Copper phosphotungstate-catalyzed microwave-assisted synthesis of 5-hydroxymethylfurfural in a biphasic system

Green synthesis of 5-hydroxymethylfurfural and 5-acetoxymethylfurfural using a deep eutectic solvent in a biphasic system assisted by microwaves

“…The yield of HMF only changed when the temperature was lowered further to 100 °C and 90 °C (Table 2, entries 13 and 14), following which it dropped to 81% and 69%, respectively. This drop in yield at milder temperatures also occurred in previously reported works 33,44,68 and, possibly, occurs because the reaction does not have the necessary energy to occur as quickly as using temperatures equal to or greater than 110 °C.…”

“…This effect was not observed in previous studies, where increasing temperature and increasing time led to a drop in HMF yield due to the occurrence of parallel reactions. 33,44,55,60,68 Given these results, it can be concluded that HMF is more stable in the system studied in this work than in previous works, in which they used systems consisting of, for example, dimethylsulfoxide, 55 a biphasic system with a reaction phase of saline solution 33,60 and/or other extraction solvents. 44,72…”

“…The quantification of HMF was performed based on the external standard technique, with the addition of TMB as an internal standard, as described by Castro and Fernandes and Castro et al 33,60 The standard solutions were prepared in ethyl acetate with HMF at concentrations of 0.25-2.00 mg mL −1 and TMB at a fixed concentration of 1.00 mg mL −1 . Posteriorly, 1 μL of these solutions was injected into the GC-MS system.…”

“…IR (cm −1 )  max : 2920, 2851, 1742, 1673, 1520, 1373, 1216, 1019, 802, 764. GC-MS (m/z) (abundance %): 168 (1, M + ), 126 (100), 109 (20), 79 (35), 43 (33). 1 H NMR (CDCl 3 ) δ 9.63 (s, 1H), 7.20 (d, J = 3.6 Hz, 1H), 6.59 (d, J = 3.6 Hz, 1H), 5.11 (s, 2H), 2.10 (3H).…”

“…This is an important advance for the transformation of biomass and/or carbohydrates into fine chemicals, since it is still a challenge to obtain HMF with high yield and conversion, in addition to the difficulty of obtaining the isolated product with high purity. [31][32][33] An example of the potential of HMF in obtaining biofuels is 5-acetoxymethylfurfural (AMF), which has an energy density value that is higher than that of ethanol and similar to that of gasoline. 34 In addition to biofuels, HMF can also be used in the production of polyesters, 35,36 agrochemicals, 37 pharmaceutical products, 38,39 industrial sectors, and materials, among others.…”