Synthesis Of Cellulose Esters Research Articles

Effect of green co-solvents on properties and synthesis of cellulose esters in superbase ionic liquid

Effect of green co-solvents on properties and synthesis of cellulose esters in superbase ionic liquid

MODIFICATION OF WOOD WITH FATTY ACIDS OBTAINED FROM SOAP STOCK

The paper considers the study of obtaining fatty acids from soap stocks. The proposed method of chemical processing of soap stock was applied for the first time and is not found in the previously published literature on the problems of chemical processing of vegetable oil waste. The composition of the isolated fatty acids of soap stock was studied by mass spectroscopy and the main chemical characteristics of the obtained fatty acids were determined. The isolated fatty acids are valuable not only as a feed additive for livestock, but also as a raw material for the chemical industry, in particular for the production of cellulose esters. The resulting fatty acids were used in the acylation of wood to obtain cellulose esters. The paper considers the kinetic regularities of the reaction of wood acylation with fatty acids of soap stock and studies the optimal conditions for the synthesis of cellulose esters from wood depending on the temperature and time of synthesis. The resulting products were investigated by IR spectroscopy, which proved the formation of an ester bond in the products obtained. When studying the kinetic regularities of the acylation of wood with fatty acids, the energy parameters were calculated in accordance with the kinetics of heterogeneous processes, which include the acylation of wood.

以离子液体为介质的纤维素均相衍生化

Cellulose derivatives are important fine chemicals with a wide range of applications in modern industries, so that cellulose derivatization has been one of hot topics for a long time. However, the existence of numerous hydroxyls in cellulose also generates a well-developed intra- and inter-molecular hydrogen bonding network, thus natural cellulose is neither meltable nor soluble in conventional solvents. Until today, the preparation method for cellulose esters begins with a heterogeneous reaction between cellulose and a large excess of the acylation reagent in the presence of pyridine or sulfuric acid as the catalyst. These heterogeneous reactions cause some problems, such as uneven distribution of substituents, side reactions, time consumption and considerable degradation of cellulose. Homogeneous esterification of cellulose in appropriate media, the alternative procedure for heterogeneous process, has been one focus in cellulose chemistry. It not only provides opportunities to obtain the effective control of degree of substitution (DS), distribution and uniformity of the functional groups along cellulose chains, but also creates more options to induce novel and functional groups. Recently, the advent of ionic liquids that can dissolve cellulose provides a new and versatile platform for the efficient and homogeneous derivatization of cellulose. A variety of well-known, novel and functional cellulose esters have been successfully synthesized in ionic liquids. Meanwhile, development of esterification techniques, utilization of agricultural residues, and pilot scheme of up-scaling esterification in ionic liquids have been in progress continuously. This review summarizes the development in homogeneous synthesis of cellulose esters in ionic liquids published in the recent decade.

Rapid Synthesis of Cellulose Esters by Transesterification of Cellulose with Vinyl Esters under the Catalysis of NaOH or KOH in DMSO

Traditionally, a long reaction time was required in the synthesis of cellulose esters (CEs). In this work, dimethyl sulfoxide (DMSO)/aqueous NaOH or KOH was introduced as an efficient reaction system for rapidly synthesizing CEs by transesterification. Surprisingly, cellulose could react with vinyl acetate, vinyl propionate, and vinyl butyrate and synthesized cellulose acetate, cellulose propionate, and cellulose butyrate with a high degree of substitution (2.14-2.34) in 5 min, which was in sharp contrast to hours of existing methods. The effects of solvents, catalysts, and esterifying agents on the synthesis of CEs were comparatively investigated to better understand this method. The structure and thermal properties of obtained CEs were characterized by Fourier transform infrared (FTIR) and (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopies and differential scanning calorimetry. Results from these spectra confirmed the successful synthesis of these CEs. Furthermore, these CEs showed similar thermal properties compared to products obtained from other methods.

Rapid homogeneous esterification of cellulose extracted from Posidonia induced by microwave irradiation

AbstractIn this article, we report on the synthesis of cellulose esters by the reaction of cellulose and some cyclic anhydrides, such as succinic, maleic, and phthalic anhydrides. For this, an esterification method was finalized. Indeed, cellulose extracted from Posidonia biomass was first solubilized in the solvent system lithium chloride (LiCl)/N,N‐dimethylacetamide and then esterified by cyclic anhydride in the presence of catalysts such as N,N‐dimethyl‐4‐aminopyridine, tripropylamine, tributylamine, and calcium carbonate. This method was fast and reproducible with the LiCl system as a solvent and with an efficient activation by controlled microwave power. In this way, the reaction time was reduced from several hours to just a few minutes. The reaction products were characterized by IR and solid‐state cross‐polarization/magic angle spinning 13C‐NMR spectroscopy. The degree of substitution (DS) and the grafted ester group content of the different products were obtained by alkali saponification followed by titration of the excess alkali. Two activation methods were compared, and the results show that the application of classical heating gave less successful results than those obtained by microwave activation. Indeed, with microwave activation, a higher DS (2.25) was obtained after 10 min. However, with classical heating, a value of DS equal to 1.2 was obtained after 12 h. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Application of 1‐Allyl‐3‐(1‐butyl)imidazolium Chloride in the Synthesis of Cellulose Esters: Properties of the Ionic Liquid, and Comparison with Other Solvents

The ionic liquid (IL), 1-allyl-3-(1-butyl)imidazolium chloride (AlBuImCl), has been synthesized and its properties determined. Increase in the temperature increased its conductivity and decreased its density, polarity, and viscosity. Microcrystalline cellulose (MCC), dissolves in this IL by heating at 80 degrees C; this did not affect its degree of polymerization, decreased its index of crystallinity (Ic), and changed in morphology after regeneration. Convenient acylation of MCC was achieved by using 50% excess anhydride at 80 degrees C, for 24 or 48 h for acetic and butyric anhydride, respectively. The composition of the mixed esters depended on the initial ratio of the anhydrides, and their order of addition.

Synthesis of cellulose esters with aliphatic hydroxy acids from aspen wood

Synthesis of cellulose esters with aliphatic hydroxy acids from aspen wood was studied in relation to the reaction and isolation conditions.