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Self-association behavior and conformation variation of long chain branched (LCB) poly(2-ethyloxazoline) (PEOx) with a CH3-(CH2)17 (C18) modified surface are investigated using light scattering techniques in various solvents. It is found that this LCB-PEOx self-associates in less polar solvents to form metastable nanoaggregates instead of undergoing precipitation. The critical aggregation concentration (cac) of this LCB polymer was obtained from the sharp increase of both hydrodynamic radius (Rh) and scattering light intensity measured in dynamic light scattering. The cac strongly depends on solvent polarity, decreasing as the solvent becomes more hydrophobic. As the polarity of the solvent increases, C18 chains move from the outside surface to the interior. Inward movement of C18 chains can cause coupled LCB-polymer chains to move with them, resulting in shrinkage of the particle size. The self-association process in the LCB-PEOx involves intrachain (C18 chains) collapse and interchain association. By a ...

Chemical neutralization is being explored as an alternative to incineration for a variety of demilitarization programs. Analytical methods are needed to detect and quantify residual agent in reaction masses produced from chemical neutralization to verify destruction of the agent and to clear a reaction mass for further processing. This paper describes the development and validation of gas chromatography–mass spectral methods for the trace determination of the chemical warfare agents isopropyl methylphosphonofluoridate (GB) and bis(2-chloroethyl)sulfide (HD) in solutions of the agents chemically neutralized with ethanolamine. ©2000 John Wiley & Sons, Inc. J Micro Sep 12: 87–92, 2000

Two series of 2,4,6-triphenylverdazyls substituted at the C(3) position of the heterocyclic ring are obtained using new convenient synthetic methodology. Thus, crown ether assisted solid–liquid phase-transfer catalysis promotes the formation of 3-n-alkyl-substituted 2,4,6-triphenylverdazyls in the reactions of 1,3,5-triphenylformazan with n-alkyl bromides. Under PTC conditions, methylation of 3-(4-nitrophenyl)-1,5-diphenylformazan with methyl iodide exclusively gives the corresponding verdazyl radical. 3-Substituted 2,4,6-triphenylverdazyls containing various di(cyclo)alkylamino moieties at the C(3) position of the verdazyl ring are prepared by the reaction of 1,3,5-triphenylformazan with the corresponding 1-[N,N-di(cyclo)alkylaminomethyl]benzotriazoles under the efficient catalysis of barium hydroxide monohydrate. Sonication of this reaction allows the yields of the verdazyls to be substantially increased. A bis-verdazyl N,N-bonded in the C(3) positions was synthesized. All the radicals obtained were characterized by microanalysis, and by UV–visible and ESR spectroscopy.

β-(N,N-Dialkylamino)ethyl arylthiosulfonates 2, new simulants for the hydrolysis and oxidation chemistry of VX (1), are prepared in good yield by reaction of a potassium arylthiosulfonate with a 2-chloroethylamine. Alkaline hydrolysis of 2 results in cleavage of the S-S bond to give sulfinic acids and disulfides. Like VX, oxidation of 2 by N-sulfonyloxaziridine 12 occurs exclusively on nitrogen to give the corresponding amine oxide which subsequently undergoes a Cope elimination reaction affording the vinyl sulfide 14

The syntheses of five new 4-alkyl-2-iodosobenzoic acids (3) are described. The iodine atom was introduced by ortho-directed lithiation of 4-alkylbenzyl alcohols followed by treatment with I 2 . The catalytic effectiveness of each of the products in the hydrolysis of 4-nitrophenyl diphenyl phosphate in microemulsions was studied. The 4-methyl- and 4-ethyl-substituted products were each found to be significantly better catalysts than the standard nonalkylated 2-iodosobenzoic acid (3, R = H). These results would indicate that microemulsions of these materials may find use in detoxification procedures

We have measured the second order rate constants for the uncatalyzed and o-iodosobenzoate catalyzed hydrolysis of p-nitrophenyldiphenyl phosphate in microemulsions containing the surfactant cetyltrimethyl ammonium bromide, the cosurfactants 1-alkyl-2-pyrrolidinones, and the oils hexadecane, toluene, and 4-tert-butyltoluene. Pseudo-ternary phase maps have been prepared for systems containing 1-methyl-2-pyrrolidinone and 1-cyclohexyl-2-pyrrolidinone as cosurfactants. Microemulsions containing N-alkyl-2-pyrrolidinones as cosurfactants effectively penetrate polymers, solubilize phosphate esters, and provide media in which phosphate esters hydrolyze rapidly.

Poly(amidoamine) (PAMAM) dendrimer shell reagents possessing either nucleophilic (i.e., primary amines) or electrophilic (i.e., carboxymethyl esters) functional groups have been covalently assembled around appropriate electrophilic or nucleophilic dendrimer core reagents to produce partial shell filled/core-shell tecto(dendrimers). Partial shell-filled products with saturation levels ranging from 28% to 66% were obtained. These metastable, remarkably monodispersed assemblies possess functionally differentiated nano-cusps and clefts that exhibit “autoreactive” behavior. Pacification of these autoreactive products with appropriate alkanolamine reagents produced robust, nonreactive, “hydroxy-amine-differentiated” surfaces that exhibit very active self-assembly properties. Based on the monodispersity, dimensional scaling, and electrophoretic similarities of PAMAM dendrimers to globular proteins, these assemblies may be viewed as crude biomimetics of classical core shell-type protein aggregates. These dimensionally larger, but analogous PAMAM core-shell tecto(dendrimer) architectures extend and complete a similar pattern of autoreactivity and pacification that was observed earlier for traditional mono PAMAM dendrimer core-shell modules possessing unsaturated shell levels.

The 13C NMR, IR, and UV spectra of 3- and 4-iodobenzoic, 3- and 4-iodosylbenzoic, and 3- and 4-iodylbenzoic acids and their sodium salts have been measured and compared with those of the corresponding 2-isomers. Kinetic data for the catalytic microemulsion hydrolysis of 4-nitrophenyl diphenyl phosphonate in the presence of the iodosyl and iodyl compounds have been obtained. Catalytic efficiency of the 3- and 4-substituted isomers are measured to be three to six orders of magnitude less effective than the corresponding 2-substituted isomers. Possible structural configurations are suggested and discussed.

The principles involved in macroheterocycle chemistry are discussed. Classes and types of macroheterocycles, synthetic approaches (including the template effect), complexation and complexes are mentioned. The utilization of crown ethers in synthetic organic chemistry is also surveyed. 1. Introduction 1.1. History 1.2. Nomenclature and Characteristics 1.3. Classes of Crowns and Related Molecules 2. Synthetic Access 2.1. Templated Syntheses 2.2. Non-Williamson Syntheses 3. Complexation 3.1. The Complexation Phenomenon 3.2. Types of Complexes 4. Synthetic Utility 4.1. Solubilization and Phase Transfer 4.2. Cation Effects 4.3. Crowns as Reagents and Catalysts 4.4. Complexation Specificity 5. Toxicity 6. Conclusions

The 13C NMR spectra for selected 2-iodosobenzoic acids, their sodium salts and the sodium salts of the corresponding iodoxybenzoic acids were measured and carbon assignments made using 2D and NOE experiments and relaxation times. Iodoso and iodoxy groups deshielded the ipso-carbon in these compounds by approximately 25 and 55 ppm, respectively, relative to the corresponding iodo compounds. The 13C NMR spectra of the 2-iodosobenzoate anions were almost identical with those of the corresponding free acids, both possessing cyclic structures. The iodoxybenzoic acids are either insoluble in, or oxidize, suitable NMR solvents (i.e. DMSO-d6, DMF-d7). The cyclic structure postulated for iodoxybenzoate anions is supported by their 13C chemical shifts.

Two polymer-bound iodosobenzoate derivatives have been prepared and found to be phosphorolytically active against both p -nitrophenyldiphenyl phosphate and the nerve agent, Soman.

Spectre RMN, de 13 C de cryptands [2.1.1], [2.2.1] et [2.2.2] en presence de Li + , Na + , K + , Ca 2+ et Ba 2+ en solution dans D 2 O/MeOH ou CDCl 3 . La relaxation longitudinale presente une augmentation surprenante pour la plupart des metaux alcalins mais pas pour les alcalinoterreux. Interpretation de cette augmentation

Recently it has been found that homogenates of Tetrahymena thermophila can hydrolyze the potent acetylcholinesterase inhibitors O,O-diisopropylphosphofluoridate (DFP) and O-1,2,2-trimethylpropylmethylphosphonofluoridate (soman). Upon purification of the DFP hydrolyzing activity 10-fold it had been noted that the soman hydrolyzing activity increased only 2-3 fold. Treatment with manganous ion and comparison of the soman and DFP hydrolysis rates of the homogenate indicated that a mixture of the squid-type and Mazur-type DFPases may be present. Subsequent purification of the enzymatic activities within the Tetrahymena-homogenate demonstrated that there are at least five functioning proteins of molecular weights 67,000 to 96,000. None are directly homologous to the DFPases found in hog kidney or squid. The enzymatic activities are designated DFPase-1 through DFPase-5. A hypothesis is presented that the functions of DFPases are in the normal metabolism of organophosphates naturally synthesized by T. thermophila.

Although common spectroscopic methods have largely supplanted the more classical methods for distinguishing aldehydes from ketones in many applications, aldehyde classification tests remain very useful in actual laboratory practice as well as important pedagogical device in qualitative organic chemistry.