Acetylene ozonization

The primary step of acetylene ozonation has been studied by BILYP, PBEO, CASSCF, MRMP2, and CCSD methods using the 6-31-l-G, aug-cc-p VDZ, cc-pVTZ, and aug-cc-p VTZ basis sets. The study confirms that the intermediate complex, the transition states of the concerted addition (Criegee s mechanism) and unconcerted addition (DeMore s mechanism) are involved in this reaction. Although Criegee s mechanism is dominant, the DeMore mechanism also contributes. ... 

Carbon—nitrogen double bonds in imines, hydrazones, oximes, nitrones, azines, and substituted diazomethanes can be cleaved, yielding mainly ketones, aldehydes and/or carboxyHc acids. Ozonation of acetylene gives primarily glyoxal. With substituted compounds, carboxyHc acids and dicarbonyl compounds are obtained for instance, stearoHc acid yields mainly azelaic acid, and a smaH amount of 9,10-diketostearic acid. 

Nickel peroxide is a solid, insoluble oxidant prepared by reaction of nickel (II) salts with hypochlorite or ozone in aqueous alkaline solution. This reagent when used in nonpolar medium is similar to, but more reactive than, activated manganese dioxide in selectively oxidizing allylic or acetylenic alcohols. It also reacts rapidly with amines, phenols, hydrazones and sulfides so that selective oxidation of allylic alcohols in the presence of these functionalities may not be possible. In basic media the oxidizing power of nickel peroxide is increased and saturated primary alcohols can be oxidized directly to carboxylic acids. In the presence of ammonia at —20°, primary allylic alcohols give amides while at elevated temperatures nitriles are formed. At elevated temperatures efficient cleavage of a-glycols, a-ketols... 

Ozone also adds to the carbon-carbon triple bond of acetylenic compds, the usual products being diketones and carboxylic acids. In polynuclear aromatic compds, the various carbon bonds and atoms have different reactivities. The reaction with ozone is more complex and the compn of products is difficult to predict... 

Acetyl eneozonide. C2H2 03, has never been isolated, According to Briner et al (Ref 3), ozoniza-tion of acetylene in gaseous form resulted in expins. However, when the ozonization was conducted in an anhydr solvent by one of the methods described by Harries (Ref 2) for ozonization of unsaturated hydrocarbons, Briner was able to obtain some crystals which were unstable and exploded before they could be examined. When the solvent used in the prepn was rapidly evaporated, the residue exploded... 

Violent reactions have occurred between ozone and many chemicals, a small selection being acetylene, alkenes, dialkyl zincs, benzene/rubber solution, bromine, carbon monoxide and ethylene, diethyl ether, hydrogen bromide, and nitrogen oxide. 

Finally, acetylene detonates violently when it comes into contact with an ozone/oxygen mixture in which the quantity of ozone exceeds 50 mg/l. 

See Dinitrogen oxide or Halogens, both above Oxygen, below Calcium hypochlorite Acetylene Nitric acid Acetylene, Mercury(II) salts Nitrogen oxide Dienes, Oxygen Ozone Acetylene... 

Passage of ozone (endothermic oxidant) into acetylene (endothermic reducant) leads to a violent explosion when 50 mg/1 of ozone is present. 

A similar situation arises in the ir-v excited states of ethylene and acetylene where the n interactions become antibonding the excited states are consequently twisted (11) and bent (12) respectively. Another example is provided by triatomic molecules formed by second row atoms ifthe total number of valence electrons exceeds 16, the molecules are bent 33) since there are now antibonding electrons present and bending reduces the resulting unfavourable 7r interaction by replacing p AOs by hybrid AOs (cf. ozone, 13). 

All of the theoretically possible high-energy (and potentially hazardous) oxidant-fuel systems have been considered for use, and many have been evaluated, in rocket propulsion systems (with apparently the sole exception of the most potent combination, liquid ozone-liquid acetylene). Some of the materials which have been examined are listed below, and it is apparent that any preparative reactions deliberately involving oxidant-fuel pairs must be conducted under controlled conditions with appropriate precautions to limit the rate of energy release. 

DuPont was looking for a synthetic rubber (SR). Carothers assigned Arnold Collins to carry out this research. Collin s initial task was to produce pure divinylacetylene. While performing the distillation of an acetylene reaction, in 1930, he obtained a small amount of an unknown liquid, which he set aside in a test tube. After several days the liquid turned to a solid. The solid bounced and eventually was shown to be a SR polychloroprene, whose properties were similar to those of vulcanized rubber but was superior in its resistance to ozone, ordinary oxidation, and most organic liquids. It was sold under its generic name neoprene and the trade name Duprene. ... 

Magnesium nitrate, Tin(ll) fluoride, 4693 Manganese(lV) oxide, Calcium hydride, 4705 Molybdenum(VI) oxide, Graphite, 4717 Nitric acid, Formaldehyde, 4436 Nitric acid, Formic acid, 4436 Nitric acid, Formic acid. Urea, 4436 Nitric acid, Metal thiocyanate, 4436 Oxalic acid, Urea, 0725 Ozone, Acetylene, 4846... 

Schindler and coworkers verified the formation of hydroxyl radicals kinetically and further RRKM calculations by Cremer and coworkers placed the overall concept on a more quantitative basis by verifying the measured amount of OH radical. An extensive series of calculations on substituted alkenes placed this overall decomposition mechanism and the involvement of carbonyl oxides in the ozonolysis of alkenes on a firm theoretical basis. The prodnction of OH radicals in solution phase was also snggested on the basis of a series of DFT calculations . Interestingly, both experiment and theory support a concerted [4 4- 2] cycloaddition for the ozone-acetylene reaction rather than a nonconcerted reaction involving biradical intermediates . 

Predict the structure of the van der Waals complex between ozone and acetylene. Indicate which frontier orbital interactions should be most important. How does your prediction compare with the experimental structure (Gillies, J. Z. Gillies, C. 

Acetylene Ozonide. Briner Wunenburger (Ref 1) reported that the action of ozone on acetylene carried out in a gaseous phase, resulted in expln, but few crysts of ozonide were obtained when reaction was carried out in soln and at low temps. These crysts could not be properly investigated because they exploded violently a short time after their prepn. Hurd Christ(Ref 2) conducted ozonization of some acetylene derivs with 5-10% solns of ozone in chlf. Jacobs (Ref 3) conducted ozonization of some disubstituted acetylenes. Dallwigket al (Ref 4) detd infrared spectra of ozonides of some acetylene derivs... 

Predict the structure of the van der Waals complex between ozone and acetylene. Indicate which frontier orbital interactions should be most important. How does your prediction compare with the experimental structure (Gillies, J. Z. Gillies, C. W. Lovas, F. J. Matsumura, K. Suenram, R. D. Kraka, E. Cremer, D., J. Am. Chem. Soc., 1991, 113, 6408) ... 

Of all the reactions studied, only the synthesis of nitrogen oxides and acetylene in arcs or plasma torches and that of ozone in glow and corona discharges are of major importance. In addition, a few small-scale preparations of inorganic compounds have been developed, e.g. synthesis of hydrazine and of hydrides and halides of silicon, germanium, tin, lead, phosphorus or arsenic 3> ... 

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