The use of pseudoephedrine as a practical chiral auxiliary for asymmetric synthesis is described in full. Both enantiomers of pseudoephedrine are inexpensive commodity chemicals and can be N-acylated in high yields to form tertiary amides. In the presence of lithium chloride, the enolates of the corresponding pseudoephedrine amides undergo highly diastereoselective alkylations with a wide range of alkyl halides to afford α-substituted products in high yields. These products can then be transformed in a single operation into highly enantiomerically enriched carboxylic acids, alcohols, aldehydes, and ketones.

Atomically dispersed Zn–N–C nanomaterials are promising platinum‐free catalysts for the oxygen reduction reaction (ORR). However, the fabrication of Zn–N–C catalysts with a high Zn loading remains a formidable challenge owing to the high volatility of the Zn precursor during high‐temperature annealing. Herein, we report that an atomically dispersed Zn–N–C catalyst with an ultrahigh Zn loading of 9.33 wt % could be successfully prepared by simply adopting a very low annealing rate of 1° min−1. The Zn–N–C catalyst exhibited comparable ORR activity to that of Fe–N–C catalysts, and significantly better ORR stability than Fe–N–C catalysts in both acidic and alkaline media. Further experiments and DFT calculations demonstrated that the Zn–N–C catalyst was less susceptible to protonation than the corresponding Fe–N–C catalyst in an acidic medium. DFT calculations revealed that the Zn–N4 structure is more electrochemically stable than the Fe–N4 structure during the ORR process.

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NiFe-layered double hydroxides (NiFe-LDH) are among the most active catalysts developed to date for the oxygen evolution reaction (OER) in alkaline media, though their long-term OER stability remains unsatisfactory.H erein, we reveal that the stability degradation of NiFe-LDH catalysts during alkaline OER results from adecreased number of active sites and undesirable phase segregation to form NiOOH and FeOOH, with metal dissolution underpinning both of these deactivation mechanisms.F urther,w ed emonstrate that the introduction of cation-vacancies in the basal plane of NiFe LDH is an effective approach for achieving both high catalyst activity and stability during OER. The strengthened binding energy between the metals and oxygen in the LDH sheets, together with reduced lattice distortions,b oth realized by the rational introduction of cation vacancies,d rastically mitigate metal dissolution from NiFe-LDH under high oxidation potentials,r esulting in the improved long-term OER stability. In addition, the cation vacancies (especially M 3+ vacancies) accelerate the evolution of surface g-(NiFe)OOH phases, therebyboosting the OER activity.The present study highlights that tailoring atomic cation-vacancies is an important strategy for the development of active and stable OER electrocatalysts.

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Microporous framework membranes with well-defined micropore structure such as metal-organic framework membranes and covalent organic framework membranes hold great promise for the enormous challenging separations in energy and environment fields.

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Encouraged by the great promise of heteroatoms-doped carbon materials for catalyzing the oxygen reduction reaction (ORR) in fuel cells, phosphorus-doped carbon has exhibited high catalytic activity for the ORR. Here, by means of comprehensive density functional theory (DFT) computations, we explored the relationships among the catalytic activity, stability, and the local chemical bonding states at dopant sites of Pdoped graphene sheets for ORR to identify the most optimized P-doped graphene structure. The structures show that the P atom can substitute one or two C atoms to form P-doped graphene structures with three or four P−C bonds (PC3G or PC4G), respectively, and these structures are easily oxidized into the OPC3G and OPC4G models with P−O bond. The further calculations reveal that the stability, band structure, surface charge distribution, potential active sites, and free energy of the rate-determining step of P-doped graphene can be modulated effectively by the chemical bonding states of P atom and the formation of C−P−O bond. The OPC3G model is the most effective and stable P-doped graphene for ORR due to its stability, activity, and the amount of the potential active sites. Another significant finding is that the C atoms possessed high negative charge, which also can be the optimal active sites for ORR. Our work provides useful guidance for the rational design and fabrication of P-doped graphene framework and helpful further activity enhancement.