Mei-Hong Wei

PEG-SUPPORTED SULFONIC ACID AS AN EFFICIENT AND RECYCLABLE CATALYST FOR THE SYNTHESIS OF 1,1-DIACETATES UNDER SOLVENT-FREE CONDITIONS

Abstract An operationally simple, efficient, and environmentally benign synthesis of 1,1‐diacetates in good yields by reaction of different aldehydes with acetic anhydride in the presence of PEG‐supported sulfonic acid under solvent‐free conditions is described.

Rapid Microwave‐Assisted Liquid‐Phase Synthesis of 4‐Substituted‐5‐methoxycarbonyl‐6‐methyl‐3,4‐dihydropyridones on Poly(ethylene Glycol) Support

Abstract 4‐Substituted‐5‐methoxycarbonyl‐6‐methyl‐3,4‐dihydropyridones have been efficiently prepared on the soluble polymer polyethylene glycol (PEG) 4000 by solvent‐free microwave irradiation through a one‐pot condensation of PEG‐bound acetoacetate, Meldrums acid, ammonium acetate, and the appropriate aldehyde in the presence of a catalytic amount of polyphosphoric acid. The polymer‐supported synthesis provided the target compounds in excellent yield and purity with a facile workup procedure.

Synthesis and characterization of novel fluorinated pyridine-based polyimides derived from 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine and dianhydrides:

A series of new fluorinated pyridine-based polyimides (PIs) was synthesized by polycondensation of 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine with various aromatic dianhydrides in N,N-dimethylacetamide (DMAc) via the conventional two-step method. The inherent viscosities of the resulting poly(amic acid)s and PIs were 0.54–0.94 and 0.58–0.88 dLg−1, respectively. The obtained PIs were predominantly amorphous and soluble in polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, and DMAc at room temperature or upon heating at 70°C. They also displayed good thermal stability with the glass transition temperature of 324–416°C, the temperature at 5% weight loss of 546–584°C, and the residue of 58–69% at 750°C under nitrogen, as well as outstanding mechanical properties with tensile strengths of 69132 MPa, tensile moduli of 1.1–2.0 GPa, and elongations at break of 7–27%. Meanwhile, these PI films had dielectric constants of 2.95–3.22 (1 MHz), low water uptake 0.44–0.71%, and high optical transparency with the ultraviolet cutoff wavelength in the 388–406 nm range and the wavelength of 80% transparency in the range of 550–680 nm.

Polyethylene glycol supported phosphorus chloride: An efficient and recyclable catalyst for the preparation of nitriles from aldoximes

GRAPHICAL ABSTRACT ABSTRACT Polyethylene glycol (PEG) supported phosphorus chloride has been developed and used as an efficient and recyclable catalyst for dehydration of various aldoximes into the corresponding nitriles. This protocol has many advantages such as high conversion, high selectivity, short reaction time, mild reaction conditions, and simple experimental procedure.

Preparation and characterization of new aromatic poly(ether ester)s bearing cardo xanthene groups

A series of new aromatic poly(ether ester)s containing cardo xanthene groups were synthesized by phase transfer–catalyzed interfacial polycondensation of three cardo bisphenols such as 9,9-bis(4-hydroxyphenyl)xanthene, 9,9-bis (4-hydroxy-3-methylphenyl)xanthene, and 9,9-bis(4-hydroxy-3,5-dimethylphenyl)xanthene with terephthaloyl chloride and isophthaloyl chloride. Inherent viscosities and number average molecular weights of the polymers were in the range 0.56–0.80 dL g−1 and 30,300–36,200, respectively. The resulting poly(ether ester)s exhibited high glass transition temperatures ranged from 208°C to 274°C, and their 10% weight loss temperatures were in the range of 440–458°C with char yields above 45% at 600°C under a nitrogen atmosphere. All the poly(ether ester)s were amorphous and readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, meta-cresol, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidinone at room temperature and could be cast into tough, transparent, and flexible films with tensile strengths of 68.2–86.8 MPa, elongations at break of 2–3%, and tensile moduli of 5.7–7.8 GPa.

Simple synthesis of 1-substituted-4-vinyl-1,2,3-triazoles based on polystyrene-supported sulfonyl chloride

ABSTRACT Polystyrene-supported but-3-ynyl sulfonate reagent has been developed and applied to the traceless solid-phase organic synthesis of 1-substituted-4-vinyl-1,2,3-triazoles by CuI-promoted 1,3-dipolar cycloaddition reaction with various organic azides and subsequent cleavage from the polymer support through elimination reaction mediated by 1.8-diazabicyclo[5,4,0]undec-7-ene (DBU). The advantages of this new synthetic method include simple operation and moderate to good yields of the products, as well as good stability of the reagent. GRAPHICAL ABSTRACT

A facile one-pot solid-phase synthesis of oxazolidin-2-ones using polymer-supported 2-hydroxyalkyl selenide reagent

A simple, efficient and environmentally friendly procedure for one-pot solid-phase synthesis of 2-oxazolidinones in moderate to good yields by reaction of polystyrene-supported 2-hydroxyalkyl selenide with benzoyl isocyanate and subsequent oxidation/cyclisation-hydrolysis using a selenium traceless linker strategy is described.