A I R POLLUTION to representative atmospheric samples. The presence of a single crystalline form in the sublimation tube, together with melting point and infrared spectroscopy, indicated the presence of only a single aldehyde-formaldehyde. The results were consistent with both bismethone and xanthene derivatives. Formaldehyde cannot be considered the exclusive aldehyde present: The preponderance of formaldehyde may interfere with the detection of other aldehydes; other aldehydes may be present in quantities too small to be detected by this method (sensitivity, 1 5 y of xanthene derivative per 3 ml. of solvent, with ultraviolet spectra) ; or aldehydes are present that cannot be detected by the proposed method. T o determine under what conditions aldehydes are produced, the analytical technique was applied to the combustion effluent of fuels burned under conditions of complete and incomplete combustion. Samples were obtained by specifications slightly modified from those of previous work (3, 5). All atmospheric and combustion samples were in an aqueous phase, obtained by condensation of the gaseous combustion effluent or steam stripping of the particulate component. Formaldehyde was again the only detectable aldehyde and was produced under all but stoichiometric conditions. Even under conditions of apparently complete combustion large quantities of formaldehyde may be produced, proportional within limits to the flow of secondary air. This increase in production is probably due to a cooling action. During incomplete combustion, formaldehyde is always produced in relatively large quantities, but as the flow of secondary air increases, the flame and effluent characteristics begin to approach that of complete combustion, with the aldehyde production being inversely proportional to the flow of secondary air. Beyond a certain point with respect to secondary air flow the cooling effect again becomes dominant, causing an increase in aldehyde production. Because of inherent limitations during combustion, this latter point can be only quantitatively exemplified by using methane as the fuel. Quantitative measurements of the effect of secondary air on aldehyde production during combustion are given in Table 11. The inference from this study on possible atmospheric contamination by controlled combustion processes is selfevident. I n general practice large quantities of secondary air may be introduced to eliminate the smoke plume. A visible atmospheric contaminant may be replaced by an invisible contaminant unless close control over secondary air is maintained.
CONDENSERS
CHAMBER
Samples were handled in an aqueous phase in this burner and combustion system
(REAGENT GRADE) TANK SOURCE
I1 I~T~AIR
SUCTION PUMP
I*AIR TANK SOURCE
FREEZE-OUT TRAPS
EXHAUST
literature Cited (1) Horning, E. C., Horning, M. G., J . Org. Chem. 11, 95 (1946). (2) Klein, G., Linser, H., Mikrochem. PregE Festschr. 204 (1929). (3) Tebbens, B. D., Thomas, J. F., Sanborn, E. N., Mukai, M., Am. Znd. Hyg. Assoc. Quart. 18, 165 (1957). (4) , , Thomas. J. F.. Sanborn. E. N.. Mukai. M., Tebbkns, B,’ D., Anal.‘Chem. 30, 1954 (1958’1. (Sf Thomas, J. F., Tebbens, B. D., Mukai, M., Sanborn, E. N., Zbid., 29, 1835 (1 957). (6) Vorlander, D., Z. anal. Chem. 77, 32 (1929). (7) Yoe, J. E., Reid, L. C., IND. ENG. CHEM.,ANAL.ED. 13, 238 (1941). RECEIVED for review September 18, 1958 ACCEPTEDFebruary 17, 1959 Work supported by research grant RG.4281, National Institutes of Health, U. S.
Public Health Service. A cooperative effort within the University of California of the School of Public Health and the College of Engineering.
The Physiological Response of Guinea Pigs to Atmospheric Pollutants Mary 0. Amdur D e p a r t m e n t of Physiology, H a r v a r d School of Public Health, Boston, Mass.
The complete manuscript, condensed here, was published in the lnfernafional Journal of Air Pollution 1,
170-83 ( 1 959).
IF
THE RESULTS of toxicological studies are to be applied to air pollution, the gradient between the low concentrations occurring even during periods of prolonged meteorological inversion over heavily polluted urban areas and the
high concentrations necessary to produce lung damage and death in experimental animals must be overcome. Methods used in this investigation permit quantitative evaluation of the response of guinea pigs to irritant air pollutants at concentrations of the order of magnitude of those occurring during episodes of acute pollution and below those encountered routinely within industrial plants. The primary response to the irritants tested was bronchial constriction, which produced an increase in the resistance offered to flow of air in and out of the lungs. As evaluated by the increase in pulmonary flow resistance and in the work of breathing, the most potent irritant gas tested was formic acid, followed by formaldehyde, acetic acid, and sulfur dioxide in that order. A considerable amount of soluble gas is removed during passage through the upper respiratory tract. In the case of sulfur dioxide, acetic acid, and formaldehyde the response was greater when the gas was breathed through a tracheal cannula, thus bypassing the protective scrubbing effect of the upper airway. The experimental study of mixtures of gases and aerosols has been the subject of much speculation in connection with the acute air pollution disasters. A synergistic toxic action with sulfur dioxide was observed with sulfuric acid mist of 0.8 but not 2.5 microns. The response to sulfur dioxide was increased by a sodium chloride aerosol of 0.04 but 2.5 microns; hence particle size is an important factor in the potentiation of the response to an irritant gas by an aerosol. When the four irritant gases were studied in combination with 10 mg. of sodium chloride per cu. meter, 0.04 micron in diameter, which was itself without effect, the response to sulfur dioxide and to formaldehyde increased but the response to acetic and formic acids remained unchanged. The aeroVOL. 51, NO. 6
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JUNE 1959
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sol, however, prolonged the response after termination of exposure in the case of all four gases. The important factor in the potentiation of an irritant gas by an inert aerosol is not the increase in the actual amount of irritant gas reaching the lungs, but the fact that even a small amount is carried on the aerosol. This is supported experimentally by the fact that the response to formaldehyde plus aerosol is greater than the response to the same amount of the gas alone reaching the lungs through a tracheal cannula. Furthermore, the increase in toxicity is directly related to the aerosol entity as such. This is supported experimentally by the fact that as the aerosol concentration is increased from 3 to 10 to 30 mg. per cu. meter, the response to a given concentration of formaldehyde increases. These data support the suggestion that the inert aerosol carrying irritant gas is deposited on the lung tissue, thus setting up high local concentrations of irritant and producing a response proportionately far greater than would be obtained with the free gas alone. This being the case, further study of mixtures of gases and aerosols is of practical as well as theoretical interest. RECEIVED for review September 18, 1958 ACCEPTED October 28, 1958
Gas Phase Reactions of Nitrogen Oxides with
Olefins Aubrey P. Altshuller and Israel Cohen
Air Pollution Engineering Research, R o b e r t A. Taft Sanitary Engineering Center, Public Health Service, U. S. D e p a r t m e n t of Health, Education, and Welfare, Cincinnati, O h i o
ALTHOUGH
the liquid phase reactions of nitrogen oxides and olefins have been studied (7, 4, 6, 7), relatively little consideration has been given to gas phase reactions, particularly at low partial pressures of reactants (7-4). Some preliminary measurements were made on the products of the reactions between nitric oxide and various olefins. Most of the work was concerned with the reaction of nitrogen dioxide with 2-methyl-l,3-butadiene, 2-methyl-2butene, and 1-pentene at room temperature. In the present study, a film of condensation usually formed on the surface of the reaction flasks during the reactions. These condensates were washed out with solvents and analyzed.
776
With reactant concentrations in the 0.1- to 2.5-mm. range, oxidation as well as nitration occurs. The same two processes have been observed at higher concentrations in the gas phase reactions of olefins with nitrogen oxides ( I , 3, 6). I n liquid phase reactions nitration appears to be the only type of reaction leading to products, and these often include organic nitrates and nitroso compounds (7, 6, 7). Greenish blue solutions indicating nitroso compounds and the ultraviolet spectra of alkyl nitrites were observed when nitrogen dioxide was added to liquid olefins. However, in the gas phase reaction products, no positive indications are found of alkyl nitrites or nitroso derivatives. The oxidation products appear to be the stable ketone or acid which is the end product of the oxidation. Thus in the 2-methyl-2-butene reaction with nitrogen dioxide, acetone and acetic acid appear as oxidation products. A very clear-cut difference in reactivity exists between the 2-methyl-l,3-butadiene and 2-methyl-2-butene and the much less reactive 1-pentene. This greater reactivity of diolefins and internally double bonded olefins with nitrogen oxides has been observed (5). The diolefin, 2-methyl-I ,3-butadiene appears to be somewhat more reactive with nitrogen dioxide and nitric oxide than an internally bonded olefin, 2methyl-2-butene. The diolefin also appears reactive with nitric oxide. In contrast, at all concentrations of 1pentene and nitrogen dioxide used, up to 0.5 mm. of 1-pentene and 2.5 mm. of nitrogen dioxide, a large part of the 1pentene remains even after 24 hours. The nitration products observed in these reactions include nitro compounds and organic nitrates. Certain types of organic nitrogen compounds, including conjugated nitro-olefins, gem-dinitroalkanes, organic nitrites, and nitroso compounds, are not present in detectable quantities. I t is more difficult to ascertain whether the nitro and nitrate groups are present as nitro paraffins, alkyl nitrates, nitro alcohols, nitro nitrates, or dinitro compounds with the nitro groups on adjacent carbons. Some types of nitro nitrates are excluded by the absence of the 7.7- and 7.9-micron bands in the infrared. The absence of 0 - H stretching bands of product in carbon tetrachloride would seem to reduce considerably the possibility of major amounts of simple nitro monoalcohols. However, the C - 0 stretching bands of nitro alcohols are far stronger than the 0 - H stretching bands, so that the weak bands at 8 to 9 microns observed in the condensate from the 2methyl-2-butene and 2-methylbutadiene reactions with nitrogen dioxide could be the strong C - 0 bands in the infrared spectra of pure nitro alcohols. The presence of 1,2- or 2,3-dinitro compounds
INDUSTRIAL AND ENGINEERING CHEMISTRY
cannot be proved conclusively, but their infrared spectra are in agreement with the observed spectra of the condensates. A number of types of carbonyl compounds are indicated by the infrared spectra. The infrared absorption bands of acetone, acetic acid, and formic acid appear in the infrared analysis of the gaseous products and condensate. Traces of aliphatic esters and possibly of ketones are present in the condensate. Very small quantities of a,@-unsaturated carbonyl compounds are also indicated by the infrared spectra of the condensate. Semiquantitative determinations were made of carbonyl compounds in 21 condensates prepared using olefin and nitrogen dioxide concentrations ranging from 0.0 to 0.15 weight yo diluted to 0.25 to 0.5 ml. with carbon tetrachloride. From 0.2 to 2 weight yo water was found in all the condensates. The presence of a trace of methanol was indicated by the infrared spectra in the gas phase of the 2-methyl-2-butene-nitrogen dioxide reaction. Traces of alcohols were probably present in the condensates from the 2-methyl-2-butene and 2methyl-l,3-butadiene reactions with nitrogen dioxide. Small amounts of ketoximes were present in the condensates from both reactions. Automobile exhaust or other combustion effluent stream products cannot be kept at room temperature for more than a few minutes before appreciable amounts of reaction products are formed. Storage of grab samples at reduced temperatures is an obvious alternative. Use of liquid nitrogen temperatures in the handling of automobile exhaust products prior to gas chromatography has been useful (5). Dry ice-acetone temperature or less probably ice-water temperature may be a convenient compromise. I t does not seem possible at present to remove the nitrogen oxides without also removing the oxygenated reaction products. These and previous experiments point up the importance of internally bonded olefins and diolefins in the over-all automotive exhaust problem. literature Cited
(1) Brown, J. F., J . Am. Chem. Sac. 79, 2480 (1957). (2) Brown, J. F., Burkhard, C. A., “Reaction of Nitric Oxide with Isobutylene,” General Electric Research Laboratory Report. (3) Cottrell, T. L., Graham, T. E., J. Chem. Sac. 1953, p. 556; 1954, p. 3644. (4) Gray, P., Yoffe, A. D., Chem. Reus. 5 5 , 1069 (1955). (5) Hurn. R. W.. U. S. Bur. Mines, ’ unpublished work. (6) Michael, A., Carlson, G. H., J . Org. Chern. 4,167 (1939); 5 , l (1940). (7) Riebsomer, J. L., Chem. Revs. 3 6 , I 5 7 (1945). RECEIVED for review September 18, 1958 ACCEPTED April 6 , 1959
