Activity allowance

Soluble anode materials are not always a pure metal. In acid, low chloride nickel solutions, pure nickel does not corrode well, and small amounts of specific impurities are added to make the nickel more active, allowing more efficient dissolution. For example, since the early 1960s, nickel anode material containing a small amount of nickel sulfide [16812-54-7] NiS, has been commercially available and important in nickel sulfamate [13770-85-3] Ni(H2N02S)2, plating baths. These anodes corrode at a lower potential then pure nickel or other nickel anode materials (see Nickel and nickel alloys). 

BLOOD CLOTTING. The formation of blood clots is the result of a series of zymogen activations (Figure 15.5). The amplification achieved by this cascade of enzymatic activations allows blood clotting to occur rapidly in response to injury. Seven of the clotting factors in their active form are serine proteases ... 

The use of activities allows us to write a general expression for the equilibrium constant for any reaction ... 

The benzyl—nitrogen bond is not so easily cleaved as the benzyl—oxygen bond, unless the O-benzyl group is sterically hindered. This difference in activity allows the selective removal of the O-benzyl function in a molecule containing both N-benzyl and O-benzyl protecting groups. The selectivity can be reversed if the amine is protected by the Cbz group. If a small amount of amine (e g., butylamine) is added, then the selective removal of N-benzyl amines can be achieved.292... 

As with signal transduction and second messenger systems, the mechanism of gene activation allows for amplification of the hormone s effect. 

Ca++ channels start to become activated allowing Ca++ ion influx, which continues to depolarize the membrane toward threshold. 

Reserpine s strong inhibition of sympathetic activity allows increased parasympathetic activity to occur, which is responsible for side effects of nasal stuffiness, increased gastric acid secretion, diarrhea, and bradycardia. 

Activation. Erdik1 has reviewed the methods used since 1970 for activation of zinc and of organozinc reagents. Although chemical activation is still useful, ultrasound activation is being used increasingly. Thus sonic activation allows use of ordinary zinc for cyclopropanation of alkenes with CH2I2 in 67-97% yield and for Reformatsky-type reactions at room temperatures. 

The bidentate oxazoline ligands 85 and 86 (and derivatives thereof) are excellent reporter ligands, and several studies have used NOEs to determine the nature of their chiral pockets [61, 113, 114, 126]. NOESY studies on the cations [Ir(l,5-COD)(86)]+ and several cationic tri-nudear Ir(iii)(hydrido) compounds [110], e. g. [Ir3(p3-H)(H)5(86)3] +, 87, in connection with their hydrogenation activity, allowed their 3-D solution structures to be determined. In addition to the ortho P-phenyl protons, the protons of the oxazoline alkyl group are helpful in assigning the 3-D structure of both the catalyst precursors and the inactive tri-nudear dusters. Specifically, for one of these tri-nudear Ir(iii) complexes, 87 [110], with terminal hydride ligands at d -17.84 and d -21.32 (and a triply bridging hydride at 5 -7.07), the P-phenyl and oxazoline reporters define their relative positions, as shown in Scheme 1.5. 

As an alternative to addition of anionic nucleophiles followed by reoxidation, rhodium(l)-catalyzed C-H activation allowed the nucleophilic addition of alkenes to the intermediate Rh(i) carbene complex <2002JA13964, 2004JOC7329>. Purine behaved anomalously compared to other heterocycles, for which selective monoalkylation was observed, and underwent sequential substitution first at C-8 and then at C-6 (Equation 8). Caffeine was monoalkylated at C-8 in low yield (15%). Selectivity for C-8-arylation was also observed in the palladium-catalyzed C-H activation of 6-phenyl-9-benzylpurine (aryl iodides, 0.05 equiv Pd(OAc)2, 3 equiv Cul, 2.5 equiv CS2CO3, DMF, 160 °C, 60 h, 48-95% yields) <2006OL5389>. 

Other compounds cause liver necrosis because of biliary excretion. Thus, the drug furosemide causes a dose-dependent centrilobular necrosis in mice. The liver is a target as a result of its capacity for metabolic activation and because furosemide is excreted into the bile by an active process, which is saturated after high doses. The liver concentration of furosemide therefore rises disproportionately (chap. 3, Fig. 34), and metabolic activation allows the production of a toxic metabolite (Fig. 6.6). The drug proxicromil (chap. 5, Fig. 11) caused hepatic damage in dogs as a result of saturation of biliary excretion and a consequent increase in hepatic exposure. 

Receptor or carrier proteins which, when activated, allows the passage of ions across cell membranes. 

Alkane isomerization equilibria are temperature-dependent, with the formation of branched isomers tending to occur at lower temperatures (Table 4.1). The use of superacids exhibiting high activity allows to achieve isomerization at lower temperature (as discussed below). As a result, high branching and consequently higher octane numbers are attained. Also, thermodynamic equilibria of neutral hydrocarbons and those of derived carbocations are substantially different. Under appropriate conditions (usual acid catalysts, longer contact time) the thermodynamic... 

The latter is in loop 4, a part of the sequence that appears especially mobile but is highly conserved. These mutations all activate the protein, i.e., they decrease the GTPase activity, allowing the G protein to remain in its active conformation longer than normal. 

The most recent advances in methanol synthesis are the Invv- and intermediate-pressure processes of (he type shown in Fig. I. The synthesis step of this process- relies upon a copper-based catalyst, which sites good yields or melhanol at pressures of 50 and 100 atmospheres. These pressures are substantially below those of the 250-350 atmospheres required hy earlier processes. The high catalyst activity allows the synthesis reaction to lake place at a relatively low temperature of 250-270 C. As a result, ineihunution is avoided, and byproduct formation is lower, giving increased process efficiency. 

Knowledge of the heat of activation allows us to determine the temperature interval in which the chemical reaction occurs and the order of magnitude of the volumetric rate of heat release in the zone of highest reaction rate. 

Chromium activation allows a strategy for aryl ether synthesis in four stages (i) electrophilic chlorination (ii) chromium coordination (iii) alkoxide substitution for chloride and (iv) oxidative decomplexa-tion.33 The process is effective for the synthesis of 6-methoxytetrahydroquinolines and 5-methoxydihydroindole derivatives, for example. Chlorination of iV-acetyltetrahydroquinoline with SO2CI2 followed by deacetylation provides 6-chlorotetrahydroisoquinoline in 77% yield (equation 11).33 Complexation with [Cr(CO)6] in diglyme-cyclohexane at 125 °C for 53 h using the Strohmeier apparatus gave the chromium complex (13) in 85% yield, based on 40% recovery of starting material. The unre-... 

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