Molecules 2012, 17(5), 6001-6010; doi:10.3390/molecules17056001
Article

Metathesis Transformations of Natural Products: Cross-Metathesis of Natural Rubber and Mandarin Oil by Ru-Alkylidene Catalysts

Received: 16 March 2012; in revised form: 30 April 2012 / Accepted: 3 May 2012 / Published: 18 May 2012
(This article belongs to the Special Issue Olefin Metathesis and Its Application)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: This study reports on the degradation of natural rubber (NR) via cross-metathesis with mandarin oil and d-limonene, an abundant compound in essential oils; that were used as chain transfer agents (CTAs) and green solvents. Reactions were performed in the presence of the ruthenium-alkylidene catalysts (PCy3)2(Cl)2Ru=CHPh (I) and (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) (PCy3)Cl2Ru=CHPh (II), respectively. Catalyst II bears an N-heterocyclic carbene ligand (NHC) bounded to the ruthenium atom, which has a strong basic character; therefore it is more active toward trisubstituted olefins in comparison with catalyst I. In both cases, isolated monoterpene-terminated isoprene oligomers were obtained as products of the cross-metathesis degradation of NR. In the presence of catalyst II molecular weight values around Mn × 102 and yields of 80% were obtained; whereas with catalyst I, the molecular weights of products were about Mn × 104 with yields ranging 70 to 74%. The composition and yield of NR degradation products were determined by GC/MS (EI) analysis and it was found that the oligomers obtained have primarily one vinyl group and one terpene-monocyclic group at the chain end, with isoprene units Am = 2, 3 y 4.
Keywords: metathesis degradation; natural rubber; mandarin oil; alkylidene-ruthenium catalysts
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MDPI and ACS Style

Martínez, A.; Gutiérrez, S.; Tlenkopatchev, M.A. Metathesis Transformations of Natural Products: Cross-Metathesis of Natural Rubber and Mandarin Oil by Ru-Alkylidene Catalysts. Molecules 2012, 17, 6001-6010.

AMA Style

Martínez A, Gutiérrez S, Tlenkopatchev MA. Metathesis Transformations of Natural Products: Cross-Metathesis of Natural Rubber and Mandarin Oil by Ru-Alkylidene Catalysts. Molecules. 2012; 17(5):6001-6010.

Chicago/Turabian Style

Martínez, Araceli; Gutiérrez, Selena; Tlenkopatchev, Mikhail A. 2012. "Metathesis Transformations of Natural Products: Cross-Metathesis of Natural Rubber and Mandarin Oil by Ru-Alkylidene Catalysts." Molecules 17, no. 5: 6001-6010.

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