Moles Of Ozone Research Articles

The ozonation of unsaturated fatty acids: aldehydes and hydrogen peroxide as products and possible mediators of ozone toxicity

The products of the reactions of ozone with aqueous emulsions of unsaturated fatty acids and with liposomes made from phosphatidylcholine esters were characterized. Ozonolysis of emulsions of methyl oleate yields approximately 1 mol of hydrogen peroxide and 2 mol of aldehydes per mole of ozone used and fatty acid reacted. That is, the net equation that occurs is RCH = CHR' + O3 + H2O----RCHO + R'CHO + H2O2 . Ozonolysis of emulsions of oleic, linoleic, linolenic, and arachidonic acids gives 1 mol of hydrogen peroxide per mole of ozone used. Only very low yields (less than 5%) of reducible materials other than hydrogen peroxide are observed, suggesting that the yields of organic peroxidic materials, including Criegee ozonides and lipid hydroperoxides, are small. Ozonolysis of rat erythrocyte ghost membranes and rat bronchoalveolar lavage also gives significant yields (about 50%) of hydrogen peroxide based on the moles of ozone consumed. Reactions of ozone with bovine serum albumin, glutathione, and glucose do not produce hydrogen peroxide, implying that the hydrogen peroxide formed during the ozonation of biological materials arises almost exclusively from ozone/olefin reactions. Hydrogen peroxide and aldehydes are suggested to be important mediators of the modifications observed in both the lung and extrapulmonary tissues when ozone is inhaled.

ChemInform Abstract: Ozonolysis of Tetramethoxyethene.

AbstractOzonolysis of tetramethoxyethene (I) produces the products (II)‐(IV).

Ozonolysis of tetramethoxyethene

Ozonolysis of tetramethoxyethene 1 produces 20–40% of dimethyl carbonate 3, 35–60% of methyl trimethoxyacetate 7, and 20–35% of the dioxetane 8 of 1. Yields vary with initial concentration of 1, temperature, and solvent. Singlet oxygen is produced, which reacts with 1 to form 8 and can be trapped with 2,5-dimethylfuran. No evidence for the formation of the molozonide of 1 was obtained. Up to 2.5 moles of 1 are consumed per mole of ozone. Ozonolysis of a mixture of 1 and 2,3-dimethyl-2-butene 12 gave the epoxide of 12 and three times the expected amount of the allylic hydroperoxide of 12. A competing radical chain oxidation reaction is proposed to account for these products and the stoichiometry of the ozonolysis. The initial reaction in the ozonolysis of 1 is proposed to be an electron transfer reaction that is calculated to be exothermic by > 35 kcal/mol. The resulting radical ions initiate the radical chain oxidation and combine to form the oxygenated epoxide 9 of 1. Loss of singlet oxygen from 9 forms the epoxide 10, which rearranges to 7. At −95 °C the zwitterion from 10 is trapped by CD3OD to produce a mixture of 7 with one α OCD3 group and pentamethoxyethanol with one β OCD3 group from which a CH3OD group is lost at ~ −10 °C to form more deuterated ester.

Ozonation du naphtalene en milieu aqueux—I. Consommation d'ozone et produits de reaction

Polyaromatic compounds are frequently found in surface waters. Ozonation of these compounds was previously studied, mainly in the presence of an organic solvent, because of their low solubility in water. In the first part of this work, ozonation of a polyaromatic compound, naphthalene, was studied in a dilute aqueous medium, in order to determine the consumption of ozone and to quantify by HPLC the ozonation by-products. In the second part, an identification of by-products by GC/MS technique was undertaken from a concentrated solution of naphthalene in a H 2O/CH 3OH mixture. We carried out the ozonation of aqueous solution of naphthalene (2.5 10 −4 mol l −1; pH = 5.9) in a continuous semi-batch reactor, i.e. a bubble column reactor. The HPLC analysis of naphthalene and of ozonation by-products and the determination of ozone consumed showed that, when naphthalene has completely disappeared: The ozone consumption was 2 mol mol −1, naphthalene. The concentrations of by-products were: orthophthaldialdehyde ∼ 0.38 10 -4 mol 1- phthalaldehydic acid = 0.30 10 4 mol 1 ∼ phthalic acid = 0.05 10 4 mol 1 oxalic acid ∼ 0.50 10 4 mol 1 formic acid - 0.38 10 -4 mol 1 -I hydrogen peroxide - 2.00 I0 4 mol I i This means that the analysed products represent only 30% of the initially introduced organic carbon. Consequently, we undertook the separation and the identification of ozonation by-products from a more highly concentrated solution of naphthalene (10 −2 mol l −1) in a mixture H 2O/CH 3OH (50/50 v/v) by means of an adequate experimental process. On this basis the analysis GC/MS of the extract obtained allowed the identification of: oxalic acid, oxomalonic acid, a cyclic peroxide, phthalic acid and phthalaldehydic acid. Taking into account the consumption of 2 mol of ozone per mol of compound removed, the identified oxidation products and the data found in the literature, we can propose three reactional pathways for the initial attack of ozone on naphthalene, an electrophilic substitution of ozone on carbon 1 (or 2) of the naphthalene, two simultaneous 1,3-dipolar cycloadditions of ozone on both 1,2 and 3,4 bonds of naphthalene, one 1,3-dipolar cycloaddition of ozone on 1,2 bond of naphthalene. A kinetic study will provide further information concerning the initial ozone attack on naphthalene. This will be presented in part II (kinetic studies of initial step of the reaction).

Formaldehyde evolution from an ethylene-using ozone chemiluminescence meter: A new method of calibration

An ethylene-using ozone chemiluminescence meter produces 1.3 moles of formaldehyde per mole of ozone over ozone concentrations of 0.040 to 0.45 ppm. The formaldehyde was quantitated by a variation of the West-Gaeke technique for sulfur dioxide, and is specific for formaldehyde. The constancy of the stoichiometry allows formaldehyde collection to be the basis of a new calibration technique for the meter.

On the adsorption of ozone on silica gel

The adsorption of ozone at −80°C. on silica gel as a function of the thermal history of the gel was evaluated by application of the BET equation. Within the range of annealing temperatures of 105° to 850°C. maximum values for the monolayer concentration (m0) of ozone were observed for silica gel that had been annealed at 150°C. For this annealing temperature the ratio of m0 to the number of surface silanol groups approaches a value of 0.5. The m0 (T) relationship is represented by the equation m0−1 = (933-273 × 103/T)103 for the range of annealing temperatures of 150° to 850°C. with m0 expressed in moles of ozone per square meter and T in °K. An average value of 98 for the BET constant C was obtained for silica gel annealed at temperatures between 105° and 400°C. Annealing at or below 105°C. resulted in a reduction of the value for C to about 20, and in about a twofold increase of m0 as compared to the value pertaining to the annealing temperature of 150°C. It is assumed that in this case ozone is adsorbed onto a water monolayer.

The ozonisation and the ozonolysis of furan and of some methylated furans in connection with the reactivities of the bonds in the ringsystem

AbstractThe ozonisation and ozonolysis of the following compounds have been investigated: furan, 2‐methylfuran, 2,3‐, 2,4‐ and 2,5‐dimethylfuran and 2,3,5‐trimethylfuran. When dissolved in chloroform, these compounds take up about 1.6 mol of ozone per mol of furan derivative at –60°, and resinification is practically absent under these conditions. On decomposition of the resultant ozonides under a variety of conditions, dicarbonyl compounds are produced and they have been determined both qualitatively and quantitatively. Glyoxal, which may be produced from either the two β‐C atoms or one α‐ and one β‐C atom of the furan nucleus, is the sole dicarbonyl compound produced in the ozonolysis of furan. The same holds, mutatis mutandis, for the ozonolysis of 2,4‐dimethylfuran, where methylglyoxal is the sole dicarbonyl compound produced. In the ozonolysis of the remaining furan derivatives along with dicarbonyl compounds produced from the two β‐C atoms in the furan nucleus, there are produced also those derived from an α‐ and a β‐C atom of the furan nucleus. Thus, for example, in the ozonolysis of 2,3‐dimethylfuran, glyoxal and dimethylglyoxal are produced as well as methylglyoxal. Besides dicarbonyl compounds, considerable amounts of formic and acetic acids are also produced in the decomposition of the ozonides and these have been determined approximately.The experimental results may be explained by assuming that two different reactions occur in the interaction of ozone and the furan derivatives examined. In the first reaction two molecules of ozone are taken up on the two α‐β‐bonds of the furan nucleus. On decomposition of the diozonide obtained there is produced a dicarbonyl compound containing the two β‐C atoms of the furan nucleus. In the second reaction only one molecule of ozone is absorbed. The mono‐ozonide on decomposition produces two dicarbonyl compounds, which contain one α‐ and one β‐C atom of the furan nucleus. During the decomposition of the ozonides hydroperoxides derived from the dicarbonyl compounds are produced as by‐products. The hydroperoxides partly decompose by peroxide transformation into carboxylic acids.A reaction mechanism put forward by Bailey and Colomb to explain the occurrence of dicarbonyl compounds containing an α‐ and a β‐C atom from the furan nucleus, must be rejected for the furan derivatives we have studied on the fact that the take up of ozone was found to be 1.6 mol per mol of furan derivative.

The ozonolysis of phenanthrene)

AbstractPhenanthrene reacts quickly with one mole of ozone at the 9,10‐double bond. In chloroform a polymeric mono‐ozonide (II) is obtained, which can be converted into diphenic acid. In methanol the reaction takes a different course resulting in the formation of a cyclic methoxy‐hydroxy‐peroxide (V) and a cyclic dimethoxy‐peroxide (VI).

Ozone absorption and ozonolysis of cyclooctatetraene

AbstractAt −31° cyclooctatetraene absorbs 3.5 moles of ozone. Among the products of the ozonolysis of cyclooctatetraene, ethane‐1,1,2,2‐tetracarboxylic acid and succinic acid were found. The results may be interpreted either in terms of an equilibrium between cyclooctatetraene and bicyclo‐(4.2.0)‐octatriene or in terms of a reaction mechanism analogous to the one postulated by Friess and Boekelheide for halogen addition.

Ozone absorption and ozonolysis of cyclooctatetraene

AbstractAt −31° cyclooctatetraene absorbs 3.5 moles of ozone. Among the products of the ozonolysis of cyclooctatetraene, ethane‐1,1,2,2‐tetracarboxylic acid and succinic acid were found. The results may be interpreted either in terms of an equilibrium between cyclooctatetraene and bicyclo‐(4.2.0)‐octatriene or in terms of a reaction mechanism analogous to the one postulated by Friess and Boekelheide 10) for halogen addition.

The Experimental Determination of the Heat Capacity of Gaseous Ozone

The mean heat capacity of ozone between 300 and 476°K has been determined from explosions of mixtures of ozone and oxygen in a spherical bomb by the method the authors described in a previous paper. The value obtained is 10.94 calories per mol of ozone. The value obtained from band spectra is 10.39 calories per mol. The difference cannot be accounted for by incorrect assignment of the optical frequencies of ozone, and it is larger than the probable experimental error. It is proposed that the difference may be due to a contribution to the heat capacity of an electronic level lying close to the ground state of the ozone molecule. It is estimated that this supposed level has an energy of 0.1 to 0.2 volt. The existence of low-energy electronic levels probably implies an isosceles triangle structure and paramagnetic properties of the ozone molecule in the normal and the low excited states.