14739-11-8Relevant articles and documents
A transesterification-acetalization catalytic tandem process for the functionalization of glycerol: The pivotal role of isopropenyl acetate
Calmanti, Roberto,Perosa, Alvise,Rigo, Davide,Selva, Maurizio
, p. 5487 - 5496 (2020/09/23)
At 30 °C, in the presence of Amberlyst-15 as a catalyst, a tandem sequence was implemented by which a pool of innocuous reactants (isopropenyl acetate, acetic acid and acetone) allowed upgrading of glycerol through selective acetylation and acetalization processes. The study provided evidence for the occurrence of multiple concomitant reactions. Isopropenyl acetate acted as a transesterification agent to provide glyceryl esters, and it was concurrently subjected to an acidolysis reaction promoted by AcOH. Both these transformations co-generated acetone which converted glycerol into the corresponding acetals, while acidolysis sourced also acetic anhydride that acted as an acetylation reactant. However, tuning of conditions, mostly by changing the reactant molar ratio and optimizing the reaction time, was successful to steer the set of all reactions towards the synthesis of either a 1?:?1 mixture of acetal acetates (97% of which was solketal acetate) and triacetin, or acetal acetates in up to 91% yield, at complete conversion of glycerol. To the best of our knowledge, a one-pot protocol with such a degree of control on the functionalization of glycerol via transesterification and acetalization reactions has not been previously reported. The procedure was also easily reproduced on a gram scale, thereby proving its efficiency for preparative purposes. Finally, the design of experiments with isotopically labelled reagents, particularly d4-acetic acid and d6-acetone, helped to estimate the contribution of different reaction partners (iPAc/AcOH/acetone) to the formation of final products. This journal is
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Barbosa, Sandro L.,Lima, Pamela C.,dos Santos, Wallans T.P.,Klein, Stanlei I.,Clososki, Giuliano C.,Caires, Franco J.
, p. 76 - 79 (2019/01/03)
Amorphous SiO2-SO3H [1] with a small surface area and 1.32-mmol H+/g was used for the one-step preparation of solketal from glycerol and acetone; a 20%-w/w catalyst mixture (10% [1] and 10% (Bu4N)(BF4) was found to be very efficient for the synthesis of disolketal ether and of oxygenated biofuels fatty acids solketal esters (FASEs), by direct esterification of the caprylic, lauric, stearic, oleic and linoleic acids with solketal in a 4:1 acid:solketal ratio in refluxing toluene. Solketal acetate was also produced in quantitative yields.
Green Acetylation of Solketal and Glycerol Formal by Heterogeneous Acid Catalysts to Form a Biodiesel Fuel Additive
Dodson, Jennifer R.,Leite, Thays d C. M.,S. Pontes, Nathália,Peres Pinto, Bianca,Mota, Claudio J. A.
, p. 2728 - 2734 (2016/12/23)
A glut of glycerol has formed from the increased production of biodiesel, with the potential to integrate the supply chain by using glycerol additives to improve biodiesel properties. Acetylated acetals show interesting cold flow and viscosity effects. Herein, a solventless heterogeneously catalyzed process for the acetylation of both solketal and glycerol formal to new products is demonstrated. The process is optimized by studying the effect of acetylating reagent (acetic acid and acetic anhydride), reagent molar ratios, and a variety of commercial solid acid catalysts (Amberlyst-15, zeolite Beta, K-10 Montmorillonite, and niobium phosphate) on the conversion and selectivities. High conversions (72–95 %) and selectivities (86–99 %) to the desired products results from using acetic anhydride as the acetylation reagent and a 1:1 molar ratio with all catalysts. Overall, there is a complex interplay between the solid catalyst, reagent ratio, and acetylating agent on the conversion, selectivities, and byproducts formed. The variations are discussed and explained in terms of reactivity, thermodynamics, and reaction mechanisms. An alternative and efficient approach to the formation of 100 % triacetin involves the ring-opening, acid-catalyzed acetylation from solketal or glycerol formal with excesses of acetic anhydride.
