Bacterial metabolism of fluorene, dibenzofuran, dibenzothiophene, and carbazole

2000 ◽  
Vol 46 (5) ◽  
pp. 397-409 ◽  
Author(s):  
David C Bressler ◽  
Phillip M Fedorak
Keyword(s):  
Environmental Concern ◽  
Bacterial Degradation ◽  
Bacterial Metabolism ◽  
Aromatic Rings ◽  
Methylene Carbon ◽  
Initial Oxidation ◽  
Methylene Carbon Atom ◽  
Methylene Group ◽  
Angular Dioxygenase ◽  
Chlorinated Dibenzofurans

Fluorene and its three heteroatomic analogs, dibenzofuran, dibenzothiophene, and carbazole, are environmental contaminants in areas impacted by spills of creosote. In addition, dibenzofuran has been used as an insecticide, and it is formed from the photolysis of chlorinated biphenyl ethers. Many biodegradation studies of dibenzofuran have considered it as a model for chlorinated dibenzofurans, which are of greater environmental concern. This paper reviews the bacterial degradation of fluorene and its analogs. These compounds are susceptible to three different modes of initial oxidation: (i) the naphthalene-like attack, in which one of the aromatic rings is oxidized to a dihydrodiol; (ii) an angular dioxygenase attack, in which the carbon bonded to the methylene group in fluorene or to the heteroatoms in the analogs, and the adjacent carbon in the aromatic ring are both oxidized; and (iii) the five-membered ring attack, in which the methylene carbon atom in fluorene or the sulfur atom in dibenzothiophene is oxidized. The metabolites, enzymology, and genetics of these transformation are summarized. Literature data are presented, indicating that the electronegativity of the atom connecting the two aromatic rings influences the attack of the angular dioxygenase. In dibenzofuran and carbazole, the connecting atoms, O and N respectively, have high electronegativities, and these compounds serve as substrates for angular dioxygenases. In contrast, the connecting atoms in dibenzothiophene and fluorene, S and C respectively, have lower electronegativities, and these atoms must be oxidized before the angular dioxygenases attack these compounds.Key words: angular dioxygenase, carbazole, dibenzofuran, dibenzothiophene, fluorene.

scholarly journals Current Status of- and Future Perspectives in- Bacterial Degradation of Benzo[a]pyrene

2020 ◽  
Author(s):  
Alexis Nzila ◽  
Musa M. Musa
Keyword(s):  
Molecular Weight ◽  
Current Knowledge ◽  
Bacterial Degradation ◽  
Current Status ◽  
Low Molecular Weight ◽  
Future Perspectives ◽  
Aromatic Rings ◽  
Compound A ◽  
Current Review ◽  
Polycyclic Aromatic

Polycyclic aromatic hydrocarbons (PAHs), which consist of low-molecular-weight PAHs (LMW-PAHs) and high-molecular-weight PAHs (HMW-PAHs), form an important class of pollutants. Pyrene and benzo[a]pyrene (BaP) are the main pollutants belonging to HMW-PAHs, and their degradation by microorganisms remains an important strategy for their removal from the environments. Extensive studies have been carried out on the isolation and characterisation of microorganisms that actively degrade LMW-PAHs, and to a certain extent, the HMW-PAH pyrene. However, so far, limited work has been carried out on BaP biodegradation. BaP consists of five fused aromatic rings, which confers this compound a high stability, rendering it less amenable to biodegradation. The current review summarizes the emerging reports on BaP biodegradation. More specifically, work carried out on BaP bacterial degradation and current knowledge gaps that limit our understanding of BaP degradation are highlighted. Moreover, new avenues of research on BaP degradation are proposed, specifically in the context of the development of “omics” approaches

HINDERED CONFORMATIONAL ISOMERIZATION OF 9,10-DIHYDRO-9,9-DIMETHYL-10-METHYLENEANTHRACENES

1964 ◽  
Vol 42 (3) ◽  
pp. 565-571 ◽  
Author(s):  
D. Y. Curtin ◽  
C. G. Carlson ◽  
C. G. McCarty
Keyword(s):  
Room Temperature ◽  
Methyl Groups ◽  
Conformational Isomerization ◽  
Methylene Carbon ◽  
Methyl Group ◽  
First Order ◽  
Methylene Carbon Atom ◽  
Center Ring ◽  
Bromo Compound ◽  
Dibromo Derivative

While the n.m.r. spectrum of 10,10-dimethyl-9-methylene-9,10-dihydroanthracene (I) shows the geminal methyl group absorption as a sharp singlet the spectrum of the dibromo derivative, 10,10-dimethyl-9-dibromomethylene-9,10-dihydroanthracene (II) shows the methyl absorptions as two sharp well-separated peaks at room temperature which coalesce at 91°. 10,10-Dimethyl-9-phenylbromomethylene-9,10-dihydroanthracene (III), and the methyl ester (V) of IV show a broad geminal methyl spectrum at room temperature which separates to a doublet at lower temperatures and sharpens to a singlet at higher temperatures. Rate constants for the first-order processes responsible for the change in spectrum of II, III, and V have been calculated at the coalescence temperatures to be 57 (364 °K), 35 (305 °K), and 61 (300 °K) sec−1, respectively. The ΔH≠'s were used to extrapolate the rates to 305° to give values of 1, 40, and 100 sec−1, respectively. The process being studied is inferred to be the equilibrium between two boat conformations of the center ring in the dihydroanthracene system, rapid interconversion leading to identical environments for the two methyl groups. A comparison with the geometrically similar o,o′-disubstituted biphenyl racemization gives support for this explanation. A number of compounds with a proton and one substituent on the methylene carbon atom of I (substituents: bromine, chlorine, phenyl, carboxy, carbomethoxy, phenylmercapto) and also 10,10-dimethyl-9-phenylcarbomethoxymethylene-9,10-dihydroanthracene (XII) showed a single methyl absorption at room temperature. The methyl spectrum of the mono bromo compound VI did not broaden at temperatures down to 246 °K.

scholarly journals The effect of adenosine triphosphate on porphyrin excretion and on glycine metabolism in Rhodopseudomonas spheroides

1968 ◽  
Vol 106 (1) ◽  
pp. 185-192 ◽  
Author(s):  
A. Gajdos ◽  
M. Gajdos-Török ◽  
A. Gorchein ◽  
A. Neuberger ◽  
G. H. Tait
Keyword(s):  
Carbon Dioxide ◽  
Fatty Acid ◽  
Carbon Atom ◽  
Marked Effect ◽  
Methylene Carbon ◽  
Methylene Carbon Atom ◽  
Glycine Metabolism ◽  
Porphyrin Synthesis ◽  
Rhodopseudomonas Spheroides ◽  
Carboxyl Carbon

1. ATP, GTP, CTP and UTP at concentrations of 1mm markedly decrease the amount of coproporphyrin excreted by Rhodopseudomonas spheroides illuminated in a medium containing glycine, succinate and fumarate. 2. The effect of ATP is decreased if ethionine is also added to the medium. 3. Evidence is presented showing that ATP is taken up by the organisms from the medium. 4. ATP is shown to have a marked effect on the utilization of glycine. In the presence of ATP the incorporation of the methylene carbon atom of glycine into the fatty acid moieties of the phospholipids is greatly increased, and more of the carboxyl carbon atom is lost, probably as carbon dioxide. 5. ATP has little effect on the utilization of succinate or fumarate. 6. The possible significance of these results with regard to the control by ATP of porphyrin synthesis and excretion and glycine metabolism is discussed.

The stereochemistry of B -diketo complexes with trim ethylplatinum iv II. The crystal structure of ethyl(trim ethylplatini-)- acetoacetate

1960 ◽  
Vol 254 (1277) ◽  
pp. 218-228 ◽  
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Carbonyl Oxygen ◽  
Crystal Structure Analysis ◽  
Methyl Groups ◽  
Methylene Carbon ◽  
X Ray ◽  
Methylene Carbon Atom ◽  
Critical Account ◽  
Active Methylene

A three-dimensional X-ray crystal structure analysis of the complex between trimethyl platinum and ethylacetoacetate, (CH 3 ) 3 Pt CH 3 . CO. CH. CO OC 2 H 5 , has shown that the molecule is dimeric. In a monoclinic unit cell (a = 8.83, b = 14.12, c = 9.30 Å, β = 95°, space group P2 1 / c ) there are two centrosymmetrical dimeric molecules in which each platinum atom is octahedrally co-ordinated by three methyl groups, in the cis configuration, by the two carbonyl oxygen atoms of one β -ketoester and by the central, or ‘active methylene’ carbon atom of the other β -ketoester in the dimer. The structure is thus essentially the same as that of trimethyl 4:6-dioxononyl platinum (part I) and the result shows that complex formation via a tridentate β -diketo system is preferred to co-ordination through an ester oxygen. A critical account is given of the criteria used to judge the correctness of the results.

scholarly journals Crystal structure of (9S,10S)-10-ethoxy-9-hydroxy-6,6,9-trimethyl-3-pentyl-7,8,9,10-tetrahydro-6H-benzo[c]chromen-1-yl 4-methylbenzenesulfonate

2015 ◽  
Vol 71 (12) ◽  
pp. o1082-o1083 ◽  
Author(s):  
Waseem Gul ◽  
Ahmed Galal ◽  
Mahmoud A. ElSohly ◽  
Paulo Carvalho
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Hydrogen Bonds ◽  
Chair Conformation ◽  
Heterocyclic Ring ◽  
Helical Chain ◽  
Aromatic Rings ◽  
Compound C ◽  
Cyclohexene Ring ◽  
Methylene Group

In the structure of the title compound, C30H40O6S, the cyclohexene and heterocyclic rings are linked by a double bond. The cyclohexene ring has a half-chair conformation (the methylene group adjacent to the hydroxy substituent lies above the remaining atoms) and the hydroxy and ethoxy groups have equatorial and bisectional dispositions, respectively. The heterocyclic ring has an envelope conformation (with the CMe2C atom being the flap). The dihedral angle between the aromatic rings is 53.88 (10)°. A long intramolecular C—H...S interaction is noted. In the molecular packing, hydroxy-O—H...O(sulfonate) hydrogen bonds lead to a helical chain along [010]. Connections between chains are of the type methyl-C—H...O(sulfonate) and lead to supramolecular layers that lie parallel to (001). The studied crystal was an inversion twin.

The stereochemistry of β -diketo complexes with trimethylplatinum iv. III. The crystal structure of trimethyl (acetylacetonyl-) 2:2'-bipyridyl platinum

1962 ◽  
Vol 266 (1327) ◽  
pp. 527-546 ◽  
Keyword(s):  
Crystal Structure ◽  
Carbon Atom ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Method Of Least Squares ◽  
Methylene Carbon ◽  
X Ray ◽  
Methylene Carbon Atom ◽  
Active Methylene ◽  
Oxygen Atoms

The results of an X -ray crystal structure analysis of the crystalline complex, (CH 3 ) 3 Pt(CH 3 . CO . CH . CO . CH 3 )C 10 H 8 N 2 , formed by trimethylplatinum with acetylacetone and 2:2'-bipyridyl are presented. There are four monomeric molecules in a monoclinic unit cell having a = 14.863, b = 8.480, c = 13.749 Å, β = 99° 24' at 110±10 °K and space group P 2 1 / c . The atomic positions have been determined by three-dimensional analysis from observations collected at 100 to 120 °K. Refinement, including allowance for anisotropic thermal motion, was carried out by the method of least squares until the value of the residual R was 0.084. The platinum atom is octahedrally co-ordinated to three methyl groups in the cis configuration (Pt—C = 2.05 Å), to the two nitrogen atoms of the bipyridyl (Pt—N = 2.15 Å) and to the central or ‘active methylene’ carbon atom of acetylacetone (Pt—C = 2.36 Å). The oxygen atoms of the acetylacetone take no part in the co-ordination; this is the first example of a β -diketone acting as an unidentate ligand solely through a carbon atom. Comparison of the bond lengths in this and in the dimeric trimethyl 4:6-dioxononyl platinum suggests that in both compounds the β -diketone is in the keto and not the enol form; in the present compound the oxygen atoms are not chelated and the C=0 bonds are not parallel.

The Synthesis of 5,7-Dichlorocoumaran-3-one and Related Problems

1960 ◽  
Vol 13 (1) ◽  
pp. 95 ◽  
Author(s):  
WLF Armarego
Keyword(s):  
Acetic Acid ◽  
Carbon Atom ◽  
Intramolecular Cyclization ◽  
Phosphorus Pentoxide ◽  
Dichlorophenoxyacetic Acid ◽  
Methylene Carbon ◽  
Methylene Carbon Atom ◽  
Stage Synthesis ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Dichlorophenoxy Acetic Acid

5,7-Dichlorocoumaran-3-one has been prepared from methyl 2-hydroxy-3,5-dichlorobenzoate by a three stage synthesis. It could not be prepared by (i) intramolecular cyclization of 2,4-dichlorophenoxy- acetic acid or 2,4-dichlorophenoxyacetyl chloride or (ii) by the reaction of ω-bromo-2-hydroxy-3,5-dichloroacetophenone with bases. The reaction of 2,4-dichlorophenoxyacetic acid with phosphorus pentoxide in benzene gave 2,4-dichlorophenol, 2',4'-dichlorophenyl 2,4-dichlorophenoxyacetate, and diphenylmethane. By the use of 14C-labelled acids the methylene carbon atom of the diphenylmethane was shown to be derived from the methylene carbon atom of 2,4-dichlorophenoxyacetic acid. A possible mechanism is proposed for this reaction.

Study of the Molecular Dynamics from Deuterium Zeeman and Quadrupolar NMR Relaxation of 4,4´-di-n-Heptylazoxybenzene in the Nematic and Smectic A Phases

1994 ◽  
Vol 49 (1-2) ◽  
pp. 311-319 ◽  
Author(s):  
C. Forte ◽  
M. Geppi ◽  
C. A. Veracini
Keyword(s):  
Diffusion Coefficients ◽  
Pulse Sequence ◽  
Pulse Sequences ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Aromatic Rings ◽  
Spin Lattice ◽  
Smectic A ◽  
Methylene Group ◽  
Negligible Contribution

Abstract The deuterium spin-lattice (T1Z) and quadrupolar (R1Q) relaxation times of the liquid crystal 4,4´-Heptyl-azoxybenzene (HAB), deuterated on the aromatic rings and the first methylene group of the chains, have been measured by means of the Jeener-Broekaert pulse sequence at two different frequencies (10 and 46.04 M Hz) and throughout the nematic and the smectic A phase. By applying suitable models, we have determined rotational and reorientational diffusion coefficients and evalu­ated the contribution of the different motions (internal, molecular and collective) to the relaxation. In particular we have found a non negligible contribution from order director fluctuations. A comparison between the T1Z and T1Q measurements performed by means of Jeener-Broekaert and Wimperis pulse sequences is also shown.

scholarly journals SN2 and SN2′ reaction dynamics of cyclopropenyl chloride with halide ion — A direct ab initio molecular dynamics (MD) study

2005 ◽  
Vol 83 (9) ◽  
pp. 1597-1605 ◽  
Author(s):  
Hiroto Tachikawa
Keyword(s):  
Molecular Dynamics ◽  
Reaction Mechanism ◽  
Ab Initio ◽  
Gas Phase ◽  
Reaction Channel ◽  
Ab Initio Molecular Dynamics ◽  
Methylene Carbon ◽  
Methylene Carbon Atom ◽  
Halogen Exchange ◽  
Collision Angle

Direct ab initio molecular dynamics (MD) calculations have been carried out for the reaction of cyclopropenyl chloride with halide ion (F–) (F– + (CH)3Cl → F(CH)3 + Cl–) in gas phase. Both SN2 and SN2′ channels were found as product channels. These channels are strongly dependent on the collision angle of F– to the target (CH)3Cl molecule. The collision at one of the carbon atoms of the C=C double bond leads to the SN2′ reaction channel; whereas the collision at the methylene carbon atom leads to the SN2 reaction channel. The reactions proceed via a direct mechanism without long-lived complexes. The reaction mechanism is discussed on the basis of the theoretical results.Key words: SN2 reaction, direct ab initio molecular dynamics, halogen exchange, reaction mechanism.

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