Carboxymethylation Reaction Research Articles

Preparation and Application of Carboxymethyl Starch

Carboxymethyl starch (CMS) was used as printing thickener, it was synthesized by carboxymethylation reaction with acid-hydrolyzed maize starch and chloroacetic acid(MCA). The optimum conditions of synthesized CMS were as follows: the ratio of nNaOH/nAGU was 3, the ratio of nMCA/nAGU was 1.5:1, etherification temperature was 65°C. The highest degree of substitution(DS) was 0.45. The maximum value of printing viscosity index(PVI) was 0.513, the best water-retention property was 0.2cm and the solid containing rate was 8%. Compared the synthesized CMS with sodium alginate, the results on printing experiments showed the properties of the CMS were almost the same as sodium alginate. Form FT-IR, it was found carboxyl functional group were show at absorption peak of 1604cm-1,1425cm-1 and 1325cm-1, it indicated that the maize starch were substituted.

Preparation and evaluation of some amide ether carboxylate surfactants

A homologous series of new mild surfactants, namely: Alkyl amide ether carboxylates surfactants (AEC) RCO–NHCH2CH2O (CH2CH2O)6CH2COONa, were synthesized by esterification, amidation, ethoxylation and carboxymethylation reaction steps of fatty acids (Lauric, Myristic, palmitic, stearic, oleic or linoleic). The chemical structures of the prepared compounds were confirmed using different spectroscopic techniques, FTIR spectroscopy, mass spectra and HNMR. The surface properties including surface and interfacial tensions, foaming height, emulsification power, calcium ion stability, stability to hydrolysis and critical micelle concentration (cmc) were determined. The study of their surface properties showed their stability in hard water and in acidic and alkaline media. These compounds have high calcium ion stability. The low foaming power could have an application in the dyeing auxiliary industry. The lower values of the interfacial tension values indicate the ability of using these surfactants in several applications as corrosion inhibitors and biocides. The data revealed various advantages and potentials as a main surfactant as well as co- surfactants.

Optimization of Reaction Conditions for Preparing Carboxymethyl Cellulose from Corn Cobic Agricultural Waste

Carboxymethyl cellulose (CMC) is an important industrial polymer with a wide range of applications in flocculation, drag reduction, detergents, textiles, paper, foods, drugs, and oil well drilling operation. The various properties of CMC depend upon three factors: molecular weight of the polymer, average number of carboxyl content per anhydroglucose unit (AGU) i.e. degree of substitution and also on the distribution of carboxyl substituent’s along the polymer chains. The cellulose extracted from corn cobic lignocellulosic waste biomass was converted to CMC by etherification process using sodium hydroxide and monochloroacetic acid (MCA) under heterogeneous condition. The carboxymethylation reaction was optimized against the NaOH concentration, monochloroacetic acid concentration, reaction temperature and time. The degree of substitution (DS) was analyzed with respect to the reaction conditions using chemical method. The produced CMC was characterized by using Fourier transform infrared spectra and X-ray diffractogram. The optimized conditions to yield CMC with high DS of 1.18 are; concentration of aqueous NaOH 3.25 mol/AGU, 25 % (w/v); concentration of MCA, 2.4 mol/AGU; reaction time, 3.0 h and temperature, 60 °C with isopropyl alcohol as the supporting solvent medium.

Effect of Molecular Sizes, Sources of Chitosan and Plasticizer Types on Properties of Carboxymethyl Chitosan Films

Carboxymethyl chitosan (CMCH) from two molecular sizes (oligomer and polymer) and three different sources (shrimp, crab and squid) of chitosan were prepared by carboxymethylation reaction. The CMCH films were cast and their mechanical properties. For molecular sizes, the polymer CMCH films showed higher %elongation (%E) than those of oligomer CMCH films but had no effect on tensile strength (TS). The crab polymer CMCH films showed the highest TS. The different sources of chitosan had no influence on %E of CMCH films. The effect of plasticizers [glycerol (Gly), sorbitol (Sor) and polyethylene glycol 400 (PEG)] on mechanical properties of CMCH films was also investigated. Additions of Gly and Sor into films increased %E and reduced TS of CMCH films; however, films plasticizing with PEG showed no significant difference in mechanical properties. The crab CMCH films were selected to determine water vapor transmission rate (WVTR) at 25°C and 65%RH. The crab oligomer CMCH films showed higher WVTR than those of crab polymer CMCH films. Addition of Sor as plasticizer decreased WVTR of crab polymer and oligomer CMCH films whereas WVTR of films with Gly depended on molecular sizes of chitosan. Addition of PEG had no effect on WVTR of CMCH films.

Theoretical investigation into the likely reaction mechanisms of benzyl alcohol with dimethyl carbonate over a faujasite zeolite catalyst

Benzyl methyl ether (BME) compounds are largely synthesized by the chemical industry for use as a starting material for the synthesis of other organic compounds. In order to achieve the target of green chemistry, BME can be synthesized from benzyl alcohol and dimethyl carbonate (DMC) using a zeolite catalyst. DMC is a good methylating and carboxymethylating agent that is, in contrast to other such agents, a relatively non-toxic compound. In this study, the methylation and carboxymethylation reactions of benzyl alcohol over a 3T cluster of zeolite and a 36T extended framework was investigated by density functional theory (DFT) and the ONIOM approach, respectively. Both frameworks revealed two pathways for the methylation reaction, the first involving two transition states (TSs) and the second only a single TS. Methylation via the two-TS pathway was found to be more kinetically stable than the single-TS pathway whilst the methylation reaction is kinetically favored over the carboxymethylation reaction. The rate constants with the 36T cluster were increased 104–106 fold compared to the 3T quantum cluster.

Synthesis of Carboxymethyl Starch with High Degree of Substitution by a Modified Dry Process

Granular carboxymethyl starch (CMS) with high degree of substitution (DS) was synthesized using a modified dry process. The carboxymethylation reaction was carried out with granular potato starch, solid NaOH and sodium monochloroacetate (SMCA). The effects of reaction temperature, reaction time, molar ratio of NaOH and SMCA to starch on the degree of substitution (DS) and the reaction efficiency (RE) of CMS were investigated. High DS up to 0.78 was obtained for reaction at 323 K for 6 h with molar ratio of NaOH and SMCA to starch being 2:2:1. CMS was characterized by Fourier transform infrared spectrophotometer and scanning electron microscopy.

Homogenous carboxymethylation of starch using 1-butyl-3-methylimidazolium chloride ionic liquid medium as a solvent

An ionic liquid, namely 1-butyl-3-methylimidazolium chloride (BMIMCl), was employed as a reaction medium for homogenous carboxymethylation of corn starch. The process variables affecting the carboxymethylation reaction such as amount of sodium hydroxide (NaOH) and sodium monochloroacetate (SMCA), reaction time and reaction temperature were investigated regarding the degree of substitution (DS) for the carboxymethyl starch. The highest DS of 0.76 was obtained at molar ratios of NaOH and SMCA to anhydroglucose unit (AGU) of 1.2 and 1.0, respectively, and at 90°C for 3h of reaction. Results from FT-IR and 13C NMR spectra indicated that the hydroxyl groups of starches were substituted by carboxymethyl groups. SEM and XRD studies showed that the morphology and crystallinity of starch was disrupted after the carboxymethylation reaction.

Reduction of the linting and dusting propensity of newspaper using starch and microfibrillated cellulose

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Preparation and thermal stability of carboxymethyl starch/quaternary ammonium salts complexes

Starch complexes were obtained from activated and pregelatinized cassava starch (AS) or carboxymethyl starch (CMS) by using quaternary ammonium salts (QAS). The synthesis of the CMS was carried out by a single or double step carboxymethylation reaction with monochloroacetic acid. Different parameters were assayed to prepare the ionic complexes: CMS or AS as starting materials, anhydroglucose unit/QAS ratio, and length of the alkyl chain of the alkyltrimethylammonium bromide (C n TAB) salt. The products were characterized by FTIR, 1H and 13C NMR, and the Kjeldhal method. The results indicated a much more favorable complex formation when using CMS, obtaining the highest degree of substitution or complexation (0.72) and reaction efficiency (0.96) when C 18TAB was employed. DSC and WAXS experiments evidenced the crystallization of the octadecyl chain introduced in the starch, exhibiting a dependence on sample water content. TGA and TVA analysis showed the stability of the complexes up to ∼150 °C and that degradation takes place in at least two stages with the release of the surfactant moiety in a first stage and the degradation of the starch skeleton in a second stage.

Effect of carboxymethylation conditions on the water-binding capacity of chitosan-based superabsorbents

A superabsorbent polymer (SAP) from chitosan was provided via carboxymethylation of chitosan, followed by cross-linking with glutaraldehyde and freeze-drying. This work was focused on an investigation of the effects of monochloroacetic acid (MCAA), sodium hydroxide, and reaction time on preparation of carboxymethyl chitosan (CMCS). The CMCS products were characterized using FTIR spectroscopy, and their degrees of substitution (DS) were measured using conductimetry and FTIR analysis. The highest DS value was obtained when the carboxymethylation reaction was carried out using 1.75 g MCAA and 1.75 g NaOH per g of chitosan in 4 h. The water solubilities of the CMCS products at various pHs were also evaluated, and the results indicated a significant impact of the reaction parameters on the solubility of CMCS. The CMCSs with the highest DS value resulted in SAPs having the highest water-binding capacity (WBC). The WBC of the best SAP measured after 10 min exposure in distilled water, 0.9% NaCl solution, synthetic urine, and artificial blood was 104, 33, 30, and 57 g/g, respectively. The WBC of this SAP at pH 2–9 passed a maximum at pH 6.

Water absorption and ion exchange properties of some derivatives of peroxyacid viscose grade pulp

PurposeThe purpose of this paper is to study some chemical reactions of viscose grade pulp (alpha cellulose around 96 per cent) prepared by preoxyacetic acid pulping of bagasse for the preparation of some cellulose derivatives.Design/methodology/approachViscose grade pulp was prepared by using ecological chemicals. The viscose grade pulp was subjected to some chemical reactions (e.g. carboxymethylation, cyanoethylation and phosphorylation reactions). The pulping and bleaching which are two important stages involved in the complex process of converting fibrous raw material (bagasse) into viscose grade pulp are also investigated in this paper.FindingsThe viscose pulp prepared by peroxyacid pulping of bagasse was subjected to a number of chemical reactions such as: hydrogel and fibrous carboxymethyl cellulose; cyanoethyl cellulose, in which this cyanoethylcellulose (of gel properties) was prepared, the hydrophobic character of the cyanoethylcellulose was changed into hydrophilic character via hydrolysis by NaOH (2.5 per cent w/v) which converts some of the CN groups into COOH; and cellulose phosphate. Infrared spectroscopy of these derivatives was studied. New bands were observed at 3,120, 2,251, 1,200 and 980 cm−1 which characterised to groups, respectively.Originality/valueThe paper documents the preparation of some cellulose derivatives which have high water absorption and can be used as hydrogel materials such as carboxymethyl and hydrolysed cyanoethyl cellulose and ion exchange properties.

Anti-obesity effect of carboxymethyl chitin by AMPK and aquaporin-7 pathways in 3T3-L1 adipocytes

The aim of this study was to investigate the anti-obesity effect of carboxymethyl-chitin (CM-chitin), a water-soluble derivative of chitin, by measuring lipid accumulation and adipogenesis related factors in 3T3-L1 adipocytes. CM-chitin was synthesized by means of carboxymethylation reaction. Its inhibitory effect on lipid accumulation was investigated by measuring triglyceride content and glycerol release level. The gene and protein levels associated with adipogenesis were determined using reverse transcriptase-polymerase chain reaction and Western blot analysis. Treatment with CM-chitin reduced triglyceride content and enhanced glycerol secretion in a dose-dependent manner. CM-chitin induced the down-regulation of adipogenesis related transcriptional factors and adipocyte specific gene promoters. Moreover, the specific mechanism by CM-chitin was confirmed by transcriptional activations of the phosphorylated adenosine monophosphate-activated protein kinase (AMPK) and aquaporin-7. These results suggest that CM-chitin exerts anti-adipogenic effect on lipid accumulation through modulations of AMPK and aquaporin-7 signal pathways.

Valorisation of Vegetal Wastes as a Source of Cellulose and Cellulose Derivatives

Different qualities of CMC were prepared from an agricultural residue (date palm rachis) and a marine waste (Posidonia oceanica). These starting lignocellulosic materials were used as such and after chemical pulping and bleaching. The carboxymethylation reaction was carried out in presence of NaOH (40%) and monochloroacetic acid (ClCH2COOH, MAC), in n-butanol as the reaction solvent. The substitution degrees (DS) of the obtained CMCs varied from 0.67 to 1.62 and between 0.98 and 1.86, for P. oceanica and date palm rachis, respectively. The CP-MAS 13C-NMR spectra of the prepared polyelectrolytes displayed the presence of the main peaks associated with cellulose macromolecules (C1–C6) and that corresponding to carboxyl functions at around 175 ppm. Unfortunately, the peak attributed to methylene groups neighbouring carboxyl moieties are overlapped by C2 and C3, which renders them hardly detectable. Nevertheless, it is worth noting that the CP-MAS 13C-NMR spectra revealed the presence of different signals originating from residual impurities (ca. 27 ppm), such as traces of lignin macromolecules (110–150 ppm) and methyl groups attributed to hemicelluloses. Work is in progress to establish a more efficient purification procedure, in order to have more accurate values of DS.

Preparation and characterization of water-redispersible nanofibrillated cellulose in powder form

Water-redispersible, nanofibrillated cellulose (NFC) in powder form was prepared from refined, bleached beech pulp (RBP) by carboxymethylation (c) and mechanical disintegration (m). Two routes were examined by altering the sequence of the chemical and mechanical treatment, leading to four different products: RBP-m and RBP-mc (route 1), and RBP-c and RBP-cm (route 2). The occurrence of the carboxymethylation reaction was confirmed by FT-IR spectrometry and 13C solid state NMR (13C CP-MAS) spectroscopy with the appearance of characteristic signals for the carboxylate group at 1,595 cm−1 and 180 ppm, respectively. The chemical modification reduced the crystallinity of the products, especially for those of route 2, as shown by XRD experiments. Also, TGA showed a decrease in the thermal stability of the carboxymethylated products. However, sedimentation tests revealed that carboxymethylation was critical to obtain water-redispersible powders: the products of route 2 were easier to redisperse in water and their aqueous suspensions were more stable and transparent than those from route 1. SEM images of freeze-dried suspensions from redispersed RBP powders confirmed that carboxymethylation prevented irreversible agglomeration of cellulose fibrils during drying. These results suggest that carboxymethylated and mechanically disintegrated RBP in dry form is a very attractive alternative to conventional NFC aqueous suspensions as starting material for derivatization and compounding with (bio)polymers.

Carboxymethylation of maize starch at mild conditions

A process for carboxymethylation of maize starch (St.) at 30 °C was adopted. Although mild reaction conditions were employed, 100% reaction efficiency and a completely cold water soluble product with a clear and transparent solution were obtained. A multifunctional catalyst was used to accelerate the carboxymethylation reaction at 30 °C. An increase in the catalyst concentration was found to increase the reaction rate, thus the reaction time was reduced from 168 to 24 h. Factors affecting the carboxymethylation reaction such as material:liquor ratio, using different solvents in the reaction medium, the ratio between solvent and water, the sequence of addition of the reactants and cooling during addition of the reactants were studied. 100% reaction efficiency was obtained using equivalent molar ratios of etherifying agents (0.2 mol/mole St.), 0.3 mol/mole St. of catalyst; isopropanol:water ratio of 90:10 and a material:liquor ratio of 1:1.5 at 30 °C for 24 h. The carboxymethylation reaction was tested for its reproducibility and suitability for other types of starch (rice and potato) while the carboxymethyl starch (CMS) prepared was further characterized for its viscosity, transparency and suitability as a sizing agent for cotton yarns. The CMS prepared was found suitable as a sizing agent. The tensile strength of the sized samples increased by 38.6% compared with the blank samples and the desizing efficiency of the sized samples was 98% at 30 °C.

Carboxymethylations of chitosan and chitin inhibit MMP expression and ROS scavenging in human fibrosarcoma cells

The water-soluble derivatives of chitosan and chitin, carboxymethyl-chitosan (CM-chitosan) and carboxymethyl-chitin (CM-chitin), were synthesised by means of carboxymethylation reaction. Their antioxidative and matrix metalloproteinase-2 and -9 (MMP-2 and -9) inhibitory effects were investigated in HT1080 human fibrosarcoma cells. Treatment with CM-chitosan and CM-chitin suppressed the formation of intracellular reactive oxygen species (ROS), protein oxidation and lipid peroxidation in a concentration-dependent manner. In addition, a protective effect against oxidative damage of purified genomic DNA was observed in the presence of CM-chitosan and CM-chitin. Moreover, CM-chitosan and CM-chitin reduced the expression levels of MMP-2 and -9 in gelatin zymography, RT-PCR and western blot analysis without any cytotoxic influence. CM-chitin exhibited a higher MMP inhibitory effect than CM-chitosan through transcriptional down-regulations of activator protein-1 (AP-1) and nuclear factor κB (NF-κB). Findings from the present study underscore the nutraceutical value of CM-chitosan and CM-chitin as a potent antioxidant and MMP inhibitor via alleviations of radical-induced oxidative damage.

Fluorescent Polyurethane Nanocapsules Prepared via Inverse Miniemulsion: Surface Functionalization for Use as Biocarriers

The functionalization of well-defined PU nanocapsules with an aqueous core prepared by performing a polyaddition at the interface of inverse (water-in-oil) miniemulsion droplets is demonstrated. The miniemulsion technique involving the nanoreactor concept allows one to obtain an encapsulation efficiency as high as 90% within the nanocapsules. A pH independent fluorescent dye is used as a model system for the aqueous core. By varying the molar ratio of the diol to the diisocyanate at a fixed surfactant concentration, the shell thickness of the nanocapsules can be finely tuned. The carboxy- and amino-functionalized surface of the nanocapsules can be tailored by an in-situ carboxymethylation reaction and by physical adsorption of a cationic polyelectrolyte, i.e. PAEMA or PEI. The increased uptake of amino-functionalized fluorescent nanocapsules by HeLa cells clearly demonstrates the potential of the functionalized nanocapsules to be successfully exploited as biocarriers.

Dissociation behaviors of carboxyl and amine groups on carboxymethyl‐chitosan in aqueous system

AbstractSeveral carboxymethyl‐chitosan (CMCS) samples with different deacetylation degree and/or substituted degree were prepared from the carboxymethylation reaction of chitosan under soft conditions. The products were dissolved in standard HCl aqueous solution to carry out potentiometric titration by using NaOH as titrating solution at different ionic strengths. Then the dissociation behaviors of protonated carboxyl and amine groups were investigated under their degree of dissociation (α) and protonation constant (pKα) had been calculated. Moreover, influences of the intrinsic and extrinsic parameters on the dissociation behavior of CMCS were also considered in this article. As a result, dissociations of carboxyl and amine on CMCS exhibited unusual behaviors in comparison with carboxyl of carboxymethyl‐cellulose and amine groups of chitosan, respectively. The pKα values of carboxyl declined slightly at early dissociation stage but subsequently maintained constant. In contrast, the pKα of ammonium increased with its dissociation degree despite that there was an inflexed change on its dissociation curve. The potentiometric behavior of carboxyl was hardly affected by variation of deacetylation degree or substituted degree. However, these intrinsic parameters played more important role on dissociations of ammonium on CMCS. The ionic strength of media could bring screening effect on dissociaciation of both sorts of ionizable groups of CMCS. By increasing the ionic strength of media, screening effect on dissociations increased significantly. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1419–1429, 2008

Preparation and properties of glucosamine and carboxymethylchitin from shrimp shell

AbstractExport of processed and frozen shrimp products is the backbone of seafood industries. But, shrimp processing industries give rise to a large amount of waste materials. These waste products generate serious pollution hazards. A wise method to minimize environmental threats from prawn processing waste is to convert them in to useful products. Shrimp shell waste can be economically converted to chitin, a mucopolysaccharide. This marine polysaccharide and its derivatives hold a major part in our lives as medicines, cosmetics, textiles, paper, food and other branches of industry because of their unique nature in properties such as low toxicity, biocompatibility, hydrophobicity, etc. Hydrolysis of chitin yields a value added product, Glucosamine. Carboxymethylchitin is another derivative of chitin, prepared by the carboxymethylation reaction. This review article is an attempt to give an idea about the preparation, properties, and applications of the derivatives of chitin viz., glucosamine and carboxymethylchitin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Carboxymethylcellulose obtained by ethanol/water organosolv process under acid conditions

Sugar cane bagasse pulps were obtained by ethanol/water organosolv process under acid and alkaline conditions. The best condition of acid pulping for the sugarcane bagasse was 0.02 mol/L sulfuric acid at 160 degrees C, for 1 h, whereas the best condition for alkaline pulping was 5% sodium hydroxide (base pulp) at 160 degrees C, for 3 h. For the residual lignin removal, the acid and alkaline pulps were submitted to a chemical bleaching using sodium chlorite. Pulps under acid and alkaline conditions bleached with sodium chlorite presented viscosities of 3.6 and 7.8 mPa x s, respectively, and mu-kappa numbers of 1.1 and 2.4, respectively. The pulp under acid condition, bleached with sodium chlorite was used to obtain carboxymethylcellulose (CMC). CMC yield was 35% (pulp based), showing mass gain after the carboxymethylation reaction corresponding to 23.6% of substitution or 0.70 groups -CH(2) COONa per unit of glucose residue. The infrared spectra showed the CMC characteristic bands and by the infrared technique it was possible to obtain a substitution degree (0.63), similar to the substitution degree calculated by mass gain (0.70).