Direct conversion of N-methoxy-N-methylamides (Weinreb amides) to ketones via a nonclassical Wittig reaction

[reaction: see text] N-Methoxy-N-methylamides (Weinreb amides) are converted efficiently into ketones by reaction with alkylidenetriphenylphosphoranes and in situ hydrolysis of the product.     

Dinitration studies of 2,4,5-tribromo-3,6-dimethylphenol: the formation of an acyloin rearrangement product

Dinitration of 2,4,5-tribromo-3,6-dimethylphenol(1) gives either the tribromodinitro-compound(2) or its acyloin rearrangement product(3), depending on the reaction conditions: X-ray crystal structure analyses are reported for compounds (2) and (3).     

Accumulation and distribution of elements in rice /seed,brand layer,husk/ by neutron activation analysis

Various rice samples /seed, brand layer, husk/ from Vietnam were analyzed for Se, Hg, Cr, Ni, Sc, Rb, Fe, Zn and Co by neutron activation analysis. The concentration values found /seed/ were the following: Se 0.04–0.07 ppm, Hg 0.02–0.07 ppm, Cr 2.13–8.65 ppm, Ni 1.56–4.95 ppm, Sc 0.02–0.06 ppm, Rb 0.84–2.71 ppm, Fe 26.31–96.07 ppm, Zn 10.65–27.39 ppm and Co 0.02–0.15 ppm. The values were reported in ppm /dry weight/. Statistical analysis /t-test, t=0.05/ showed that the content of elements varies between sorts of rice; the content of Rb, Fe, Ni, Cr of rice husk was significantly higher than in rice seed and brand layer.     

Aggregation-free and high stability core–shell polymer nanoparticles with high fullerene loading capacity,variable fullerene type,and compatibility towards biological conditions

Fullerenes have unique structural and electronic properties that make them attractive candidates for diagnostic, therapeutic, and theranostic applications. However, their poor water solubility remains a limiting factor in realizing their full biomedical potential. Here, we present an approach based on a combination of supramolecular and covalent chemistry to access well-defined fullerene-containing polymer nanoparticles with a core–shell structure. In this approach, solvophobic forces and aromatic interactions first come into play to afford a micellar structure with a poly(ethylene glycol) shell and a corannulene-based fullerene-rich core. Covalent stabilization of the supramolecular assembly then affords core-crosslinked polymer nanoparticles. The shell makes these nanoparticles biocompatible and allows them to be dried to a solid and redispersed in water without inducing interparticle aggregation. The core allows a high content of different fullerene types to be encapsulated. Finally, covalent stabilization endows nanostructures with stability against changing environmental conditions.

A polymer nanoparticle approach to biorelevant and robust fullerene nanoparticles is presented.     

Separation and Determination of Ephedrine Enantiomers and Synephrine by High Performance Capillary Electrophoresis in Dietary Supplements

The chiral separation of ephedrine alkaloids by high performance capillary electrophoresis is of great interest since the enantiomers exhibit quantitative and qualitative differences in pharmacological activity. The isomers of (–)-ephedrine, (+)-pseudoephedrine, (–)-N-methylephedrine, (+)-N-methylpseudoephedrine, (+)-norpseudoephedrine and (–)-norephedrine are the major bioactive components of E. sinica (Ma-Huang) which is a Chinese herb used for weight loss and as an energy booster in the US. However, the compounds stereoisomers are not present in the plant material. The electrophoretic separation was performed using a 110 cm × 50 m I.D. (101.5 cm effective length) fused silica capillary. The samples were injected by pressure for 5 s at 50 mbar and the running voltage was 30 kV at the injector end of the capillary. Within 23 min, nine ephedrine compounds and synephrine were separated at 210 nm. The method was successively applied to the determination of the ephedrine compounds in dietary supplement products. Parameters affecting the resolution between (+) and (–)-enantiomers, such as pH, cyclodextrin concentration, temperature, organic modifier, buffer concentration and capillary dimensions were reported.     

Effects of mixed H2O‐CH3CN solvents on the rate of hydrazinolysis of N‐phenylphthalimide: Spectral and kinetic evidence for the occurrence of N‐aminophthalimide on the reaction path

Kinetic study on the cleavage of N‐phenylphthalimide (NPhPT) in the presence of 0.05 M NH₂NH₂ and mixed H₂O‐CH₃CN solvents reveals the occurrence of reaction scheme where A, B, C, C₁, An, E, and F represent NPhPT, o‐CO^?₂C₆H₄CONHC₆H₅, o‐CONHNH₂C₆H₄‐ CONHC₆H₅, N‐aminophthalimide, aniline, o‐CO^?₂C₆H₄CONHNH₂, and o‐CONHNH₂C₆H₄‐CONHNH₂, respectively. But, in the presence of either nonbuffered ?0.20 M NH₂NH₂ hydrazine buffer of pH ～7.30–8.26 with total buffer concentration ([Buf]_T) of >0.02 M, further conversion of F to 2,3‐dihydrophthalazine‐1,4‐dione (DHPD) has been detected depending upon the length of the reaction time (t), the values of [Buf]_T, and pH. It has been shown that the rate of conversion of C₁ to F is much faster than that of C to C₁ which is much faster than that of F to DHPD. The reaction step A → C involves general base (GB) catalysis, while step C → C₁ seems to involve specific base–general acid (GA) and GB‐GB catalysis. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 147–161, 2005     

A new approach for the derivation of bounds for the Jensen difference

There are many useful applications of Jensen's inequality in several fields of science, and due to this reason, a lot of results are devoted to this inequality in the literature. The main theme of this article is to present a new method of finding estimates of the Jensen difference for differentiable functions. By applying definition of convex function, and integral Jensen's inequality for concave function in the identity pertaining the Jensen difference, we derive bounds for the Jensen difference. We present integral version of the bounds in Riemann sense as well. The sharpness of the proposed bounds through examples are discussed, and we conclude that the proposed bounds are better than some existing bounds even with weaker conditions. Also, we present some new variants of the Hermite–Hadamard and Hölder inequalities and some new inequalities for geometric, quasi-arithmetic, and power means. Finally, we give some applications in information theory.     

Evolutionary Quasi-Variational-Hemivariational Inequalities I: Existence and Optimal Control

Journal of Optimization Theory and Applications - We study a nonlinear evolutionary quasi–variational–hemivariational inequality (in short, (QVHVI)) involving a set-valued...     

Quadratic Growth Conditions and Uniqueness of Optimal Solution to Lasso

Journal of Optimization Theory and Applications - In the previous paper Bello-Cruz et al. (J Optim Theory Appl 188:378–401, 2021), we showed that the quadratic growth condition plays a key...     

Reactions of [(Cp)2Ti(NCS)2] as a potential metalloligand; synthesis and physico-chemical investigations of novel heterobimetallic complexes

Summary Bis(cyclopentadienyl)titanium(IV) diisothiocyanate [(Cp)₂-Ti(NCS)₂] reacts with MCl₂ (M = Cu, Pd or Pt), [CuCl(PPh₃)₃], [RuCl₂(PPh₃)₃] and [RuCl₂(DMSO)₄] (DMSO = dimethylsulphoxide) giving solid compounds of stochiometry [(Cp)₂Ti(-NCS)₂MCl₂] (M = Cu, Pd or Pt), [(Cp)₂Ti(-NCS)₂CuCl(PPh₃)], [(Cp)₂Ti(-NCS)₂-RuCl(PPh₃)₂]Cl and [(Cp)₂Ti(-NCS)₂RuCl₂(DMSO)2]. These products have been characterized by physicochemical and spectroscopic methods.