Cellulose phosphate, preparation

Inorganic esters of cellulose, sulfates, phosphates and borates have also been reported. Cellulose sulfate is unstable in the free acid form. Cellulose phosphate prepared by reaction of phosphoric add with cellulose is flame retardant but has found little utility. Reactions of boric acid and borates with cellulose gave products that were not stable in the presence of water and were rapidly hydrolyzed. 

Cation-exchange columns have been used effectively by some investigators for the fractionation of casein (Annan and Manson 1969 Kim et al 1969 Kopfler et al. 1969 Snoeren et al. 1977 Saito et al 1979). Sulfoethyl-Sephadex was used by Annan and Manson (1969) with formate buffer to fractionate the as-casein complex. Cellulose phosphate, carboxyl-methyl-cellulose (CMC), potassium-K-carrageenan, and sodium Amberlite CG50 columns have also been used to fractionate the caseins (Kim et al. 1969 Kopfler et al. 1969 Snoeren et al 1977). A batch method for the preparation of para-K-casein from rennin-treated whole casein has been developed with CMC Sephadex (Saito et al. 1979). 

Considerable interest has been directed to the preparation of cellulose phosphates because of their flame retarding properties and potential use in textiles. Phosphorylation can be accomplished in several ways, e.g., by heating cellulose at high temperatures with molten urea and phosphoric acid. Other phosphor-containing esters of cellulose include phosphites, phosphinates, and phosphonites. In addition, boric acid esters have been prepared. 

Both starch and cellulose are prepared in nature by enzymatic, chain growth polymerization reactions of glucose nucleotide monomers [6]. In both cases, the monomer precursor is glucose-1-phosphate, which is enzymatically converted to the nucleotide derivative. The latter, in turn, complexes with an enzyme to form the activated monomer at the active site on the enzyme, which also contains the growing polymer molecule, as schematically illustrated below for the enzymatic polymerization of cellulose ... 

Incidental to the studies on cellulose nitrate, specifically C-la-beled cotton celluloses were prepared biologically, and some insight into biosynthesis in the cotton boll was obtained. a-D-Glu-copyranosyl phosphate, the anomer of the Cori ester, was synthesized, and a synthetic route to L-iduronic acid was devised both of these products were subsequently found by others to occur naturally. 

Water-soluble cellulose phosphate of high viscosity and a D.S. was prepared by Katsuura et al. by treating pulp, pre-swollen with zinc chloride, with phosphoric acid in molten urea at 150°C (42). 

Phosphorylated derivatives are also available. Cellulose pulp or linters can react with phosphoric acid in a urea melt or with a mixture of phosphoric acid and phosphorus pentoxide in an alcoholic medium to prepare cellulose phosphate. Cellulose phosphites and phosphonates are produced via transesterification with alkyl phosphites. All these compounds have fire-retarding properties and ion-exchange properties and cellulose phosphate is used in textile and paper manufacture, as well as in the treatment of kidney stones. 

Elution from the cellulose phosphate column is with 10 per cent ammonium carbonate solution. With as little as 2-5 bed volumes of solution, 99 per cent recovery of thorium can be achieved. Uranium absorbed by the cellulose phosphate is also completely eluted. Three washes are interposed between absorption and elution, with 2N sulphuric acid, water and ammonia respectively. The sulphuric acid prevents hydrolysis and precipitation during the water wash, and the ammonia prevents evolution of carbon dioxide on elution with ammonium carbonate. Washes with water and then 2N sulphuric acid are similarly given after elution to prepare the column for the next absorption cycle. The thorium is recovered from the ammonium carbonate solution by boiling, when a precipitate of hydrated thorium oxide is formed, 99 per cent coming out of solution within 5 min. 

The mode of preparation of the cellulose phosphate is of some importance. It is made by impregnating cellulose derived from wood pulp with a solution of 50 per cent urea and 18 per cent phosphoric acid, and curing in air at 130°C. The highest thorium capacity is obtained with a product cured for only a short time, but the physical properties are then unsuitable for satisfactory flow rates through a column of the material. In practice, it... 

Cellulose Phosphates. There are a number of strategies for preparing cellulose phosphate. Reaction of cellulose with tetrapolyphosphoric acid in the presence of triethylamine produced cellulose phosphate with DSp < 1.75 (29). Treatment of cellulose with POCI3 resulted in cellulose phosphate with low DSp, but also resulted in introduction of chloride to the cellulosic backbone (Table 6) (30). Phosphorylations of cellulose with A(-phosphoryl-A( -methylimidazole and a... 

Solubility. Cellulose sulfate and cellulose phosphate can be either water-soluble or water-swellable depending on the conditions used during preparation vide supra). Cellulose nitrate and some cellulose sulfonates are generally more hydrophobic and are typically soluble in organic solvents. In general, the level of esterification of cellulose directly impacts the solubility of the product in various solvents and solvent blends. 

Graded Adsorbents and Solvents. Materials used in columns for adsorption chromatography are grouped in Table 12 in an approximate order of effectiveness. Other adsorbents sometimes used include barium carbonate, calcium sulfate, calcium phosphate, charcoal (usually mixed with Kieselguhr or other form of diatomaceous earth, for example, the filter aid Celite) and cellulose. The alumina can be prepared in several grades of activity (see below). 

Triphenyl phosphate is a crystalline solid which has less compatibility with the polymer. This may be expected from solubility parameter data. It is often used in conjunction with dimethyl phthalate and has the added virtues of imparting flame resistance and improved water resistance. It is more permanent than DMP. Triacetin is less important now than at one time since, although it is compatible, it is also highly volatile and lowers the water resistance of the compound. Today it is essential to prepare low-cost compounds to allow cellulose acetate to compete with the synthetic polymers, and plasticisers such as ethyl phthalyl ethyl glycollate, which are superior in some respects, are now rarely used. 

These derivatives, used for 5 -phosphate protection, are prepared by using the DCC coupling protocol and are cleaved with 2 N NaOH at The protected phosphates can be purified using benzoylated DEAE-Cellulose. 

Purification of photoprotein. The dialyzed photoprotein solution was centrifuged to remove precipitates, and then subjected to fractional precipitation by ammonium sulfate, taking a fraction precipitated between 30% and 50% saturation. The protein precipitate was dissolved in 50 ml of 10 mM sodium phosphate, pH 6.0, containing 0.1 mM oxine ( pH 6.0 buffer ), dialyzed against the same buffer, and the dialyzed solution was adsorbed on a column of DEAE-cellulose (2.5 x 13 cm) prepared with the pH 6.0 buffer. The elution was done by a stepwise increase of NaCl concentration. The photoprotein was eluted at 0.2-0.25 M NaCl and a cloudy substance (cofactor 1) was eluted at about 0.5 M NaCl. The photoprotein fraction was further purified on a column of Sephadex G-200 or Ultrogel AcA 34 (1.6 x 80 cm) using the pH 6.0 buffer that contained 0.5 M NaCl. 

The varions flavin phosphates and their acetyl derivatives were identified by pH titration, electrophoresis, and H-NMR, which permit direct analysis of crude reaction prodncts as well as rapid purity check of commercial flavin mononucleotide or riboflavin 5 -monophosphate (FMN or 5 -FMN) [7]. Riboflavin 4 -monophosphate was determined as the main by-product of commercial FMN by preparative TLC on cellulose with n-butanol/acetic add/water (5 2 3, v/v) as a solvent [7]. 

Preparative electrophoresis on Sephadex G-25 (Ref. 168) or double isoelectric focusing,208 preceded by chromatography on Sephadex G-75, CM-cellulose, and calcium phosphate, was used for the isolation of endo-D-galacturonanase from the filtrate of a Verticillium albo-atrum culture. The homogeneity was confirmed in both cases by electrophoresis on poly(acrylamide) gel. The molecular weight of the enzyme was close to the values found for Aspergillus endo-D-galacturonanases. 

Figure 3.7 Determination of the enantiomeric purity of SB-214857 API using CD-modified CE. Distomer content measured at 0.06% by area. (Conditions plain fused silica capillary, 50 cm effective length, 57 cm total length, 75 pm i.d. buffer lithium phosphate [pH 3.0, 100 mM] containing 0.05% (w/v) hydroxyethy[cellulose and 1.5 mM dimethyl- 8-CD voltage 30 kV temperature 20°C detection UV at 200 nm sample preparation 0.2 mg/ml in water sample introduction 5 s at 35 mbar, capillary inlet at anode.)...

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