Enhancer Decalin

AXB) shows time courees of amounts of evolved hydrogen and decalin conversions with caibon-supported platinum-based catalysts unda" supeiheated liquid-film conditions. Enhancement of dehydrogenation activities for decalin was realized by using fiiese composite catalysts. The Pt-W / C composite catalyst exhibited the hipest reaction rate at the initial stage, whereas the Pt-Re / C composite catalyst showed the second highest reaction rate in addition to low in sensitivity to retardation due to naphthaloie adsorbed on catalytic active sites [1-5], as indicated in Fig. 2(A) ). 

The changes in the product concentrations are more pronounced in case of Pt-zeolites. Particularly the rate of decalin isomerization is considerably enhanced by the addition of platinum. The ratio of Iso/ROP decreases from the value of 12 after 1 h to the value of 1.4 after 9 h. The ratio of ROP/CP decreases from the values close to 3 within the first 3 h to the value of 1.3 after 9 h. This is in contrast to H-Beta-25, where the ratio ROP/CP is almost constant during the entire experiment and its values do not exceed 1.5. The same trends are... 

In addition, the more the number of piled catalyst sheet, the larger the dehydrogenation activities in the liquid-film state especially, as evident in Figures 13.23 and 13.24. It is easy for the liquid reactant to penetrate into the catalyst layer consisting of the ACC with lots of air space. By piling the ACC, therefore, decalin would penetrate into catalyst layer further and be kept in it for a long time, resulting in an enhanced catalytic performance. 

Kubica et al45 also investigated the effect of platinum-modified zeolites on the decalin reaction. They found that the addition of Pt enhances the catalyst activity. The initial isomerization was increased 3 times, which can be interpreted in terms of a change in the reaction initiation. In addition to initiation by a PC step over Bronsted acid sites, as proposed for H-form zeolites, a bifunctional initiation path... 

Striking evidence for the role of the hyperfine interaction on the time dependence of ion-pair recombination was found by Brocklehurst [56, 409]. He ionized a solution of p-terphenyl in decalin (benzene, squalane etc.) with 90Sr (3 particles and observed the time dependence of the fluorescence intensity. When the experiment was repeated, but with a magnetic field (< 0.16 T) applied, the fluorescence intensity was enhanced by approximately 40% after about 10—20 ns. The magnetic field splits the triplet levels so that only T0 can mix with S0 and the initial singlet... 

The opposite behavior as sketched before was detected for solutions of PS in DOP [112], Again, the critical temperature (an UCST at Tc = 12 °C in the quiescent state) turned out to be a function of the shear rate to which the solution is subjected. But, in contrast to solutions of PS and PB in DOP, here enhancements of the UCST as large as 28 °C were recorded at a shear rate of 220 s-1. Similar results have been found for PS solutions in di(2-ethyl hexyl)phthalate or in a mixture of cis- and frans-decalin [113], The solutions demixed in a converging flow from a reservoir into a capillary tube. It has been observed that an increase in the deformation rate raised the UCST or reduced the region of miscibility. In both of these studies an increase of the cloud point temperature of the polymer solutions was used as an indication of phase separation. 

The hds of benzothiophen (473-670 K, 85 atm, 8 wt.% S in decalin) proceeded by two separate mechanisms (Scheme 5) both pseudo-first order in reactant.Desulphurization to styrene was enhanced in a sulphided catalyst thiophenic ring hydrogenation was more favoured in a pre-reduced catalyst. At increased H2S levels, reaction between H2S and styrene gave 1- and 2-phenylethanethiol, the amounts of which were also increased by the presence of FeS2. 

Two other totally synthetic variants are of interest. Fluvastatin (Lescol) (marketed in 1993) has been shown to lower LDL cholesterol significantly via competitive inhibition of HMG-CoA reductase. Here an indole ring replaces the decalin structure of lovastatin. With the additional phenyl ring it easily supersedes the hydrophobic requirement for the reductase inhibition. The para-fluorine atom undoubtedly enhances potency. Another experimental entry in this effort is RG12561. 

A high degree of stereoselectivity can be achieved in chelation-controlled reactions, utilizing hydroxy groups as stereodirectors (Eq. 59) [69], Studies have revealed that non-chelation-controlled processes may also proceed with enhanced selectivities, and this led to the synthesis of the cA-decalin skeleton of vinigrol (Eq. 60) [70]. 

As can be seen from the two previous examples as well as many others cited in the literature [53], the complex stereochemistry of the decalin portion of compactin or mevinolin is not required for biological actiivity, and in many instances, replacement with flat fragments results in enhanced activity relative to the natural products. 

From Teucrium oliverianum [34,68] the two C-10 hydroxylated neo-clerodane diterpenes were isolated, teucrolivins B (115) and A (116). Both possess a C-103 hydroxyl group appeared at 8 81.53 and 81.73, respectively, the 3-configuration of them was supported by NOE experiments, which showed that C-20 methyl group and the H-1 a proton must be close (3.7 % NOE enhancement in H-1 a when the Me-20 protons were irradiated). The NOE experiments summarized in Table 15 clearly revealed that the relative stereochemistry of the substituents of decalin ring of teucrolivin B is that depicted in its formula 115. 

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