O-alkyl MPA

Procedures for identification and quantitative assessment of O-isobutyl MPA (a marker of exposure to RVX) in urine and blood plasma have been developed, and toxicokinetic experiments conducted to measure O-alkyl MPA in rat plasma after intramuscular injection of RVX at a dose of 0.8 X LD50. In addition, we have obtained a mass spectrum of human albumin after in vitro incubation of blood serum with RVX. Incubation of commercially available human albumin with RVX with subsequent trypsinolysis and MS/ MS analysis has revealed two sites of binding RVX to human albumin, Tyr 411 and Tyr 150. These data could contribute to development of sensitive and specific diagnostic methods. 

All attempts to introduce fluorosilicone oils, in which the fluoro-alkyl group was covalently bound to the Si-O-Si backbone, were without success [31,32], A new approach to create a heavier than water silicone oil was the mixture of partially fluorinated compounds and ultra-purified silicone oil. The first product on the market was Oxane Hd (Bausch Lomb Inc., Rochester, NY, USA), a mixture of 1-perfluorooctyl-5-methylhex-2-en and silicone oil 5000 mPas. The specific density of this clear mixture is 1.02 g/ml. This creates the possibility to treat the lower quadrant of the retina. An intra-ocular bubble of Oxane Hd has an ideal spherical shape as demonstrated in Fig. 4. 

Inorganic bases have been also employed in this system. When Butcher first used alkali carbonates [50], it was reported that, in DMF and at ambient temperature, the carbamation of primary and secondary aliphatic amines (or also arylamines) with alkyl halides under a C02 atmosphere (0.1 MPa) was effectively promoted by Cs2C03 [50, 51]. The Cs+ cations in the solvent used (DMF) did not form ion pairs with counterions, and favored the formation of naked carbamate anions that were more reactive at the O-ends with alkyl halides. Jung further found that the addition of tetrabutylammonium iodide (TBAI) to the system RR NH/ C02/RX/Cs2C03/DMF promoted the carbamation process with a higher yield and selectivity with respect to N-alkylation [51]. The process has been successfully extended to the synthesis of carbamate functionalities on solid phases. In this case, resin-bound carbamates are readily released from the resin by treatment with LiAlH4 in THF, yielding the respective N-methyl secondary amines [51]. 

Early studies involved pyrolysis of this residue and revealed the presence of aromatic ring systems such as benzene, naphthalene, their alkyl derivatives as well as higher aromatic hydrocarbons. Today, GC-MS analyses of super-critical fluid extracts of hydrous pyrolysates (77), Ha-pyrolysis products (72) as well as solid-state C-NMR spectroscopy (75) of meteorite organic residues are applied to provide insight into the structure of the macromolecular carbon. Most recent, hydrothermal treatment (300 °C at 10 MPa) of demineralized lOM of the Murray meteorite has yielded in the release of a wide variety of carboxylic acids and heteroaromatic compounds including C3-C17 alkyl carboxylic acids and N-, O-and S-containing hydroaromatic and aromatic compounds (74). 

Because of the different and low stability of the isoindoles obtained from the reaction of AAs with OPA/MCE reagent, alternative precolumn derivat-izations reagents, such as 3-mercaptopropionic acid (MPA) and several N-alkyl-L/o-cysteines, were proposed. The OPA/MPA and OPA/N-acetyl-L-cysteine (NAC) reagents provide more stable isoindoles compared to those formed with the OPA/MCE, and the optical resolution of enantiomeric AAs with the OPA/NAC, as well as with further N-alkyl-L/o-cysteine reagents, have opened a new area in separation of AA enantiomers. Due to robotic autosamplers, which provide excellent reproducibility even for moderately quantitative interactions, most AA analyses are performed with the OPA derivative. The unexplainable contradictions of this most popular process - relating to the particularly low stability of the OPA derivatives of six very important AAs (glycine, y-aminobutyric acid (GABA), jS-alanine,... 

Fig. 21. Initial 2-butene conversion as a function of cation content (x) and evolution of conversion with TOS for the most active catalysts during isobutane/2-butene alkylation over group B salts of HPW. Alkylation conditions fixed bed reactor, 80°C, 2.5 MPa, I/O = 15, olefin WHSV = Ih-i.

The process layout consists of two consecutive static mixers (Fig. 28). To the first mixer, the olefin feedstock is cofed with a recycled isobutane/alkylate stream. The stream coming out the first static mixer is then combined with the recycled IL-based composite catalyst and fed into the second static mixer where the alkylation reaction takes place at a reaction temperature around 15°C and a total pressure of 0.4 MPa. The reaction products are then sent to a settler where the composite catalyst is collected from the bottom, due to its higher density, and recycled. The supernatant is later split into a recycle (isobutane -I- alkylate) to the first static mixer upstream and a product effluent, which constitutes the incoming to the fractionation unit downstream. Total reaction time, considering residence times in the second static mixer and in the settler, is 10 min while the overall I/O ratio in the reactor is set to a value as high as 500. No details on catalyst regeneration or replacement have been disclosed (257). 

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