Ozone yields from

Ozone Yields in Mixtures of C02 and 02. It can be inferred from the above discussion on the effect of SF6 that the charge neutralization of C02+ in pure C02 is nondissociative, possibly caused by the participation of other negative ions and/or the formation of ion clusters, e.g., C02+(C02)w. The data on ozone yields from the gas flow experiments support this inference of nondissociative charge neutralization. We argue that the limiting yield of ozone at high gas flow rates, G(03) — 4.4 is equal to the yield of an electrically neutral oxidizing species formed solely from the dissociation of electronically excited C02 molecules. 

Since two OH radicals are originally formed for each O( D) atom having reacted with H20, the loss of ozone due to this reaction is compensated when the ozone yield from the reaction of OH with methane is 0.5. A yield of 0.5 is obtained for an NO number density of 4x 108 molecules/cm3, which corresponds to an NO mixing ratio of about 20 pptv. At lower NO... 

A cursory inspection of key intermediate 8 (see Scheme 1) reveals that it possesses both vicinal and remote stereochemical relationships. To cope with the stereochemical challenge posed by this intermediate and to enhance overall efficiency, a convergent approach featuring the union of optically active intermediates 18 and 19 was adopted. Scheme 5a illustrates the synthesis of intermediate 18. Thus, oxidative cleavage of the trisubstituted olefin of (/ )-citronellic acid benzyl ester (28) with ozone, followed by oxidative workup with Jones reagent, affords a carboxylic acid which can be oxidatively decarboxylated to 29 with lead tetraacetate and copper(n) acetate. Saponification of the benzyl ester in 29 with potassium hydroxide provides an unsaturated carboxylic acid which undergoes smooth conversion to trans iodolactone 30 on treatment with iodine in acetonitrile at -15 °C (89% yield from 29).24 The diastereoselectivity of the thermodynamically controlled iodolacto-nization reaction is approximately 20 1 in favor of the more stable trans iodolactone 30. 

As inert as the C-25 lactone carbonyl has been during the course of this synthesis, it can serve the role of electrophile in a reaction with a nucleophile. For example, addition of benzyloxymethyl-lithium29 to a cold (-78 °C) solution of 41 in THF, followed by treatment of the intermediate hemiketal with methyl orthoformate under acidic conditions, provides intermediate 42 in 80% overall yield. Reduction of the carbon-bromine bond in 42 with concomitant -elimination of the C-9 ether oxygen is achieved with Zn-Cu couple and sodium iodide at 60 °C in DMF. Under these reaction conditions, it is conceivable that the bromine substituent in 42 is replaced by iodine, after which event reductive elimination occurs. Silylation of the newly formed tertiary hydroxyl group at C-12 with triethylsilyl perchlorate, followed by oxidative cleavage of the olefin with ozone, results in the formation of key intermediate 3 in 85 % yield from 42. 

Washida, N., Y. Mori, and I. Tanaka. Quantum yield of ozone formation from photolysis of the oxygen molecule at 1849 and 1931 A. J. Chem. Phys. 54 1119-1122, 1971. 

The primary ozonation by-products of atrazine (15 mg/L) in natural surface water and synthetic water were deethylatrazine, deisopropylatrazine, 2-chloro-4,6-diamino-s-triazine, a deisopropylatrazine amide (4-acetamido-4-amino-6-chloro-5-triazine), 2-amino-4-hydroxy-6-isopropylamino-5-triazine, and an unknown compound. The types of compounds formed were pH dependent. At high pH, low alkalinity, or in the presence of hydrogen peroxide, hydroxyl radicals formed from ozone yielded 5-triazine hydroxy analogs via hydrolysis of the Cl-Cl bond. At low pH and low alkalinity, which minimized the production of hydroxy radicals, dealkylated atrazine and an amide were the primary byproducts formed (Adams and Randtke, 1992). 

Nielsen and co-workers studied the oxidation of arylhydroxylamines and their O-methyl derivatives with ozone in inert solvents at subambient temperature. 1,2,3,5-Tetranitrobenzene (54) is formed in quantitative yield from the oxidation of both N-hydroxy-2,4,6-trinitroaniline... 

Oxidation of Elaidic Acid Ozonization Products. Aliquots of the unseparated ozonization products from elaidic acid were autoxidized at 95 °C. uncatalyzed and in acetone over reduced platinum oxide as before. Total yields of acids and esters were determined by titration and were found to be 74.6 and 19.2%, respectively, in the catalyzed reaction with uptake of 63% of the theoretical volume of oxygen. Time required for uptake of half this volume was 4 hours at 21 °C. Uncatalyzed oxidation at 95°C. of the other fraction gave 27.4% yield of esters and 74.5% yield of acids, calculated on the assumption that one original olefinic linkage can produce one ester function or two acid functions. When elaidic acid was ozonized in methyl acetate and the catalyzed oxidation performed in the same solvent, acid yield was 80.8%, and ester yield was 7.3% with a half-uptake time of 5.6 hours and 88% of the theoretical quantity of... 

Fenton (Ref 5) prepd Di(methylol)-peroxide by evaporating equal volumes of formaldehyde and hydrogen peroxide. Wieland Wingler (Ref 6) prepd it in 80—90% yield from an ethereal soln of formaldehyde and hydrogen peroxide. There are other methods of prepn, such as the action of ozone on ethylene or on yS-butylene (Ref 1), p[642])... 

The stoichiometric yield of OH0 is the greatest from the photolysis of hydrogen peroxide. But - as already mentioned - the photolysis of ozone yields more OH0 than that from hydrogen peroxide because of the higher molar extinction coefficient of ozone compared to hydrogen peroxide (see Table 2-3). 

All experimental results should best be evaluated as a function of the specific ozone dose and related data such as the specific ozone absorption and/or consumption. Additionally the ozone yield coefficient, denoting the ratio of ozone absorbed in the liquid (i. e. transferred from the gas) to the DOC removed by ozonation or the total system (cf. Chapter B 1), is often of interest. 

Alkylation of the corresponding dianion of acid 32 was very convenient and led to numerous 9-alkyl products. For example, analogue 58 was prepared via the LDA-generated dianion of 32, which was alkylated with f-butyl bromoacetate to provide acid-ester 64. Crude vinylsilane 64 was submitted to successive ozone addition and acidification. The resultant tetracyclic peroxide 65 was subsequently treated with trifluoroacetic acid to cleave the f-butyl ester to the free the acetic acid appendage of target 58 in 20% overall yield from 64 (Eq. 15). 

Access to analogues with higher substitution was easily achieved. From either the propionate ester 193 or acetic acid 188, we previously made the propionic acid appendaged 189, which was in turn alkylated to the gem-dimethyl acid 194 in 76% yield (93% based on recycled starting material). The vinylsilane of 194 underwent addition of ozone to eventually afford hydroperoxide 195, and final ring closure was accomplished with trifluoroacetic acid and acetone to afford gem-dimethyl analogue 169 in 19% overall yield from 194 (Eq. 20). 

Electrochemical reduction of the ozonization products from monoterpenes, i.e., />-meth-l-ene, (-l-)-limonene, (+ )-a// /ia-pinene, (+)-car-3-ene, provides the corresponding double-bond cleavage products in 45-70% yields57. The electrolysis of the acetyloxy hydroperoxide 28 derived from p-menth-l-ene 27 is carried out in an Ac0H/H20(6/1 v/v)— AcONa— (Pb/Pb) system at —1.1 to —1.4V vs. SCE, 2.0 to 2.2 A/dm2 in a divided cell to give the corresponding keto-alcohol 29 in 70% yield (Scheme 3-10). 

The structure of XXVI was deduced from the fact that it was different from the 2-cinnamylphenol obtained by direct C-cinnamylation of phenol.16 Later investigators showed that XXVI is the sole product ozonization yielded formaldehyde but not benzaldehyde. 7-Methyl-allyl phenyl ether also rearranges with inversion, yielding 2-(a-methyl-allyl)-phenol 36 the structure of the rearrangement product has been definitely established87 38 by a combination of degradative and synthetic procedures. 

D-glucal, an acetyl group is removed from diacetyl-L-rhamnal by boiling its aqueous solution. The resulting monoacetyl-L-pseudorhamnal, however, is not as stable as diacetyl-D-pseudoglucal.7 Oxidation of diacetyl-L-rhamnal with ozone yielded 5-desoxy-L-arabinose, which was characterized as its phenylosazone and p-bromophenylosazone. 7 Deacetylation of diacetyl-L-rhamnal yields crystalline L-rhamnal (XLIV).7... 

Table 5 Range of OH yields from the reaction of ozone with alkenes...

In the presence of mineral acids, the hydroxyl groups in 44 can be replaced by alkoxy or alkylperoxy groups to give 45, 46, or 47. The monomethoxy compound (48) occurs as an intermediate in the formation of the dimethoxy compound (45). 48 was obtained by Bailey et al.i6 on ozonization of naphthalene, 2-methoxynaphthalene, and 2-ethoxynaphthalene in methanol. Ozonization of 2-ethoxynaph-thalene in ethanol leads to the diethoxy compound (46).46 The peroxides 44-46 and 48 can be converted into o-phthaldialdehyde (in 55% yield from 48) by hydrogenation in the presence of a Lindlar catalyst.45 The peroxide oxygen in 45-48 cannot be quantitatively determined by iodometry.45... 

Effect of Gaseous Diluents on Energy Yield of Ozone Generation from Oxygen... 

Takahashi, K., N. Taniguchi, Y. Matsumi, M. Kawasaki, and M.N.R. Ashfold, Wavelength and temperature dependence of the absolute 0(1D) production yield from the 305-329 nm photodissociation of ozone. J Chem Phys 108, 7161, 1998. 

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