Acetylation of alcohols, phenols and salicylic acid by heteropoly acids in acetic anhydride: a green and eco-friendly protocol for synthesis of acetyl salicylic acid (Aspirin)

Rwahwire

et al. 2019

KEM

In recent years the utilization of natural fibers as reinforcing agents in thermoplastic composites has captured major attention. This research studied the effect of reaction time on the morphology, particle size, and melting point of microcrystalline cellulose and the reinforcement ability via mechanical characterization of the modified MCC in a blend of predominantly PLA matrix. In order to accomplish this latter goal, the acetylated microcrystals were blended with polylactic acid (PLA) polymer at 5 wt% concentration. Furthermore, a new method to control the degree of substitution and particle shape, size and distribution of microcrystalline cellulose by controlling the acetylation time is presented. A series of samples were prepared by the acetylation of microcrystalline cellulose to varying levels of acetate substitution. Composites of the acetate substituted microcrystalline cellulose with polylactic acid (PLA) showed a substantial increase in the modulus of rigidity at an optimum concentration and level of acetate substitution. Spectroscopic, morphological together with thermal and mechanical property data are presented and discussed.

Section: Methodsmentioning

confidence: 99%

PLA Composite Films Based on Acetate Substituted Microcrystalline Cellulose

Rwahwire

et al. 2019

KEM

“…Among the protective groups for OH, acetyl is a group commonly used because it is stable in acidic reactions and is easily removed by hydrolysis using alkalis. The acetylation reaction is the same as the esterification reaction, which is the reaction between alcohol and acid which produces ester and water [14].…”

Section: B Modification Of α-Mangostin Compoundsmentioning

confidence: 99%

3,6-dimethyl ester-α-mangostin Compound Modified from Isolate α-mangostin Garcinia Mangostana Linn

Umami

Fadlan

Ersam

2021

IJPS

Isolate α-mangostin (1) is a phenolic compound derived from oxygenated and prenylated xanthones and major compounds obtained from the fruit peel of G. mangostana Linn., Which is stated to have inhibitory activity against α-glucosidase enzymes, serves to determine the antidiabetic activity resulting in IC50 value of 29,92 µM, is of the nature moderate to positive control (acarbose) with an IC50 value of 4.55 µM. A modified compound of α-mangostin (1) with acetic anhydride obtained by 3,6-di-methyl ester-α-mangostin (2) derivative showed the inhibitory value of α-glucosidase (IC50 13,89 μM), this value is better than the activity inhibition of α-mangostin (1), but not as active as the positive control value of the acarbose compound. The separation process to obtain α-mangostin isolates from the fruit peel of G. mangostana Linn was obtained by maceration method with ethyl acetate solvent, followed by refraction using a vacuum liquid chromatography (KCV) method over silica gel (Merck 60 G) and eluted using eluent (n-hexane: ethyl acetate) with increasing polarity, to produce as much pure crystal (21.66 g), yield (24%). While the structural characterization of the two compounds was carried out using UV-Vis, IR, HRESIMS, 1H-NMR and 13C-NMR spectroscopic methods, the antidiabetic testing was carried out using the α-glucosidase enzyme inhibition method.

“…These weak interactions contain important physical and chemical information, which is of great significance for analyzing the internal structure of organic molecular systems and the subtle differences between molecules. 2-HA (a fat-soluble organic acid), which exists in natural willow bark, white bead leaves, and sweet birch trees, is an important fine chemical raw material and can be used for the preparation of aspirin and other drugs [ 1 ], chemical reaction fluorescent indicator Agent [ 2 ], complexing agent for electroplating or electroless plating [ 3 ], and a trace amount of preservative used in food [ 4 ]. 3-HA is a positional isomer of 2-HA, which can be used as a preservative for industrial products [ 5 ], ion exchangers for chemical synthesis [ 6 ], intermediates for the preparation of pharmaceuticals [ 7 ], and azo dyes [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

Application of IRI Visualization to Terahertz Vibrational Spectroscopy of Hydroxybenzoic Acid Isomers

Tu,

Zhang,

Tang

et al. 2023

IJMS

The characteristic absorption spectra of three positional isomers of hydroxybenzoic acid are measured using a terahertz time-domain spectroscopy system (THz-TDS) in the 0.6–2.0 THz region at room temperature. Significant differences in their terahertz spectra are discovered, which indicates that THz-TDS is an effective means to identify positional isomers. In order to simulate their spectra, the seven molecular clusters of 2-, 3-, and 4-hydroxybenzoic acid (2-, 3-, and 4-HA) are calculated using the DFT-D3 method. Additionally, the potential energy distribution (PED) method is used to analyze their vibration modes. The analysis indicates that the vibration modes of 2-HA are mainly out-of-plane angle bending and bond angle bend in plane. The vibration modes of 3-HA are mainly bond length stretch and dihedral angle torsion. The vibration modes of 4-HA are mainly bond angle bend in plane and dihedral angle torsion. Interaction region indicator (IRI) analysis is used to visualize the location and type of intermolecular interactions in 2-, 3-, and 4-HA crystals. The results show that the weak interaction type of 2-, 3-, and 4-HA is dominated by van der Waals (vdW) interaction. Therefore, we can confirm that terahertz spectroscopy detection technology can be used as an effective means to identify structural isomers and detect the intermolecular interactions in these crystals. In addition, it can explain the absorption mechanism of terahertz waves interacting with matter.