1568-99-6Relevant academic research and scientific papers
Isomerization and dimerization reactions of methyloxirane over various types of zeolite and zeotype
Palinko,Fasi,Kiricsi,Goemoery
, p. 340 - 344 (2007/10/03)
A study on the ring-opening reactions of methyloxirane on different zeolites and zeotypes, i.e., HZSM-5, CuZSM-5, HY, AlMCM-41, SiMCM-41, and BMCM-41 at 363 K either in a pulse reactor or in a circulation system, in the presence of hydrogen or nitrogen showed that methyloxirane underwent single (isomerization) and double (deoxygenation) ring-opening, as well as dimerization reactions over different types of acidic zeolites and zeotypes. The acidic molecular sieves were active in isomerization (the products were propionaldehyde and acetone) and dimerization (the products were dioxolane and dioxane derivatives) reactions. The transformations proceeded on Bronsted or relatively strong Lewis acid sites, or their combination. The major products were dimers, i.e., dioxolane and dioxane derivatives. A confined environment was advantageous for dimerization to occur. However, this reaction route was also viable when the pore size was large and possibly on nonporous but acidic substances as well.
Transformation of 1,2-diols over perfluorinated resinsulfonic acids (Nafion-H)
Bucsi,Bucsi, Imre,Molnar,Molnar, Arpad,Bartok,Bartok, Mihaly,Olah,Olah, George A.
, p. 8195 - 8202 (2007/10/02)
The transformations of 1,2-diols over perfluorinated resinsulfonic acids (Nafion-H) were studied, and correlations were examined between the structures of the investigated diols, the possible dehydration routes and the catalytic properties of Nafion-H. Comparisons were also made between the catalytic properties of Nafion-H and NaHX zeolite. Because of its stronger acidity, Nafion-H functions at temperatures considerably lower than those for the usual dehydrating catalysts, e.g. the zeolites. As is well established for other solid electrophilic catalysts, the dehydration of 1,2-diols mainly proceeds via the pinacol rearrangement. The lower temperatures and the stronger acidity of Nafion-H strongly favour the pinacol rearrangement versus 1,2-elimination. The reaction conditions are also advantageous for the formation of substituted 1,3-dioxolanes in a secondary condensation step between the unreacted diol and the primarily formed carbonyl compounds. Nafion-H gradually deactivates during long use, but it can be partially reactivated by washing with acetone.
