Component in-situ

In paper and thin-layer chromatography, the separation process is halted at a stage which leaves the separated components in situ on the surface in the form of spots. The rate at which a solute has moved is then determined by its retardation factor, R, which is defined as... 

Component In situ cell Laboratory pilot reactor... 

As will be highlighted in the following examples, the most interesting feature of this strategy lies in the possibility of generating the dipole component in situ under mild, neutral conditions by simple exposure of a properly designed allylic substrate to a suitable palladium catalyst (for an updated, general review of Pd-catalyzed cyclizations of allylic compounds, see [17]). 

Dutton, P. L., and Jackson, J. B., 1972, Thermodynamic and kinetic characterization of electron transfer components in situ in Rhodopseudomonas spheroides and Rhodospirillum rubrum, Eur. J. Biochem. 30 495n510. 

Fig. 7. Redox-titration ourves of the reaction centers in (A) Rb. sphaeroides, (B) Cf. aurantiacus, (C) Rp. viridis and (D) Chromatium. See text for other details. Figure sources (A) Dutton and Jackson (1972) Thermodynamic and kinetic characterization of electron-transfer components in situ in Rhodopseudomonas spheroides and Rhodospiriiium rubrum. Eur J Biochem. 39 500 (B) Bruce, Fuiler and Biankenship (1982) Primary photochemistry in the facultatively aerobic green photosynthetic bacterium Chloroflexus aurantiacus. Proc Nat Acad, USA. 79 6533 (C) Prince, Leigh and Dutton (1976) Thermodynamic properties ofthe reaction center of Rhodopseudomonas viridis. Biochim Blophys Acta. 440 625 (D) Cusanovich, Bartsch and Kamen (1968) Light-induced electron transport In Chromatium. II. Light-induced absorbance changes in Chromatium chromatophores. Biochim Biophys Acta 153 408.

Reference was made in Chapter 16 to A. G. Green s discovery that Primuline can be diazotized on the fibre, then coupled with an aromatic hydroxyl or amino compound to give a new dye of greater wet-fastness. A logical sequence to this conception was to create an insoluble azo pigment within the fibre by coupling the two components in situ. 

Blends discussed in preceding sections were based on two or more preformed polymers. One disadvantage of such systems is that commercial melt mixing involves two viscous components. Also, intermolecular interactions, which might aid miscibihty, can further enhance the viscosity of the medium. An alternative procedure is to form at least one of the polymeric components in situ. There have been two studies to date which have involved oligomeric materials in generating PCL blends. 

The elimination of an acyl chloride by a tertiary amine base has been widely used to generate the ketene component in situ due to its convenience and the ready availability of the starting acyl chlorides. The tertiary amine must be a nucleophilic tertiary amine, and triethylamine is generally used. The tertiary amine forms an intermediate acylammonium salt that undergoes decomposition to the ketene. 

Usually, the components are mechanically mixed together (24,25), although it is sometimes possible to produce the ruhher component in situ during polymerization. Typically, the two components form interdispersed multiphase systems and a diagrammatic structure for hlends of this type is shown in Figure 3. Blends... 

Recently, the reaction has been found to proceed using on-water microwave-assisted conditions [52], Barluenga et al. have also reported a three-component variation of the methodology, in which an initial palladium-catalyzed alkenyl halide amination was used to generate the imine component in situ [53]. 

Yohe, H. C., and Rosenberg, A., 1977, Action of intrinsic sialidase of rat brain synaptic membranes on membrane sialolipid and sialoprotein components in situ, J. Biol. Chem. 252 2412-2418. 

Kobayashi has developed the zirconium-BINOL-derived complex 148 as a catalyst for enantioselective Strecker reactions with Bu3SnCN as the cyanide source [106], Subsequent investigations led to a protocol for the three-component in situ coupling of aldehydes, amines, and HCN (Equation 21) [107]. For example, aminonitrile 149 can be prepared in 99% yield and 94% ee in the presence of 5 mol% of zirconium catalyst 148. 

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