SYNTHESIS OF DIHYDRODIOLS OF PHENANTHRO[3,4-b]THIOPHENE AND PHENANTHRO[4,3-b]THIOPHENE

A number of sulfur analogs of polynuclear aromatic hydrocarbons (thia-PAHs) have been identified in cigarette smoke condensate. Phenanthro[3,4-b]thiophene (P[3,4-b]T) and phenanthro[4,3-b]thiophene (P[4,3-b]T) are sulfur analogs of benzo[c]phenanthrene, which is known to be metabolized to one of the most tumorigenic fjord region diol epoxides tested thus far. Although fjord region diol epoxides of P[3,4-b]T and P[4,3-b]T are expected to be potent mutagens and tumorigens, these two thia-PAHs differ greatly in their mutagenic potencies. In contrast to P[3,4-b]T which is as mutagenic as benzo[a]pyrene, its isoster P[4,3-b]T is a nonmutagenic compound. In order to understand the basis underlying the difference in the mutagenic potency of P[3,4-b]T and P[4,3-b]T, we require these thia-PAHs and their dihydrodiol derivatives for investigating their metabolism and mutagenic/carcinogenic activity. In these studies, we have investigated the Suzuki cross-coupling reaction for an abbreviated synthesis of P[3,4-b]T, P[4,3-b]T, and their dihydrodiol derivatives from easily available reagents.     

ALTERED MOBILITY OF BENZ[a]ANTHRACENE IN THE PRESENCE OF p-XYLENE AND ITS IMPACT ON RISK IN THE SUBSURFACE

Concerns over soil and groundwater contamination by PAHs have been raised as they are often introduced into the subsurface as nonaqueous-phase liquid (NAPL) mixtures. However, characterizing the risk posed by a mixture of chemicals is a challenging task due to its uncertainty in quantifying the effects of the interaction between substances. This study focuses on the effects of phase-transforming interaction on the fate, transport, and risk assessment of a PAH in a PAH - NAPL mixture. The cell test was carried out using benz[a]anthracene (BaA) and p-xylene to verify the increased mobility of highly sorbed pollutants in the presence of less sorbed, mobile liquid pollutants. The experimental results showed that BaA had greater mobility in the presence of p-xylene than in its absence. The main transport mechanisms in the vadose zone were by dissolution into p-xylene or water. The developed model showed that transport of BaA was significantly faster in the presence of NAPL, but needs improvement. As well, risk assessment indicated that the oral carcinogenic risk of BaA calculated with the concentration in groundwater was 15～ 87 times larger when mixed with NAPL than when present as a single contaminant. This study demonstrated that consideration of phase-transforming interaction is necessary to analyze the risk of a PAH - NAPL mixture. The improvement of the transport model will be the topic of our continuing research.     

FORMATION OF SULFATE CONJUGATES METABOLITES IN THE DEGRADATION OF PHENANTHRENE,ANTHRACENE, PYRENE AND BENZO[A]PYRENE BY THE ASCOMYCETE ASPERGILLUS TERREUS

Abstract

The metabolism of four PAHs (phenanthrene, anthracene, pyrene and benzo(a)pyrene) by an Aspergillus terreus strain, isolated from a polluted soil, was investigated in liquid submerged culture. The main metabolites identified by the HPLC-MS technique, after solvent extraction of the fermentation broth and mycelium, were aryl-sulfates and hydroxyl-aryl-sulfates. A metabolic pathway was identified involving in sequence: the hydroxylation by a monooxygenase of the PAHs, the conjugation with a sulfate ion, followed by a further hydroxylation to hydroxyl-aryl-sulfates compounds. PAHs degradation by A. terreus yielded a different number of metabolite isomers depending on the type of the parent PAH. The environmental fate and ecotoxicity of the metabolite 9-phenanthrenesulfate was also investigated by a respirometric test of ready biodegradability and by a Vibrio fischeri acute toxicity test respectively. This compound was easily degradable by microbial consortia derived from polluted soil and capable of thriving on phenanthrene as its sole carbon source. Moreover the sulfate conjugate resulted in 2 orders of magnitude less toxic than its precursors phenanthrene.     

A FACILE SYNTHESIS OF 11,12-DIMETHOXYDIBENZO[def,p]CHRYSENE,A PREFERRED PRECURSOR FOR THE SYNTHESIS OF THE PROXIMATE AND ULTIMATE CARCINOGENS OF DIBENZO[def,p]CHRYSENE (DBC)

A concise, convergent synthesis of 11,12-dimethoxydibenzo[def,p]chrysene (5), a preferred precursor for the synthesis of the carcinogenic metabolites of a highly potent carcinogen dibenzo[def,p]chrysene (DBC, 1) has been described. Suzuki cross-coupling reaction of 5,5-dimethyl-2-(3,4-dimethoxy-2-formyl)-1,3,2-dioxaborinane (6a) with 7-bromo-5,6-dihydro-4H-benz[de]anthracene (7) afforded 7-(2-formyl-3,4-dimethoxyphenyl)- 5,6-dihydro-4H-benz[de]anthracene (9). Treatment of 9 with an excess of potassium tert-butoxide produced 11,12-dimethoxydibenzo[def,p]chrysene (5) in overall 51% yield based on 6a.     

高效化学发光材料9，10－二苯乙炔基蒽的合成

以苯乙炔和蒽醌为原料，采用非氨基锂路线，合成了高效化学发光材料９，１０－二苯乙炔基蒽以质谱和荧光光谱鉴定了结构。     

高效化学发光材料9，10－二苯乙炔基蒽的合成

以苯乙炔和蒽醌为原料，采用非氨基锂路线，合成了高效化学发光材料９，１０－二苯乙炔基蒽以质谱和荧光光谱鉴定了结构。