Accommodated precursor

The quality and quantity of sites which are capable of reversible lithium accommodation depend in a complex manner on the crystallinity, the texture, the (mi-cro)structure, and the (micro)morphology of the carbonaceous host material [7, 19, 22, 40-57]. The type of carbon determines the current/potential characteristics of the electrochemical intercalation reaction and also potential side-reactions. Carbonaceous materials suitable for lithium intercalation are commercially available in many types and qualities [19, 43, 58-61], Many exotic carbons have been specially synthesized on a laboratory scale by pyrolysis of various precursors, e.g., carbons with a remarkably high lithium storage capacity (see Secs. 

In summary, large (>lpm) single crystal platelets of aurichalcite produced highly dispersed Cu and ZnO particles with dimensions on the order of 5 nm, as a result of standard catalyst preparation procedures used in the treatment of the precipitate precursors. The overall platelet dimensions were maintained throughout the preparation treatments, but the platelets became porous and polycrystalline to accommodate the changing chemical structure and density of the Cu and Zn components. The morphology of ZnO and Cu in the reduced catalysts appear to be completely determined by the crystallography of aurichalcite. 

A series of CoSx-MoSx/NaY catalysts was synthesized by intoducing Co(CO)3NO into MoSx/NaY evacuated at 673 K for 1 h, followed by second programmed sulfidation procedures. MoSx-CoSx/NaY catalysts were prepared in the reversed order of the metal sulfide accommodations into the zeolite cavities. When Co2(CO)g was used as the Co precursor, MoSx/NaY was impregnated with COj(CO)g dispersed in n-hexane, followed by evacuation at room temperature to remove the solvent. Co2(CO)g/MoSx/NaY was subsequently sulfided at 673 K to give CoSx/MoSx/NaY. The catalyst composition was determined by AAS and ICP. 

Jupiter s moon Europa has only been the subject of intense scientific investigation in recent years it is considered to be a member of that small group of heavenly bodies which could perhaps accommodate life (or a precursor of life). About 20 years ago, the Voyager passes afforded sensational pictures of Europa. These showed a network of linear bands, of differing breadths, on a very bright surface. The mean density was calculated as 3,018 35 kg/m3, and the surface temperature measured was 90-95 K. Circumstantial evidence points to either a surface consisting of water ice, or the presence of liquid water or warm ice under the surface. Three models were proposed (Oro et al., 1992) ... 

The present method is successful with a wide variety of ketones (see Table). Cyclic ketones (entries 1-4, 8) produce benzoannelated products in excellent overall yields. There is no need to purify the intermediate both the nucleophilic addition of methallylmagnesium chloride and the aromatic cyclization take place cleanly. Acyclic ketones (entries 5-7) also provide high yields of benzoannelated product. Aromatic ketones are particularly interesting substrates for this reaction since they provide substituted biphenyls, which are potentially useful materials for liquid crystal synthesis and whose preparation through classical methodology is often not straightforward. The conditions for the cationic cyclization step can be modified to accommodate acid-sensitive functionality. For example, cyclization of 3 to 4, the latter a precursor for 3-methyl-8,14-dehydromorphinan, was accomplished in 77% yield by treatment of 3 at... 

The present work deals with the study of the liquid phase phenol alkylation by (-butanol over the three types of catalysts derived from MWW-precursor MCM-22, MCM-36 and ITQ-2. It was assumed that by pillaring and/or delamination the contribution of acid sites located on the hemicages will increase and it could be evidenced during the alkylation of phenol by (-butanol, process involving large reaction intermediates and products which are difficult to be accommodated within sinusoidal channels. The reaction pathway involves many parallel and/or successive steps, the main reactions being O-alkylation and C-alkylation. The catalytic activity and selectivity of these materials are discussed. A general scheme of the process is proposed on the basis of the structural and acidic features of the catalysts. 

FIGURE 4 Ectocarpene as the product of a [3.3]-sigmatropic rearrangement. The fatty acid accommodates to the active center of the enzyme in a U-shaped fashion. Decarboxylation in conjunction with loss of the C(8) HR hydrogen atom yields, after cyclization between C(4) and C(6) of the precursor, the thermolabile (lS,2R)-cyclopropane. A subsequent spontaneous [3.3]-sigmatropic rearrangement (Cope rearrangement) proceeds via the cis-endo transition state and yields (6S )-ectocarpene. 

Conversely, the structure obtained when the precursor is only MTMS is almost entirely formed by the larger, less tensioned, six-membered rings, more able to accommodate the unreactive methyl groups. This... 

Coupling of vinyl iodides with aldehydes (12, 137). Further study1 of this 1,2-addition of alkenylchromium compounds to aldehydes to form allylic alcohols indicates that the reaction is applicable to a-alkoxy and a,(i-bisalkoxy aldehydes by use of a solvent other than DMF, which can promote elimination to an enal. A wide number of other functional groups can also be accommodated. Both vinyl iodides and p-iodo enones can be used as precursors to the alkenylchromium reagent. The reaction is only modestly diastereoselective, but the stereochemistry of a disubstituted vinyl iodide is retained. 

In the outstandingly successful Cl Reactive Black 5, two such precursor-bearing units are used in the synthesis of this near-symmetrical bifunctional structure (7.36). Following this precedent, competing bifunctional dyes of analogous structure were designed with two phenylene-l,3-diamine-4-sulphonate groupings to accommodate the reactive systems... 

Growth of particles by accumulation on existing particles can be classed as two broad processes. If the precursor is supersaturated, growth will occur at a rate limited by vapor diffusion, which depends on the supersaturation, the temperature, the particle size, and the accommodation coefficient at the surface. The proportionality of particle size changes with the ratio of particle diameter to mean free path of the suspending... 

No enetetramine formation has been observed with NHCs derived from seven-membered heterocycles. The C2 resonance in these derivatives is shifted further downfield (5 250-260 ppm) in the NMR spectra. The most striking difference in comparison to all NHCs discussed previously is the twisted, nonplanar conformation of the seven-membered heterocycle both in the azolium precursor and in the carbene ligand. The twisted conformation appears to be essential to accommodate the strain within the seven-membered heterocycle. 

It might be thought that photoisomerization and photoaquation could be competitive towards a common precursor excited state, but this explanation fails on quantitative testing. Briefly, the quantum yield for photoaquation is too high to accommodate its negative apparent activation energy. Photoaquation must then be competitive with some other process such as deactivation, or return to the original cis species. 

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