Decomposition of halogenated hydrocarbons using intense, penetrating bremsstrahlung

Radiolytic decomposition of chlorinated hydrocarbons and other toxic compounds has been experimentally measured using ionizing radiation produced by electron accelerator and nuclear isotope sources. Decomposition products have been identified. A portable, commercially available electron accelerator was set up at a Superfund site where vapor extraction wells were removing trichloroethylene (TCE) from a spill into the unsaturated soil. The extraction vapor was passed through the accelerator beam to decompose the TCE. On site radiolytic decomposition of TCE vapor using an accelerator is shown to be significantly less expensive than filtration of TCE vapor using activated charcoal.     

Synthesis of the tetrahydroisoquinoline alkaloid (+/-)-renieramycin G and A (+/-)-lemonomycinone analogue from a common intermediate

The total synthesis of tetrahydroisoquinoline alkaloids (+/-)-renieramycin G (4) and a lemonomycinone analogue (7) is described. A general strategy to synthesize both the mono- and bistetrahydroisoquinoline alkaloids from a common advanced intermediate, 17, is presented.     

Crystal structures of dicarboxy-2,2'-bipyridyl complexes: the role of hydrogen bonding and stacking interactions

The crystal structures of three complexes of dicarboxy-2,2'-bipyridyl ligands, 5,5'-dicarboxy-2,2'-bipyridyl (1) and 4,4'-dicarboxy-2,2'-bipyridyl (2) are reported. [Rh(1H)3] shows two interpenetrating, homochiral rhombohedral networks linked by short carboxylate-carboxylic acid hydrogen bonds, in which each complex acts as a node for six hydrogen bonds. [Ru(1H2)(1H)2] forms only four such hydrogen bonds, leading to the formation of heterochiral chains held together by stacking between bipyridyls. [Co(2H)3] can in principle form six hydrogen bonds, but in practice forms only four in a layer structure where stacking interactions are important. This is attributed to differences in molecular shape.     

A novel general route for the preparation of enantiopure imidazolines

A novel procedure for the preparation of enantiopure 1,4-disubstituted 2-imidazolines is reported. Enantiopure beta-amino alcohols are converted into N-hydroxyethylamides, which are reacted with excess thionyl chloride, or with thionyl chloride followed by phosphorus pentachloride to yield N-chloroethylimidoyl chlorides. These intermediates are treated with amines and anilines to produce N-chloroethylamidines, which are converted into imidazolines upon workup with aqueous hydroxide. The method is simple and efficient and has been used to prepare a wide variety of enantiopure imidazolines, in a modular fashion, from readily available amino alcohols.     

High-energy irradiation of chlorinated hydrocarbons

The Lawrence Livermore National Laboratory (LLNL) and the Idaho National Engineering Laboratory (INEL) are jointly investigating the decomposition of chlorinated hydrocarbons using bremsstrahlung radiation produced by electron accelerators and gamma photons from spent reactor fuel. Experimental results demonstrate an exponential type decay of concentration with dose for volatile organic compounds (VOCs) in ground water and for both polychlorinated biphenyls (PCBs) and insecticides in organic solutions. Experiments were performed at several photon energies and dose rates with various initial concentrations. Mass balance analysis suggests complete mineralization of VOCs in ground water and indicates significant degradation of PCBs and insecticides to VOC type compounds in organic solutions.Work performed under the auspices of the U.S. Department of Energy, DOE Contract Nos. W-7405-ENG-48 and DE-AC07-76IDO1570.     

State-resolved unimolecular dissociation of cis-cis HOONO: Product state distributions and action spectrum in the 2nuOH band region

Nascent OH fragment product state distributions arising from unimolecular dissociation of room temperature HOONO, initiated by excitation in the region of the 2nu(OH) band, are probed using laser-induced fluorescence at sub-Doppler resolution. Phase-space simulations of the measured OH rotational distributions are consistent with the dissociation dynamics being statistical and confirm that all major features in the room temperature action spectrum belong to the cis-cis conformer. The phase-space simulations also allow us to estimate the HO-ONO bond dissociation energy of cis-cis HOONO to be D(0)=19.9+/-0.5 kcal/mol, which when combined with the known heat-of-formation data for the OH and NO(2) fragments gives DeltaH(f) (0)(cis-cis HOONO)=-2.5 kcal/mol. In addition to fragment energy release, spectral features in the cis-cis HOONO action spectrum are examined with respect to their shifts upon (15)N isotope substitution and through ab initio spectral simulation using a two-dimensional dipole surface that takes into account the influence of HOON torsional motion on the OH stretching overtone. The two-dimensional spectral simulations, using CCSD(T)/cc-pVTZ dipole surface, qualitatively reproduces features appearing in the action spectrum and suggest that the strong broad feature occurring approximately 570 cm(-1) to the blue of the cis-cis HOONO 2nu(OH) peak, likely involve excitation of HOON-torsion/OH-stretch combination bands originating from thermally populated excited torsional states. A closer examination of the predictions of the two-dimensional model with experiments also reveals its limitations and suggests that a more elaborate treatment, one which includes several additional modes, will likely be required in order to fully explain the room temperature action spectrum. Ab initio calculations of the HOON torsional potential at the CCSD(T)/cc-pVTZ level of theory are also presented and confirm that cis-perp configuration does not correspond to a bound localized minimum on the HOONO potential energy surface.     

SENSITIVITY OF Porphyromonas AND Prevotella SPECIES IN LIQUID MEDIA TO ARGON LASER

Abstract— The phototoxicity of argon laser irradiation was studied in aqueous suspensions of Porphyromonas endodontalis (American Type Culture Collection [ATCC] 35406), Porphyromonas gingivalis (ATCC 33277), Prevotella denticola (ATCC 33184) and two strains of Prevotella intermedia (ATCC 15033 and 49046), all "black-pigmented bacteria," BPB, that accumulate cellular porphyrins. Several of these species have been implicated in the etiology of Periodontol disease. Non-black-pigmented bacteria were also studied to test the specificity of irradiation as a potential photodynamic treatment for Periodontol infections. Cell suspensions were irradiated with an argon laser at fluences of 20–200 J/cm². When cultured in hemin-supplemented media, ATCC 15033 was the most sensitive to irradiation. However, a second strain of the same species (ATCC 49046) was resistant. The photosensitivity of other species ranked ATCC 33277 > 35406 = 33184 = 35496. When hemin was replaced in media by hemoglobin, ATCC 33277 became resistant to irradiation. Protoporphyrin IX content in BPB cells was shown not to be a major factor determining photosensitivity. Oxygen was required during irradiation for BPB species to be affected. Non-black-pigmented bacteria were much less sensitive to irradiation than BPB.     

Synthesis and characterisation of transition metal halide complexes of the xylyl-distibine, 1,2-bis(dimethylstibanylmethyl)benzene

Complexes of the title ligand with Cu(I), Ag(I), Au(I), Pd(II), Pt(II), Rh(III), and rare examples with Ni(II) and Co(III) have been prepared and characterised by analysis, IR, UV-vis, 1H, 63Cu and 59Co NMR spectroscopy and ES+ mass spectrometry as appropriate. The structures of [Cu[1,2-C6H4(CH2SbMe2)2]2]BF4, [PtCl2[1,2-C6H4(CH2SbMe2)2]], [M[1,2-C6H4(CH2SbMe2)2]2][PF6]2 (M = Pd or Pt), and [NiI[1,2-C6H4(CH2SbMe2)2]2]ClO4 have been determined, and the varying chelate bite and conformations of the xylyl backbone in these structures are discussed. Despite the unfavourable seven-membered chelate ring and the large soft antimony donors, 1,2-C6H4(CH2SbMe2)2 proves to be a surprisingly good ligand for late transition metals in medium oxidation states.     

Internal Methylene Transfer Reactions Employing Sulfur Ylides: Stereospecific Epoxide formation 1 2 3

The synthetic utility of sulfur ylides in orgnic chemistry has been successfully explored over the past several years and has provided an easily accessible route to a number of functional groups,⁴ including cyclopropanes,⁵ and optically active epoxides⁶.     

The Effect of Silver Perchlorate of the Reaction of Trialkyl Phosphite with α-Halogenoketones

Abstract

Trialkyl phosphites are known to react with α-halogenoketones to yield β-ketophosphonates (Arbuzov product) or vinyl phosphates (Perkow product) according to coniiitions.¹ α-Hydroxyphosphonate may be formed in addition, in prcltic media.² We have now shown that none of these products is formed in the presence of silver perchlorate (in benzene sclutim); nor could we detect the ketophosphonium perchlorate reported previously. Phosphorus-31 nmr showed the formation of trimethyl phosphate and tetramethyl pyrophosphate as the exclusive phosphorus-containing products. The sequence of possible reaction is complex and the overall stoichiometry may vary somewhat according to the rate and order of rixing. Trialkyl phosphate could be formed by elimination of alkyne from vinyloxyphosphonium intermediate produced together with silver iodine in first stage of the interaction. Pyrophosphate formation would then result from nucleophilic attack of trimethyl phosphate on the trimethoxy(1-nethylvinyloxy)phosphoniun ion, which may be formed as a reactive intermediate. Evidence for formation of methyl perchlorate in the final dealkylation of the quasiphosphonium intermediate is provided by proton nmr spectroscopy and by the formation of the N-methylquino-linium salt on addition of quinoline. No change in the ³¹P nmr spectrum occurs at this stage. Other by-products of the main reactions include the dehalogenated ketone (acetone from iodoacetone or acetnphenone from α-iodoacetophenone).