Alkenes, ozonolysis formation

Neeb, P., F. Sauer, O. Horie, and G. K. Moortgat, Formation of Hydroxymethyl Hydroperoxide and Formic Acid in Alkene Ozonolysis in the Presence of Water Vapour, Atmos. Environ., 31, 1417-1423 (1997). 

Orzechowska, G.E., Nguyen, H.T., and Paulson, S.E., Photochemical sources of organic acids. 2. Formation of C5-C9 carboxylic acids from alkene ozonolysis under dry and humid conditions using SPME, J. Phys. Chem., 109, 5358, 2005. 

Formation of C5-C9 carboxyhc acids from alkene ozonolysis under dry and humid conditions, J. Phys. Chem. A, 109, 5366-5375. 

Dehydration of 2 2 3 4 4 pentamethyl 3 pentanol gave two alkenes A and B Ozonolysis of the lower boiling alkene A gave formaldehyde (H2C=0) and 2 2 4 4 tetramethyl 3 pentanone Ozonolysis of B gave formaldehyde and 3 3 4 4 tetramethyl 2 pentanone Identify A and B and suggest an explanation for the formation of B in the dehydration reaction... 

The location of the position of double bonds in alkenes or similar compounds is a difficult process when only very small amounts of sample are available [712,713]. Hass spectrometry is often unsuited for this purpose unless the position of the double bond is fixed by derivatization. Oxidation of the double bond to either an ozonide or cis-diol, or formation of a methoxy or epoxide derivative, can be carried out on micrograms to nanograms of sample [713-716]. Single peaks can be trapped in a cooled section of a capillary tube and derivatized within the trap for reinjection. Ozonolysis is simple to carry out and occurs sufficiently rapidly that reaction temperatures of -70 C are common [436,705,707,713-717]. Several micro-ozonolysis. apparatuses are commercially available or can be readily assembled in the laboratory using standard equipment and a Tesla coil (vacuum tester) to generate the ozone. Reaction yields of ozonolysis products are typically 70 to 95t, although structures such as... 

The reaction takes place in the medium of acetic acid and yields are generally good. This is why the route to obtain aldehydes or ketones from alkenes via glycol formation is preferred over that of ozonolysis. Other compounds which are readily cleaved include those with the groups ... 

It has been suggested that the oligomers and polymers formed in the ozonolysis reactions of some alkenes arise from the reactive 1,2,3-trioxolane intermediates or their fragmentation products (cf. Section 4.15.4.1) , though relatively little is known about the mode of formation of many of these polymeric species. The tendency of simple 1,2,3-trithiolanes to polymerize has... 

The formation of 1,2,3-trioxolanes from an alkene and ozone is the first step in the ozonolysis reaction, which is widely used in synthesis to convert alkenes to aldehydes or carboxylic acids. No instances of double bond migration during ozonolysis are known (since the first step is a cyclo-... 

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 . 

Gutbrod, R., R. N. Schindler, E. Kraka, and D. Cremer, "Formation of OH Radicals in the Gas Phase Ozonolysis of Alkenes The Unexpected Role of Carbonyl Oxides, Chem. Phys. Lett., 252, 221-229 (1996). 

Interesting variations in product distributions could be observed when ozonolysis was carried out with alkenes adsorbed on silica gel.628 The low-temperature ozonolysis on dry silica gel of cyclopentene led to the formation of the normal, monomeric ozonide in high yield [Eq. (9.114)]. This corresponds to the product formed in aprotic and nonparticipating solvents. In contrast, reaction of cyclopentene on wet silica gel resulted in the formation of the corresponding oxo acid... 

Ozonolysis of cyclic olefins in the presence of carbonyl compounds gives the corresponding cross-ozonides.1329 In the ozonation of 1,2,4,5-tetramethyl-1,4-cyclohexadiene, oxidative dehydrogenation (formation of 1,2,4,5-tetramethylben-zene) was found to compete with oxidative cleavage because of steric hindrance.1330 Secondary ozonides (the 76 1,2,4-trioxolanes) are formed in high yields in the gas-phase, low-temperature ozonation of terminal and disubstituted alkenes.1331... 

Intramolecular Dieckmann cyclization of polystyrene-bound pimelates has been used to prepare (l-keto esters (Entry 4, Table 3.41). Oxidative cleavage reactions leading to the formation of aldehydes include the ozonolysis of resin-bound alkenes, the periodate-mediated cleavage of 1,2-diols, and the oxidation of Wang resin derived ethers (Entries 5-7, Table 3.41). 

Depending on the alkene cation radical nature, open-chain oxygenation and epoxida-tion take place as well as the formation of other trivial ozonolysis products. Alkylaromatic compounds are also oxidized by ozone via the ion radical mechanism. Ethylbenzene, for example, undergoes ozone attack on the ring (80%) and on the alkyl group (20%). According to kinetic studies, the ozone consumption obeys the chain law (Galstyan et al. 2001). 

Ozonolysis of alkenes in the presence of amine A-oxides resulted in reductive ozonolysis, i.e, the direct formation of aldehydes in high yields, avoiding the generation and isolation of ozonides or other peroxide products. Use of DMSO and tertiary amines improved the yield of aldehydes but some amount of ozonides remained. This... 

An older paper <1971MI873> reported that ozonolysis of alkenes in the presence of tertiary amines resulted in the formation of aldehydes. A recent reinvestigation <20060L3199> has shown that amine oxides were responsible for this reductive ozonolysis . Indeed, pretreatment of the tertiary amines with ozone, giving rise to amine oxides, accounted for this phenomenon. A preparative method emerged, by treating the alkene (e.g., 1-decene) at 0 °C with a solution of 2% 03/02 in dichloromethane (2 equiv of ozone relative to the alkene) in the presence of an excess (about threefold molar excess) of A-methylmorpholine A-oxide, pyridine A-oxide, or l,4-diazabicyclo[2.2.2]octane A-oxide (DABCO A-oxide). Yields of aldehydes (nonanal in the above example) were 80-96%, and the excess of amine oxide ensured the absence of residual ozonide (Scheme 21). 

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