Platinum limonene

In this pyrolysis, sub atmospheric partial pressures are achieved by employing a diluent such as steam. Because of the corrosive nature of the acids (HE and HCl) formed, the reactor design should include a platinum-lined tubular reactor made of nickel to allow atmospheric pressure reactions to be mn in the presence of a diluent. Because the pyrolysate contains numerous by-products that adversely affect polymerization, the TFE must be purified. Refinement of TFE is an extremely complex process, which contributes to the high cost of the monomer. Inhibitors are added to the purified monomer to avoid polymerization during storage terpenes such as t7-limonene and terpene B are effective (10). 

The monosubstituted double bond in 4-vinylcyclohexene is hydrogenated over P-1 nickel in preference to the disubstituted double bond in the ring, giving 98% of 4-ethylcyclohexane [73]. Similarly in limonene the double bond in the side chain is reduced while the double bond in the ring is left intact if the compound is treated with hydrogen over 5% platinum on carbon at 60° and 3.7 atm (yield 97.6%) [348]. 

Independently, the epoxide 40 has been synthesized by electrolysis of 39 in a THF/ H20—NaOH—(C) system, yielding a 5 1 mixture of cis- and trans-isomers. The stereoselective formation of 40 is explained by assuming the existence of a heterogeneous process caused by the absorption of limonene, which takes place on one of the sides of the double bond on a graphite electrode. The platinum anode does not work efficiently for the same conversion. 

One of the principal components of lemon grass oil is limonene, C10H16. When limonene is treated with excess hydrogen and a platinum catalyst, the product is an alkane of formula CioH2o- What can you conclude about the stmcture of limonene ... 

The selective hydrogenation of the disubstituted double bond of limonene (52) took place over a platinum catalyst at 60°C and 3 atmospheres pressure (Eqn. 15.33). 5 1,5-Undecadiene was hydrogenated to 5-undecene with 78% selectivity at 97% conversion over a Pt/A 2eolite catalyst that was treated with diphenyldiethoxysilane. 9... 

The ease of reduction of an alkene decreases with the degree of substitution of the double bond, and this sometimes allows selective reduction of one double bond in a molecule which contains several. For example, limonene 7 can be converted into p-menthene (by reduction of the terminal alkene) in almost quantitative yield by hydrogenation over platinum oxide if the reaction is stopped after absorption of one molar equivalent of hydrogen. In contrast, the isomeric diene 8, in which both double bonds are disubstituted, gives only the completely reduced product (7.7). 

In a patent by Mitsubishi, it is available via hydroformylation of limonene and subsequent acid-catalyzed intramolecular cyclization of the aldehyde [1]. The alcohol can also be produced in one step by Pt/Sn-catalyzed hydroformylation, suggested by a protocol of Gusevskaya and coworkers (Scheme 5.123) [2, 3]. Platinum and tin are essential for the cychzation in the last step. Alternatively, the tandem reaction has been investigated in detail with rhodium complexes based on PPhg, P[0(o-fBu)Ph]3, or PPTS (pyridinium / -toluenesulfonate)... 

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