Advanced Materials Research Vol. 830

Abstract: A novel method for the synthesis of azetidine via phosphoramidate intermediate has been developed. In the key step, cleavage of the PN bond in azetidin-1-ylphosporamidate with hydrochloric acid furnished a high-yielding conversion to azetidine hydrochloride.

Abstract: Four deoxynucleoside 5′-phosphoromorpholidates were prepared from carboxybenzyl-protected 2′-deoxyribonucleosides. The synthetic route involved three consecutive steps including phosphitylation, acid-catalyzed hydrolysis, and oxidative coupling reactions.

Abstract: A series of α-L-rhamnosyl-1-H-phosphoramidates of amino acid methyl esters were synthesized via an improved H-phosphonate protocol. Their structures were confirmed by NMR, IR, and MS analysis.

Abstract: A series of d4T 5′-selenophosphoramidates were prepared in good yields from d4T 5′-H-phosphonamidates. H-Phosphonamidates were silylated with TMSCl, and then oxidized with selenium in the presence of DBU to afford d4T 5′-selenophosphoramidates. Due to the lowered electron density on the P atom of H-phosphonamidates, these intermediates were less prone to be oxidized than their P–O counterparts.

Abstract: Derivatives of 3β-amino-5-cholestene are of substantial interest to chemical biologists and have potential medicinal value. A novel and practical method for the preparation of 3β-amino-5-cholestene from inexpensive cholesterol has been developed. To synthesize the epicholesterol intermediate, the KO₂ method reported by Corey and coworkers was applied in this synthetic route and solved the problems of the known synthetic route involving epicholesterol intermediate.

Abstract: Treatment of peracetylated pyranoses with FeCl₃·6H₂O in acetonitrile under microwave conditions provides an efficient and mild method for regioselective deprotection of anomeric O-acetyl group. The experimental results indicated that the employment of microwave could notably improve the reaction efficacy compared with the conventional heating condition.

Abstract: A novel and efficient method for the preparation of O-AZT-5′- O-glycosyl-1-H-phosphonate diesters has been developed. The H-phosphonate diesters were synthesized by tandem substitution reaction on PCl₃ with 2,6-lutidine as base.

Abstract: Dissolution of absorbent cotton (DP above 4000) using ionic liquids as solvent and regeneration was investigated. The results show that 1-ally-3-methylimidazolium chloride (AMIMCl) was a good solvent to dissolve absorbent cotton and a solution of 3 wt% can be reached in 18 min at 120°C. Besides, as the dissolving temperature increased the time needed for the cotton linters to dissolve decreased. The physic-chemical properties of the regenerated cellulose films were also characterized by XRD, FTIR and TGA analysis.

Abstract: Due to the unique molecular structure, hyperbranched polymers showed many characteristics,such as high solubility, low viscosity and high-activity. Therefore, it had been widely applied in different areas. In this paper, isophthaloyl chloride (IPC) was used as A₂ monomer and tri (3-aminophenyl) phosphine oxide (TAPPO) was used as B₃ monomer, compounding hyperbranched polyamide with triphenyl phosphorus structure . The best reaction conditions were obtained that the molar ratio of TAPPO and IPC was 1.5:1, the reaction temperture was 50°C, the reaction concentration was 0.1 mol/L and the reaction time was 2h.Besides, the structure of the polymer was characterized by FT-IR and H1-NMR analysis.The ¹H-NMR result showed that the branched degree of hyperbranched polyamide was 0.36.The DSC result showed that the glass transition temperature (Tg) was 130.7 °C. When the addition of P-HBPA content was 0.5% in PA6/P-HBPA blends, the properties of tensile strength, elongation at break and impact strength reached the maximum.

Abstract: Ethylene glycol (EG) and polyethylene glycol (PEG) were added as plasticizers to improve the processing performance of cellulose acetate (CA). The CA with 30% plasticizers were melted by HAAKE at 200 °C. The effects of EG and PEG (degree of polymerization in 200-800) on rheological properties and mechanical properties of CA were investigated. The results show that the plasticizing time, equilibrium torque and melt viscosity of the plasticizing system increase with the increase of PEG molecular weight, while the processing performance decreased. The tensile strength of the system decrease as the PEG molecular weight increased. The plasticizing system which contents 30% PEG-200(degree of polymerization is 200) shows the maximum elongation at break. The minimum values appeared in both flexural strength and flexural modulus in the CA/PEG-200 system.