Organic & Biomolecular Chemistry
Paper
Interestingly, the use of propylene carbonate is important oxon, only one phosphorylic compound was found in contrast
to control the selectivity of this reaction. Previously, we have to the three phosphorylic compounds observed in the nucleo-
2
7
reported the degradation of paraoxon with piperidine in some philic degradation of paraoxon in other solvents.
conventional organic solvents and the S 2(C) pathway is the This study highlights the efficiency of the microwave-
main degradation route (above 75%) in solvents less polar assisted degradation of OPP in propylene carbonate that pro-
N
2
7
than DMSO, such as 1,4-dioxane and acetonitrile. The kobsd ceeded at a significantly higher rate compared to conventional
value found for the degradation of paraoxon in PC with Bmim heating and silent conditions.
Ala] as the nucleophile (this study) is similar (9.6 × 10−6
s )
−1
[
to those reported for the degradation of paraoxon in conven-
tional ionic liquids such as Bmim[NTF ], B mim[NTF ] and
B mim[BF ] by the same reaction pathway. On the other
2
2
2
2
7
Conflicts of interest
2
4
hand, in a previous study, the degradation of fenitrothion with
piperidine was carried out in some bio-based solvents and con-
ventional ionic liquids and the only reaction pathway found
There are no conflicts to declare.
N
was the S 2(C) pathway, propylene carbonate being the best
2
8
solvent to degrade this pesticide. Finally, for malathion Acknowledgements
degradation, this study showed that the t1/2 value was around
This work was supported by Fondecyt, grant 1170976,
1170569 and postdoctoral grant 3150122. The authors would
also like to acknowledge the NMR facility in the Unidad
Central de Investigación at the Pontificia Universidad Catolica
de Chile for NMR support.
1
0 minutes with both nucleophiles, which is a very promising
1
result since in previous works the degradation of malathion
was studied in aqueous solutions using strong chemical oxi-
dants and UV irradiation. The t1/2 values were higher than
1
2 hours while the best method to degrade this pesticide was
4
4
under O radiation with a t value of 2.4 hours.
3
1/2
These results are interesting from the toxicity point of view
since it is known that phosphate monoesters and diesters are
much less lipophilic, and therefore less toxic, than their trie-
ster precursor, paraoxon or parathion. It is important to
mention that even at long reaction times under MW heating,
the same products of the reaction were found in all cases.
References
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. Conclusions
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