Ozonation Procedure

The following procedure is a modified version of that used by Nakano and his coworkers (Habu et al. 1990 and references therein). It was turned to here after 

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This dry ozonation procedure is a general method for hydrox-ylation of tertiary carbon atoms in saturated compounds (Table 1). The substitution reaction occurs with predominant retention of configuration. Thus cis-decalin gives the cis-l-decalol, whereas cis- and frans-l,4-dimethylcyclohexane afford cis- and trans-1,4-dimethylcyclohexanol, respectively. The amount of epimeric alcohol formed in these ozonation reactions is usually less than 1%. The tertiary alcohols may be further oxidized to diols by repeating the ozonation however, the yields in these reactions are poorer. For instance, 1-adamantanol is oxidized to 1,3-adamantane-diol in 43% yield. Secondary alcohols are converted to the corresponding ketone. This method has been employed for the hydroxylation of tertiary positions in saturated acetates and bromides. 

General. The ozonation procedures are those described in the literature, both using ozone-oxygen and ozone-nitrogen. Oxygen analyses... 

Effects of Oxides of Nitrogen. To determine the effects of oxides of nitrogen on the chromogenic reaction investigated, the ozonization procedure was repeated after passing the ozonized air through approximately 20 ml. of potassium permanganate absorbant. 

Applicability of Method. The potential suitability of the colorimetric technique, for use in measuring atmospheric ozone concentration, was determined by repeating the ozonization procedure with unozonized air flowing at 0.40 cubic meter per hour, lodometric measurements of atmospheric ozone concentration were made simultaneously. 

Some waterborne microbes produce polysaccharides that can cause asbestos fibers to become stuck to the walls of collection vessels. Hence water samples should be kept chilled (4°C) and filtered within 48 h of collection to minimize microbial growth and fiber loss. Use of mercuric chloride as a preservative is no longer allowed because of its hazardous properties. If samples cannot be kept cold and filtered within 48 h of collection, a UV-ozonation procedure must be used to destroy any microbes and their polysaccharides before filtration is done [19]. 

Ozone can be analyzed by titrimetry, direct and colorimetric spectrometry, amperometry, oxidation—reduction potential (ORP), chemiluminescence, calorimetry, thermal conductivity, and isothermal pressure change on decomposition. The last three methods ate not frequently employed. Proper measurement of ozone in water requites an awareness of its reactivity, instabiUty, volatility, and the potential effect of interfering substances. To eliminate interferences, ozone sometimes is sparged out of solution by using an inert gas for analysis in the gas phase or on reabsorption in a clean solution. Historically, the most common analytical procedure has been the iodometric method in which gaseous ozone is absorbed by aqueous KI. 

G. Procedure and calibration of apparatus. For satisfactory use of an ozonizer it is desirable to obtain data relating rate of flow and secondary voltage with the amount of ozone produced. 

This method for the preparation of cyclobutanone via oxaspiropentane is an adaptation of that described by Salaiin and Conia. The previously known large-scale preparations of cyclobutanone consist of the reaction of the hazardous diazomethane with ketene, the oxidative degradation or the ozonization in presence of pjrridine of methylenecyclobutane prepared from pentaerythritol, or the recently reported dithiane method of Corey and Seebach, which has the disadvantage of producing an aqueous solution of the highly water-soluble cyclobutanone. A procedure involving the solvolytic cyclization of 3-butyn-l-yl trifluoro-methanesulfonate is described in Org. Syn., 54, 84 (1974). 

Hundreds of chemical species are present in urban atmospheres. The gaseous air pollutants most commonly monitored are CO, O3, NO2, SO2, and nonmethane volatile organic compounds (NMVOCs), Measurement of specific hydrocarbon compounds is becoming routine in the United States for two reasons (1) their potential role as air toxics and (2) the need for detailed hydrocarbon data for control of urban ozone concentrations. Hydrochloric acid (HCl), ammonia (NH3), and hydrogen fluoride (HF) are occasionally measured. Calibration standards and procedures are available for all of these analytic techniques, ensuring the quality of the analytical results... 

In this reaction, iodine is liberated from a solution of potassium iodide. This reaction can be used to assess the amount of ozone in either air or water. For determination in air or oxygen, a measured volume of gas is drawn through a wash bottle containing potassium iodide solution. Upon lowering the pH with acid, titration is effected with sodium thiosulfate, using a starch solution as an indicator. There is a similar procedure for determining ozone in water. 

CFCs have been widely used as cleaning solvents, as they are nonflammable and their toxicity is low. Now, flammable solvents are coming back into favor. A news item from a manufacturer described "a new ozone-friendly cleaning process for the electronics industry, which "uses a unique hydrocarbon-alcohol formulation. It did not remind readers that the mixture is flammable and that they should check that their equipment and procedures are suitable. 

Oxidative cleavage of olefins is frequently a useful procedure synthetically as well as analytically. Ozonization is an effective means of carrying out such a cleavage under... 

Toxicity and Hazards. The odor cf ozone can be detected in concn as low as several parts per hundred million by vol (pphm). The threshold limit value (TLV) is O.lppmor 0.2mg/m3 its toxic dose level (TDL), 50% kill concn is 2ppm (Ref 6) Pure 100% liq ozone may be kept safely at 90°K (cooled by liq oxygen) for indefinite periods of time, but the smallest provocation, such as a spark or fast warming, even only up to bp (161°K), causes detonation. The evapn of liq ozone, for example, in the process of the prepn of pure gaseous ozone is, therefore, a dangerous procedure (Ref 3, p 224)... 

Caution Ozone is toxic and potentially explosive. This procedure should be carried out in an efficient hood and behind a suitable protective shield. 

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