Decomposition Of Ozonide Research Articles

Role of water on ozonation of cinnamaldehyde to benzaldehyde under Ca(OH)2 catalysis: A combined in situ DRIFTS and DFT study

The role of water on cinnamaldehyde ozonation to benzaldehyde under Ca(OH)2 catalysis was studied by in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) and Density Function Theory (DFT). According to the thermogravimetry results, the water, generated in the ozonation, reacted with CaO to form Ca(OH)2 and then existed on the Ca(OH)2 surface in the form of adsorbed and interlayer water. The experiment results showed that lab-made and pre-processed Ca(OH)2 had better catalytic activities because their specific surface area values were 3.59 and 4.46 times larger than CaO. DFT results indicated that the competitive adsorption between water and ozone was weak due to the difference of their average adsorption energy difference. The major effect of water was to promote ozonide decomposition and ·OH formation. At the presence of water, the DRIFTS signals of physisorption ozone and ozonide disappeared within 20 min, but the signals of oxygen atoms and O2– had about 12% and 33% increasing, respectively. As the water content increased in the system and the key intermediates, ozonides, and ·OH, changed, the ozonation mechanism was changed from the Criegee mechanism to the free radical mechanism, resulting in a significant decrease in the selectivity of benzaldehyde.

Oxidation of 4­brometylbenzene by ozone in acetic acid

The kinetics and the mechanism of ozonation of 4-bromethylbenzene in acetic acid was studied. The constants of the rate of reaction of ozone with 4-bromethylbenzene and 4-bromacetophenone at different temperatures were determined. We showed the possibility of conducting the process not only by the aromatic ring of the substrate in accordance with the Krige mechanism, but also with the formation of 4-bromacetophenone, which will be used when creating new methods of synthesis of oxygen-containing derivatives of ethylbenzene. It was established that oxidation of 4-bromethylbenzene by ozone in acetic acid flows mainly by the aromatic ring with the formation of ozonides – peroxide products of aliphatic nature. Up to 35 % of 4-bromacetophenone and trace amounts of 1-(4-bromphenyl)ethanol were identified among the products of oxidation reaction by the side chain. The reaction of ozone with 4-bromethylbenzene in acetic acid at temperatures of up to30 °Chas the first order by initial components and the value of constant of reaction rate does not depend on the concentration of reactants. With increasing temperature, constant of reaction rate begins to depend on the concentration of reagents, and in this case, ozone consumption increases significantly. This indicates that under experimental conditions, ozone is consumed simultaneously at different stages of oxidation. It was proved that ozonation of 4-bromethylbenzene is a complicated process, in which the substrate is oxidized by the non-chain mechanism. Ozone is consumed in two directions: in the reaction with the substrate by non-chain mechanism and by the chain mechanism at the stage of chain continuation in the reaction with the products of thermal decomposition of ozonides. This fact gives grounds to argue that at an increase in temperature, unproductive consumption of ozone will grow rapidly and, vice versa, under conditions of prevention of ozonolysis, ozone will participate in the reaction with formation of the target aromatic product. Thus, the experimentally obtained data are the basis for the development of the process of oxidation of derivatives of ethylbenzene and creation of the foundations of technology of 4-bromacetophenone synthesis with the help of ozone. This will considerably simplify the apparatus design of the process, enhance the output of the target product and will contribute to subsequent improvement of the method of oxidative processing of reagents

Surface modification of activated carbon fabric with ozone. Part 2: Thermal analysis with TGA-FTIR and DTA

ABSTRACTTwo samples of activated carbon fabrics (ACF) with very high surface area (>1300 to >1800 m2/g) fully ozonized in the part 1 of this study were analyzed by thermogravimetric analysis (TGA) coupled both with differential thermal analysis (DTA) and FT-IR spectroscopy (TGA-FTIR). The adsorbed water and the amount of oxygenated functional groups were determined. The ozonized ACF shows an exothermal decomposition at about 181–189°C which may be due at least in part to the decomposition of ozonide and/or peroxide groups. The TGA-FTIR has revealed that the main products released from the thermal decomposition are CO2 followed by CO. Formic acid was detected only in correspondence to the exothermal transition at 181°C and was taken as a proof of the decomposition of secondary ozonides.

Facile one-pot synthesis of anisaldehyde

At room temperature, anisaldehyde (4-methoxybenzaldehyde) is synthesized based on the ozonolysis of anethole (1-methoxy-4-(1-propenyl)-benzene) in a novel and environmentally friendly system composed of water and ethyl acetate. In the presence of water, ozonolysis of anethole results in the direct formation of anisaldehyde, avoiding the isolation or decomposition of ozonide.

Kinetics and Thermodynamics of Limonene Ozonolysis

Using density functional methods, the initial reaction steps of limonene ozonolysis have been investigated with a focus on primary ozonide formation and its decomposition to Criegee intermediates and carbonyl compounds. The ozonide formation is highly exothermic, and the decomposition channels have similar free energies of activation, ΔG(‡), indicating that there is no primary pathway for ozonide decomposition. Assuming that ozonide formation is the rate limiting step, the theoretical rate coefficient, k = 1.6 × 10(-16) molecule(-1) cm(3) s(-1), evaluated at the CCSD(T)/6-31G(d,p)//BHandHLYP/cc-pvdz level and 298.15 K for d-limonene is in good agreement with the experimental value, k(exp) = 3.3 × 10(-16) molecule(-1) cm(3) s(-1). The theoretical Arrhenius expression is also in good agreement with experimental results.

Reaction of Stabilized Criegee Intermediates from Ozonolysis of Limonene with Sulfur Dioxide: Ab Initio and DFT Study

The mechanism of the reaction of the sulfur dioxide (SO(2)) with four stabilized Criegee intermediates (stabCI-CH(3)-OO, stabCI-OO, stabCIx-OO, and stabCH(2)OO) produced via the ozonolysis of limonene have been investigated using ab initio and DFT (density functional theory) methods. It has been shown that the intermediate adduct formed by the initiation of these reactions may be followed by two different reaction pathways such as H migration reaction to form carboxylic acids and rearrangement of oxygen to produce the sulfur trioxide (SO(3)) from the terminal oxygen of the COO group and SO(2). We found that the reaction of stabCI-OO and stabCH(2)OO with SO(2) can occur via both the aforementioned scenarios, whereas that of stabCI-CH(3)-OO and stabCIx-OO with SO(2) is limited to the second pathway only due to the absence of migrating H atoms. It has been shown that at the CCSD(T)/6-31G(d) + CF level of theory the activation energies of six reaction pathways are in the range of 14.18-22.59 kcal mol(-1), with the reaction between stabCIx-OO and SO(2) as the most favorable pathway of 14.18 kcal mol(-1) activation energy and that the reaction of stabCI-OO and stabCH(2)OO with SO(2) occurs mainly via the second reaction path. The thermochemical analysis of the reaction between SO(2) and stabilized Criegee intermediates indicates that the reaction of SO(2) and stabilized Criegee intermediates formed from the exocyclic primary ozonide decomposition is the main pathway of the SO(3) formation. This is likely to explain the large (~100%) difference in the production rate in the favor of the exocyclic compounds observed in recent experiments on the formation of H(2)SO(4) from exocyclic and endocyclic compounds.

Ozonolysis of Cyclic Alkenes as Surrogates for Biogenic Terpenes: Primary Ozonide Formation and Decomposition

Alkene ozonolysis reactions proceed through an unstable intermediate, the primary ozonide (POZ). POZ decomposition controls the complex mechanism. We probe the kinetics of primary ozonide decomposition using temperature programmed reaction spectroscopy (TPRS), revealing primary ozonide decomposition barrier heights of 9.1 +/- 0.4, 9.4 +/- 0.4, and 11.9 +/- 1.2 kcal mol(-1) for cyclohexene, 1-methyl-cyclohexene, and methylene-cyclohexane, respectively. We compare experimental decomposition spectra with spectral predictions using density functional theory (DFT) to reveal decomposition products resembling vinyl-hydroperoxides and dioxiranes. We do not find evidence of secondary ozonides. Additional computations with DFT, scaled with the TPRS barrier height, yield barrier heights ranging from 9.4 to 12.1 kcal mol(-1) for the four competing decomposition pathways of the 1-methyl-cyclohexene POZ. Entropic differences were minimal, indicating that POZ decomposition branching is controlled purely by enthalpic variations. These kinetic computations were used to calculate a hydroxyl radical yield for 1-methyl-cyclohexene ozonolysis of 0.85 at 298 K.

Gas-phase ozonolysis of alkenes: formation of OH from anti carbonyl oxides.

Gas-phase ozone-alkene reactions are known to produce the hydroxyl radical (OH) in high yields. Most mechanistic studies to date have focused on the role of syn carbonyl oxides; however, OH production from ethene ozonolysis indicates a second, poorly understood OH-forming channel, which may contribute to OH production in the ozonolysis of substituted alkenes as well. Using laser-induced fluorescence, we have measured OH and OD yields from the ozonolysis of two partially deuterated alkenes, cis- and trans-3-hexene-3,4-d2. OD is formed from both alkenes, indicating a pathway of hydroxyl-radical formation involving vinylic hydrogens, accounting for one-third of total OH formation from cis-3-hexene. The lack of a significant kinetic isotope effect suggests this pathway is the "hot acid" channel, arising from rearrangement of anti carbonyl oxides. Measured yields also allow for the estimation of syn:anti carbonyl oxide ratios, approximately 50:50 for trans-3-hexene and approximately 20:80 for cis-3-hexene, qualitatively consistent with our understanding of ozonide decomposition pathways.

Trimethylsilyl group migrations in cryogenic ozonolysis of trimethylsilylethene: evidence for nonconcerted primary ozonide decomposition pathway.

The identification of trimethylsiloxy-1,2-dioxetane and 2-trimethylsilyloperoxyacetaldehyde and assignment of trimethylsiloxymethyl formate as products of the low-temperature ozonolysis of trimethylsilylethene demonstrate feasibility of migrations of trimethylsilyl group in a dioxygen-centered (oxyperoxy) diradical produced via a homolytic cleavage of each of both O-O bonds in the primary ozonide. The results provide the first experimental evidence on the nonconcerted decomposition of the primary ozonide.

THERMAL DECOMPOSITION OF PHOSPHOLIPID SECONDARY OZONIDES: IMPLICATIONS FOR THE TOXICITY OF INHALED OZONE

While inhalation of ozone is known to cause a variety of health effects, the reactions at a molecular level that lead to these effects are not well understood. One potential path is the reaction of ozone with the unsaturated fatty acid components of pulmonary surfactant at the air-water interface in the lung to form secondary ozonides. These have been proposed to decompose to free radicals, which can then initiate the well-known inflammatory response. We report here the first kinetic studies of the thermal decomposition of the cis and trans secondary ozonides of 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphocholine (POPC), a phospholipid found in significant quantities in lung surfactant. The ozonides were synthesized by reaction of O3 with POPC adsorbed on a glass surface, and their thermal decomposition kinetics were followed using high-performance liquid chromatography (HPLC) over the tem perature range from 50 C to 106 C in either methanol or 1,1,1,2-tetrachloroethane. The Arrhenius parameters for the thermal decomposition in methanol are A = 10 8.7+/-0.3 s-1 and E = 19.6 +/- 0.6 kcal mol-1 for the a cis ozonide, and A = 10 8.7+/-0.6 s-1 and Ea = 19.8 +/- 1.0 kcal mol-1 for the trans ozonide. In 1,1,1,2-tetrachloroethane, the parameters are A = 10 8.3+/-2.1 s-1 and Ea = 18.4 +/- 3.4 kcal mol-1 for the cis ozonide, and A = 10 9.3+/-3.2 s-1 and Ea = 20.2 +/- 5.2 kcal mol-1 for the trans ozonide (all errors cited are +/-2). Within experimental error, there is no difference in the kinetics of decomposition in the two solvents. However, both the activation energy and the preexponential factor for the decomposition of the phospholipid ozonides are significantly lower than those for decomposition of the long-chain alkene ozonide 1-octene ozonide, determined to be Ea = 26.7 +/- 3.2 kcal mol-1 and A = 10 12.7+/-1.9 s-1. The latter reaction has been proposed to be initiated by scission of the O-O bond, followed by decomposition of the peroxy biradical to generate free radicals. The kinetics for the decomposition of the POPC ozonides in solution are similar to those of simple alkene ozonides in the gas phase, where a concerted mechanism involving simultaneous intramolecular hydrogen transfer and O-O bond cleavage has been proposed. The only high-molecular-weight major product of the POPC ozonide decomposition identified using liquid secondary ion mass spectrometry (LSIMS) was the lipid acid 1-palmitoyl-2-azelaoyl- sn -glycero-3-phosphocholine, which was observed as a product in both solvents. The mechanism and implications for the toxicology of inhaled ozone are discussed.

Solvent effects on ozonolysis reaction intermediates

Solvent effects on relative stability, electronic and molecular structure of ozonolysis reaction intermediates are analyzed with the help of ab initio MP2/6-31+G * * calculations. A continuum model is employed to account for solute–solvent electrostatic interactions. The results show that there are large effects on the structure and relative stability of carbonyl oxide by substantially favoring its zwitterionic character. A complex formed by carbonyl oxide and formaldehyde is shown to be stable in the gas phase and in solution. This complex can be involved in solvent cage reactions leading to secondary ozonides. Thermodynamically, primary ozonide decomposition is favored by the solvent.

Direct mass spectrometric analysis of ozonides: application to unsaturated glycerophosphocholine lipids.

The reaction of ozone with double bonds present in glycerophosphocholine lipids results in formation of ozonides that can be directly analyzed by mass spectrometry as either positive or negative molecular ion species generated by electrospray ionization. Polyunsaturated fatty acyl groups esterified to the phospholipid yielded a mixture of ozonide species with the maximum number of ozone molecules added equal to the total number of double bonds. Ozonide decomposition resulted in omega-aldehyde and omega-carboxylic acid products as revealed by ESI-MS. Collisional activation of the ozone adducts for mono- and polyunsaturated phospholipids gave rise to fragment ions indicative of the position of the double bonds in these molecules. The major decomposition pathway for either positive or negative ozonide ion species involved charge remote fragmentation of the ozonide initiated by homolytic cleavage of the peroxide bridge followed by rearrangement to form the omega-aldehyde and omega-carboxylate acyl species. The reaction of ozone with phospholipids containing polyunsaturated fatty acyl groups is a useful method to probe the position of double bonds by electrospray ionization mass spectrometry.

Study of thermal stability of ozonides of phosphorous acid esters

1. Rate constants and activation parameters were measured for the thermal decomposition of ozonides of trimethyl, triethyl, tributyl, tricyclohexyl, trioctyl, triphenyl, tri-(2-methylphenyl), tri-(2-chlorophenyl), tri-(3-chlorophenyl), tri-(4-chlorophenyl), tri-(2,4-dichlorophenyl), tri-(2,4,6-trichlorophenyl) phosphites. 2. The dependence of the rate constant of the thermolysis of the phosphite ozonides on the structure is satisfactorily described by the Taft and Kabachnik correlation equations. A compensational effect is observed between the energy of activation and the preexponential factor.

Kinetics of overall decomposition of ozonides of 2,2?-methylene-bis-4-methyl-6-tert-butylphenyl esters of phosphorous acid

1. The decomposition of ozonides of 2,2′ methylenebis-4-methyl-6-tert-butylphenyl esters of phosphorous acid esters is described by a first order equation, and the electron donor substituents decrease the stability of the ozonides. 2. The influence of the solvent on the rate of the overall decomposition of the ozonide of phenyl 2,2′ -methylenebis-4-methyl-6-tert-butylphenyl phosphite is described according to the Koppel'-Pal'm equation.

Thermal decomposition of ozonides. A complementary method to the Baeyer–Villiger oxidation of hindered ketones

Treatment of vinyl acetate with ozone yields the mixed anhydride of acetic and formic acids and formaldehyde oxide. The formaldehyde oxide can be trapped by reaction with ketones yielding the corresponding ozonides. Thermal decomposition of these ozonides gave the corresponding lactone and (or) the corresponding olefin carboxylic acid. The ozonides were also prepared by the ozonolysis of the corresponding olefins.

Mechanisms in phosphite ozonide decomposition to phosphate esters and singlet oxygen

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanisms in phosphite ozonide decomposition to phosphate esters and singlet oxygenL. M. Stephenson and D. E. McClureCite this: J. Am. Chem. Soc. 1973, 95, 9, 3074–3076Publication Date (Print):May 1, 1973Publication History Published online1 May 2002Published inissue 1 May 1973https://doi.org/10.1021/ja00790a088RIGHTS & PERMISSIONSArticle Views178Altmetric-Citations26LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (413 KB) Get e-Alerts Get e-Alerts

Ozonolysis of unsaturated fatty acids. II. Esterification of the total products from the oxidative decomposition of ozonides with 2,2-dimethoxypropane

The total acidic products from the performic acid oxidation of the ozonide of methyl oleate formed in methanol may be esterified directly in a few hours with 2,2-dimethoxypropane. The ester concentrations are adequate for the determination of the positional isomers of monoethylenic fatty acids directly from the reaction mixture, using a hydrogen flame ionization gas–liquid chromatography detector. Dimethyl sulfoxide was not required to prevent the breakdown of 2,2-dimethoxypropane under the conditions employed.

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.