Selective Product Crystallization for Concurrent Product Separation and Catalyst Recycling in the Isomerizing Methoxycarbonylation of Methyl Oleate

Abstract

Selective product crystallization proved to be a very attractive recycling strategy for homogeneous catalysts. This approach was demonstrated for the Pd-catalyzed isomerizing methoxycarbonylation of the renewable oleochemical methyl oleate using technical-grade starting material. The corresponding product, dimethyl-1,19-nonadecanedioate, is a valuable linear platform chemical for biobased polycondensates. A pure product phase (>96%) was produced by selectively controlled cooling crystallization following the reaction, whereas at the same time, the superior chemo-and regioselectivity of the known catalyst system was not compromised. The use of auxiliaries was avoided entirely; only the deliberate exploitation of the solubility behavior of the desired product led to success. The homogeneous Pd catalyst remained in the used methanol and was successfully recycled in up to eight repetitive batch runs. More than 39 g of linear C19 diester were isolated with an average selectivity in the methoxycarbonylation of 88%. The literature-known productivity of the Pd catalyst, expressed as its turnover number, was thus more than 6-fold increased from typically 400 to >2800. For compounds having suitable solubility behavior, selective product crystallization, therefore, complements the toolbox of available recycling techniques for homogeneous catalysts. The complete elimination of auxiliaries, the production of a pure product phase, and the possible use of commercial catalyst systems are some of the particularly sustainable features of this approach.

Recent progress in the catalytic transformation of carbon dioxide into biosourced organic carbonates

“…5) that find wide application as commodity chemicals, 171 biodiesel fuel, 172 and as intermediates for further chemical diversification. [173][174][175][176][177] In particular, epoxidized fatty acid esters (EFAs, Fig. 5) can be easily obtained and display potential for applications such as lubricants, additives and plasticizers.…”

Magic of Alpha: The Chemistry of a Remarkable Bidentate Phosphine, 1,2-Bis(di-tert-butylphosphinomethyl)benzene

“…In contrast to the other recycling approaches, there is no need for any auxiliary (solvent, support, etc. ), contributing to Green chemistry . The linear product selectively crystallizes upon cooling the reaction mixture.…”

“…This approach was recently extended to a recycling technique by Seidensticker and co-workers (see section 6). 130 By subsequent reduction, initially with LiAlH 4 and polycondensation, a linear polyester was obtained (Figure 24). 131 This biobased polyester synthesis and application of the products was patented in 2013.…”

“…), contributing to Green chemistry. 130 The linear product selectively crystallizes upon cooling the reaction mixture. Thereby, a TON of >2800 was achieved at an average selectivity of 88% toward the linear ester.…”

Catalytic Synthesis of Methyl 9,10‐dihydroxystearate from Technical Feedstocks in Continuous Flow via Epoxidation and Hydrolysis

“…Our previous works showed that selective product crystallization is very efficient for purification in the methoxycarbonylation. [27,28] Thereby, auxiliaries are avoided. Regarding this work, methyl 9,10-dihydroxystearate also exhibits a high boiling point of 70 °C [29] and low solubility in suitable solvents, offering the broad potential for purification as a stable intermediate and subsequent application in other reactions, such as oxidative cleavage toward other value products.…”