Homogeneous reactions sequential steps

With homogenous catalysts such as Pd(PPh3)2Cl2 or Pd(PPh3)4 the most sequential catalyses using the Sonogashira reaction as initial step have been performed. 

The PROBE assay has been further developed into a homogeneous assay (now termed homogeneous MassEXTEND hME) using the same purification principle, whereby all sequential enzymatic steps are performed by a simple addition of the reagents to the reaction well. No washing steps are required, and the ion-... 

These unusual ethers represent major lipids in homogenates of potato tubers at pH >6.5. They are not present in intact tissue but are formed in a sequential reaction from endogenous lipids via acyl hydrolase and LOX-me-diated steps. 

FIGURE 10.1 A summary of reported selectivity-conversion relationships in the oxidative dehydrogenation of propane to propene. Solid line is the relationship for a sequential reaction of propane to propene to CO if the first-order reaction constants for the two steps are identical. Open circles are data for homogeneous noncatalytic reaction. 

Pitl975b Pittman, C.U., Jr. and Smith, L.R., Sequential Multi-step Reactions Catalyzed by Polymer-Anchored Homogeneous Catalysts, J. Am. Chem. Soc., 97 (1975) 1749-1754. 

A new synthetic approach in which thin (15-50A), amorphous, elemental layers are sequentially deposited to create a uniquely tailorable initial "reactant" is described. This synthetic approach has two key steps. The initially layered composite is diffused at low temperatures to produce a homogeneous amorphous alloy. Nucleation of this amorphous alloy is the rate limiting step in the formation of a crystalline compound. This approach overcomes the limitations of traditional, diffusion limited, solid-state synthetic methods, which offer no control of the reaction pathway and therefore no selectivity over which intermediates are formed. 

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