Dimethyl carbonate and phenols to alkyl aryl ethers via clean synthesis

Abstract

The industrially important alkyl aryl ethers (ArOR) were selectively obtained in good yields from the O-alkylation of the corresponding phenols with the environmentally benign reagents, dimethyl carbonate or diethyl carbonate. The reactions were carried out under atmospheric pressure, in a homogenous process, without solvent and in the presence of potassium carbonate as catalyst. Green ContextThe replacement of salt-forming reagents with more efficient systems is exemplified by the use of dimethyl carbonate (DMC) in place of e.g. methyl chloride. Here, DMC is successfully used to methylate phenols in good yield and with only (recyclable) methanol and CO 2 as co-products. Separation is relatively simple.

Sustainable allylation of organosolv lignin with diallyl carbonate and detailed structural characterization of modified lignin

“…1 With a content of [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] wt%, lignin is a main component of biomass such as wood and annual plants. The total lignin resources on earth are estimated to be 300 billion tons, with a natural production of 20 billion tons per year.…”

Dimethyl sulfite a potential agent for methylation

“…Moreover, the etherification of glycerol formal or solketal was done by Selva, 14 at T ≥ 200 °C both were efficiently alkylated affording the corresponding methyl ethers with selectivity up to 99% and excellent yields (86-99%). The O-methylation of phenols with dimethyl carbonate was also reported in the literature using different catalysts, such as potassium carbonate at 160 °C, 15 ionic liquids such as 1-n-butyl-3-methylimidazolium chloride at 120 °C, 16 and 1,8-diazabicyclo[5.4.0]undec-7-ene at 220 °C. 17 All of these catalysts gave yield up to 90%.…”

Catalytic Upgrading of Phenolic Oil by Etherification with Methanol

“…Presently, the preparation of ethers oil from O‐methylation, i.e., methylation at the phenolic hydroxy group, of a phenolic mixture has never been described in literature, while reports on methylation of an individual phenolic compound such as phenol and methyl phenol are quite abundant. Taking the anisole preparation from phenol as an example, the synthesis of anisole from phenol with dimethyl carbonate (DMC) has been intensively investigated 16–19. DMC, as a frequently used green chemical for methylation, can be synthesized from oxidative carbonylation of methanol 20, but the synthesis of DMC increased the complexity of the anisole synthetic process.…”