Observation probabilities

In some cases, especially in the presence of strongly electron attracting substituents, isomerization to acid amides has been observed, probably preceded by deprotonation at ring carbon. Even (56), known for its stability towards common alkali, undergoes this rearrangement when a lithium amide is used as the base (80JOC1489). 

The Auger depth profile obtained from a plasma polymerized acetylene film that was reacted with the same model rubber compound referred to earlier for 65 min is shown in Fig. 39 [45]. The sulfur profile is especially interesting, demonstrating a peak very near the surface, another peak just below the surface, and a third peak near the interface between the primer film and the substrate. Interestingly, the peak at the surface seems to be related to a peak in the zinc concentration while the peak just below the surface seems to be related to a peak in the cobalt concentration. These observations probably indicate the formation of zinc and cobalt complexes that are responsible for the insertion of polysulfidic pendant groups into the model rubber compound and the plasma polymer. Since zinc is located on the surface while cobalt is somewhat below the surface, it is likely that the cobalt complexes were formed first and zinc complexes were mostly formed in the later stages of the reaction, after the cobalt had been consumed. 

However, no tautomeric interconversions between 1,2-dihydro- and 1,4-dihydropyridine analogs have been observed, probably because a high energy barrier is inherent to this transformation. 

Related platinum compounds such as 69 have thus been synthesized from a-keto or cyano-stabilized ylides. A selective C-coordination trans to the P phosphorus atom of the ligand is observed, probably resulting from steric interactions. 

Both PtRu/MgO catalysts prepared from cluster precursor and organometallic mixture were active for ethylene hydrogenation. The apparent activation energy of the former catalyst obtained from the Arrhenius plot during -40 to -25°C was 5.2 kcal/mol and that of the latter catalyst obtained during -50 to -30°C was 6.0 kcal/mol. The catalytic activity in terms of turn over frequency (TOP) was calculated on the assumption that all metal particles were accessible for reactant gas. Lower TOP of catalyst prepared from cluster A at -40°C, 57.3 x lO" s" was observed probably due to Pt-Ru contribution compared to that prepared from acac precursors. 

Fig. 3 shows the desulfurization activity of the absorbent at a reaction temperature ranging from 65°C to 400°C. The feed concentration of SO2 was fixed at 1000 ppm. When the reaction temperature was increased from 65°C to 80°C and then to 100°C, the changes in the reactivity of the absorbent could not really be observed probably due to the small increment in the reaction temperature. However, when the reaction temperature was further increased to 200°C, there is a significant increase in the reactivity of the absorbent. Similarly, when the reaction temperature was increased from 200°C to 300°C, the reactivity of the absorbent also increased. The increase in the reactivity of the absorbent at higher reaction temperature is due to the increase in the reaction rate constant at higher reaction temperature. 

The first correlation is observed at 40 ppm ( 48 ppm relative to the transmitter position) in the Fi frequency domain at the F2 shifts of the anisochronous Hll methylene protons in Figure 13. Rather than an m/cH transfer across three bonds, instead a 2/ch transfer is observed, probably an effect of the oxygen of the oxepin ring being attached to Cl 2 as shown by 43. The Jcc long-range correlation in this case is to the C7 resonance. 

This was the first example in which models for presumed Fischer-Tropsch intermediates have been isolated and their sequential reduction demonstrated. Neither methane nor methanol was observed from further reduction of the methyl and the hydroxymethyl complexes. The use of THF/H20 as solvent was crucial in this sytem in THF alone CpRe(C0)(N0)CH3 was the only species observed, probably because the initial formyl complex was further reduced by BH3.— When multihydridic reagents are reacted with metal carbonyl complexes, formyl species are usually not observed. The rapid hydrolysis of BH3 by aqueous THF allowed NaBH to act as a... 

Similar observations were made when BrCN was replaced by C1CN. Then the chlorine analogue S-60 was observed. Probably we were also successful in transferring photochemically both isocyanocarbenes 58 and 60 into the corresponding halogenated cyanocarbenes. But their identification has to remain tentative, since only two IR bands could be found for each of the new cyano carbenes. 

The other was derived from the Poisson equation and the observed probability of no response, or failures, upon nerve stimulation ... 

On the above basis, the differences between the velocities of the two types of particles should increase with concentration and, consequently, the concentration of the two separated zones should become increasingly different. This is found to be so at volumetric concentrations up to 20 per cent. At higher concentrations, the effect is not observed, probably because the normal corrections for settling velocities cannot be applied when particles are moving in opposite directions in suspensions of high concentration. 

De Queiroz et al. (2006) performed mass-spectrometric experiments in which gas-phase reactions of the isolated N02 and benzene derivatives were studied. The reaction results in the predominant electron abstraction yielding exclusively ionized benzenes. None of the expected adducts (such as a complexes) were observed. Probably because direct addition of NO, to benzene is strongly exothermic, the nascent product is too hot to survive when it is isolated in the gas phase. 

The relaxation rates calculated from Eq. (15) are smaller than the measured ones at low field, while they are larger at high field. OST is thus obviously unable to match the experimental results. However, water protons actually diffuse around ferrihydrite and akaganeite particles and there is no reason to believe that the contribution to the rate from this diffusion would not be quadratic with the external field. This contribution is not observed, probably because the coefficient of the quadratic dependence with the field is smaller than predicted. This could be explained by an erroneous definition of the correlation length in OST, this length is the particle radius, whilst the right definition should be the mean distance between random defects of the crystal. This correlation time would then be significantly reduced, hence the contribution to the relaxation rate. 

The small 110 a.a. ribonuclease from B. amyloliquefaciens, bamase, has been studied extensively in A.R.Fersht s laboratory (Sali, Bycroft and Fersht, 1988 Matouschek et al, 1990 Bycroft et al., 1990 Serrano and Fersht, 1989) using NMR as an essential experimental techniqne. The df-helices of bamase have been studied with respect to stability and it was found that mutation of the THR and THR residnes located at the N-terminal of the helix (Serrano and Fersht, 1989) could destabilize the protein with up to 2.5 kcal mol b The THR and SER residnes are capable of facilitating the formation of an additional hydrogen bond in the first him of the df-helix. If THR is snbstitnted with ASP or GLU no marked change in stability was observed, probably dne to the known charge-dipole interaction between the negative charge of the ASP or GLU and the positive end of the helix macro-dipole. 

Han [17] has shown that the effect of silane coupling agents on the viscosity of filled thermoplastics is not consistent. Melt viscosity may be decreased or increased depending on the chemical structure of the treatment and the nature of the polymer/filler combination under consideration. These observations probably reflect the effectiveness of the coupling agent in promoting bonding between filler and polymer, and hence the extent of polymer immobilization. 

The probabilities of different outcomes can thus be seen as resulting from the causal powers and capacities of the system and their arrangement. This makes probability a function of the nature of the system, not merely a statement of degrees of belief or the frequency with which an outcome occurs. We can account for the observed probability (in a frequency sense) by the interplay of capacities or causal powers, and we can estimate a probability (in the epistemic sense) if we know something about the capacities of the things that may influence the outcome. 

Table 3 shows that the fluoroarene yield increases with the irradiation power and is dependent again on the hydrogen fluoride/pyridine ratio (cf. 2-methoxy-4-nitroaniline). An optimum ratio must, most probably, be determined for each substrate. It should also be noted that photochemical fluorodediazoniation does not occur in pure hydrogen fluoride. This observation probably implies that not only light is involved in the weakening of the C-N bond. On the other hand, benzene is formed together with fluorobenzene when pyridine is replaced by 2,4,6-trimethylpyridine such a phenomenon is consistent with the occurrence of aryl radicals."... 

The 1,3-dichlorohexafluoropropane is once again assumed to arise by the addition of CF2C1 radicals to the CF3 formed by disproportionation processes. Its rate of formation is much slower than in the case of the photolysis of 1,3-dichlorotetrafluoroacetone, probably due to the reduced radical concentration. The analysis is obviously incomplete because no corresponding halogenated propanes, from the addition of CFCh radicals to CF2, have been observed, probably owing to their low volatility. 

Figure 2 shows the results of isohexane cracking on MCM-41 and HZSM-5 as examples of mesoporous silica and acidic catalysts. On all the catalysts, products mainly composed of C2 to C4 components as cracking products and C6 components as isomerization products, and the products of possible secondary reactions were not appreciably observed probably because of low conversion level. Since the amount of C2 component was very close to that of C4 components, it is considered that isohexane is cracked in two modes giving C2+C4 and two C3 molecules. In the case of MCM-41, cracking of isohexane proceeded above 598 K, and temperature dependence was not so large below 723 K, but very large above it, as shown in Fig. 2a. On the other hand, HZSM-5 gave smooth temperature dependence as shown in Fig. 2b. Another significant difference between MCM-41 and HZSM-5 was the distribution of cracking products The ratio of C3/C4 was much larger on HZSM-5 than on MCM-41.

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