97-64-3Relevant articles and documents
Enhancing Effect of Residual Capping Agents in Heterogeneous Enantioselective Hydrogenation of α-keto Esters over Polymer-Capped Pt/Al2O3
Chung, Iljun,Song, Byeongju,Kim, Jeongmyeong,Yun, Yongju
, p. 31 - 42 (2021/01/11)
Heterogeneous enantioselective catalysis is considered a promising strategy for the large-scale production of enantiopure chemicals. In this work, polymer-capped Pt nanocatalysts having a uniform size were synthesized using poly(vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) and supported on γ-Al2O3. After a facile heat treatment process, their catalytic performance for enantioselective hydrogenation of α-keto esters, a structure-sensitive reaction, was investigated. The presence of residual capping agents on the Pt surface often perturbs the adsorption of reacting species and reduces performance in structure-sensitive reactions. However, the 1 wt % PVP-Pt/Al2O3 catalyst exhibited an enhancement in both activity and enantioselectivity compared to a reference Pt/Al2O3 catalyst prepared by wet impregnation. Under optimized reaction conditions, the cinchonidine-modified PVP-Pt/Al2O3 gave an enantiomeric excess of 95% for the enantioselective hydrogenation of methyl pyruvate despite the low Pt loading. We demonstrate that depending on the type of polymers, the residual capping agents can lead to site-selective blockage of the Pt surface, that is, defects or terraces. Quantitative and qualitative analyses also show that the noticeable improvement in enantioselectivity is attributed to the stable adsorption of chiral modifiers on selectively exposed Pt terrace sites. The findings of this work provide a promising strategy to prepare metal nanoparticles having selectively exposed sites and offer insights into the enhancing effect of residual capping agents on the catalytic properties in structure-sensitive reactions.
Ni-Catalyzed C(sp3)–O Arylation of α-Hydroxy Esters
Monteith, John J.,Rousseaux, Sophie A. L.
supporting information, p. 9485 - 9489 (2021/12/09)
A Negishi cross-coupling of α-hydroxy ester derivatives and arylzinc reagents has been developed. This reaction tolerates both primary and secondary C(sp3)–O alcohol precursors and achieves efficient cross-coupling under Ni catalysis without the need for added external metal reductant, photocatalyst, or additives. The arylation of readily accessible C(sp3)–O electrophiles in this operationally simple, rapid, and mild reaction provides a complementary way of accessing desirable α-aryl ester products.
Method for preparing lactate
-
Paragraph 0084-0085, (2020/06/30)
The invention relates to a method for preparing lactate. The method comprises the following steps: contacting pyruvic aldehyde and alcohol with a catalyst in a reactor, and reacting to obtain a lactate-containing product, wherein the molar ratio of the pyruvic aldehyde to the alcohol is 1:(20-225), the reaction temperature is 30-180 DEG C, the reaction time is 1-10 hours, the catalyst contains a mixture of a titanium-silicon molecular sieve and a tin-silicon molecular sieve, and the weight ratio of the pyruvic aldehyde to the mixture of the titanium-silicon molecular sieve and the tin-siliconmolecular sieve based on dry basis weight is 1:(0.1-6). The method provided by the invention has high pyruvic aldehyde conversion rate and high lactate yield.