Sulfonation of lignin

Figure 3.13 Sulfonation of lignin a-carbon atoms during sulfite pulping.

A considerable part of the hydrogen sulfite ions is consumed in reactions other than the sulfonation of lignin. In the absence of wood, sulfur dioxide solutions are decomposed at elevated temperatures according to the equation ... 

Beatson RP, Heitner C, Rivest M, Atack D (1985) Sulphite treatment of aspen Factors affecting the formation of carboxylate and sulphonate groups Pap Puu 11 702-708 Brauns FE (1952) The sulfonation of lignin In Brauns FE (ed) The chemistry of lignin Academic Press, New York, 359-393... 

Brauns FE, Brauns DA (1960) The sulfonation of lignin In Brauns FE, Brauns DA (eds) The chemistry of lignin Supplement volume Academic Press, New York, 313-386 Canadian Pulp and Paper Association (1970) Standard Method G28 In Standard Testing Methods, Technical Section, Canadian Pulp and Paper Association, Montreal, Canada Canadian Pulp and Paper Association Useful Method G 7U In Standard Testing Methods, Technical Section, Canadian Pulp and Paper Association, Montreal, Canada Cappelen H, Schoon N-H (1966) Determination of sulfonic acid groups in unbleached sulfite pulps Sven Papperstidn 69 322-325... 

Lignin sulfonates are, technically, low-molecular-weight polymers containing a witch s brew of primary and secondary alcohols, phenols, and carboxylic acid functionalities. They are prepared by the sulfonation of lignin byproducts of pulp and paper manufacture, followed by neutralization to the sodium, calcium, or ammonium salt. The resulting materials are useful as dispersing agents for solids and oil/water emulsions, and as stabilizers for aqueous dispersions of dyes, pesticides, and cement. They are very inexpensive relative to other materials and are very... 

Substitution Reactions on Side Chains. Because the benzyl carbon is the most reactive site on the propanoid side chain, many substitution reactions occur at this position. Typically, substitution reactions occur by attack of a nucleophilic reagent on a benzyl carbon present in the form of a carbonium ion or a methine group in a quinonemethide stmeture. In a reversal of the ether cleavage reactions described, benzyl alcohols and ethers may be transformed to alkyl or aryl ethers by acid-catalyzed etherifications or transetherifications with alcohol or phenol. The conversion of a benzyl alcohol or ether to a sulfonic acid group is among the most important side chain modification reactions because it is essential to the solubilization of lignin in the sulfite pulping process (17). 

Finally, the sulfonate content of lignin is deterrnined by two main methods one typified by conductometric titration in which sulfonate groups are measured direcdy, and the other which measures the sulfur content and assumes that all of the sulfur is present as sulfonate groups. The method of choice for determining the sulfonate content of lignin samples that contain inorganic or nonsulfonate sulfur, however, is conductometric titration (45). 

The aromatic nature of lignin contrasts with the aliphatic stmcture of the carbohydrates and permits the selective use of electrophilic substitution reactions, eg, chlorination, sulfonation, or nitration. A portion of the phenoUc hydroxyl units, which are estimated to comprise 30 wt % of softwood lignin, are unsubstituted. In alkaline systems the ionized hydroxyl group is highly susceptible to oxidative reactions. 

During the first trials with synthetic separators around 1940 it had already been observed that some of the desired battery characteristics were affected detrimentally. The cold crank performance decreased and there was a tendency towards increased sulfation and thus shorter battery life. In extended test series, these effects could be traced back to the complete lack of wooden lignin, which had leached from the wooden veneer and interacted with the crystallization process at the negative electrode. By a dedicated addition of lignin sulfonates — so called organic expanders -— to the negative mass, not only were these disadvantages removed, but an improvement in performance was even achieved. 

Organophilic polyphenolic materials for oil-based drilling fluids have been described [407], The additives are prepared from a polyphenolic material and one or more phosphatides. The phosphatides are phosphoglycerides obtained from vegetable oils, preferably commercial lecithin. Humic acids, ligno-sulfonic acid, lignins, phenolic condensates, tannins the oxidized, sulfonated, or sulfomethylated derivatives of these polyphenolic materials may serve as polyphenolic materials. 

A polymeric composition for reducing fluid loss in drilling muds and well cement compositions is obtained by the free radical-initiated polymerization of a water-soluble vinyl monomer in an aqueous suspension of lignin, modified lignins, lignite, brown coal, and modified brown coal [705,1847]. The vinyl monomers can be methacrylic acid, methacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, vinylacetate, methyl vinyl ether, ethyl vinyl ether, N-methylmethacrylamide, N,N-dimethylmethacrylamide, vinyl sulfonate, and additional AMPS. In this process a grafting process to the coals by chain transfer may occur. 

Sulfonated cation exchangers, 14 402 Sulfonated DNA probe, 14 153-154 Sulfonated kraft lignins, 15 20 toxicology of, 15 20... 

The present paper describes the fractionation of lignin sulfonates and kraft lignin by gel permeation chromatography (GPC) and the method developed and used for several years at the Finnish Pulp and Paper Research Institute. 

Elution of Lignin Sulfonates with Water. As can be seen from Figures 1, 2, 3, and 4, the fractionation of lignin sulfonates on elution with water through Sephadex G-50 and G-75 takes place in such a way that the logarithms of... 

Figure 1. Fractionation of lignin sulfonates in spent sulfite liquor on Sephadex G-50. Eluent water. (Reprinted with permission from ref. 1. Copyright 1969 Wiley.)...

Elution of Lignin Sulfonates with Electrolyte Solution and Calibration of Columns... 

The effects caused by the electrolyte nature of lignin sulfonates are eliminated by using a 0.5M sodium chloride solution as eluent. This eluent is made 0.1M with respect to Tris-HCl and buffered to pH 8 with hydrochloric acid in order to dissolve the proteins used as calibration standards (Fig. 5). 

Figure 5. Fractionation of lignin sulfonates on elution through Sephadex G-75. Eluent 0.5M NaCl, 0.1M Tris-HCl (pH 8).

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