A transesterification–acetalization catalytic tandem process for the functionalization of glycerol: the pivotal role of isopropenyl acetate

Abstract

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...

Concatenated Batch and Continuous Flow Procedures for the Upgrading of Glycerol-Derived Aminodiols via N-Acetylation and Acetalization Reactions

“…Notwithstanding the presence of residual iPAc in the reacting mixture, the competitive acid-catalyzed transesterification of hydroxyl groups of amide 1a took place to a very minor extent or was not observed at all, it even at a high/quantitative conversion: the acetal was obtained on an exclusive basis (>99%) in the presence of ≥20 molar equivs of acetone (entries 3-7); while, if the Q1 ratio was reduced to 5, the selectivity towards compound 1b decreased to 91-94% due to the concurrent formation of O-acetyl derivatives of 1a (6-9%) (entries 1-2; other details are in the SI section, Figure S11). A similar remarkable preference for the acetalization with respect to the transesterification process was noticed by us also during previous studies on the tandem reactions of diols mediated by iPAc [17]. This behavior was consistent with the higher reactivity of carbonyl compounds compared to esters toward nucleophilic additions/substitutions.…”

“…As a part of our research program on the design of eco-friendly protocols for the valorization of bio-based products, particularly glycerol and its derivatives [14,15], we were prompted to investigate new reactions for the chemoselective conversion of either the amino or the hydroxyl group of APD compounds. N-acetylation and acetalization processes mediated by isopropenyl acetate (iPAc) and acetone were selected to this purpose, based on a literature survey and results recently published by us [14][15][16][17][18]. Nontoxic, commercially available, and cheap iPAc has emerged as a privileged compound since its reactions with a variety of N-and O-nucleophiles result in the formation of acetylated derivatives and prop-1-en-2-ol that, as an enol, quickly converts into acetone, thereby making the overall transformations irreversible.…”

Perspectives for the Upgrading of Bio‐Based Vicinal Diols within the Developing European Bioeconomy

“…Further experiments highlighted that modulation of the AcOH content to 1.5 equivalents in conjunction with an external intake of acetone 2 5 (tune to 5 equiv.) led to the formation of solketal acetate 94 as the major product (91 %) and only traces of 71 / 77 (3 %), as well as 2 % 1,2‐diacetin 97 /1,3‐diacetin ( 98 ) and 7 % triacetin 95 [229] …”

“…led to the formation of solketal acetate 94 as the major product (91 %) and only traces of 71/77 (3 %), as well as 2 % 1,2-diacetin 97/1,3-diacetin (98) and 7 % triacetin 95. [229] Animashaun and Amarasekara described a one-pot ketalization/esterification toward the manufacturing of ketals derivatives of EG and levulinic acid 83 in presence of either Amberlyst-15 or homogeneous p-toluenesulfonic acid. The authors relied on benzene as solvent for assessing both catalysts.…”

“…2,2‐Dimethyl‐1,3‐dioxolane‐4‐methanol (aka solketal, 71 ) is a well‐known upgraded polyol synthesized from the reaction between GL and acetone 35 (Figure 12). Its preparation comes with an appealing atom economy and has a current market value estimated to 22 billion US$ per year [23,205] . Solketal 71 is primarily used as a fuel additive.…”