Catalytic conversion of vanillic acid to catechol by palladium acetate/bis(aminomethyl)-nido-dicarba-undecaborane (11) system

Advancements and Perspectives toward Lignin Valorization via O‐Demethylation

“…[101] Pd(OAc) 2 /[Na] + [7,8-bis(aminomethyl)-nido-dicarba-undecaborane (11)] À catalyst yielded 61 % pyrogallol from syringic acid, involving additional Cdecarboxylation. [102] Both catalysts were also reported for guiacol (see above). Syringol conversion (89 %) in the presence of vanadium powder in hot pressurized water (280 °C) yielded 43 % pyrogallol and 40 % 3-methoxycatechol at � 90 % conversion.…”

“…Syringol is completely converted to pyrogallol with Ru−Co bimetallic catalyst, triphos, and LiI, under an atmosphere of CO 2 and H 2 , with ethanol as by‐product (Entry 64, Table 1). [101] Pd(OAc) 2 /[Na] + [7,8‐bis(aminomethyl)‐ nido ‐dicarba‐undecaborane (11)] − catalyst yielded 61 % pyrogallol from syringic acid, involving additional C ‐decarboxylation [102] . Both catalysts were also reported for guiacol (see above).…”

“…[Na] + [7,8-bis(aminomethyl)-nido-dicarba-undecaborane-(11)] À . [102] The acidic zeolite HZSM-5 presented a meager guaiacol conversion and catechol yield (< 1% in water at 200 °C for 40 min). [65] When the reaction was carried out in benzene under 50 bar H 2 at 350 °C for 2 h, 54 % of guaiacol was converted yielding 31 % catechol.…”

Advancements and Perspectives toward Lignin Valorization via O‐Demethylation

“…Guaiacol and vanillic acid have been converted into catechol with more than 90 % yield using Pd(OAc) 2 /[Na] + [7,8‐bis(aminomethyl)‐ nido ‐dicarba‐undecaborane(11)] − ( viz . Figure 6) in 1 M aqueous K 2 CO 3 and DMA (1 : 2) at 240 °C in 4 h, the latter involving additional C ‐decarboxylation [102] …”

“…Figure 6) in 1 M aqueous K 2 CO 3 and DMA (1 : 2) at 240 °C in 4 h, the latter involving additional C-decarboxylation. [102] Various ionic liquids, with or without transition metal catalyst, have been used for the ODM of aryl methyl ethers, but only a few have been applied to lignin-derived monomers. Guaiacol was converted into catechol ( � 70 % yield) by catalytic MeReO 3 in [Bmim]Cl in 5 minutes under microwave irradiation.…”