Chemiluminescent sulfide-ozone

Kummer et al. 8) have reported that at pressures of about 0.5 torr, the relative emission intensities of the higher olefins and of the organic sulfides were substantially greater than that of ethylene Table II summarizes the reported relative emission intensities. Since a recently developed commercial ozone monitor is based on the chemiluminescent reaction between ozone and ethylene, this suggests the possibility of using the sulfide-ozone chemiluminescent reaction to monitor the low concentration of sulfur compounds in ambient air. This possibility is being further investigated now. 

Chemiluminescence is also shown with a few simple mineral compounds. Otto (21) expressed the opinion that, if ozone causes a luminescence in the presence of water, it acts upon impurities therein. Hydrogen sulfide gives rise to an ultraviolet chemiluminescence with ozone (Zabiezynski and Orlowski, 33). Several oxygen compounds of nitrogen, especially nitric oxide, show, under the action of ozone, a spectrum different from that of active nitrogen [Morren (20), Sarrasin (23), Strutt (26), Knauss and Murrey (17) ]. Solid phosphorus trixode becomes luminescent [Thorpe and Tutton (29)]] and so do carbon monoxide, carbonyl sulfide, and carbonyl chloride at 200 C. The first of these furnishes a band spectrum of 4000 to 5000 A. which corresponds to a bimolecular process [Trautz and Seidel (31) and Trautz and Haller (30)]. Siloxane too shows oxyluminescence [Kautsky and Zocher (16)] under the influence of ozone. 

More recently, chemiluminescence detectors based on redox reactions have made possible the detection of many classes of compounds not detected by flame ionization. In the redox chemiluminescence detector (RCD), the effluent from the column is mixed with nitrogen dioxide and passed across a catalyst containing elemental gold at 200-400°C. Responsive compounds reduce the nitrogen dioxide to nitric oxide. The nitric oxide is reacted with ozone to give the chemiluminescent emission. The RCD yields a response from compounds capable of undergoing dehydrogenation or oxidation and produces sensitive emissions from alcohols, aldehydes, ketones, acids, amines, olifins, aromatic compounds, sulfides, and thiols. 

The Chemiluminescent Reactions of Ozone with Olefins and Organic Sulfides... 

Spectra from the chemiluminescent gas phase reactions at 0,5 torr, of ozone with ethylene, tetramethylethylene, trans-2-hutene, and methyl mercaptan at room temperature are presented, and a summary of the general features of the emissions obtained from reaction in the gas phase of ozone with fourteen different olefins is given. The emitting species in the ozone-olefin reactions have been tentatively identified as electronically excited aldehydes, ketones, and a-dicarbonyl compounds. The reaction of ozone with hydrogen sulfide, methyl mercaptan, and dimethylsulfide produces sulfur dioxide in its singlet excited state. 

Although higher olefins do not produce detectable chemiluminescence when reacting with ozone at atmospheric pressure (7) at pressures of about one-half torr, light is emitted by these reactions (8). Several organic sulfides also give an emission when they react with ozone at these pressures. 

These reactions may be important for several reasons. It may be possible to use the chemiluminescent reaction of ozone with organic sulfides to monitor the low concentrations of sulfur compounds in urban atmospheres. Also, excited species are being formed, and these reactive intermediates may be important in high altitude atmospheric reactions. Finally, identifying these emitting species should give information about the mechanisms of gas phase ozone reactions. Current progress on these reactions by the authors is reviewed here. 

The chemiluminescence spectrum obtained from the reaction of ozone with methyl mercaptan at a pressure of 0.2 torr is shown in Figure 5. Reaction of hydrogen sulfide with dimethylsulfide with ozone give identical spectra consisting of a broad structureless band centered at approximately 370 nm (uncorrected for spectral sensitivity of the detection system). We have recently shown that this emission is identical to the fluorescence spectrum of sulfur dioxide (16). Since ozone oxidizes hydrogen sulfide to sulfur dioxide and water in the gas phase 17, 18), this result is not surprising. 

The same principle can be applied to measuring sulfur first transformed to sulfur dioxide (SO2) by combustion in the presence of oxygen (Figure 11.16), then reduced to hydrogen sulfide (H2S) before being finally re-oxidized by ozone (with chemiluminescence). 

This reaction enables the detection of sulfur monoxide and other reduced sulfur compounds that can react with ozone to initially form sulfur monoxide. The chemiluminescence intensity depends on the type of compound, with thiols giving the largest response followed by alkyl sulfides, hydrogen sulfide, and thiophenes. Detection limits in the parts per billion range can be achieved for thiols. Alkenes, which also react with ozone to give emission centered at 354 nm, potentially interfere but selectivity can be achieved with a suitable optical filter. 

This is carried out by operating a chemiluminescent NOj analyzer (cf. NO, analysis) at a NO excess condition. As the reaction of ozone with NO is faster and gives more intense CL than that with ethene, this method is preferred for some purposes in which a fast response is required (i.e., aircraft flux measurements). However, this CL method is subject to interference from water vapor and may contaminate the environment with NO. The ozone-NO reaction is also known as a gas-phase titration reaction, in which sample gas is mixed with a low-concentration standard NO gas and the NO2 formed in quantities equivalent to ozone is determined by an appropriate method. While CL reactions of ozone with other alkenes, alkyl sulfides, phosphine, arsine, and stibine... 

B. J., "The Chemiluminescent Reactions of Ozone with Olefins and Organic Sulfides," AdV. Chem. (1972) 113, 256. 

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