All solvents and chemicals used were as obtained from commercial sup­pliers, unless otherwise indicated. 1H-NMR spectra were recorded on a

Bruker Avance 300 instrument using CDC13 as solvent and TMS as the internal standard. GC-MS spectra were performed on an HP G1800B GCD system.

Eucalyptus globulus wood powder and its ensuing kraft pulp were examined as well as a Norway Spruce sample of unbleached thermome­chanical pulp, which was sampled in a Swedish mill of approximate 38% consistency and 85 mL Canadian Standard Freeness prepared by one-stage refining and a subsequent reject refining (about 20%) stage. All wood ma­terials used in this work represent standard samples, being the subject of Cost action E 41 entitled; “Analytical tools with applications for wood and pulping chemistry” operated by the European Union. The sugar profiling for these materials was examined according to the procedure of Min et al. followed by ion chromatography (Dionex IC-3000; Dionex, Sunnyvale, CA, USA) (Table 6) [32,33].

8.3.1 GENERAL PROCEDURE FOR THE SYNTHESIS OF CMF FROM MODEL CARBOHYDRATES

The selected carbohydrate (5.0 mmol) was added in a mixture of 37% HCl (4.0 mL), 85% H3PO4 (1.0 mL), and CHCl3 (5.0 mL) and it was stirred continuously at 45 °C for 20 h. Then an equal volume of water (5.0 mL) was added to quench the reaction. The reaction mixture was then extracted with CHCl3 3 times. The combined organic extracts were then dried with anhydrous Na2SO4 for 4 h. Finally, the organic extracts were subjected to liquid chromatography (silica gel, CH2Cl2 as eluent) to offer the desired 5-chloromethylfurfural. The procedure of treating lignocellulose sample (Table 6) was almost the same as the carbohy­drate, except adding the selected simple 1.0 mg each trial. The structure of 5-chloromethylfurfural was confirmed using 1H-NMR and GC-MS as follows: 1H-NMR (CDCl3): 5 = 4.60 (s, 2H), 6.58 (d, J = 3.6 Hz, 1H), 7.18 (d, J = 3.6 Hz, 1H), 9.64 (s, 1H) ppm. GC-MS (EI, 80 eV): m/z 146 (M+, 37Cl, 10.53), 144 (M+, 35Cl, 32.0), 109 (C6H5O2+, 100), 81 (C5H5O+, 17.3).

8.3 CONCLUSIONS

In summary, this note describes an optimized biphasic system (HCl — H3PO4/CHCl3) that may pave the way for the development of a simple, mild, and cost-effective protocol for the conversion of various carbohy­drates to CMF. The systematic optimization effort undertaken here delin­eates the structural features of carbohydrate residues that offer optimum CMF yields. Overall, the described procedure offers several advantages over other methodologies including mild reaction conditions; satisfactory product yields; and a simple experimental and isolation process.