M, Somani RS. Synthesis of aluminium triflate-grafted MCM-41 as a water-tolerant acid catalyst for the ketalization of glycerol with acetone

An aluminium triflate species grafted over MCM-41 (Al(TF)–MS) was synthesized by a novel route as an inexpensive and water-tolerant solid acid catalyst for the ketalization of glycerol with acetone to solketal (solketal synthesis).

The synthesis of butene glycol ethers with aluminium triflate

The use of aluminium triflate as a ring-opening catalyst for butene oxide (BuO) was evaluated in the presence of different alcohols such as methanol, ethanol, n-propanol, n-butanol, 2-propanol, 2-methyl-1-propanol, and 2-methyl-2-propanol. The reaction with methanol was studied kinetically by varying the temperature, catalyst concentration, and methanol – butene oxide molar ratio. These reactions yielded two major products (2-methoxy-1-butanol and 1-methoxy-2-butanol) in a approximate ratio of 1:1. It was noted that at low catalyst concentrations (<5 ppm), low temperatures (<90 °C), and a MeOH–BuO molar ratio of 8:1, the selectivity of the reaction could be kinetically manipulated to shift the product ratio towards 1-methoxy-2-butanol, the α-alkoxyalcohol. This result was confirmed by an experimental design program. Statistical calculations using the data from the experimental design identified a feasible region in which reactions with methanol could be carried out, which would lead to slightly higher selectivities to 1-methoxy-2-butanol. This region shows that the methanol – butene oxide ratio should be 8:1, the temperature between 80 and 85 °C, and the catalyst concentration between 3.9 and 5 ppm. These reaction conditions were used to carry out a test reaction with methanol and an extended series of alcohols. All the alcohols, except for 2-methyl-2-propanol, reacted with butene oxide under these conditions, with the selectivity to the α-alkoxyalcohol higher than to the β-alkoxyalcohol. To obtain a ring-opening reaction with 2-methyl-2-propanol, it was found that a higher catalyst concentration (approximately 10 ppm) and a lower alcohol – butene oxide ratio (6:1) at a temperature of 80 °C were necessary. This reaction led to a mixture of 1-tert-butoxy-2-butanol and 2-tert-butoxy-1-butanol with the selectivity to the α-alkoxyalcohol being somewhat higher because of the steric influence of the bulky tert-butoxy group.Key words: aluminium triflate, alcohols, butene oxide, ring opening, α-alkoxyalcohol, β-alkoxyalcohol.