected as surrogate for carboxylic acids because of their key role in various industrial applications (combustion of ethyl biodiesel; production of biofuel and biosourced chemicals).

Molecular Descriptors and Topological Analysis of Cyclooctane Derivatives

Cyclooctane is mainly used in the synthesis of cyclooctanone, cyclooctanol, caprolactam and octanoic acid. At the same time, it can also be used as an intermediate in organic synthesis and a chemical reagent. By discussing the resistance distance between any two points of cyclooctane derivative Tn(C8), some invariants about resistance distance are obtained, such as Kirchhoff index, multiplicative degree-Kirchhoff index, and additive degree-Kirchhoff index. Topological index can help scholars better understand some physical and chemical properties of compounds, and we obtain the closed expressions of valency-based topological indices for Tn(C8), such as ABC index, GA index, etc.

Preliminary investigation of the presence of PFOS and PFOA in water and sediment in Cau river

Perfluoro-octane sulfonate (PFOS) and Perfluoro-octanoic acid (PFOA) are recognised as emerging environmental pollutants because of their high persistence in various environmental matrices and toxic effects on humans and animals. The objectives of this study were to preliminarily investigate the occurrence of PFOS and PFOA in the water and sediment of the Cau river in Thai Nguyen city. The concentration of PFOS and PFOA in water ranged from <LOQ-0.67 ng/l and 0.05-8.11 ng/l; 1.19-4.73 ng/g, and 0.17-1.78 ng/g in sediment, respectively. The highest total concentrations of PFOS and PFOAwere recorded in the areas that directly received wastewater from domestic and industrial activities. The water-sediment distribution coefficient (Kd) was relatively different for PFOS and PFOA, with Kd ranged from 20.51-72.83 l/g and 1.21-20.31 l/g for PFOS and PFOA, respectively. This result suggested the distribution of PFOS and PFOA between water and sediment, in which PFOS will preferentially deposit in the sediment, and PFOA will tend to distribute in the liquid phase of the aquatic environment.