This study aimed to optimize the synthesis of trimethyl chitosan (TMC) with a high degree of N,N,N-trimethylation (DTM) through a one-step procedure, minimizing reagent use, reaction time, and avoiding O-methylation, using the Design of Experiments (DoE) approach. Initially, sequential designs were done. Following the determination of the initial conditions a Fractional Factorial Design was used, investigating methyl iodide (MeI) and NaHCO molar ratios, temperature, and reaction time on DTM. MeI and NaHCO molar ratios were found to be significant (p-values equal to 0.02 and 0.02, respectively), the reaction temperature (p = 0.04) displayed a non-linear effect, while the reaction time was found to be non-significant (p = 0.93). Finally, a Full Factorial Design was done to optimize temperature and base addition methods. Incremental addition of the base was determined to be feasible without affecting the DTM, thereby preventing any viscosity-related problems. DTM was achieved up to 72 % in a one-step procedure, with no O-methylation. These optimized conditions offer a cost-effective, one-step synthesis method for TMC production, holding significant promise for industrial applications by avoiding multistep reactions, ensuring minimal reagent use, and preventing O-methylation. The findings mark a substantial advancement in TMC synthesis, presenting a streamlined and efficient approach with substantial practical implications for process development.
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http://dx.doi.org/10.1016/j.carbpol.2024.122065 | DOI Listing |
Chemistry
December 2024
Tohoku University - Katahira Campus: Tohoku Daigaku, Advanced Institute for Materials Research, Advanced Institute for Materials Research, 980-8577, Sendai, JAPAN.
A series of CoFe2O4 materials derived from metal-organic framework were successfully constructed by the solvent-thermal method. The morphology of a typical sample CoFe2O4-1 was mostly in the form of a cubic rod-like structure with a size distribution of 3.2 ± 0.
View Article and Find Full Text PDFOdontology
December 2024
Pontifícia Universidade Católica Do Paraná. Imaculada Conceição, 1155, Prado Velho, Curitiba, PR, 80215-901, Brazil.
To investigate the association of NANOG polymorphisms with oral leukoplakia. In this case-control study, 68 cases of oral leukoplakia, and 21 of normal oral mucosa (control) were submitted to genotyping of tagSNPs polymorphisms: rs877716 and rs10845877 in NANOG, through real-time polymerase chain reaction (PCR). Pearson's chi-squared and Fisher's exact statistical tests were used, with a significance of 5%.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Northwestern Polytechnical University, Department of Applied Chemistry, School of Science, Youyi Xilu 127#, 710072, Xi'an, CHINA.
Limited by the two mutually exclusive physicochemical processes of separation and recombination of photogenerated carriers, achieving photoluminescence and photocatalysis simultaneously is extremely challenging but essential for ever-growing complex issues and specialized scenarios. Here we proposed a biomimetic isolation-conduction strategy induced by an arene-perfluoroarene (A-P) interaction for enabling photoluminescence and photocatalytic hydrogen evolution reaction (HER) activity in the co-assembly of aromatic monomers and octafluoronapthalene (OFN). Inspired by the isolation-conduction effect of periodic isolation of myelin sheaths on the axons of vertebrate nerve fibers by node of Ranvier, we use OFN as a molecular isolator embedded in the aromatic monomers array to block the singlet-to-triplet pathway, while the enlarged intermolecular dipoles resulting from the A-P interactions facilitate the conduction of photogenerated carriers in the isolated regions.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
University of Pennsylvania, Department of Earth and Environmental Science and Department of Chemistry, 251 Hayden Hall, 240 South 33rd Street, 19104-6316, Philadelphia, UNITED STATES OF AMERICA.
Nitrogen (N2) has long been considered as stable atmospheric reservoir for N element and has a persistence time of hundreds of years. This study reveals that oxygen (O2) at typical tropospheric concentrations can rapidly activate N2, leading to substantial production of nitrous oxide (N2O), the third most impactful greenhouse gas, at rates approaching 2.83 ± 0.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Capital Normal University, Department of Chemistry, No. 105 Xisan Huan Bei Road, Haidian Dist. Beijing, CHINA.
Whether the catalyst can realize the non-CO pathway is the key to greatly improve the catalytic activity and stability of methanol oxidation reaction (MOR). It is feasible to optimize the reaction path selectivity by modifying organic ligands and constructing single-atom systems. At the same time, heterogeneous metal nanosheets with atomic thickness have been shown to significantly enhance the catalytic activity of materials due to their ultra-high exposure of active sites and synergistic effects.
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