Esterification of bagasse cellulose with metal salts as efficient catalyst in mechanical activation-assisted solid phase reaction system

The present study focused on investigating the catalytic mechanism of metal salts (sodium hypophosphite, sodium bisulfate and ammonium ferric sulfate) for esterification of bagasse cellulose carried out by mechanical activation-assisted solid phase reaction in a stirring ball mill. FTIR analysis of the products confirmed that these metal salts could catalyze the esterification of cellulose. XRD, SEM, FTIR, and ³¹P-NMR analyses of different samples indicated a synergistic effect between metal salt and ball milling, and the presence of metal salts enhanced the destruction on crystal structure of cellulose by mechanical force. The catalytic mechanism of three metal salts was difference: sodium bisulfate and ammonium ferric sulfate belonged to the catalytic mechanism of protonic acid and Lewis acid, respectively, while the catalytic mechanism of sodium hypophosphite was considered as that it could react with maleic acid to form active intermediates under ball milling.     

FT-IR and FT-raman spectroscopy study of the cyclic anhydride intermediates for esterification of cellulose: I. Formation of anhydrides without a catalyst

In recent years, extensive efforts have been made to find nonformaldehyde durable press finishes to replace the traditional formaldehyde-based reagents for producing wrinkle-free cotton fabrics. 1,2,3,4-butanetetracarboxylic acid (BTCA) has been the most effective nonformaldehyde crosslinking agent. Our previous research has indicated that a polycarboxylic acid esterifies cellulose in two steps: the formation of a 5-membered cyclic anhydride intermediate by the dehydration of two adjacent carboxyl groups, and the reaction between cellulose and the anhydride intermediate to form an ester linkage. In this research, we used Fourier transform infrared and Fourier transform Raman spectroscopy to study the formation of cyclic anhydride intermediates by BTCA and other polycarboxylic acids without the presence of a catalyst. We found that BTCA and other polycarboxylic acids in a crystalline state start to form 5-membered cyclic carboxylic anhydrides when the temperature reaches the vicinity of their melting points with the exception of bifunctional acids, which form cyclic anhydrides at temperatures much higher than their melting points. Intermolecular hydrogen bonding between carboxylic acid groups prevents the formation of the cyclic anhydride intermediates at lower temperatures. We also found that polycarboxylic acids in an amorphous state form cyclic anhydrides at much lower temperatures.     

Hydrolytic ring opening reactions of anhydrides for first row transition metal dicarboxylate complexes

Ring opening reactions of 2,3-pyridine dicarboxylic anhydride are studied with hydrated salts of cobalt, nickel and zinc. The hydrated metal salts preferentially hydrolyze 2,3-pyridine dicarboxylic anhydride rather than causing esterification in methanol medium. Hydrolytic opening of 2,3-pyridine dicarboxylic anhydride by hydrated cobalt(II) acetate and nickel(II) acetate resulted in the corresponding chelate complexes of monodeprotonated 2,3-pyridine dicarboxylic acid. The reaction of copper acetate with pyromellitic dianhydride in the presence of 1,10-phenanthroline gives a dinuclear copper complex whereas a similar reaction with copper(II) chloride gives a mononuclear copper complex.     

Infrared spectroscopy studies of the cyclic anhydride as the intermediate for the ester crosslinking of cotton cellulose by polycarboxylic acids. III. Molecular weight of a crosslinking agent

Polycarboxylic acids have been used as nonformaldehyde crosslinking agents for cotton fabrics to replace the traditional N-methylol reagents. In this research, we compared 1,2,3,4-butanetetracarboxylic acid (BTCA) with poly(maleic acid) (PMA) as crosslinking agents for cotton cellulose. BTCA and PMA have similar molecular structures with carboxyl groups bonded to their molecular backbones, and both form five-membered cyclic anhydride intermediates during a curing process. However, BTCA is a more effective crosslinking agent for cotton cellulose than PMA. This is mainly attributed to the differences in the mobility of the anhydride intermediates to access the cellulosic hydroxyl groups during a curing process. The mobility of the anhydride intermediate of PMA is reduced due to its molecular size and multiple bonding between a PMA molecule and cellulose. Consequently, more anhydride and less ester are detected on the cotton fabric treated with PMA than on the fabric treated with BTCA. The amount of the unreacted anhydride intermediate on the fabric treated with PMA is reduced whereas the amount of ester is increased when another hydroxyl-containing compound of low molecular weight is present. Thus, the infrared spectroscopy data show a clear link between the molecular weight of a polycarboxylic acid and its effectiveness for crosslinking cotton cellulose. © 1997 John Wiley & Sons, Inc.     

Infrared spectroscopy studies of the cyclic anhydride as the intermediate for the ester crosslinking of cotton cellulose by polycarboxylic acids. I. Identification of the cyclic anhydride intermediate

The mechanism of esterification of cotton cellulose by a polycarboxylic acid was investigated using Fourier transform infrared spectroscopy (FT-IR). The infrared spectroscopic data indicate that a polycarboxylic acid esterifies with cotton cellulose through the formation of an acid anhydride intermediate. A five-member cyclic anhydride intermediate was identified in the cotton fabric treated with poly(maleic acid). The five-member cyclic anhydride is a reactive intermediate and readily esterifies when reaction sites are available. We also found that those polycarboxylic acids, which form five-member cyclic anhydride intermediates, crosslink cotton cellulose more effectively than those polycarboxylic acids which form six-member cyclic anhydride intermediates. © 1993 John Wiley & Sons, Inc.     

FT-IR and FT-raman spectroscopy study of the cyclic anhydride intermediates for the esterification of cellulose: III. Cyclic anhydrides formed by the isomers of cyclohexanedicarboxylic acid

Multifunctional carboxylic acids have been used as crosslinking agents for cotton and wood pulp cellulose. In our previous research, we found that a polycarboxylic acid esterifies cellulose through the formation of a 5-membered cyclic anhydride intermediate by the dehydration of two carboxyl groups. In this research, we studied the formation of cyclic anhydride intermediates by different isomers of cyclohexanedicarboxylic acid (CHA) so that we can elucidate the effects of molecular structure on the formation of the anhydride intermediates. We found that both cis-and trans-1,2-CHA form 5-membered anhydride intermediates when temperature reaches their melting points and that cis-1,2-CHA forms the cyclic anhydride at temperatures lower than does trans-1,2-CHA. 1,3-CHA forms 6-membered cyclic anhydride at temperatures much higher than its melting point. The formation of a 5-membered cyclic anhydride intermediates takes place at temperatures lower than that of a 6-membered anhydride. This is probably the main reason why those polycarboxylic acids with their carboxylic acid groups bonded to the adjacent carbons of the molecular backbones are more effective crosslinking agents for cellulose than those with their carboxylic groups bonded to the alternative carbons. No formation of cyclic anhydride was found for 1,4-CHA. The formation of a five-membered cyclic anhydride was accelerated by monosodium phosphate, which is used as a catalyst for the esterification of cotton cellulose by polycarboxylic acids.     

Electrometric indicators in the amperometric titration of cations and acids

Amperometric titration is carried out at zero potential in the presence of hydroquinone and p-aminophenol as electrometric indicators. Solutions of sodium carbonate, sodium arsenite, sodium tetraborate and potassium cyanide have been used as reagents in neutralisation, precipitation and complex formation reactions for the determination of cations separately, the simultaneous determination of several cations in one sample and of acid and cations present simultaneously. After the equivalence point has been reached, hydroxyl ions appear in the solution as a result of salt hydrolysis and a considerable increase in the current voltage occurs. The indicator in alkaline solution induces the depolarisation of the electrode.     

Investigation of the Hydrolysis Stability of Triazine Tricarboxylate in the Presence of Transition Metal(II) Ions and Synthesis and Crystal Structure of the Alkaline Earth Triazine Tricarboxylates M3[C3N3(CO2)3]2·12H2O (M = Sr,Ba)

The stability against hydrolysis of triazine tricarboxylate (TTC) in the presence of divalent transition metal and alkaline earth ions was investigated by means of X‐ray diffraction and FTIR spectroscopy. Depending on the size of the cation either formation of the respective triazine tricarboxylate salts or hydrolysis of TTC yielding oxalate was observed. The hydrolysis of TTC induced by transition metal ions could be explained in analogy to the hydrolysis of triazine tris(2‐pyrimidyl) as a result of ring tension caused by the coordination of these ions. By the reaction of potassium triazine tricarboxylate with alkaline earth salts in aqueous solution the alkaline earth triazine tricarboxylates M₃[C₃N₃(CO₂)₃]₂ · 12H₂O (M = Sr, Ba) were obtained and analyzed by single‐crystal X‐ray diffraction. The isotypic salts represent the first examples of alkaline earth triazine tricarboxylates and the first TTC salts comprising solely divalent cations.     

Non-formaldehyde,crease-resistant modification of cellulosic material by means of an organotrialkoxysilane and metal alkoxides

Cellulosic material is chemically modified to impart crease-resistant properties to textile products. Due to health considerations formaldehyde-free chemicals are preferred. For this purpose, (3-glycidyloxy)propyltrimethoxysilane (GPTMS) in combination with metal alkoxides aluminium isopropoxide (AIP), titanium tetraisopropoxide (TTP), zircon tetrabutoxide (ZTB) were applied to cotton raw material and cotton fabrics which were pre-treated with butane-1,2,3,4-tetracarboxylic acid (BTCA)/sodium hypophosphite. The as-prepared samples were tested for dry crease recovery angle, tensile strength, tear strength, air permeability, contact angle and whiteness index. The application of GPTMS/AIP resulted in excellent crease resistance values, whereas TTP and ZTB provided a moderate improvement of the wrinkle resistance. The application of the hydrophobic methyltriethoxysilane, octyltriethoxysilane and Dynasylan F8815 (fluoroalkylfunctional water-borne oligosiloxane) caused a significant increase in the contact angle. Fourier-transform-infrared spectroscopy proved the formation of an ester-linkage between BTCA and the cellulose.     

The thermal decomposition of alkali metal formates

The thermal decompositions of lithium, sodium, potassium, rubidium and caesium formates were investigated by a complex dynamic thermoanalytical method. The ratio of the products in reactions resulting in alkali metal carbonates and oxalates depended variously on the atmosphere used. Differences were found compared to isothermal investigations, in that the catalytic effects of bases could not be observed and the oxalate-conversion was lower. The formation of oxalate did not occur in the cases of lithium and caesium formates; the order for the other salts was sodium formate < potassium formate > rubidium formate.     

Preparation and properties of some salts of perfluorooctanoic acid

The sodium, potassium, lithium, caesium, barium, calcium, silver, lead and ammonium salts of perfluorooctanoic acid were prepared. Their thermal stabilities, and some spectroscopic data are reported. An attempt is made to correlate some of these measurements with the properties of the metal ions or metals concerned.     

Polymers based on divalent metal salts of p-aminobenzoic acid: a review

Divalent metal salts of p-aminobenzoic acid are useful starting materials for syntheses of ionic polymers into which metal is firmly incorporated. This paper is a review of a series of polymers that have been prepared using the metal salts. The salts can react with compounds having functional groups capable of reacting with amino groups. By polyaddition reactions of the salt–aromatic diamine with diisocyanate, and with isocynate-terminated adducts of diisocyanate and dialkylene glycol, halatotelechelic polyureas and polyurethane-ureas are obtained. By amine–epoxy reactions of systems of the salt–diamine–bisepoxide, and addition reactions of systems of the salt–dicarboxylic acid anhydride–bisepoxide, metal-containing cured resins are obtained. In this case, the metal carboxylate groups of the salts have catalytic activities for the curing reactions, and also for etherification of epoxy groups as a side reaction. Therefore, crosslinking of bisepoxide with the salts, and with adducts of the salts and the anhydride, has been investigated by taking advantage of the catalytic activity of the metal carboxylate groups for the etherification of epoxy groups. Interestingly, the metal-containing cured resins obtained by crosslinking by etherification of bisepoxide with the adducts show very high impact strength. © 1997 John Wiley & Sons, Ltd.     

Preparation and Analytical Application of a New Chelating Ion Exchange Resin Containing Thioglycolic Acid

Starting from copolymerization of acrylonitrile and divinylbenzene by emulsion polymerization technique, a macroporous, crosslinked polyacrylonitrile copolymer was synthesized. The nitrile groups on the copolymer resin were converted into carboxylic acid groups by hydrolysis with strong alkaline solution of sodium hydroxide to obtain the resin matrix with carboxylic acid groups. A new chelating ion exchange resin containing alkylthioglycolate was prepared by esterification of carboxylic acid groups on the resin matrix and thioglycolic acid with 1,6-hexanediol as binding part. After studies of the basic characters, ion exchange ability, exchange rate and acidity of the medium, it was found that the new resin obtaind was highly selective for silver(I), mercury(II), gold(III) and bismuth(III) in acidic-aqueous solution. Separation of these metal ions from each other and concentration of these metal ions from very dilute solution were studied by liquid chromatography using a short column of this new resin. The analytical applications of this new resin are reported.     

Study of the effect of oxidative-bisulfite modification of the cotton cellulose on its ion exchange properties

The effect of chemical modification on the sorption properties of cotton cellulose toward Cu(II) and Ni(II) ions was studied. The modification was carried out in two stages: oxidation of cellulose with the formation of dialdehydocellulose, followed by its sulfonation. The optimal conditions for modifying the cellulose to produce a sorbent capable to remove effectively the heavy metal ions from aqueous solutions of corresponding salts were elucidated. The modified sorbent exceeds the native cellulose in the sorption capacity (in terms of sorption maximum) about 3 times, therewith the time of extraction of heavy metal ions is reduced from 45 to 8 min. The high sorption properties are defined by the formation of new sorption sites -SO₃Na along with initially formed -COOH groups on the sorbent surface.     

强酸性阳离子交换树脂负载金属离子改性催化合成乙酸丁酯

用两种强酸性阳离子交换树脂进行金属离子负载改性制备酯化催化剂,考察了金属盐种类,盐浓度,沉浸时间,沉浸温度等因素对催化剂性能的影响.用在优化条件下制备的催化剂催化乙酸和正丁醇酯化反应体系,反应1h乙酸的转化率达到69%.     

Autocatalytic behaviour in esterification between anhydrides and alcohols

In this work the Arrhenius parameters and heat of reaction for the esterification of acetic anhydride by methanol and the esterification of propionic anhydride by 2-butanol were determined using a CPA 202 reaction calorimeter (ChemiSens). Three reaction rate models were tested for each of the esterification reactions, two of which assumed autocatalytic behaviour. The autocatalytic models were based on a carboxylic acid dependency; acetic acid and propionic acid being side products in the reactions studied. The two catalytic models gave excellent fits to the experimental results thus indicating autocatalytic behaviour.     

Influence of alkali and alkaline earth ions on the O -alkylation of the lower rim phenolic-OH groups of p-tert -butyl-calix[4]arene to result in amide-pendants: Template action of K+ and the structure of K+ bound tetra-amide derivative crystallized with a p-tert -butyl-calix[4]arene anion

Role of alkali and alkaline earth ions on the formation of calix[4]arene-amide derivatives through O-alkylation of the lower rim phenolic-OH groups in general and template action of K⁺ in particular have been explored. Na⁺ and K⁺ ions among alkali, and Ca²⁺ and Sr²⁺ ions among alkaline earth have shown tetra-amide derivatives bound to metal ion species. Among all these, potassium salts act as template and yields a K⁺ bound tetra-amide derivative where the charge is counter balanced by a calix[4] arene-monoanion and the product is crystallographically characterized. Change in the amide precursor used in these O-alkylation reactions has no effect on the type of the amide derivative formed. Also demonstrated is a direct one-step reaction for the preparation of 1,3-di-amide derivative in high yield and low reaction period using CsHCO₃.     

Silver Intercalation into Cellulose Matrix. An X-Ray Scattering,Solid-State 13C NMR,IR, X-Ray Photoelectron,and Raman Study

Diffusion of silver ions into a cellulose matrix and their subsequent reduction both with the matrix itself and with specific reducers lead to preparation of cellulose materials containing silver(0). Most silver metal is intercalated into the cellulose matrix when glycerol is used as solvent and potassium hypophosphite or sodium boron hydrate are used as reducers.     

Bi-acylation of cellulose: determining the relative reactivities of the acetyl and fatty-acyl moieties

The global reaction between acetic anhydride and a fatty acid yields, at equilibrium, an asymmetric acetic-aliphatic anhydride in a medium containing finally: acetic-fatty anhydride, acetic anhydride, fatty acid, acetic acid and fatty anhydride. No solvent or catalyst was used to evaluate the impact of the actual reactivity of the anhydrides. The competition between the formation of acetyl and fatty acyl ester functions was evaluated by determining the ratio of acetyl/fatty acyl groups grafted on solid cellulose. The influence of temperature, reaction time, and length of fatty chain on the total degree of substitution and on the ratio of acetyl/fatty acyl ester functions was investigated. For the first time, a correlation has been established between esterification and the length of the aliphatic chain of the fatty acid. Reactivity of the medium decreased with the number of carbons in the fatty acid, raised to the power 2.37.     

Identification of condensed-phase species on the thermal transformation of alkaline and alkaline earth metal sulphates on a graphite platform

Thermal treatment of alkaline and alkaline earth metal sulphates on a graphite platform was performed over the temperature range 200–2000 °C. The solid residues produced at each temperature were located by scanning electron microscopy (SEM) and then identified by energy-dispersive (ED) X-ray spectroscopy and Raman microanalysis. Additional experiments involved the dissolution of the residues from the platform and analysis by ion chromatography to determine the concentration of sulphate and other ions. A decomposition pattern was derived for the alkaline and alkaline earth metal sulphates. The transformation of the metal sulphates was dependent on temperature and the cation present. In general, the metal sulphates do not undergo significant decomposition to other species at temperatures less than 900 °C, with the exception of magnesium and beryllium sulphates, which are transformed into metal oxides to some extent. Above 900 °C, major transformations occur mainly for sodium, magnesium, and beryllium sulphates. For all the salts studied, there is evidence of the formation of species such as metal sulphides and elemental sulphur.