Soot extracts

Anacleto, J. F., QuiUiam, M. A. and Boyd, R. K., Analysis of fuUerene soot extracts by liquid chromatography-mass spectrometry using atmospheric pressure ionization , in Proceedings of the 41st ASMS Conference on Mass Spectrometry and Allied Topics, San Francisco, CA, May 30-June 4, 1993, p. 1083. 

To surpass the above limitations, new developments have recently enabled access to all of the metallofiillerenes generated by the arc process, not just M C82 (Bolskar and Alford, 2003 Bolskar et al., 2003). Other metallofiillerenes such as M C60, M C70, and M C74 are more prevalent in the arc products, but are not as soluble as M C82 (Diener and Alford, 1998). A recent study of arc-generated Gd metallofiillerenes found that soluble Gd C82 comprises only about 10% of the total metallofullerene product, with the majority, 90%, being other insoluble Gd C2n (Raebiger and Bolskar, 2008). To access the total Gd metallofullerene content, processes other than just arc soot extraction with solvents were implemented. Sublimation effectively removed all fullerenes and metallofiillerenes from the arc soot, leaving the non-fullerene amorphous carbon behind. Direct solvent extraction... 

Cancer was first recognized as an occupational hazard in 1775 when the prevalence of scrotal cancer among London chimney sweeps was noticed. The chemical origin of this form of cancer was not universally accepted until 1922 when it was demonstrated that tumors could be induced on mouse skin using an etheral soot extract (60). Skin cancer was also noted to be an occupational hazard of workers exposed to pitch dust in the coal-briquetting industry (61) and to workers exposed to cmde tar (62). In 1915, tumors were produced in rabbits ears by prolonged application of cmde coal tar (63). Some 38 cases per year have been reported of cutaneous epithelioma in the tar distilling industry over a 25-year period up to 1945 (64). 

We pleasantly remember stimulating discussions on chirality and configurational descriptors with Professor Vladimir Prelog. Our work was supported by the Swiss National Science Foundation. We thank Hoechst AG for samples of pure C70 and fullerene-soot extract enriched in higher fullerenes. 

ESR spectra of La Cs2/ Y Cs2, Ho Cs2, and Tm C82 taken from the solid soot extract were reported by Bartl et al. (1994, 1995a,b, 1996) and showed low resolved but split hyperfine structure, indicating that the metal atoms exist in ionic form in the fullerene cage also in the solid state. The research group also reported (Knorr et al., 1998) the principal values of the hyperfine tensor A and the relative orientation of g and A tensors of M C82 (M = Sc, Y, La) applying three- and four-pulse electron spin-echo envelope modulation techniques (ESEEM). 

Figure 116. Ammonia production based on heavy fuel oil (l.inde flow scheme with Texaco gasification) a) Air separation unit h) Soot extraction c) C02 absorption d) Methanol/H,() distillation e) Stripper f) Mol regenerator g) Refrigerant h) Dryer i) liquid N2 scrubber j) Syngas compressor k) Nil, reactor Material Balance...

The discovery that exposure to exogenous chemicals could lead to cancer in humans was first made in the late 18th century, when Percival Pott demonstrated the relationship between cancer of the scrotum and the occupation of chimney sweepers exposed to coal tar/soot. Other examples noted later were scrotal cancers in cotton spinners exposed to unrefined mineral oils, and cancers of the urinary bladder in men who worked in textile dye and rubber industries due to their exposure to certain aromatic amines used as antioxidants. Experimental induction of cancer by chemicals was first reported in detail by Yamagiwa and Ichikawa in 1918, when repeated application of coal tar to the ear of rabbits resulted in skin carcinomas. Over the next few years, Kennaway and Leitch confirmed this finding and demonstrated similar effects in mice and rabbits from the application of soot extracts, other types of tar (e.g., acetylene or isoprene), and some heated mineral oils. These researchers also observed skin irritation sometimes accompanied by ulcers at the site of application of the test material. Irritation was thought to be an important factor in skin tumor development. However, not all irritants (e.g., acridine) induced skin cancer in mice and conversely, some purified chemicals isolated from these crude materials... 

Figure 32F-5 Chromatograms of whole soot extract (a) and a higher fiillerene fraction (b) obtained with a polymeric ODS column and an ace-tonitriledoluene mobile phase. (Reprinted with permission from F. Diederich and R. L. Whetten, Acc. Chem. Res., 1995, 25, 121. Copyright 1995 American Chemical Society.)...

Recently, in HPLC separations of fullerenes, the octadecyl silica (ODS) bonded stationary phase has been extensively used. " Both polymeric and monomeric ODS phases have been used, and these provide a higher selectivity than other phases. Figure 32F-5 shows the preparative separation of whole soot extract and a higher fullerenes fraction on a polymeric ODS column. These were among the first separations of the individual higher fullerenes. Note the excellent resolution compared with the size-exclusion separation of Figure 32F-4. 

C76 fullerene [135113-15-4] M 912.85, melts above 350". It is now available commercially. After the sequential removal of and C70 fullerenes from soot extracts (see above) on gel permeation columns (e.g. Buckyclutcher 1 column), C76 and higher fullerenes are obtained. These are further separated on a Tridait-TriDNP functionalised silica column. After two HPLC runs on a Cjg reverse phase (Vydac 201 TP C,g) column and eluting with 1 1 MeCN/toluene, pure C76 fuUerene is obtained. The identity is confirmed by HPLC/GPC system with Waters 600E UV/VIS detection, mass and NMR spectroscopy. [Seleque et al. In Kadish and Ruoff (Eds) Fullerenes Recent Advances in the Chemistry and Physics of Fullerenes and Related Mfltena/i The Electrochemical Soc. Inc, Pennington, NJ, 1994 ISBN 1566770823, Diederich Whetten Acc Chem Res 25 119 1992, Diederich et al. Science 254 1768 1991.]... 

Webber et al. (43) investigated the use of the acetone extracts of various soots. Soots were obtained by burning several substances in air, collecting the black residue in acetone, then applying a thin film of soot on the crystal. The extract of chlorobenzoic acid soot provided the best coating, and was sensitive to H2S in the concentration rage 1-60 ppm. Attempts were made to characterize the reaction by gas chromatographic measurement of major components, elemental analysis and IR. However, there was not sufficient information either to determine the reaction mechanism or characterize the soot extract. 

The isolation and characterization of D2 Synmictrical Cyg in 1991 [1] led to important conclusions It was shown that pure fuUerenes with more than 70 carbon atoms could be isolated in macroscopic quantities from soot produced by the Kratschmer-Huffrnan method [2] and that the vaporization of achiral graphite was able to generate chiral carbon cages. Mass spectrometric evidence for the presence of higher fullerenes - that is, carbon molecules (n > 70) - in crude fullerene soot extract had been obtained shortly before, and optimization of the fullerene purification protocol soon afforded milligram samples of material enriched in higher fullerenes [3]. 

Hydroxylated metabolites of PAH [Me Clusky (49)), amino-derivatives of PAH [Wilson [43)) in solvent refined coal and nitro-PAH [Schuetzle et al. (44)) in fractions of diesel soot extract have all been identified and sometimes quantified by MS-MS procedures. 

Only one year after fullerenes Cgo and C70 became available in multigram amounts, the first chiral carbon cage Cj -D2 was chromatographically isolated from fullerene soot extract [47]. Since then, a large number of chiral fullerene derivatives have been obtained [48] and classified on the base of their chirality as follows ... 

Fig. 4.24. HPLC profiles of soot extracts in the separation of fullerenes. (a) Crude extract of the soot (b) higher fullerene mixture after removal of Ceo and most of the C70. S = solvent, x = unknown impurities. Reproduced with permission from Diederich F, Whetten RL (1992) Acc. Chem. Res. 25 119...

Figure 38 Raman spectrum of a final soot extract [112]. (Reproduced from Chemical Physics Letters, 256, Voicu, L, et aL, Laser synthesis of fullerenes from benzene-oxygen mixtures, pp. 261-268. Copyright 1996, with permission from Elsevier Science.)... 

As an example of a complex mixture of compounds requiring metabolic activation, we have used the methylene chloride extract of kerosene soot. Figure 9 illustrates the induction of 6TG mutants in human lymphoblasts. Kerosene soot, at a concentration of 26 /ig/ml, induces a mutant fraction of 12 X 10 . This dose level contains about 0.52 lg/m benzo [a]pyrene (B[a]P), a concentration at which B[a]P is not significantly mutagenic. (No significant increase in mutation at 1 ig/m was observed.) We have tested cyclopenta-[c,d/]pyrene, which constitutes 15% (wt./wt.) of the kerosene soot extract ... 

Figure 1.3 Schematic diagram of the process of generation of fullerene containing soot, extraction of the soluble portion, and chromatography on charcoal-silica for purification.

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