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Modified Vegetable Oils for Environmentally Friendly Lubricant Applications
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
Brajendra K. Sharma, Gobinda Karmakar, Sevim Z. Erhan
This reaction has been used for natural VOs containing a hydroxy group or chemically modified VOs (CMVO) with a hydroxyl group in their structure. The acetylation is accompanied by using acetic anhydride, acetic acid, acetyl chloride as the reagents. The hydroxyl group present in the castor oil is converted into an acetate giving rise to a hydrocarbon soluble acetate glyceride. Acetylation of hydroxyl fatty acid ester yield diesters of the octadecanoic fatty acid (Scheme 24.7) [43]. These esters have high VI and low freezing points below −30 or −40°C. The thermo-oxidative stability is poor and can be improved upon by alkylarylation or some other method to saturate double bonds to yield a product of higher stability. Castor oil has been acetylated in quantitative yield with acetic anhydride using sulfuric acid as catalyst. Acetylation with acetic acid gives product containing free fatty acid. Catalysts like p-toluene sulfonic acid can be used, but they produce more free fatty acids resulting from hydrolysis of castor oil. The hydrolysis can be reduced to minimum by continuous removal of water [124]. Acetylation of fatty acid ester.
List of Chemical Substances
Published in T.S.S. Dikshith, and Safety, 2016
Acetyl bromide is a colorless fuming liquid, with a pungent odor, combustible and turns yellow on exposure to air. It is used as an acetylating agent in the synthesis of fine chemicals, agrochemicals, and pharmaceuticals. It is also used as an intermediate for dyes. Acetylation, a case of acylation, is an organic synthesis process whereby the acetyl group is incorporated into a molecule by substitution for protecting -OH groups.
Chemical Modification Processes
Published in Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones, Wood Modification Technologies, 2021
Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones
Although acetylation is more complicated than other methods, e.g., thermal modification, it gives a material that is more stable under a variety of conditions (ground contact or in load-bearing conditions) than these other methods.
Sugarcane bagasse fiber reinforced composites: Recent advances and applications
Published in Cogent Engineering, 2020
Deepa G. Devadiga, K. Subrahmanya Bhat, GT Mahesha
Introducing acetyl group into cellulose fibers can be obtained by esterification method using acetylating reagents (Zhao et al., 2008). Reduction of the polar nature of natural fibers increases the dimensional stability of composites. The hydroxyl groups of the fiber (OH) reacts with acetyl groups (CH3CO-) to make the surface more hydrophobic. The acetylation reduces the moisture absorption tendency of the fibers by about 50%. It is reported that hydroxyl groups present in the hemicellulose, lignin, and cellulose undergo acetylation (John & Ananddjiwala, 2008). Studies on effect of acetylation on mechanical and thermal properties of sugarcane bagasse reinforced polypropylene composites were carried out. The fibers were initially treated with alkali followed by an acid before acetylation procedure was adopted. Polypropylene matrix was used for the composite preparation. Acetylation process increased the flexural strength and modulus but tend to decrease mechanical properties due to the chemical modification (Luz et al., 2008).
Fabrication of a nano-biocatalyst for regioselective acylation of arbutin
Published in Green Chemistry Letters and Reviews, 2018
Lu Zheng, Xiaona Xie, Zhi Wang, Yuxin Zhang, Lei Wang, Xiuyun Cui, He Huang, Hong Zhuang
Lipase always exhibits high enzyme activity in the organic medium due to its feature of interfacial activation (19–23). As a widely applied biocatalyst for organic synthesis (24–28), lipase has also been prepared into hNPs (15, 29,30). However, the existence of Cu2+ might have some negative effects on the conformation of lipase and depress its enzyme activity to a certain extent. To solve this problem, we have prepared a zinc-containing nanoparticle via the coordination between zinc ion and the nitrogen atoms of the amide groups in the Candida sp. 99-125 lipase (CSL). After characterization, the as-prepared nano-biocatalyst by scanning electron micrograph (SEM), FTIR and XRD, the prepared hNPs have been applied for regioselective acylation of arbutin. As a simple natural polyphenol, arbutin has many fascinating bioactivities. Regioselective acetylation can improve its cell membrane penetration and enhance its biological activity. For a kinetically controlled synthesis, the used enzyme and type of enzyme (free enzyme of immobilized enzyme) may alter the enzyme performance and affect the yields (31). So in this study, regioselective acylation of arbutin was selected as a model reaction to evaluate the effect of immobilization (Scheme 1).
A review on waste wood reinforced polymer composites and their processing for construction materials
Published in International Journal of Sustainable Engineering, 2023
Katleho Keneuwe Khoaele, Oluwatoyin Joseph Gbadeyan, Viren Chunilall, Bruce Sithole
Acetylation is a treatment that utilises acidic catalysts to improve the interfacial adhesion in NFs. Chemicals consisting of the acetyl (CH3CO) group, essentially acetic acid, and acetic anhydride, are used for acetylation. The cellulose fibres and the CH3CO group react to lose −OH groups. This reaction results in a reduction of moisture absorption. Acetylation yields a rugged surface topography with less porosity than other chemical processes, improving interlocking characteristics (Birniwa et al. 2023).