CHEMISTRY OF 1,2,4—TRIAZINES XIX THE ANOMALOUS SUBSTITUTED BENZENE SULFONATION AND PROPERTIES OF NUCLEOPHILIC ATTACK ON 6-CARBON OF 3-METHYLTHIO-5-HYDROXY-1,2,4-TRIAZINE

3-Methylthio-5-hydroxy-1,2,4-triazine(1c)reacted with substituted benzenesulfonyl chloride to give 3-methylthio-5-oxy-1,2,4-triazin-6-yl pyridinium betaine(4)in anhydrous pyridine.But when NaOH/H_2O/CH_3COCH_3 or NaOH/CH_3OH were used as reactant and solvent,3-methylthio-4-substituted benzenesulfonyl-5-oxo-6-hydroxy-1,4,5,6-tetrahydro-1,2,4-triazine(6)or 1-tosyl-3-methylthio-5-oxo-6-methyloxy-1,4,5,6-tetrahydro-1,2,4-triazine(7)was obtained respectively.The above reactions show anomalous properties of nucleophilic attack on 6-carbon in 1,2,4-triazine ring.

A New Asymmetric Synthesis of (+)-(3R, 4S, 5R, 7S)-Neoclausenamide via Intramolecular Nucleophilic Attack of Carbon Anion onto Cyclic Sulfate

An intramolecular nucleophilic substitution of carbon anion to cyclic sulfate was first employed in asymmetric synthesis of (+)-(3R, 4S, 5R, 7S)-neoclausenamide 1 which is a novel hepatoprotective lactam isolated from the dry leaves of Chinese folk medicine Clausena lansium (Lour) Skeel. The regioselectivity of beta-attack to this cyclic sulfate, just like its epoxide counterpart was attributed to the increased reactivity of beta-position by the phenyl group.

Comparative Theoretical Studies of the Reactivity and Stability of Selected Groups of Isomers with Carbon-Oxygen and Carbon-Nitrogen Bonds

Electronic structure calculations have been carried out to study various closely related isomers with propane backbone which form part of our quantum chemical approach to inter and intra-molecular kinetics. The usefulness of UCA-FUKUI developed by Jesús Sánchez-Márquez to facilitate the theoretical study of chemical reactivity is exploited. All isomers are identified as local minima with single-point calculations on DFT/B3LYP/6-31G(d,p). The increasing order of stability by groups of isomers are group I;propn-2-ol, propan-1-ol, group II;propanone, propanal, group III;Ethylmethanoate, Propanoic acid, Methylethanoate, group IV;N,N-dimethylformamide, propanimino, and propanamide. The trend in reactivity of the various groups of isomers and specific points of nucleophilic and electrophilic attacks are presented. We noticed that most of the properties of these isomers taught at the fundamental levels are proven true theoretically.

Identifying the Active Site of Water Oxidation Catalyst Based on Defective Fe-Doped Ni Oxyhydroxide

Electrochemical water splitting plays a crucial role in storing sustainable energy into H2 as an ideal fuel,in which the anodic oxygen evolution reaction(OER)is the bottleneck.Currently,Fe-doped NiOOH(Ni_(1−x)Fe_(x)OOH)is a promising OER catalyst under alkaline conditions.However,the specific active sites responsible for their good performances remain debatable.Here,we identify a nickel-oxygen radical(Ni–O·)and an iron-oxo(Fe=O)group as two essential states for adsorbed oxygen.Meanwhile,both thermochemical O–O coupling and electrochemical OER elementary steps are considered on the Ni_(1−x)Fe_(x)OOH catalysts.Sophisticated mechanistic studies with a combined density functional theory simulation and experimental analysis unravel that both the Ni and Fe centers can act as the active sites for the defective Ni_(1−x)Fe_(x)OOH to catalyze OER,depending on the nature of the defect.The presence of Fe can benefit the stabilization of the defective surface and influence the electronic property of the nearby Ni site.This work not only identifies the intrinsic active sites of Ni_(1−x)Fe_(x)OOH,but also illustrates the essential roles of defects in catalysis,which sheds light on the design of more efficient OER catalysts in the future.