THE ROLE OF METAL (HYDR) OXIDES IN CATALYZING THE HYDROLYSIS OF QUINALPHOS

Catalysis of the hydrolysis of the organ phosphorus compound, quinalphos (Q) by (hydr) oxides was studied at pH 4.0, 7.0, and 10.0, and at 25oC. FeOOH and Al(OH)3 were the used solids for this research. Catalysis of quinalphos was followed by determining the disappearance of Q and the appearance of 2-hydroxyquinoxaline (HQ) product in the absence and presence of (hydr) oxides using HPLC with UV detector. Under these conditions, both hydroxides (FeOOH and Al(OH)3) have catalyzed the hydrolysis of quinalphos. In this study, FeOOH was found to be the best catalyst at the used pHs. It is apparent that at pH 10.0, Kobs for disappearance of Q is almost equal to that for the appearance of HQ, which indicates that hydrolysis of Q at pH 10.0 follows SN2 (P) pathway. On the other hand, at pH 4.0 and 7.0, hydrolysis of Q may have followed two pathways, SN2 (P) and SN2 (C), as Kobs for producing HQ is smaller than that for loss of Q.

Application of α-Amino-β-fluorophosphonates in Construction of their Dipeptide Analogues

Herein, we present application of α-amino-β-fluorophosphonates for the construction of their dipeptide analogues. α-Amino-β-fluorophosphonates were prepared in a XtalFluor-E mediated deoxyfluorination of α-hydroxy-β-aminophosphonates. The reaction proceeds through an aziridinium ion formation, which was confirmed by the formation­ of a hexacoordinate phosphorus compound. Moreover, the absolute configuration of the obtained compounds was determined by X-ray analysis, which proved the stereochemistry.

Preparation and properties of flame-retardant epoxy resins containing reactive phosphorus flame retardant

To prepare flame-retardant epoxy resin, phosphorus compound containing di-hydroxyl group (10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phospha phenanthrene-10-oxide, DOPO-HQ) was reacted with uncured epoxy resin (diglycidyl ether of bisphenol A, YD-128) and then cured using a curing agent (dicyandiamide, DICY). This study focused on the effect of phosphorus compound/phosphorus content on physical properties and flame retardancy of cured epoxy resin. The thermal decomposition temperature of the cured epoxy resins (samples: P0, P1.5, P2.0, and P2.5, the number represents the wt% of phosphorus) increased with increasing the content of phosphorus compound/phosphorus (0/0, 19.8/1.5, 27.8/2.0, and 36.8/2.5 wt%) based on epoxy resin. The impact strength of the cured epoxy resin increased significantly with increasing phosphorus compound content. As the phosphorus compound/phosphorus content increased from 0/0 to 36.8/2.5 wt%, the glass transition temperature (the peak temperature of loss modulus curve) increased from 135.2°C to 142.0°C. In addition, as the content of phosphorous compound increased, the storage modulus remained almost constant up to higher temperature. The limiting oxygen index value of cured epoxy resin increased from 21.1% to 30.0% with increasing phosphorus compound/phosphorus content from 0/0 to 36.8/2.5 wt%. The UL 94 V test result showed that no rating for phosphorus compounds less than 19.8 wt% and V-1 for 27.8 wt%. However, when the phosphorus compound was 36.8 wt%, the V-0 level indicating complete flame retardancy was obtained. In conclusion, the incorporation of phosphorus compounds into the epoxy chain resulted in improved properties such as impact strength and heat resistance, as well as a significant increase in flame retardancy.