Synthesis of methylethers by reaction of alcohols with dimethylcarbonate

Abstract

A new synthetic procedure to methylethers has been developed by the reaction of alcohols with dimethylcarbonate, a non-toxic and environmentally friendly reagent. The methylation of alcohols is catalysed by alumina or hydrotalcite. The methylcarbonate formed in the first step undergoes decarboxylation in the second step, to give the corresponding methylether. The reactivity follows the order: primary > secondary ≫ tertiary alcohols. The reaction can be efficiently performed under both batch and continuous flow conditions

Green Synthesis of Dimethyl Isosorbide

“…However, methylation of secondary alcohols was never obtained quantitatively due to the formation of elimination products. [11] On the other hand, this is not the case in the present work; the secondary hydroxyls groups of isosorbide are efficiently methylated at reflux temperature (90 8C) by reaction with DMC in the presence of a range of bases (Table 1). This is quite surprising, especially in consideration of all the possible products that could be formed by reacting isosorbide with DMC, which include three classes of compounds ( Figure 1): carboxymethyl derivates (MC-1, MC-2, dicarboxymethyl isosorbide (DC)), carboxymethyl methyl derivates (MCE-1, MCE-2), and methyl derivates (MMI-1, MMI-2 and DMI).…”

“…However, we previously reported that under similar conditions the reaction of hard alkoxides and DMC gave exclusively the transesterified methylcarbonates derivatives (via B Ac 2 mechanism), also at high temperatures. [11] On the contrary, other softer nucleophiles such as anilines, phenols and methylene-active compounds were easily methylated by DMC via a B Al 2 mechanism. [4,12] Methyl ethers of primary alcohols can be obtained through two steps: a B Ac 2 transesterification followed by the decarboxylation of the resulting methylcarbonate.…”

5-Membered cyclic ethers via phenonium ion mediated cyclization through carbonate chemistry

“…So far, only limited work has been reported on either amphoteric or acid catalysts [17,47,48]. In this prospect, acid-catalyzed cyclization of this substrate was also attempted in the presence of other acids such as an organic acid, i.e.…”

Green syntheses of biobased solvents

“…Recent work by Tundo et al [46] showed the efficiency of such a reaction using K 2 CO 3 : a high temperature (200 8C) and a considerable excess of DMC were needed to obtain a good yield and high selectivity. These conditions require a batch autoclave, which is not suitable for large-scale industrial production.…”