Ozonolysis 1-decene

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). 

There are no considerable differences between the values of the activation energy (E) and reaction order ( ) of the ozonide thermal decomposition with E-IR and Z-IR (Table 10.7). The smaller E values of the polyiso-prene ozonides in comparison with those of E-BR ozonides and 1-decene ozonide are, most probably, due to the lower thermal stability of small amounts of oligomeric peroxides, which are present among the reaction products of E-IR and Z-IR ozonolysis [36]. 

The idea of using microstructured reactors for preparative oxidations with ozone was firstly picked up by Wada et ol. [33]. Ozonolysis reactions of triethyl phosphite (Figure 6.30a), octylamine (Figure 6.30b), and 1-decene with subsequent reductive treatment (Figure 6.30c) served as model reactions, which were all conducted in ethyl acetate as solvent. 

Figure 6.30 Ozonolysis reactions of (a) triethyl phosphite (55), (b) octylamine (57), and (c) 1-decene (61).

For all studied reactions, 100% substrate conversion was obtained at contact times lower than 1 s at room temperature, that is, at a temperature much higher than commonly used for ozonolysis reactions. Under optimal conditions, the selectivity to triethyl phosphate (56) was higher than 98%. For nitrooctane (60), a selectivity of 80% was achieved while a selectivity of 100% toward the corresponding aldehyde nonanal (62) was observed in the ozonolysis of 1-decene (61). 

In 2010, the authors described the ozonolysis of 1-decene (61) in different solvents (dichloromethane, methanol, and a mixture of both) [35]. Results obtained in the falling film microreactor were compared to those obtained in a semibatch reactor with continuous ozone dosing to the reaction mixture. The reaction mechanism and the assumed species in the reaction mixture are summarized in Figure 6.33. 

Figure 6.33 Suggested reaction scheme of the 1-decene (61) ozonolysis in CH2CI2 and CH3OH. (Reproduced from Ref [35] with permission of the American Chemicai Society.)...

The ozonolysis of 1-decene (61, see Figure 6.33) was also studied by Roydhouse et al. in 2011 [36]. The group investigated the reaction with subsequent quenching of the formed ozonides to the corresponding aldehydes in a commercially available cooled Vapourtec (www.vapourtec.co.uk) reactor module that is in principle a PFA capillary reactor with an inner diameter of 1 mm (Figure 6.35). 

The mixture of aldehydes can be made by ozonolysis of this disubstituted alkene (/raws-2-methyl-4-decene), as described above. (Note that the E alkene is shown here, but ozonolysis of the Z alkene would also produce the same two aldehydes.)... 

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