Ozonation reaction products

Ozone Reaction product of VOC and nitrogen oxides Not produced directly Irritant to eyes and respiratory system... 

The most effective antiozonants are the substituted PPDs. Their mechanism of protection against ozone is based on the scavenger-protective film mechanism [68-70]. The reaction of ozone with the antiozonant is much faster than the reaction with the C=C bond of the rubber on the rubber surface [56]. The rubber is protected from the ozone attack tUl the surface antiozonant is depleted. As the antiozonant is continuously consumed through its reaction with ozone at the mbber surface, diffusion of the antiozonant from the inner parts to the surface replenishes the surface concentration to provide the continuous protection against ozone. A thin flexible film developed from the antiozonant/ozone reaction products on the mbber surface also offers protection. 

Ozone. Reaction products with ozone are particularly dangerous.5... 

The protective film mechanism in which the antiozonant diffuses to the surface and forms a protective film over the rubber in a manner similar to that of the protective waxes. A modification of this proposal suggests that it may be an antiozonant-ozone reaction product that is the effective agent. 

Oxidation of vinyl chloride with ozone [10028-15-6] in either the Hquid or the gas phase gives formic acid and formyl chloride. The ozone reaction with vinyl chloride can be used to remove it from gas streams in vinyl chloride production plants. 

Several theories have appeared in the Hterature regarding the mechanism of protection by -PDA antiozonants. The scavenger theory states that the antiozonant diffuses to the surface and preferentially reacts with ozone, with the result that the mbber is not attacked until the antiozonant is exhausted (25,28,29). The protective film theory is similar, except that the ozone—antiozonant reaction products form a film on the surface that prevents attack (28). The relinking theory states that the antiozonant prevents scission of the ozonized mbber or recombines severed double bonds (14). A fourth theory states that the antiozonant reacts with the ozonized mbber or carbonyl oxide (3) in Pig. 1) to give a low molecular weight, inert self-healing film on the surface (3). 

The relinking (14) and self-healing film (3) theories require chemical interaction between the antiozonant and ozonized mbber. The evidence for these interactions is meager (35,36). Overall, there seems to be no clear evidence in the Hterature for PDA derivatives becoming attached to mbber chains as a result of ozone attack. Much fundamental work in this area remains to be done, however. It seems clear at this point that any antiozonant—mbber interaction must be much less important than the scavenging effect of the antiozonant. In summary, the scavenger model is beheved to be the principal mechanism of antiozonant action. Ozone—antiozonant reaction products form a surface film that provides additional protection (37). 

The location of the position of double bonds in alkenes or similar compounds is a difficult process when only very small amounts of sample are available [712,713]. Hass spectrometry is often unsuited for this purpose unless the position of the double bond is fixed by derivatization. Oxidation of the double bond to either an ozonide or cis-diol, or formation of a methoxy or epoxide derivative, can be carried out on micrograms to nanograms of sample [713-716]. Single peaks can be trapped in a cooled section of a capillary tube and derivatized within the trap for reinjection. Ozonolysis is simple to carry out and occurs sufficiently rapidly that reaction temperatures of -70 C are common [436,705,707,713-717]. Several micro-ozonolysis. apparatuses are commercially available or can be readily assembled in the laboratory using standard equipment and a Tesla coil (vacuum tester) to generate the ozone. Reaction yields of ozonolysis products are typically 70 to 95t, although structures such as... 

Vinylidene Chloride Monomer , 9, Midland (Mich ), Dow Chemical Co., 1968 The reaction products formed with ozone are particularly dangerous. 

In this study, synthetic aqueous solutions of phenol were treated with ozone. The reaction of ozone with phenol was investigated at several conditions, such as different phenol and ozone concentrations, and contact times. Total Organic Carbon (TOC) and UV analysis of the aromatic by-products formed during and after the ozonation reaction were employed. The reaction rates calculated from TOC analysis were investigated. 

Seventy-five milliliters of samples were collected from reaction column upper end at different time intervals during the ozonation reaction for the determination of the by products. Ozonation of phenol was carried out at four different initial concentrations, 25, 50, 75 and 100 mg/L, with three different ozone concentrations 2, 4 and 6 g/L h. 

This initial attack of the ozone molecule leads first to the formation of ortho- and para-hydroxylated by-products. These hydroxylated compounds are highly susceptible to further ozonation. The compounds lead to the formation of quinoid and, due to the opening of the aromatic cycle, to the formation of aliphatic products with carbonyl and carboxyl functions. The nucleophilic reaction is found locally on molecular sites showing an electronic deficit and, more frequently, on carbons carrying electron acceptor groups. In summary, the molecular ozone reactions are extremely selective and limited to unsaturated aromatic and aliphatic compounds as well as to specific functional groups. 

The main purpose of this chapter is to survi atmospheric concentrations of photochemical oxidants, with emphasis on surface concentrations and the distribution patterns associated with them. The reason for that em> phasis is that the photochemical oxidants that affect public health and welfare are largely concentrated in this region. The whole subject of stratospheric ozone (and its filtering of ultraviolet light and interactions with supersonic-transport exhaust products), nuclear weapon reaction products, and halogenated hydrocarbon decomposition pr ucts is not treated here. 

To prevent the formation of reaction products from the interaction of the ozone-air sample with Alters, they arc intentionally not used at probe inlets (see Table 6-4). Some of the newer instruments, however, require Alters at the inlet of their sampling ports to prevent the particulate matter in the ambient air from fouling reaction-chamber cells or from clogging the gas-flow controllers. When the same type of Alter also precedes the calibration and zero gas sampling ports (which has not always been the practice), the problem is minimized to the extent that similar events occur during the calibration and sampling. 

Bell, K. A., W. S. Linn, and J. D. Hackney. Effects on pulmonary function of humans exposed to mixtures of ozone, sulfur dioxide, and their reaction products. Fed. Proc. 34 428, 1975. (abstract)... 

These studies, although few, suggest that exposure to photochemical oxidants can influence fertility and fecundity in animals and that the genera] health of newborn animals is much more likely to be impaired by exposure to oxidants than that of their parents. Whether the changes observed in reproduction variables can be related to mutagenic actions of ozone, discussed earlier, remains to be determined. In any event, it seems logical that effects of low concentrations of ozone and other photochemical oxidants on reproduction must be indirect and may be mediated by endocrine or ozone-biologic reaction products. 

There are several reports of noteworthy extrapulmonary effects in laboratory animals with concentrations of about 0.2 ppm. These include reduced voluntary activity, chromosomal aberrations in circulating lymphocytes of hamsters, increased neonatal mortality, and greater incidence of jaw abnormalities in offspring of ozone-exposed mice. The mechanisms of these reported effects and whether th are due to direct actions of absorbed ozone, some secondary reaction product, or secondary responses to the stress of local actions in the lung are largely unknown. However, reported analogous effects in humans exposed to ozone, such as changes in visual acuity and headache (possibly related to the reduced activity in... 

Taylor, O. C., E. A. Cardiff, J. D. Mersereau, and J. T. Middleton. Effect of airborne reaction products of ozone and 1-N-hexene vapor (synthetic smog) on growth of avocado seedlings. Proc. Amer. Soc. Hort. Sci. 71 320-325, 1958. 

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