2396-83-0Relevant articles and documents
Synthesis of α,β- and β-Unsaturated Acids and Hydroxy Acids by Tandem Oxidation, Epoxidation, and Hydrolysis/Hydrogenation of Bioethanol Derivatives
Faria, Jimmy,Komarneni, Mallik R.,Li, Gengnan,Pham, Tu,Resasco, Daniel E.,Ruiz, Maria P.,Santhanaraj, Daniel
supporting information, p. 7456 - 7460 (2020/03/23)
We report a reaction platform for the synthesis of three different high-value specialty chemical building blocks starting from bio-ethanol, which might have an important impact in the implementation of biorefineries. First, oxidative dehydrogenation of ethanol to acetaldehyde generates an aldehyde-containing stream active for the production of C4 aldehydes via base-catalyzed aldol-condensation. Then, the resulting C4 adduct is selectively converted into crotonic acid via catalytic aerobic oxidation (62 % yield). Using a sequential epoxidation and hydrogenation of crotonic acid leads to 29 % yield of β-hydroxy acid (3-hydroxybutanoic acid). By controlling the pH of the reaction media, it is possible to hydrolyze the oxirane moiety leading to 21 % yield of α,β-dihydroxy acid (2,3-dihydroxybutanoic acid). Crotonic acid, 3-hydroxybutanoic acid, and 2,3-dihydroxybutanoic acid are archetypal specialty chemicals used in the synthesis of polyvinyl-co-unsaturated acids resins, pharmaceutics, and bio-degradable/ -compatible polymers, respectively.
"Syn-Effect" in the Conversion of (E)-α,β-Unsaturated Esters to the Corresponding β,γ-Unsaturated Esters
Guha, Samar Kumar,Shibayama, Atsushi,Abe, Daisuke,Ukaji, Yutaka,Inomata, Katsuhiko
, p. 778 - 779 (2007/10/03)
The stereochemistry in the conversion of (E)-α,β-unsaturated esters to the corresponding β,γ-unsaturated esters by treatment with lithium hexamethyldisilazide in the presence of HMPA was investigated. The Z/E ratios of the resulting β,γ-unsaturated esters varied according to the γ-substituents of the (E)-α,β-unsaturated esters. This phenomenon was rationalized by "syn-effect" which may be attributed primarily to σ → π* interaction and/or 6π-electron homoaromaticity.
