Mamta Sharma

Fluorinated phosphonium ylides: versatile in situ Wittig intermediates in the synthesis of hydrofluorocarbons

Abstract A simple and convenient technique has been developed for the synthesis, characterisation and isolation of hydrofluoro/hydrohalofluorocarbons such as chlorodifluoromethane (CF2ClH), difluoromethane (CF2H2), bromodifluoromethane (CF2BrH) and dibromofluoromethane (CFBr2H) as possible chlorofluorocarbon (CFC) alternatives. The Wittig reaction of carbonyl compounds with in situ generated triphenylphosphonium ylides in DMF forms terminal fluoroolefins. However, in the absence of the carbonyl moiety these ylides undergo decomposition. The high reactivity of fluoromethylene triphenylphosphonium ylides in DMF in the absence of the carbonyl moiety has been exploited for the first time to design the synthesis of hydrofluorocarbons.

The Mechanism of Thionyl Chloride Reaction with Dialkyl Alkylphosphonothionate Using 31 P NMR

Based on 31 P NMR studies of thionyl chloride reaction with dialkyl alkylphosphonothionates, a method for preparation of alkylphosphonic dichloride has been investigated. A mechanism via intermediacy of ester chloride is suggested.

Synthesis, characterisation and mass spectrometric fragmentation of O-(chlorodifluoroacylated) alcohols

Abstract An indirect and uncatalysed esterification of chlorodifluoroacetic acid with polyfluoro and hydrocarbon alcohols has been developed. The method which involves the reaction between sodium chlorodifluoroacetate and alcohols in dimethylformamide (DMF) is particularly facile with polyfluorinated alcohols resulting in esters in 71–85% yield. The esters have been characterised on the basis of 1 H and 19 F NMR and mass spectral data. The electron impact (EI) mass spectrometric fragmentation of these polyfluorinated esters have shown some interesting features which have been substantiated by using tandem mass spectrometry.

A Simple and Efficient Chemical Decontamination of Sulfur Mustard (HD) Using 1,8-Diazabicyclo[5,4,0]Undec-7-Ene Hydrobromide-Perbromide

Abstract A simple and efficient chemical decontamination method was developed against sulfur mustard (HD), an extremely toxic and persistent chemical warfare agent. The method involves treatment of chemical warfare agent HD and its simulants, i.e., methyl p-tolyl sulfide, 2-chloroethyl phenyl sulfide, and 2-chloroethyl ethyl sulfide, with 1,8-diazabicyclo[5,4,0]undec-7-ene hydrobromide-perbromide at room temperature in 1:3 acetonitrile–water system as well as in aqueous medium. The reagent has efficiency to oxidize sulfur mustard in a controlled manner to form nontoxic sulfoxide avoiding overoxidation to the toxic sulfone. Reaction products of the oxidation were isolated and analyzed by gas chromatography-mass spectrometry and 1H NMR. GRAPHICAL ABSTRACT

Direct detection of alkylphosphonic acids in environmental matrices by proton coupled phosphorus NMR.

A simple, convenient, and direct one‐dimensional (1D) 31P NMR technique is demonstrated for the detection of alkylphosphonic acids (marker of nerve agents). The results of detection were validated after conducting various in‐house exercises. The confidence generated by this study was found very useful in detection of different alkylphosphonic acids spiked in various official interlaboratory proficiency tests conducted by Organisation for the Prohibition of Chemical Weapons (OPCW). Copyright

Overview of Bulk Nanostructured Material by Severe Plastic Deformation(SPD)

--The quest for ever-higher performance in structural applications has resulted in the ongoing development of new processes that can improve material properties. Severe plastic deformation methods are used to convert coarse grain metals and alloys into ultrafine grained (UFG) materials. It is one of the successful top to bottom technique for obtaining UFG materials then possess improved mechanical and physical properties which destine them for a wide commercial use. This paper, in one direction, looks into historical development of SPD processes and their effect at obtaining fine crystalline structure

Complete 1H, 13C, 19F and 31P NMR data assignment of CWC-related chemicals N,N-dialkyl-P-alkyl phosphonamidic fluorides

The complete multinuclear 1H, 13C, 31P and 19F NMR data of symmetrically substituted amines containing N,N‐dialkyl‐P‐alkyl phosphonamidic fluorides are presented. Assignment was achieved, using various one‐and two‐dimensional NMR experiments. Copyright

One Pot Synthesis of Diastereomeric Phosphonates

Abstract The reaction of diaryl methylphosphonate with sterically hindered alcohols in presence of sodium hydride provide arylalkyl methylphosphonate esters with high diastereoselectivity at the phosphorus center.