Alpha-functionalization

Shono and others have shown that electrochemical oxidation of amides in nucleophilic media results in incorporation of the nucleophile into the alpha-position of the N-alkyl group via an intermediate iminium species (equation 36). This so-called anodic alpha-functionalization reaction has been shown to be of considerable synthetic value. The reaction has been extensively reviewed98. 

With this method, thus, it is possible to accurately evaluate the area under die curve. Darken and Gurry have introduced a new function called the alpha function, a ... 

Fig. 7. Differential mobility spectra (intensity vs. compensation voltage plot). The relationship between AK and the compensation voltage is shown for ions with positive and negative alpha functions.

The mechanism of clustering and declustering for ions with positive alphas was developed and supported by results from the study of the changes in alpha functions with moisture in the gas atmosphere in the DMS analyzer [37,38], Gas-phase protonated... 

Fig. 13. (a) Alpha functions [alpha vs. E (Td)] of the explosives ions in pure air (top left) and a lOOOppm mixture of methylene chloride/air (top right) [57], (b) Differential mobility spectra of the explosives in purified air (bottom left) and lOOOppm of methylene chloride in air (bottom right). Explosives are from top 1,2,3-propanetriol trinitrate (NG) 1,3-dinitrobenzene (DNB) 2,6-dinitrotoluene (DNT) 2,4,6-trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN) [57]. 

Amatore C, Bayachou M, Boutejengout F, Verpeaux J-N (1993) Evidences for the generation of alpha-alkoxy and alpha-alkyl thioalkyl radicals upon reduction of alpha-functionalized... 

The main advantage of using a custom function instead of worksheet formulas is minimization of errors occurring when formulas are entered. The main disadvantage is that custom functions are slower than worksheet formulas. For example, in a sheet that uses worksheet formulas to calculate the four alpha values for phosphoric acid in 0.1 pH increments from pH 0 to 14 (calculation of 564 cells) using worksheet formulas (see Chapter 20), there was no detectable delay when the sheet was recalculated. On the same PC, when the ALPHA function was used, it took three seconds to recalculate the sheet. 

Twu, C. H., Coon, J. E., and Cunningham, J. R., 1995a. New generalized alpha function for a cubic equation of state Part 1. Peng-Robin.son equation. Fluid Phase Eq., 105 49-59. 

PGC-1 alpha. Functional implications in hepatic cholesterol and glucose metabolism. J. Biol. Chem. 279, 45139-45147. 

The correction factor of the parameter a is designated often by alpha function. For the RK-EOS this factor a(T) = 1 /. ... 

Much later Soave (1972) proposed a new modification, known as Soave-Redlich-Kwong EOS, abbreviated here SRK-EOS, in which the model incorporates another important molecular parameter, the acentric factor co(see later the equation 5.12). The result was that the accuracy of VLE computations improved considerably. In the case of SRK-EOS the alpha function is ... 

The first modified EOS for polar fluids have been proposed by Soave (1979). The modification called SRK2-EOS consists of two adjustable parameters in the alpha function ... 

Similarly, other EOS for polar components, this time implemented in Aspen Plus, makes use of variations in the alpha function. Among these we may cite ... 

As mentioned, the ability of a cubic equation of state to describe accurately the physical properties and behaviour of a fluid depends both on the alpha function and the mixing rules (see Chapter 6). A discussion about the last development in commercial simulators, namely in Aspen Plus and Hysys, can be found in a recent article written by Twu, Sim and Tassone (2002). 

Patton, J.S., Shepard, H.M., Wilking, H., Lewis, G., Aggarwal, B.B., Eessalu, T.E., Gavin, L.A., and Grunfeld, C. 1986. Interferons and tumor necrosis factors have similar catabolic effects on 3T3-L1 cells. Proc. Natl. Acad. Sci. USA. 83 8313-8317. Uysal, K.T., Wiesbrock, S.M., Marino, M.W., and Hotamisligil, G.S. 1997. Protection from obesity-induced insulin resistance in mice lacking TNF-alpha function. Nature. 389 610-614. 

The second chapter highlights the past, present and future of the asymmetric phospho-aldol reaction, one of the most powerful method to control the stereochemistry at the alpha-carbon of alpha-functionalized phosphonic systems (T.P. Kee and T.D. Nixon). Attention focused for the future to the design of new catalysts, improved processing and to medicinal chemistry and disease targets. 

Yamada and Zucker [1992] have tested various kinetic mechanisms to model calcium control of presynaptic release of transmitters. The classic model of postsynaptic response to a synaptic input is the so-called alpha function due to Rail [1967] and has the form ... 

The effects of variations in moisture with differential mobility methods in ion formation are identical to those observed in low-field methods, although the consequences for ion mobility are distinctive to this method. Effects were studied in detail using a set of organophosphorus compounds whose mobility dependence on field, or alpha functions, were determined at EIN values between 0 and 140 Td at ambient pressure in air with moisture levels between 0.1 and 15,000 ppm. At moisture levels of 0.1 to 10 ppm, the alpha function for protonated monomers was unchanged (Figure 11.6). At 50 ppm, there was an onset of change in the alpha function that increased twofold when moisture level was raised from 100 to 1,000 ppm at all EIN values. Changes of... 

---