Methylation of Polyols with Trimethylphosphate in the Presence of a Lewis or Brønsted Acid Catalyst

Abstract

The alkylation of alcohols and polyols has been investigated with alkylphosphates in the presence of a Lewis or Brønsted acid catalyst. The permethylation of polyols was developed under solvent-free conditions at 100 °C with either iron triflate or Aquivion PW98, affording the isolated products in yields between 52 and 95 %. The methodology was also adjusted to carry out peralkylation with longer alkyl chains.

Mild and controlled lignin methylation with trimethyl phosphate: towards a precise control of lignin functionality

“…Al-OH groups can potentially be methylated by TMP, but this involves the use of strong Brønsted (sulfuric or trifluoro-methanesulfonic acid) or Lewis acids (transition metals or lanthanide triflates) as a catalyst. 27 Their methylation under neutral conditions has also been reported, but only at high temperature (T > 160°C) and for extended reaction times. 38 In our case, the use of relatively low temperature (120°C) and short reaction time (1 h) prevents the reaction of most of the (Fig.…”

“…of alkyl phosphate. 27 They proposed a reaction mechanism under acid catalysis that leads to the formation of a dialkyl phosphate, and further showed that the dialkyl phosphate is unable to alkylate aliphatic alcohols.…”

“…26 More recently, TMP has been used to methylate aliphatic polyols in melt-phase reactions with iron triflate as a catalyst. 27 In this paper, we describe for the first time the use of TMP to methylate various lignins in a precisely controlled manner, leaving the aliphatic OH (Al-OH) groups largely unaffected (Scheme 1). We first determined the best conditions to obtain fully methylated lignin in agreement with several green chemistry principles, i.e.…”

Selective catalytic oxidation of diglycerol

“…22 Diglycerolbased surfactants can be also produced such as diglycerol esters, 23 acetals, 24 and ethers. 18 Other ether derivatives can be also prepared by dehydrogenative arylation 25 or permethylation 26 to give hydrotropes and solvents, respectively. The selective oxidation of polyols, especially those incorporating a 1,2-diol motif, provides -hydroxyketones, that are encountered in natural products and serve as useful synthetic intermediates.…”

α‐Methylation of Ketones with Methanol Catalyzed by Ni/SiO2‐Al2O3

“…In recent years, methylation methods were developed with greener agents, such as CO 2 , formic acid or dimethyl carbonate . Other alternative reagents such as dimethyl sulfite and trimethylphosphate were also proposed by our group. The borrowing hydrogen methodology allows the use of alcohols as alkylating agents through an aldehyde intermediate, generating water as the sole by‐product .…”