No abstract

Over the years, several drugs have been developed deriving from plants to investigate possible therapeutic roles. Among them, curcuminoids and coumarins, which, display a wide range of biological activity against several strains. Therefore, it was synthesized a curcuminoids-coumarin derivative by a mechanochemical multicomponent reaction. By NMR and HRMS results confirmed the formation of a mixture of three curcuminoids-coumarin derivatives in the same sample. The Influence of time during the milling process was evaluated, resulting in a crystalline product in only 30 min. The LAG milling carried out with different solvents showed that the product is obtained regardless of the solvent polarity. Furthermore, the biological evaluation showed that the curcuminoidscoumarin derivative has better activity against S. aureus than curcumin and 4-hydroxycoumarin. Lastly, the cell viability study exhibited a decrease of cytotoxicity of the derivative, compared to curcumin, against NIH3T3 cells.

The aim of this paper is to replace toxic coinitiators (tertiary amines) by non-toxic compounds such as glycerol and inositol (polyalcohol) in dimethacrylate resins. For this purpose, mid infrared spectroscopy (MIR) was used to calculate the monomers' degree of conversion (%DC); as well as simultaneous Thermogravimetric Analysis -Differential Thermal Analysis (TGA-DTA) and Differential Scanning Calorimetry (DSC) were conducted to evaluate thermal stability, degradation steps, and thermal events. The use of different initiator systems did not modify the thermal events or the thermal stability of each of the dimethacrylate resins. Results show a substitution of system 2 (toxicity) by system 3 (low toxicity), which had a good conversion velocity and total conversion in some monomers, is plausible.

Grape seed is a waste product from the wine and juice industries. However, vegetable oil can be extracted from it, which is a renewable chemical with a huge potential application after chemical modifications, such as epoxidation and maleinization processes. This paper therefore deals with the use of grape seed oil, to produce its epoxidized and maleinized derivatives. Both derivatives were synthesized in order to improve the conversion (99.4%), yield (98.9%) and selectivity (99.5%) values, as well as to decrease the reaction time (3 h) using cleaner energy sources and heterogeneous catalysts, which can be used 4× without regeneration and obtaining similar conversion and yield values, and at least 5× keeping high selectivity. Based on the characterization results, both grape seed oil derivatives may be applied in different fields, including polymer chemistry as a monomer, coating, and paint. In addition, they can be an option to industries that use petrochemical derivatives as precursors.

The ability to produce new and renewable, epoxidized Brazilian vegetable oils from baru nut (Dipteryx alata Vogel) and macaw palm (Acrocomia aculeata) oil, using a fast and clean heterogeneous catalytic method, was investigated. The Wijs method and Proton Nuclear Magnetic Resonance ( 1 H-NMR) analysis were utilized, and compared to one another, to calculate the iodine value (IV), average number of double bonds (DBaverage) and fatty acid content, and thus degree of epoxidation, for both vegetable oils. This analysis indicated that alkene conversions of 100 and 95.3% were obtained for baru nut oil and macaw palm oil, respectively; which is an excellent result when compared with some works in literature. The epoxidized Baru nut oil is a solid at room temperature, which was related to the percentage of mono-unsaturated fatty acids present in its structure. Epoxide samples were also analyzed via mid-Infrared Spectroscopy and 13 C NMR analysis. Thermogravimetry-differential thermal analysis (TG-DTA) was used to determine the thermal stability of these epoxidized oils. Differential Scanning Calorimetry (DSC) also provided information about their crystallization, melting and solid-solid transition processes.

The objectives of this study were to verify thermal properties, degree of conversion, and morphological features of several dimethacrylate polymers with different glycerol content and obtain the better proportion system to decrease cost of final polymer. These polymers were synthesized by photopolymerization, which has economic and ecological advantages. The glycerol can be used as a coinitiator in photopolymerization and has the advantage of being inexpensive and non-toxic; thus, it is in the scope of the green chemistry principles. Simultaneous thermogravimetry-differential thermal analysis and derivative thermogravimetric, differential scanning calorimetry, middle infrared spectroscopy, and scanning electronic microscopy were used to determine thermal properties, degree of conversion, and morphological characteristics of polymers obtained. The thermoanalytical results showed that glycerol addition in the dimethacrylate system caused few modifications in the thermal stability of the polymer and thermal events when compared with pure polymers (without glycerol). Two dimethacrylate systems (UDMA/glycerol and Bis-GMA/glycerol) showed good results for conversion degree and morphological aspects when compared with pure systems.

The objectives of this study were to verify the viability of the photoinitiating system using curcumin as a photoinitiator and glycerol as a coinitiator, to analyze the thermal and morphological features of the polymers produced, and finally evaluate the possibility of removing toxic Ethyl-p-dimethylaminobenzoate from the photoinitiating system. Curcumin, an orange-yellow dye extracted from the rhizoids of the plant Curcuma longa, is known to be a common photosensitizer, and the type II photoinitiating system consisting of a dye and an amine is long known to be effective. In recent years, the production of biodiesel has increased, and consequently, so has the generation of its main by-product, glycerol. Thus, it becomes necessary to study ways to incorporate glycerol into products. Using thermoanalytical methods (Thermogravimetry, Differential Thermal Analysis, and Differential Scanning Calorimetry), Middle Infrared Spectroscopy, and Scanning Electronic Microscopy, it was possible to assess the thermal and morphological characteristics of the polymers produced, and compare whether the presence or lack of tertiary amine, as well as the addition of different molar ratios of glycerol, had any significant impact on these characteristics. Results suggested that neither the removal of tertiary amine nor the addition (in different proportions) of glycerol affected the thermal stability of the polymers. Also, removing the tertiary amine enhanced the total conversion degree of the polymers.

Graphical abstractThis work shown synthesis of dimethacrylate polymers using a new fluorescein dye derivatives by blue light LED. The thermal characterization was made by TG-DTA, conversion degree was obtained by MIR and DSC, and morphological aspects was obtained by SEM. Highlights New fluorescein dyes derivatives was used to inititors in photopolymerization. The chlorinated dyes showed higher conversions. Brominated dyes showed good radical stabilization and low conversion. AbstractThis work investigates the degree of conversion, thermal properties, and morphological features of polymers obtained using UDMA monomer and fluorescein and its derivatives dyes as photoinitiator. Photopolymerization has opened new research and material due to its synthesis ability as well as ecological and economic advantages.Fluorescein is a dye with great fluorescent properties; therefore, it could be used as initiator in photopolymerization, including its derivatives. SimultaneousTermogravimetry-Differential Thermal Analysis and Derivative Thermogravimetric (TG/DTG-DTA), Differential Scanning Calorimetry (DSC), Middle Infrared Spectroscopy (MIR), and Scanning Electronic Microscopy (SEM) were used to determine thermal properties, degree of conversion, and morphological characteristics of polymers obtained. The data show that the use of fluorescein and its derivatives as photoinitiators did not change the thermal stability of the polymer (193.13±7.9 °C);however, the chlorinated dyes produced a better degree of conversion (78.73% to F-2 and 69.36% to F-5) than brominated dyes (21.18% to F-3 and 1.21% to F-6), resulting in solid rigid polymers.