Ozonolytic degradation

Barnard, D. Ozonolytic degradation of interpolymers of natural rubber with methyl methacrylate and styrene. J. Polymer Sci. 22, 213 (1956). 

The diol 59 was used for an ingenious synthesis of L-mycarose (62, 2,6-dideoxy-3-C-methyl-L-n bo-hexose) and olivomycose (63, 2,6-dideoxy-3-C-methyl-L-ara /no-hexose). The sequence of reactions consisted in 1 epoxidation of the double bond and separation of both stereoisomeric epoxides formed, 2° reduction of the oxirane ring to form two triols 60 and 61, and 3° ozonolytic degradation of the aromatic ring to a carboxyl group. Each trihydroxyacid was converted into a lactone and the lactones were eventually reduced to the required branched-chain sugars 62 and 63. 

In this case, diol 66 was converted into the monobenzoate 67 and was epox-idized at the trisubstituted double bond. The epoxide was reduced and the triol obtained was ozonolytically degraded to the lactone of olivomycosonic acid (68). The half-reduction of the lactone 68 with diisobutylaluminum hydride (DIBAH) furnished 63. 

The geminally dialkylated building blocks 111 and 116 for rings A and B of the macrotetracycle are obtained from cobyrinic acid hepta-methylester, a vitamin B12 derivative, by ozonolytic degradation and... 

As mentioned above, Calderon recognized in 1972 that metathesis polymerization and metathesis of acyclic olefins are two aspects of the same reaction [10]. As early as 1968 he had identified the double bonds as the reactive centers in the metathesis of acyclic olefins. Apart from the educts the metathesis reaction of dg-2-butene with 2-butene yielded only d4-2-butene, so he could exclude the cleavage of any single bond [39,40]. Dali Asta and Motroni drew an analogous conclusion for ROMP by copolymerization of 1- C-cyclopentene and cyclooctene (3). After ozonolytic degradation of the polymers the complete radioactivity was found in the C5-fraction, showing the exclusive cleavage of the double bonds (pathway (3b)) [41,42]. 

Either photocatalysis or ozonation alone achieved rapid disappearance of aromatic pesticide. In contrast, mineralization (TOC removal) was slow for both. However, photocatalytic mineralization was enhanced considerably by ozone pretreatment (Fig. 9.16).31) This effect may be explained by ozonolytic cleavage of the aromatic ring and subsequent formation of aliphatic compounds which are more degradable by photocatalysis. Simultaneous use of photocatalyst and ozonation (illuminated by 254 nm light) showed synergetic effect on TOC removal (Fig. 9.17).32) In this process scavenging of electrons by ozone is considered to play the most important role. 

Curtius degradation 16, 560 enamines 16, 65 ethylene derivatives by reductoamination, ozonolytic 18, 530 ethyleneketones 18, 465 hydrazines s. N-Deamina-tion... 

Mention may also be made of the controlled ozonolytic or oxidative degradations of high MW iso tactic poly(oxypropylene), poly(vinyl chloride), and poly(isobutene-co-2,3-dimethylbuta-diene) " to give oligomers with functional end groups. However, no effective synthesis has yet been devised for a, co-difunctional polymethylene oligomers which would be of considerable interest as precursors of block copolymers. 

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