Glycerol Isopropyl Ethers: Direct Synthesis from Alcohols and Synthesis by the Reduction of Solketal

Abstract

The catalytic reduction of solketal ((2,2‐dimethyl‐1,3‐dioxolan‐4‐yl)methanol) over bifunctional heterogeneous palladium catalysts is proposed as an alternative to the synthesis of glycerol isopropyl ethers by the etherification of glycerol. The direct synthesis of glycerol isopropyl ethers from isopropanol and glycerol requires severe conditions (T=130–150 °C, p(H2)=20–35 bar) and a large excess of isopropanol to reach a considerable yield. The main reaction products in the catalytic reduction of solketal are glycerol mono‐ and di‐isopropyl ethers and solketal isopropyl ether. Solketal conversion over Al‐HMS‐supported palladium catalysts (T=120 °C and p(H2)=20 bar) affords a mixture of ethers with a high degree of conversion (87 %), 78 % selectivity, and excellent regioselectivity between isomeric ethers. Zeolite‐BEA‐supported palladium catalysts also exhibit high activity but much lower selectivity because of intense acetone aldol condensation. The effects of Si/Al ratios in BEA zeolites and Al‐HMS aluminosilicates and the amounts of supported palladium (1 and 2 wt %) on the properties of the catalysts at different reaction temperatures and hydrogen pressures are considered.

Transacetalization of Solketal: A Greener Route to Bioglycerol‐Based Speciality Chemicals

“…In the comparison of three mesoporous aluminosilicas (Al‐HMS) with various Si/Al ratio the most Al‐rich material (Al‐HMS(10)) was less active, whereas on going to Al‐HMS(40) the activity has increased. This correlation is quite typical for reactions where glycerol is alkylated (or acetalised),,, but surprisingly K‐10 was far more active that zeolite BEA‐40. To all appearances, since no water is liberated in the transacetalization reaction, the hydrophobicity of the aluminosilica catalyst exerts the reversed influence.…”

Bio-Based Solvents and Gasoline Components from Renewable 2,3-Butanediol and 1,2-Propanediol: Synthesis and Characterization

“…The acidity of the mesoporous aluminosilicas demonstrates a non-linear growth with the increase in the Al content. The acidity strength distribution pattern for Al-HMS aluminosilicas determined previously has shown that strong acid sites are practically absent, what might provide the high selectivity in the reaction of the cyclic ketals hydrogenolysis [39].…”

“…The properties of the catalysts used for 1,2-PD and 2,3-BD monoether synthesis are given in Table 3. The performance of Pd/Al-HMS materials in the cyclic glycerol ketal hydrogenolysis reaction and the characterization details have been previously reported [39], so in this paper only the brief description is given. The values of the specific surface areas for the catalysts indicate well-developed pore structures (between 680 m 2 g −1 and 850 m 2 g −1 ) and a narrow pore size distribution with mean pore sizes of about 3-5 nm.…”

“…The combination of the ketalization process with the non-destructive ketal hydrogenolysis reaction that yields the corresponding ethers (Scheme 2) offers intriguing prospects. This reaction can be conducted with various reductive agents such as LiAlH4-AlCl3 [28][29][30][31], LiAlH4-BF3 [32], NaBH4 [33,34], TMDS [35,36] and hydrogen [37][38][39][40]. In the latter case a bifunctional catalyst system is required, consisting of either a heterogeneous Pd/C hydrogenation catalyst in combination with a homogeneous acid (p-TSA or camphorsulfonic acid) or one based on palladium supported on an acidic aluminosilicate or an acidic carbon [41,42].…”

Catalytic Processes for The Valorization of Biomass Derived Molecules

“…Among many, hydrogenation/hydrogenolysis [8,9] and transfer hydrogenolysis [10][11][12] of cellulose, hemicellulose, lignin, C6-C3 polyols, furan derivatives and aromatic ethers represent a core technology of modern biorefineries. Glycerol (C3 polyol) and glycidol (2,3-epoxy-1-propanol) can be converted into hydrogen (via APR process), C3-C1 alcohols, as well as to cyclic acetals and ketals [13][14][15][16]. Accordingly, reforming processes are surely a new way for the production of H 2 and liquid hydrocarbons from lignocellulosic biomasses or their derived molecules [17][18][19][20].…”