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140. Extensive reduction of coal by a new electrochemical method
394
CARBON
The spectrum of the maximum extinction coefficient showed a peak near 256OA, and that of the maximum refractive index near 27OOA. This is typical of resonance phenomena associated with anomalous dispersion. The spectra of the minimum refractive index and extinction coefficient showed no significant peaks near the above-mentioned wavelength. 137. Acidic surface oxides on carbon H. P. Boehm, E. Diehl and R. Sappok (Anorganisch-Chemisches Institut der Universitat, Heidelberg, Germany). Heat-treated sugar charcoal was oxidized with oxygen at ca. 450°C. By neutralization with bases of varying basicity, 4 groups of different acidity were detected. These groups were present in equivalent amounts and, therefore, probably belong to a larger grouping. The different acid functions were characterized by other reactions. The presence of carboxyl groups, fluorescein-type Iactones and phenolic hydroxyl groups is likely. A model explaining the observed reactions is discussed. Surface oxides were also formed by oxidation of diamond. The normally hydrophobic diamond became hydrophilic on treatment with NaOCl solutions or other oxidizing agents. Some reactions of the surface oxides on diamond are described. 138. Hydrogen
reaction
with carbon
and nickel
evaporated
arns
V. R. Dietz and E. F. McFarlane (U.S. Department of Commerce, National Bureau of Standards, Washington, DC.). Stacked films of carbon and nickel were prepared in vacuum by intermittent evaporation from separate filaments and a few properties of these films studied. The surface areas were determined by krypton adsorption. The temperature was progressively increased from that of liquid nitrogen, at which the films were prepared, to 300°C and the reaction of hydrogen with the stacked film was followed at each temperature by pressure change and by gas-phase composition. Methane was formed in appreciable amounts; pure carbon films under the same conditions did not react with hydrogen to form methane. The deliberate introduction of oxygen poisoned the hydrogen reaction with stacked films. The yield of methane is directly proportional to the hydrogen chemisorbed at the temperatures studied (2%300°C). 139. Surface
hydroxyl
groups
in carbon
blacks
P. H. Given and Loren W. Hill (Pennsylvania State University, University Park, Pennsylvania). Most previously reported methods for determining hydroxyl groups on the surface of carbon blacks have been unsatisfactory, and various new procedures have been explored. Radiochemical counting of the product obtained by treating blacks with C’*-labelled acetic anhydride in pyridine at 90-100” indicates an acetyl content corresponding to O&3.2% 0 as OH in a series of blacks of volatile matter ranging from 2 to 14%; these figures represent roughly 50-60x of the total oxygen. Only about one-third of the C’” activity is removed by conventional acid hydrolysis. Subsequent hydrolysis of acid-hydroiysed products with sodium hydroxide in 50% methanol-water removed a further 20-35% of the radioactivity. The acetyl content of treated blacks, as measured by acid hydrolysis of non-labelled acetylation product, appears to be still increasing slowly after 144 hours reaction. The silicon content of these blacks treated with hexamethyldisilazane in pyridine indicated trimethylsilyl ether formation corresponding to 0.3-0.4x 0 as OH (compare, for the same blacks, 0.2-0.3 % 0 as OH by acetylation and acid hydrolysis). The results suggest that (a) in treatment with acetic anhydride some acetyl is introduced in a nonhydrolysable form, e.g. on C-atoms instead of 0, and (b) reactions of OH in blacks are slow. It is suggested that the results considered as a whole provide a reasonably satisfactory proof that phenolic OH groups are present in blacks, though their exact nature and amount are not yet established. 140. Extensive reduction of coal by a new electrochemical method Raymond E. Markby, Heinz W. Sternberg and Irving Wender (Pittsburgh Research Center, U.S. Bureau of Mines, ~ttsburgh, P~~lva~a). Electrolytic reduction at room temperature of a high rank,
395
ABSTRACTS
low volatile bituminous coal in ethylenediamine saturated with lithium chloride resulted in addition of 36 hydrogens per 100 carbon atoms. The reduced coal is a tan-grey in color; 73 per cent of this material is soluble in pyridine at room temperature. The solubility of the original coal in pyridine is about 3 per cent. Until this work, the best electrochemical reduction reported was carried out in dimethylformamide and resulted in the addition of 14 hydrogens per 100 carbon atoms. The advantage of ethylenediamine over dimethylformamide is probably connected with the fact that ethylenediamine can solvate lithium. Experiments indicate that lithium acts as an electron transfer agent in the reduction of benzene in the ethylenediamine-lithium chloride system.
141. Oxidation of carbon black with oxygen: formation of surface oxygen groups A. I. Medalia and E. Hagopian (Cabot Corporation, Cambridge, Massachusetts). The oxidation
of pelletized carbon black with oxygen-nitrogen mixtures has been studied in a batch process in a fluid bed reactor. Samples were withdrawn at intervals during each run and analyzed for surface oxygen groups (carboxyl, phenol, quinone, and Iactone) by the method of Rivin (Proceedings of the Fourth Rubber Technology Conference, London, May, 1962, in press). The surface area (by nitrogen adsorption) and the total amount of combined oxygen per gram of carbon increased during an oxidation run, but the rate of combustion and of formation of oxygen groups decreased. The concentration of various oxygen groups per unit surface area reached a limiting value during an oxidation run. The oxygen groups which are analyzed are stable under the reaction conditions and are not intermediates in the combustion. They appear to be formed at a definite concentration on favored sites distributed over the fresh surface area developed by combustion. X-ray diffraction studies indicate that the amorphous carbon or single layer planes are burned away preferentially. 142. Chemical
properties of C,, a dicarbene* P. S. Skell and L. D. Wescott (PennsyZvaniu State University, University Park, Pennsylvania).
The chemical properties of C,, a substance which has been detected in cometary atmospheres (A. E. DOUGLAS, Astrophys. J. 114, 455, 1951), as well as in carbon vapor (W. A. CHUPKA and M. G. INGHRAM, J. Phys. Chem. 59,100,1955), are being investigated. Carbon vapor produced in vacua (10-3-10*-5mm) reacts at a liquid nitrogen cooled surface with olefins to produce homologs of the parent substance bis-ethanoallene. Isobutylene reacts to produce l,l,l’,l’-tetramethyl-bis-ethanoallene. A low voltage mass spectrum shows a parent peak at 148 mass units. A strong adsorption in the infrared at 4.88~ is attributed to the strained allene system (H. D. HARTZLES, J: Amer. Chem. Sot. 83, 4990, 1961). The proton magnetic resonance shows two unsplit absorptions with intensities of 1:3 at 8.67 and 8.722 respectively. In the case of the reaction with propylene, three diasteroismers, in the ratio 1:2:1 are predicted, and found by high resolution gas chromatography. These findings offer chemical proof that C, is the major constituent of carbon vapor and provide a way of more thoroughly studying its chemical properties. *This work was supported Grant AF-AFOSR 62-52.
by the Directorate
of Chemical
Sciences,
Air Force Office of Scientific
Research
under
143. Surface orientations and operating characteristics of some carbon brushes G. Kaye (Morganite Research and Development Limited, Northjields Laboratories, Wandsworth, London, England). Electron diffraction techniques have been used to relate the surface structure of carbon brush materials to their operational behaviour (friction, contact drop, etc.). Two sets of carbons were examined, (a) two-phase carbons prepared from five raw materials (Ceylon graphite, petroleum coke, pitch coke, electrographite and carbon black) which were pitch bonded, kilned at 1250°C and graphitised at 2300 and 2600°C; (b) a set of commercial carbon brush materials. The carbon surfaces were prepared by two techniques, first by multidirectional polishing using diamond pastes and secondly by running on a copper slotted slip ring. The results obtained so far are summarized as follows: (i) On the basis of the
CARBON
The spectrum of the maximum extinction coefficient showed a peak near 256OA, and that of the maximum refractive index near 27OOA. This is typical of resonance phenomena associated with anomalous dispersion. The spectra of the minimum refractive index and extinction coefficient showed no significant peaks near the above-mentioned wavelength. 137. Acidic surface oxides on carbon H. P. Boehm, E. Diehl and R. Sappok (Anorganisch-Chemisches Institut der Universitat, Heidelberg, Germany). Heat-treated sugar charcoal was oxidized with oxygen at ca. 450°C. By neutralization with bases of varying basicity, 4 groups of different acidity were detected. These groups were present in equivalent amounts and, therefore, probably belong to a larger grouping. The different acid functions were characterized by other reactions. The presence of carboxyl groups, fluorescein-type Iactones and phenolic hydroxyl groups is likely. A model explaining the observed reactions is discussed. Surface oxides were also formed by oxidation of diamond. The normally hydrophobic diamond became hydrophilic on treatment with NaOCl solutions or other oxidizing agents. Some reactions of the surface oxides on diamond are described. 138. Hydrogen
reaction
with carbon
and nickel
evaporated
arns
V. R. Dietz and E. F. McFarlane (U.S. Department of Commerce, National Bureau of Standards, Washington, DC.). Stacked films of carbon and nickel were prepared in vacuum by intermittent evaporation from separate filaments and a few properties of these films studied. The surface areas were determined by krypton adsorption. The temperature was progressively increased from that of liquid nitrogen, at which the films were prepared, to 300°C and the reaction of hydrogen with the stacked film was followed at each temperature by pressure change and by gas-phase composition. Methane was formed in appreciable amounts; pure carbon films under the same conditions did not react with hydrogen to form methane. The deliberate introduction of oxygen poisoned the hydrogen reaction with stacked films. The yield of methane is directly proportional to the hydrogen chemisorbed at the temperatures studied (2%300°C). 139. Surface
hydroxyl
groups
in carbon
blacks
P. H. Given and Loren W. Hill (Pennsylvania State University, University Park, Pennsylvania). Most previously reported methods for determining hydroxyl groups on the surface of carbon blacks have been unsatisfactory, and various new procedures have been explored. Radiochemical counting of the product obtained by treating blacks with C’*-labelled acetic anhydride in pyridine at 90-100” indicates an acetyl content corresponding to O&3.2% 0 as OH in a series of blacks of volatile matter ranging from 2 to 14%; these figures represent roughly 50-60x of the total oxygen. Only about one-third of the C’” activity is removed by conventional acid hydrolysis. Subsequent hydrolysis of acid-hydroiysed products with sodium hydroxide in 50% methanol-water removed a further 20-35% of the radioactivity. The acetyl content of treated blacks, as measured by acid hydrolysis of non-labelled acetylation product, appears to be still increasing slowly after 144 hours reaction. The silicon content of these blacks treated with hexamethyldisilazane in pyridine indicated trimethylsilyl ether formation corresponding to 0.3-0.4x 0 as OH (compare, for the same blacks, 0.2-0.3 % 0 as OH by acetylation and acid hydrolysis). The results suggest that (a) in treatment with acetic anhydride some acetyl is introduced in a nonhydrolysable form, e.g. on C-atoms instead of 0, and (b) reactions of OH in blacks are slow. It is suggested that the results considered as a whole provide a reasonably satisfactory proof that phenolic OH groups are present in blacks, though their exact nature and amount are not yet established. 140. Extensive reduction of coal by a new electrochemical method Raymond E. Markby, Heinz W. Sternberg and Irving Wender (Pittsburgh Research Center, U.S. Bureau of Mines, ~ttsburgh, P~~lva~a). Electrolytic reduction at room temperature of a high rank,
395
ABSTRACTS
low volatile bituminous coal in ethylenediamine saturated with lithium chloride resulted in addition of 36 hydrogens per 100 carbon atoms. The reduced coal is a tan-grey in color; 73 per cent of this material is soluble in pyridine at room temperature. The solubility of the original coal in pyridine is about 3 per cent. Until this work, the best electrochemical reduction reported was carried out in dimethylformamide and resulted in the addition of 14 hydrogens per 100 carbon atoms. The advantage of ethylenediamine over dimethylformamide is probably connected with the fact that ethylenediamine can solvate lithium. Experiments indicate that lithium acts as an electron transfer agent in the reduction of benzene in the ethylenediamine-lithium chloride system.
141. Oxidation of carbon black with oxygen: formation of surface oxygen groups A. I. Medalia and E. Hagopian (Cabot Corporation, Cambridge, Massachusetts). The oxidation
of pelletized carbon black with oxygen-nitrogen mixtures has been studied in a batch process in a fluid bed reactor. Samples were withdrawn at intervals during each run and analyzed for surface oxygen groups (carboxyl, phenol, quinone, and Iactone) by the method of Rivin (Proceedings of the Fourth Rubber Technology Conference, London, May, 1962, in press). The surface area (by nitrogen adsorption) and the total amount of combined oxygen per gram of carbon increased during an oxidation run, but the rate of combustion and of formation of oxygen groups decreased. The concentration of various oxygen groups per unit surface area reached a limiting value during an oxidation run. The oxygen groups which are analyzed are stable under the reaction conditions and are not intermediates in the combustion. They appear to be formed at a definite concentration on favored sites distributed over the fresh surface area developed by combustion. X-ray diffraction studies indicate that the amorphous carbon or single layer planes are burned away preferentially. 142. Chemical
properties of C,, a dicarbene* P. S. Skell and L. D. Wescott (PennsyZvaniu State University, University Park, Pennsylvania).
The chemical properties of C,, a substance which has been detected in cometary atmospheres (A. E. DOUGLAS, Astrophys. J. 114, 455, 1951), as well as in carbon vapor (W. A. CHUPKA and M. G. INGHRAM, J. Phys. Chem. 59,100,1955), are being investigated. Carbon vapor produced in vacua (10-3-10*-5mm) reacts at a liquid nitrogen cooled surface with olefins to produce homologs of the parent substance bis-ethanoallene. Isobutylene reacts to produce l,l,l’,l’-tetramethyl-bis-ethanoallene. A low voltage mass spectrum shows a parent peak at 148 mass units. A strong adsorption in the infrared at 4.88~ is attributed to the strained allene system (H. D. HARTZLES, J: Amer. Chem. Sot. 83, 4990, 1961). The proton magnetic resonance shows two unsplit absorptions with intensities of 1:3 at 8.67 and 8.722 respectively. In the case of the reaction with propylene, three diasteroismers, in the ratio 1:2:1 are predicted, and found by high resolution gas chromatography. These findings offer chemical proof that C, is the major constituent of carbon vapor and provide a way of more thoroughly studying its chemical properties. *This work was supported Grant AF-AFOSR 62-52.
by the Directorate
of Chemical
Sciences,
Air Force Office of Scientific
Research
under
143. Surface orientations and operating characteristics of some carbon brushes G. Kaye (Morganite Research and Development Limited, Northjields Laboratories, Wandsworth, London, England). Electron diffraction techniques have been used to relate the surface structure of carbon brush materials to their operational behaviour (friction, contact drop, etc.). Two sets of carbons were examined, (a) two-phase carbons prepared from five raw materials (Ceylon graphite, petroleum coke, pitch coke, electrographite and carbon black) which were pitch bonded, kilned at 1250°C and graphitised at 2300 and 2600°C; (b) a set of commercial carbon brush materials. The carbon surfaces were prepared by two techniques, first by multidirectional polishing using diamond pastes and secondly by running on a copper slotted slip ring. The results obtained so far are summarized as follows: (i) On the basis of the