The Bílik Reaction

Catalytic Isomerization of Biomass‐Derived Aldoses: A Review

“…The epimerization takes place under mild reactionc onditions, that is, the reaction equilibrium in 10-20 wt %a queous solution of as ubstrate is usually reached after 2-6 ha t7 0-90 8Cb yu tilizing 0.1-0.2 %m olybdic acid. [106] The reactioni s very sensitivet ot he pH of the solution, and the highest epimerization rate is obtainedi nt he pH range of 1.5 to 3.5. The epimerization follows the carbon-shift mechanism (Figure 12 a) through coordination of as ubstrate toward aM o VI dimer.Interestingly, the epimerization of aldoses by carbon shift is sometimes referred to as the "Bílik mechanism"o rt he "Bílik reaction".…”

“…Al arge number of publications and patentsf ocusing on Bílik epimerizationh ighlight the great commercial importance of this process. Given that the early literature was thoroughly reviewed by Petruš et al, [106] herein, we concentrate on more recent publications. Chethana et alhaveperformed acomputational study explaining the dependence of the rate of epimerization on the pH.…”

Conformation, dynamics, solvation and relative stabilities of selected β-hexopyranoses in water: a molecular dynamics study with the gromos 45A4 force field

“…Metal complexes can also catalyze epimerization at the C 2 carbon. [364][365][366][367] Focusing on studies where the obtension of an equilibrium C 2 -epimer mixture was assessed, the free energies associated with the metal-catalyzed Glc!Man and Gal!Tal epimerization processes in water are estimated to be 364,365,367,368 2.3-2.7 and 365,367,369 3.0-3.4 kJ mol À1 , respectively. The present simulation estimates (DG MD ) of 1.8 and 2.7 kJ mol À1 , respectively, are in reasonable agreement with these numbers (although somewhat lower), while the values estimated Table 7.…”

One-pot conversion of cellobiose to mannose using a hybrid phosphotungstic acid–cerium oxide catalyst

“…7,8 For example, mannose, a monosaccharide which is only found as part of complex polysaccharides in nature, has many important uses such as a precursor for sweeteners, vitamin production, antitumor agents and immunoregulatory agents. 8,12 The possibility of combining an inorganic epimerization catalyst with a catalyst capable of causing cellulose depolymerization raises the exciting prospect that a one-pot hybrid catalyst system can be designed for the conversion of cellulose to mannose. 9 While fructose is found in abundance in the edible portion of many plants, it is present in only small amounts in the nonedible biomass portion.…”