Potassium synergism

Potassium salts may considerably potentiate other anesthetics. However, this seems to hold mainly for motor fibers and not for sensory. A 1% potassium chloride solution could be used with some advantage in place of sodium chloride for making up isotonic anesthetic solutions. 

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Deactivation rates and aged catalyst properties have been investigated as a function of time on stream for iron-based Fischer-Tropsch catalysts in the presence/absence of potassium and/or silicon. There is a synergism in activity maintenance with the addition of both potassium and silicon to an iron catalyst. The addition of silicon appears to stabilize the surface area of the catalyst. Catalysts containing only iron or added silicon with or without potassium consist mainly of iron oxide at the end of the run. However, iron carbides are the dominant phase of the iron catalyst with added potassium alone. Catalyst surface areas increase slightly during synthesis. The bulk phase of the catalyst does not correlate to the catalyst activity. The partial pressure of water in the reactor is lower for potassium-containing catalysts and is not a reliable predictor of catalyst deactivation rate. 

Increasing and decreasing deactivation rates of iron FTS catalysts are obserx ed upon the addition of potassium and/or silicon respectively. There is a synergism in the maintenance of activity with the addition of both potassium and silicon leading to a low deactivation rate. 

Potassium loaded La203 are active and stable catalysts for diesel soot combustion. A synergic La-K effect takes place, by which mechanical mixtures of soot with K-La203 showed higher combustion rates than those observed when K, La or both were directly deposited on soot surface. 

In this chapter, we reviewed recent developments regarding lithium, sodium, and potassium salt based-catalysis, with a particular focus on asymmetric catalysts. While these alkali-metal salts have traditionally been used as simple bases, recent advances based on chiral multifunctional acid-base combination chemistry, using chiral crown-alkali-metal complexes, chiral lanthanoid/alkali-metal complexes, chiral alkali-metal alkoxides, and chiral alkali-metal phosphates, have also been outstanding. These synergic acid-base catalyst systems should enable more efficient and/or new transformations that have not been possible thus far using conventional catalysts that only rely on Lewis acidity or Bronsted/Lewis basicity. 

A well-known example of the synergistic effect is the inhibition of steel corrosion in acidic media by a mixture of iodide ions and amines or imines. The synergism was mainly explained by coulombic attraction between the charges of the adsorbed ions (Aramaki and Hackerman, 1969 Kordesch and Marko, 1960 McKee, 1967 Kemball, 1959). The strong chemisorption of iodide ions on the metal surface yields coulombic repulsion. Stabilization of the adsorbed iodide ions by means of electrostatic interaction with amines leads to enhanced adsorption and a higher inhibition effect. Insoluble surface complex formation between iodide ions and amines was also assumed and verified (Syed Azin et al., 1995 Donahue and Nobe, 1967). Potassium iodide also improves the inhibition efficiency of trans-cinnamaldehyde and alkynols on steel corrosion in 20% HCl solution (Rozenfeld, 1981). 

Clegg W, Forbes GC, Kennedy AR et al (2003) Potassium-zinc induced synergic enhancement of the basicity of hexamethyldisilazide (HMDS) towards methylbenzene molecules. Chem Commun 406-407. doi 10.1039/b211392a... 

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