The reaction of diethyl α-oxoethylphosphonate and diethyl oxobenzylphosphonate with diethyl phosphite, dimethyl phosphite, and diphenylphosphine oxide affords, depending on the substrates and conditions (nature and quantity of the amine catalyst, temperature, and solvent), the Pudovik adduct and/or the corresponding >P(O)–CH–O–P(O)< product formed by rearrangement. The nature of the substituent on the central carbon atom (a methyl or phenyl group) influences the inclination for the rearrangement. The asymmetric products (either adducts or rearranged species) with different P(O)Y functions (Y = RO or Ph) exhibit interesting NMR features.
Durable and formaldehyde-free flame-retardant (FR) modification of wool fabric using phosphorous compounds is of great interest. In this study, Schiff base imine groups were firstly introduced onto wool fiber through aldehyde-amine condensation between p-hydroxybenzaldehyde and wool fiber. Then, an efficient and durable FR wool fabric was fabricated by incorporating diethyl phosphite (DEP) into a Schiff base intermediate via the Pudovik reaction. The potential reaction mechanism among p-hydroxybenzaldehyde, DEP and wool fiber was explored. The thermal stability, smoke generation ability, FR ability and washing durability of the modified wool fabric were studied. The FR modification significantly increased the thermal resistance of wool fabric and suppressed smoke generation by half. The wool fabric modified by 20 g/L DEP was able to self-extinguish during the burning test, suggesting the higher FR efficiency of the DEP-incorporated Schiff base system. The modified wool fabric still self-extinguished after 20 commercial launderings, which is attributed to the covalent grafting of DEP onto wool fiber. Char residue analyses revealed the condensed charring FR mechanism of the DEP-incorporated Schiff base system on wool. This work provides a novel approach to prepare efficient and durable FR functional wool fabric via the Schiff base reaction and Pudovik reaction among p-hydroxybenzaldehyde, DEP and wool fiber.
A simple, rapid, selective, and reproducible Gas chromatographic mass spectrometry (GC-MS) method has been developed and validated for the estimation of Diethyl Phosphite content in Foscarnet Sodium USP Drug substance. The drugs were estimated using HP-5, Length-30 M, Internal diameter 0.32 mm; Film thickness 1 μ at a total flow rate of 11.9 ml/min, and column flow of 1.49 ml/min was used for the separation. Flow control mode was pressure. Column oven temperature 70°C and injector temperature 220°C. Oven program modified for proper elution of peak. The linearity range used was 0.025-0.120µg/ml and (Rt) was 6.7 min. The correlation coefficient values were found to be 0.997. Precession studies showed % RSD values less than 15.0% for all the selected concentrations. The percentage recovery of Diethyl phosphite from LOQ to 150% was found in range of 100.7 -116.7%. The content results of Phophite content were within the limits of less than 0.12 ppm. The method was validated as per the International Conference on Harmonization (ICH) guidelines. The developed method was successfully used for the quantitative analysis of commercially available dosage forms.
New α-aminophosphonates were synthesized and characterized by the interaction of cyclohexylamine and 1-ethynyl-1-amino-cyclohexane with various benzaldehydes and diethyl phosphite under the conditions of the Kabachnik-Filds reaction. The composition and structure of the synthesized compounds were confirmed by IR, NMR 1 H and 31P spectroscopy
Three α-aminophosphonates, namely diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl) methyl]phosphonate (3a), diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(2-methoxyphenyl)methyl]phosphonate (3b) and diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-nitrophenyl)methyl]phosphonate (3c), were synthetized via the Pudovik-type reaction between diethyl phosphite and imines, obtained from 5-phenyl-1,2,4-oxadiazol-2-amine and aromatic aldehydes, under microwave...
A silver-catalyzed three-component reaction involving alkynes, Selectfluor®, and diethyl phosphite was employed for the one-pot formation of C(sp2)–F and C(sp2)–P bonds to provide an efficient access to β-fluorovinylphosphonates in a highly regio- and stereoselective manner under mild reaction conditions. This reaction is operationally simple and offers an excellent functional group tolerance as well as a broad substrate scope that includes both terminal and internal alkynes. The reaction proceeded through the oxidative generation of a P-centered radical and subsequent fluorine atom transfer.
Tetraalkyl Hydroxymethylene-bisphosphonate and Dialkyl 1-Diphenylphosphinoyl-1-hydroxy-ethylphosphonate Derivatives by the Pudovik Reaction and Their Rearranged Products