Ferric perchlorate as an efficient and useful catalyst for the selective benzylation and methylation of alcohols with benzyl chloride and methyl iodide

Abstract  A mild and efficient method was developed for selective benzylation and methylation of hydroxyl compounds in the presence of a catalytic amount of ferric perchlorate. We showed that ferric perchlorate was very effective in selectively promoting the benzylation and methylation of primary aliphatic and benzylic alcohols versus secondary aliphatic alcohols and phenolic hydroxy groups. Graphical abstract        

Polyamide as an efficient sorbent for simultaneous interference-free determination of three Sudan dyes in saffron and urine using high-performance liquid chromatography-ultra violet detection北大核心CSCD

With polyamide( PA)as an efficient sorbent for solid phase extraction( SPE)of Sudan dyes II,III and Red 7B from saffron and urine,their determination by HPLC was performed. The optimum conditions for SPE were achieved using 7 mL methanol/water( 1:9,v/v,pH 7)as the washing solvent and 3 mL tetrahydrofu-ran for elution. Good clean-up and high( above 90%)recoveries were observed for all the analytes. The opti-mized mobile phase composition for HPLC analysis of these compounds was methanol-water( 70:30,v/v). The SPE parameters,such as the maximum loading capacity and breakthrough volume,were also determined for each analyte. The limits of detection( LODs),limits of quantification( LOQs),linear ranges and recoveries for the analytes were 4. 6-6. 6 μg/L,13. 0-19. 8 μg/L,13. 0-5 000 μg/L( r2> 0. 99)and 92. 5% -113. 4%,respec-tively. The precisions( RSDs)of the overall analytical procedure,estimated by five replicate measurements for Sudan II,III and Red 7B in saffron and urine samples were 2. 3%,1. 8% and 3. 6%,respectively. The developed method is simple and successful in the application to the determination of Sudan dyes in saffron and urine sam-ples with HPLC coupled with UV detection.     

Whey Proteins as a Potential Co-Surfactant with Aesculus hippocastanum L. as a Stabilizer in Nanoemulsions Derived from Hempseed Oil

The use of natural surfactants including plant extracts, plant hydrocolloids and proteins in nanoemulsion systems has received commercial interest due to demonstrated safety of use and potential health benefits of plant products. In this study, a whey protein isolate (WPI) from a byproduct of cheese production was used to stabilize a nanoemulsion formulation that contained hempseed oil and the Aesculus hippocastanum L. extract (AHE). A Box–Behnken experimental design was used to set the formulation criteria and the optimal nanoemulsion conditions, used subsequently in follow-up experiments that measured specifically emulsion droplet size distribution, stability tests and visual quality. Regression analysis showed that the concentration of HSO and the interaction between HSO and the WPI were the most significant factors affecting the emulsion polydispersity index and droplet size (nm) (p < 0.05). Rheological tests, Fourier transform infrared spectroscopy (FTIR) analysis and L*a*b* color parameters were also taken to characterize the physicochemical properties of the emulsions. Emulsion systems with a higher concentration of the AHE had a potential metabolic activity up to 84% in a microbiological assay. It can be concluded from our results that the nanoemulsion system described herein is a safe and stable formulation with potential biological activity and health benefits that complement its use in the food industry.     

Synthesis of Dialkyl 4-Ethoxy-2,5-dihydro-1-(9,10-dihydro-9,10-dioxoanthracen-1-yl)-5-oxo-1H-pyrrole2,3-dicarboxylates

Abstract

The reaction of ethyl 9,10-dihydro-9,10-dioxoanthracen-1-yl-carbamoyl-formate with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine leads to dialkyl 4-ethoxy-2,5-dihydro-1-(9,10-dihydro-9,10-dioxoanthracen-1-yl)-5-oxo-1H-pyrrole-2,3-dicarboxylates in fairly good yields. A dynamic NMR effect is observed as a result of restricted rotation around the single bond linking the anthraquinone moiety and the heterocyclic ring system, which is attributed to the interaction between the pyrrole residue and the peri C═O group.     

MgCl2 and its applications in organic chemistry and biochemistry: a review

Molecular Diversity - MgCl2 has been reported to be a versatile reagent especially as a Lewis acid catalyst in a variety of organic transformations including the preparation of heterocyclic...     

Transetherification of Allylic and Benzylic Ethers in the Presence of Ferric Ion

Alcoholysis of allylic, secondary and tertiary benzylic ethers is proceeded efficiently in the presence of catalytic amounts of ferric ion as anhydrous FeCl₃ and Fe(ClO₄)₃.     

Two Novel Push?Pull Series of Benzothiazole‐Based Dyes: Synthesis and Characterization

New dichromophoric cyanine dyes based on benzothiazol‐2‐amines as push? pull systems were synthesized in two series of disperse and cationic forms (see 4 in Scheme 1 and 5 in Scheme 2, resp.). Their thermal stabilities, UV/VIS, fluorescence, and solvatochromic behavior, which are important parameters in push? pull systems, were also studied.     

A capable neural network model for solving the maximum flow problem

This paper presents an optimization technique for solving a maximum flow problem arising in widespread applications in a variety of settings. On the basis of the Karush–Kuhn–Tucker (KKT) optimality conditions, a neural network model is constructed. The equilibrium point of the proposed neural network is then proved to be equivalent to the optimal solution of the original problem. It is also shown that the proposed neural network model is stable in the sense of Lyapunov and it is globally convergent to an exact optimal solution of the maximum flow problem. Several illustrative examples are provided to show the feasibility and the efficiency of the proposed method in this paper.