Inulin oxidation

On the other hand, polymeric carriers can also be modified to introduce reactive groups. Polysaccharides such as dextran and inulin may be activated [149] by periodate oxidation to create aldehyde groups, by succinic anhydride activation to create carboxylic groups, or by p-nitrophenyl chloroformate activation to create reactive ester groups. 

Fuller s earth (hydrated aluminosilicate) Magnesium oxide Charcoal Alumina Magnesium trisilicate Silica gel Calcium hydroxide Magnesium carbonate Calcium phosphate Calcium carbonate Sodium carbonate Talc Inulin Sucrose = starch Petroleum ether, b 40-60°- Petroleum ether, b 60-80°. Carbon tetrachloride. Cyclohexane. Benzene. Ethyl ether. Chloroform. Ethyl acetate. Acetone. Ethanol. Methanol. Pyridine. Acetic acid. 

Furan-2,5-dicarboxylic add also has tremendous industrial potential, because it could replace oil-derived diadds such as adipic or terephthalic acid as monomers for polyesters and polyamides [98, 99]. This diadd can be synthesized by Pt-catalyzed oxidation with 02 of 5-hydroxymethylfurfural the latter is obtained by acid-catalyzed dehydration of D-frudose or frudosans (inulin) the latter, however, are too expensive as starting materials, and yields from glucose-based waste raw materials are no higher than 40%. Therefore, the potential attractive option of furan-2,5-dicarboxylic acid will develop only after an effident generation of 5-hydroxymethylfurfural from forestry waste materials has been developed. The same compound is also the starting material for the synthesis of other interesting chemicals obtained by oxidative processes, such as 5-hydroxymethylfuroic add, 5-formylfuran-2-carboxylic add and the 1,6-dialdehyde. 

Detailed studies of the periodate oxidation of dextran and inulin (4-6) have shown evidence for the occurrence of hemiacetal structures formed by reaction of aldehydes with hydroxyl groups of either the same unit (intra-residual) or a neighbouring unit (inter-residual). Inter-residual hemiacetal formation reduces the number of diol struc-... 

The only dimethyl-D-fructose which has been characterized, 3,4-di-methyl-D-fructose, has been prepared by McDonald and Jackson141 from di-D-fructose anhydride I. Tritylation of this anhydride gives the 6,6 -ditrityl derivative which is methylated to 3,4,3, 4 -tetramethyl-6,6 -di-trityl-di-D-fructose anhydride I. Removal of the trityl groups followed by hydrolysis yields liquid 3,4-dimethyl-D-fructose, [ ]d —60.66° in water. It has also been obtained, with 4-methyl-D-fructose, from the hydrolysis of methylated di-D-fructose anhydride III. The structure of this dimethyl-D-fructose follows from its method of preparation from di-D-fructose anhydride I whose structure is known.10 McDonald and Jackson also prepared 3,4-dimethyl-D-fructose from inulin by the following method inulin — monotrityl inulin — monotrityl inulin diacetate — dimethyl monotrityl inulin — dimethyl isopropylidene-D-fructose — methyl dimethyl-D-fructoside —> 3,4-dimethyl-D-fructose. Its structure was confirmed by its oxidation without loss of methyl to the same lactol of the dimethyl dibasic acid obtained from 1,3,4-trimethyl-D-fructose (see page 78). The phenylosazone made from 3,4-dimethyl-D-fructose has m. p. 126° that from 3,4-dimethyl-D-glucose has not been recorded. 

D-Mannitol has a diverse range of industrial applications. It is a nonhydroscopic, low-calorie, noncariogenic sweetener utilized by the food industry as well as a feedstock for the synthesis of other compounds. For example, mannitol can be oxidized at the 3 or 4 position to form two molecules of glyceraldehyde or glyceric acid, which can be used as building blocks for other compounds (Heinen et al., 2001 Makkee et al., 1985 van Bekkum and Verraest, 1996). Mannitol is formed from inulin via hydrolysis followed by catalytic hydrogenation. This yields mannitol and sorbitol from which the mannitol can be readily crystallized (Fuchs, 1987). Currently mannitol is primarily synthesized from starch. 

Complete methylation of inulin (4) can be achieved by reaction with potassium hydroxide solution followed by the addition of dimethyl sulfate (Figure 5.5) (Irvine and Steele, 1920 Irvine and Montgomery, 1933 Irvine et al., 1922). Alternatively, complete methylation can be accomplished using methyl iodide and silver oxide (Karrer and Lang, 1921 Vaughn and Robbins 1975). Trimethyl inulin can be hydrolyzed to form 3,4,5-trimethylfructofuranose (Smeekens et al., 1996). 

By altering the degree of oxidation, a diverse range of potential products can be formed from inulin. For example, selective oxidation yields polycarboxylates, having a number of possible applications. 

The direct oxidation of hydroxyls on inulin allows the potential introduction of carbonyl and carboxyl groups, altering the properties of the polysaccharide and opening additional commercial applications (Bragd et al., 2004). The primary hydroxyl in the C-6 position on the fructofuranoside subunits can be selectively oxidized using 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO). This forms a stable radical that can be oxidized by hypobromite, or similar reagent, to give a nitrosonium... 

Inulin can be modified to compounds that display good heavy metal complexing properties similar to ethylene diamine tetra-acetic acid (EDTA) but with better biodegradation properties (Bogaert et al., 1998). Inulin is first oxidized using sodium periodate to the dialdehyde, and then reduced to a polyol using Pt/C and hydrogen. The polyol can then be modified with carbon disulfide to form xanthate or with S03-pyridine to obtain an inulin sulfate. Alternatively, the dialdehyde can be animated with diaminoethane and sodium cyanoborohydride and the product reacted with monochloroacetic acid sodium salt to form carboxymethylamino inulin. Each of these compounds can be used to precipitate heavy metals. 

Besemer, A.C., The Bromide-Catalyzed Hydrochlorite Oxidation of Starch and Inulin Calcium Complexation of Oxidized Fructans. Ph.D. thesis, Delft University of Technology, Delft, The Netherlands, 1993. 

Besemer, A.C. and van Bekkum, H., The hypochlorite oxidation of inulin, Recueil des Travaux Chimiques des Pays-Bas, 113, 398 -02, 1994a. 

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