15 mg catalyst. see article for more examples. Accordingly, R2 may be independently from R1, an amino group or a chemical moiety carrying an amino group for example an hydrazide group i.e., NH2—NH—CO—. Use the link below to share a full-text version of this article with your friends and colleagues. Aromatics from Lignocellulosic Biomass: A Platform for High-Performance Thermosets, cctc201901662-sup-0001-misc_information.pdf. pneumo type 7F). Acetic acid may be used as If a diaminoalkyl is used as a spacer, the linker suitably is a succinimidyl compound such as disuccinimidyl suberate (DSS), bis (sulfosuccinimidyl) suberate (BS3), disuccinimidyl glutarate (DSG), succinimidyldiester of adipic acid (SIDEA), succinimidyldiester of succinic acid (SIDES). A. Bacterial polysaccharides can be capsular polysaccharides or the O-antigen moiety (also called O-specific side chain) of cell-wall lipopolysaccharides (LPS), which comprises 2-deoxy-keto-octulosonic acid (KDO). The method of the present invention can be applied to any type of polysaccharide, in particular fungal or bacterial polysaccharides. In this case, the choice of the linker depends upon the nature of the spacer molecule. al. That chemical reactions in general can be accelerated by heating is well-known. Polysaccharides usually are T-independent antigens unable to elicit an anamnestic (memory) response.

For example, in pure 1,4‐dioxane, roughly 96 % yield of the secondary imine is formed at equilibrium, with 98 to 99 % carbon balance. A minor amount of 2‐methylfuran (2‐MFUR) is produced as a result of hydrogenolysis (an equivalent amount of FAM also forms) with a maximum 5 % yield of 2‐MFUR forming over Rh/SiO2 (Table 3). The results are set forth in Table 4 below. Have questions or comments? More generally, the compositions of the invention can be prepared in accordance with standard techniques well known to those skilled in the pharmaceutical or veterinary art. The possibility that ammonia can selectively poison sites responsible for coupling reactions has been speculated in the past.4, 33 Co‐adsorbed ammonia is found to significantly impact the reactivity of methanol amination over Pd(111) and Ni(111) via density functional theory (DFT) calculations.34 However, it is experimentally challenging to deconvolute two potential effects of ammonia: the ammonia concentration certainly shifts the equilibrium towards the preferred products via Le Châtelier's principle, but ammonia may also inhibit hydrogenation via competitive adsorption.
It was also checked that no depolymerization occurred and that no additional reducing sugar is formed during the microwave treatment. When a plateau is reached, this does not mean that all the carbonyl groups present on the polysaccharide molecules have been reductively aminated; number of these carbonyl groups remain non-reduced, especially when cyanoborohydride is used as a reducing agent. Reductive amination of the secondary imine over time over metal supported silica catalysts. For purposes of the present invention, conventional microwave ovens may be used but they are not preferred. showed that when used as the reaction substrate, furfurin produced less than 1 % yield of FAM, suggesting that furfurin formation is a mostly irreversible reaction pathway.14 The secondary imine (formed from condensation of furfural with furfurylamine) exhibits significantly improved resistance to homogeneous reactions with ammonia and only displays about 10 % loss of the initial carbon after 24 h at 130 °C (Figure 2). Biochem. bonds and cyano and nitro groups are tolerated. Chemical molecules useful either as a linker or spacer include for example (i) a dihydrazide alkyl; (ii) an amine for example an amino-thiol alkyl such as cysteine or cysteamine; or (iii) a diamine for example a diamino-thiol alkyl such as cystamine, or a diamino alkyl or alkylene, substituted or not, wherein the alkyl or alkylene is a C1-12, preferably C1-8, more preferably C1-6 alkyl or alkylene. DCE, DCM, THF, or dioxane ). Purified capsular polysaccharide from Haemophilus influenzae type b has been covalently attached to a number of protein molecules, e.g. (1971) 93:2897 or Gray et al, Arch. Also, the term “polysaccharide” designs a population of polysaccharide chains of various lengths and therefore a given polysaccharide size usually corresponds to a mean value. Borohydride and cyanoborohydride which allow for reaction in an aqueous medium, are particularly preferred. Altogether, the term “aminated polysaccharide” is accordingly understood to encompass a partially aminated polysaccharide molecule as well as an heterogeneous population of aminated and non-aminated molecules. While a definitive characterization of the operando M0/M+ reduction state within the Parr reactor is challenging without exposure to air, the effect of the reduction temperature will be studied in more detail later in this work. Thus, an increase in the ammonia concentration will favor the formation of amine products over alcohols. Sodium triacetoxyborohydride, The thermodynamics of the reaction are relatively temperature insensitive, as the equilibrated mixture displays a similar composition at 20 °C and 130 °C in a common solvent. Reductive Amination: A Remarkable Experiment for the Organic Laboratory, Bard College, Annandale-on-Hudson, NY 12504. The results are set forth in Table 2 below. (DCE) is the preferred reaction solvent, but reactions can also be carried out Alternatively, they may even be created on purpose by a chemical treatment. E The American Chemical Society holds a copyright ownership interest in any copyrightable Supporting DOI: Then, the polysaccharide submitted to reductive amination under microwave radiation was purified from the reagents as described in Example 1 and the purified polysaccharide was submitted again to reductive amination as described above. (1949) 181:149. The Leuckart reaction also differs from reductive amination under mild conditions in that reductive amination is accompanied by decarboxylation (see the reaction scheme on page 8180 of Loupy et al). Except for Pt/SiO2, this selectivity trend for nitriles agrees well with that observed in the reductive amination of the secondary imine (Figure 5). The imine is reduced to an amine in the second step by sodium borohydride. No such decarboxylation occurs when reductive amination is carried out under mild conditions. Polygalacturonic acid has the following general structure:[βD GalcA p(1→4)−] Polygalacturonic acid (mean molecular weight, 50,000 equivalent dextran) obtained from Sigma, was dissolved in 0.05 M borate buffer, pH 8.5 to a final concentration of 12 mg/ml. Vi polysaccharide from Salmonella typhi is a polysaccharide with a net negative charge having the following general structure: [βD GalcA pN Ac 3—O—Ac(1→4)—]. Privacy Policy One such microwave apparatus is the SYNTHEWAVE™ 402 instrument manufactured and sold by Prolabo, Fontenay-Sous-Bois, France, the use of which is preferred for the purposes of the present invention.

Certain of these obstacles have been overcome by development of microwave apparatuses capable of providing a focused or localized beam of microwave radiation at a specified position within the apparatus. It is within the skills of the man in the art to determine the suitable amounts of the products to be reacted. These data reveal that the reductive amination achieved under microwave radiation, reaches a plateau within 15 minutes, yielding an aminated polysaccharide product comparable to that obtained after 48 hours in the water-bath. This procedure was modified to use NaBH 4 in methanol (instead of NaBH 3 CN⧸ethanol) with better results.