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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Vapor liquid equilibrium of pure and aqueous Methyl diethanolamine (MDEA), 2-Dimethylmonoethanolamine (DMMEA), N-Methylmonoethanolamine (MMEA) and 1-(2-Aminoethyl)piperazine (AEP): Experimental results and modeling

This work presents new vapor-liquid data for the pure components 2-dimethylmonoethanolamine (DMMEA) and N-methylethanolamine (MMEA) and for the binary systems of aqueous methyldiethanolamine (MDEA), DMMEA, MMEA, and 1-(2-aminoethyl)piperazine (AEP). New Antoine models are developed for the pure component systems, and new and improved NRTL models for the binary systems. In the model development, together with new data from this work, all available data on VLE, excess heat of mixing, H E , freezing point depression, and specific heat were gathered, evaluated and used selectively for parameter optimization. Emphasis has been put on a best possible representation of amine volatility to enable reasonable predictions of amine emissions from absorption plants and to form a basis for subsequent models of ternary systems with CO 2 . In conclusion, model predictions are compared with experimental results and other models, source by source, and the overall results are satisfactory.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Assessment of two benzylation strategies for the analysis of nerve-agent derived ethyl- and pinacolyl methyl phosphonic acids in sandy loam soil by GC–MS

Despite their prohibition by the Chemical Weapons Convention, nerve agents (NAs) remain in use against military and civilian targets. Due to their high reactivity, NAs readily degrade to phosphonic acids, making them important markers in the inspection of areas of presumed NA use. In this work, we assess the use of benzylation to modify ethyl- and pinacolyl methylphosphonic acids, degradation products of VX and Soman respectively, for their efficient detection in a soil matrix at ~10 and ~1 μg/g using GC–MS. The soil matrix, Sandy Loam (SL), was chosen for its ubiquitous nature, complex composition with silica particles embedded in clay, and low organic content. In this study, we demonstrate that benzylation via benzyl bromide yields a LOD = 25.6 ng/mL for benzylated-EMPA and LOD = 30.1 ng/mL for benzylated-PMPA. This is superior to the use of p-methoxybenzyl trichloroacetimidate in providing stable phosphonic acid ester derivatives for analysis. A base-modified procedure for p-methoxybenzylation was explored in this study yielding a LOD = 29.1 ng/mL for p-methoxybenzylated-EMPA and LOD = 39.8 ng/mL for p-methoxybenzylated-PMPA. Both benzylation pathways (benzyl bromide and p-methoxybenzyl trichloroacetimidate) can be used to yield phosphonic acid derivatives that provide further confirmation of these Soman and VX degradation products in soil samples in investigative scenarios. The work herein represents the first application of benzylation methods for the analysis of these NA markers in the acidic, silicon-based SL soil.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Synthesis and structural characterization of bis (2-pyridylthio)( p -tolylthio)methyl zinc complexes and the catalytic hydrosilylation of CO 2

Bis(2-pyridylthio)(p-tolylthio)methane, [Bptm STol ]H, has been synthesized by treatment of a 2:1 mixture of 2-mercaptopyridine and p-thiocresol with NaH, followed by addition of CHI3. Access to zinc complexes is provided by the reaction of [Bptm STol ]H with Zn[N(SiMe 3 ) 2 ] 2 to afford [Bptm STol ]ZnN(SiMe 3 ) 2 , from which the halide derivatives [Bptm STol ]ZnX (X = Cl, Br, I) are obtained via reaction with Me 3 SiX (X = Cl, Br, I), and the formate complex, [Bptm STol ]ZnO 2 CH, is obtained by treatment with CO 2 in the presence of PhSiH 3 . Here, the molecular structures of [Bptm STol ]ZnN(SiMe 3 ) 2 , [Bptm STol ]ZnX (X = Cl, Br, I) and [Bptm STol ]ZnO 2 CH have been determined by single crystal X-ray diffraction, which indicate that the four coordinate zinc centers adopt structures that are intermediate between idealized trigonal monopyramidal and seesaw geometries. [Bptm STol ]ZnO 2 CH is a catalyst for the hydrosilylation of CO 2 by (RO) 3 SiH at room temperature to afford the silyl formate, HCO 2 Si(OR) 3 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗