C6 sugars

The hemicellulose forms the glue around and between the cellulose bundles. It consists of shorter, branched polymer chains of various C6 and C5 sugars. The C6 sugars consist mainly of glucose together with mannose and galactose. The C5 sugars include xylose and arabinose. The steric hindrance offered by the side-... 

Ohgren et al., 2006). Recent work suggests that L. brevis and L. buchneri simultaneously consume C5 and C6 sugars (Kim et al., 2007 Liu et al., 2008), a factor that facilitates complete consumption of all lignocellulosic-derived sugars without catabolite repression. As a result, these strains are desirable hosts for additional manipulations toward efficient conversion of biomass to fuels and chemicals. 

The removal of water from initially formed biomass sugars is an important process for the production of primary biorefinery building blocks. Of particular interest are 5-hydrox-ymethylfurfural and levulinic acid (from the dehydration of glucose or other C6 sugars) and furfural (from xylose dehydration). Recent research has led to new catalytic processes for the production of each of these materials. 

Levulinic Acid. Dehydration of glucose or other monomeric and polymeric C6 sugars leads to the direct formation of levulinic acid (LA) as a potential primary building block for the biorefinery, and several reviews have described its potential commercial utility 477,478 The preparation of levulinic acid is not difficult, although the mechanism of its formation from carbohydrates is complex, and offers several alternative decomposition pathways (equation 3).479... 

Bis(hydroxymethyl) furan and 5-hydroxymethyl furfural (available from C6 sugars) have been oxidized to furan-2,5-dicarboxylic acid (44)- Linear polyesters, polyurethanes, and polyamides containing these monomers have been described in the literature (45-43) and have been made via condensation polymerization techniques including bulk, solution, and interfacial mixing procedures. Gandini (5,34) reviewed the poly condensation reactions up to 1986 and... 

Example 8.4. Phosphate transfer catalyzed by hexokinase. The enzyme hexokinase catalyzes transfer of phosphate to C6 sugars. Table 8.2 shows results reported for the reaction... 

According to Scheme 6.27, GLA/DH A can he obtained from C6 sugars (glucose and fructose) via retro-aldol condensation. This reaction can he catalyzed hy a hase as well as Lewis acid. A Br0nsted hase HT catalyst has also heen shown to produce lactic acid from glucose in basic aqueous solution [138]. 

Concentrated sulfuric acid has been used to dissolve and hydrolyse native cellulose (see Figure 7.6). The concentrated acid can disrupt hydrogen bonding between the cellulose chains and thus decrystallize the eellulose. Then, water is added to rapidly hydrolyse cellulose into glucose. The diluted sulfuric acid is re-concentrated for the next eyele of decrystallization and hydrolysis steps. The final produets inelude a mixture of C5 and C6 sugars. The hydrolysis proeess is generally more complex than pyrolysis or liquefaction. However, hydrolysis enables selective decomposition of the biomass polymers and thus provides access to useful platform chemicals that are unavailable from pyrolysis or liquefaction techniques. 

Furan dicarboxylic acid Oxidative dehydration of C6 sugars... 

Cobalt Technologies 2005 Mountain View, CA, USA An immobilized cell technology using a proprietary, nongeneticaUy modified Clostridia strain with high productivity and ability to convert both C5 and C6 sugars into butanol for operation in a continuous fermentation reactor Currently operating a 5000 GPY pilot facility since June 2009. Cobalt is now in the process to commission a 470,000 GPY ceUulosic biobutanol facility... 

Tetravitae Bioscience (Eastman Chemical) 2006 Chicago, IL, USA The platform is based on a stable, nongeneticaUy modified C. beijerinckii strain which offers high butanol yields, reduced product inhibition, and the ability to utilize both C5 and C6 sugars Trying to adapt the technology to process ceUulosic feedstocks acquired by Eastman Chemical Company in November 2011 (Eastman press release, 2011)... 

D-Sorbitoi a C6-sugar alcohol found widely in plants Af, 182.17, m.p. 97°C, [a]D-2° (water). It can be prepared by catalytic or electrochemical reduction of the configurationally related o-glucose, d-fructose or L-sorbose. Technically, it is prepared by catalytic hydrogenation of o-glucose. o-S. is the starting material for the technical synthesis of ascorbic... 

C6 sugar platform biorefinery for bioethanol and animal feed from starch crops... 

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