ISSN:1040-6638    

DOI:10.1080/10406639008034743

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

2,9-Dimethylpicene (2,9-DMPic) has been conveniently synthesized via a new route involving oxidative photocyclization of suitable substituted diarylethylenes and has been characterized by high-resolution 400-MHz1H-NMR spectroscopy. Furthermore, 2,9-DMPic exhibits a typical line narrowed emission spectrum inn-decane matrix frozen at 15 K (Shpol'skii effect). Its unambiguous identification in a natural sample has been performed by this technique, providing strong evidence for the formation of this compound through aromatization of triterpenoid natural precursors. The mutagenicity of this naturally occurring methylated polycyclic aromatic hydrocarbon (PAH) has been examined in sixhis−strains ofSalmonella typhimurium(TA 97, TA 98, TA 100, TA 102, TA 104, TA 1537) in the presence of a hepatic xenobiotic-metabolizing system. While carcinogenic PAH, used as positive controls, showed potent effects in this system, 2,9-DMPic proved completely inactive.

ISSN:1040-6638    

DOI:10.1080/10406639008034744

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The synthesis of a novel thiophene isoster of aceanthrylene is reported. The sequence involves, a newly observed regiospecific condensation of oxalylchloride to naphtho[2,3-b]thiophene. Reduction of the quinone and dehydrogenation gave the title compound in 28% overall yield. The proton nmr signals of the title compounds were assigned on the basis of COSY and NOE difference spectroscopy. Its isolectronic nature with aceanthrylene is seen in the similarity of the UV spectra.

ISSN:1040-6638    

DOI:10.1080/10406639008034745

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

1,3-Di-tert-butylhexahelicene1was synthesized in 95% yield by irradiation of 2-(3,5-di-tert-butylstyryl)-benzo[c]phenanthrene in hexane in the presence of iodine under anaerobic conditions. NMR-spectroscopy, X-ray analysis and force-field calculations give a consistent picture of the spatial structure of1in solution and in the solid phase. Partial resolution of the mixture of enantiomers was performed by chromatography over silicagel, coated with TAPA. The enantiomers of1are very resistant to racemization, which occurs only with a detectable rate at temperatures above 300°C. Racemization parameters reveal a high enthalpy and in contrast to other helicenes a positive entropy of activation. The mechanism of the racemization is discussed.

ISSN:1040-6638    

DOI:10.1080/10406639008034746

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The atmospheric chemistry of 2-methyl-1-nitronaphthalene and the photolysis of 3- nitrobiphenyl have been investigated. Under atmospheric conditions, photolysis was the dominant loss process for 2-methyl-1-nitronaphthalene, while no photolysis of 3- nitrobiphenyl was observed. These data have been used, together with our previous data concerning the atmospheric reactions of 1-and 2-nitronaphthalene and the formation of nitroarenes from the gas-phase atmospheric reactions of the 2- to 4-ring PAH, to predict ambient nitroarene concentrations. The predicted concentrations of the nitronaphthalenes, 3-nitrobiphenyl, 2-nitrofluoranthene and 2-nitropyrene are compared with ambient air data from Torrance and Glendora, CA, USA.

ISSN:1040-6638    

DOI:10.1080/10406639008034747

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Fifteen cyclopenta[a]phenanthrenes and two chrysenes, previously tested for their ability to induce skin tumours in mice of the Theiler's Original (TO) strain, were retested in Sencar mice by the initiation/promotion regime. The five compounds found to be strong carcinogens in TO mice were approximately equally active in Sencar mice with latent periods not noticably shorter, as had been anticipated from the results of others with polycylic aromatic hydrocarbons such as benzo[a]pyrene. Ten compounds inactive in TO mice also failed to induce tumours in Sencar mice. Of the remaining two compounds, both ethyl derivatives, one was apparently more active in Sencar mice, whilst the other showed the opposite behaviour. Possible reasons for these results are tentatively discussed.

ISSN:1040-6638    

DOI:10.1080/10406639008034748

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Comparative studies of tumor-initiating activity in mouse skin and carcinogenicity in rat mammary gland were conducted with 7,12-dimethylbenz[a]anthracene (DMBA) and selected derivatives. Female SENCAR mice were initiated with DMBA, 1,2,3,4-tetrahydro-DMBA, 2-, 4-, 5-, 9-, and 10-fluoro DMBA, (FDMBA), and promoted with tetradecanoyl phorbol acetate. The same compounds were tested by intramammillary injection in female Sprague-Dawley rats. DMBA, 9-FDMBA, 10-FDMBA and 1,2,3,4-tetrahydr DMBA were strongly tumorigenic in both mouse skin and rat mammary gland, whereas 2-, 4- and 5-FDMBA were weakly active or inactive. In a third experiment DMBA, benzo[a]pyrene, 1,2,3,4-tetrahydro DMBA and 9,10-dimethylanthracene were tested by repeated application on the dorsal skin of Swiss mice. DMBA was the most carcinogenic, followed by benzo[a]pyrene and 1,2,3,4-tetrahydro DMBA, whereas 9,10-dimethylanthracene was inactive. The potent activity of 1,2,3,4-tetrahydro DMBA suggests that the bay-region diol epoxide pathway may not play a significant role in the activation of DMBA in these two target tissues. Some of these compounds can serve as useful models for elucidating the mechanism(s) of activation of DMBA.

ISSN:1040-6638    

DOI:10.1080/10406639008034749

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

PAH metabolism is known to proceed in two successive steps the first one resulting in the production of activated metabolites which are subsequently transformed by the different pathways involved in the second step. Microspectrofluorometry enables the study of the kinetics of these steps on living intact cells in which no imbalance has been introduced artefactually. We have used this technique in order to check the influence of glucose deprivation on these kinetics. 9 and 3-OH-B(a)P have been selected as fluorescent substrates for there are potential substrates for the different pathways of the second step. The physiological cell status was controlled through the level of the intrinsic cellular fluorescence. Glucose deprivation results in a strong decrease of the experimental rate constants characteristic of the metabolism of 9 and 3-OH-B (a)P both in RTG2 and 3T3 cells. Nevertheless the metabolism of 3-OH-B(a)P in 3T3 cells appears to be less sensitive to glucose starvation, a result which remains to be explained.

ISSN:1040-6638    

DOI:10.1080/10406639008034750

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Liquid chromatography (LC) with fluorescence detection and gas chromatography/mass spectrometry (GC/MS) have been compared for the determination of polycyclic aromatic hydrocarbons (PAHs) in a variety of environmental samples. Three sets of data are presented in this paper in which LC/fluorescence and GC/MS were used for the analysis of the same samples. These three data sets include the comparison of results from: (1) certification measurements for three natural matrix Standard Reference Materials (SRM's), (2) an international round robin for the determination of PAHs in air and diesel particulate samples, and (3) the analysis of four marine sediment reference materials. The results from these studies indicate that the two techniques generally provide comparable results for the measurement of PAHs in environmental samples (in the range of 0.1 to 300 ng/g), with differences in the two techniques between 5–20%. However, at low levels, anthracene and perylene are best measured using LC/fluorescence because of their selective and sensitive fluorescence detection characteristics. In contrast, GC/MS provides more accurate results for the determination of benzo[ghi]perylene because of its low fluorescence sensitivity.

ISSN:1040-6638    

DOI:10.1080/10406639008034751

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The solubility of: naphthalene, fluorene, phenanthrene, pyrene, and chrysene in supercritical CO2at two temperatures and pressures up to 200 atm were calculated from fugacities derived via the Peng-Robinson equation of state. The calculated solubilities were correlated with the results of experiments in which polycyclic aromatic hydrocarbons (PAH) in fuel mixtures were extracted with supercritical CO2and analysed by supercritical fluid chromatography and by gas chromatography.

ISSN:1040-6638    

DOI:10.1080/10406639008034752

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor