Apparent extract

Increasing the hydrophobicity of quaternary ammonium salts increases the apparent extraction constants for the ion pair and therefore leads to a higher catalytic activity (Brandstrom, 1977). The same phenomenon has been observed by Cinquini and Tundo (1976) for crown ether catalysis (Table 35). The catalytic activity of 18-crown-6 [3] and alkyl-substituted derivatives [117]—[ 119] in the reaction of n-CgH17Br with aqueous KI follows the order [117], [118] > [119] s> [3]. The alkyl-substituted [2.2]-cryptand derivatives are also much more efficient than the parent compound [86]. Increasing the hydrophobicity of [2.2.2]-cryptand (Cinquini et al., 1975) and even of polypode ligands (Fornasier et al., 1976) leads to higher catalytic activity. The tetradecyl-substituted compounds show the reactivity sequence [2.2.2]-cryptand at 18-crown-6 > [2.2]-cryptand on the reactivity scale that can be distilled from Table 35. 

The addition of an alcohol to the basic two-phase system increases the apparent extraction of base into the organic phase, but it is generally acknowledged that it is the alkoxide anion which is being transferred [e.g. 43-50]. Optimum conditions for this co-catalytic effect requires the formation of highly lipophilic and highly basic alkoxides anions, either in the aqueous phase or at the interface. 

Mutagens were formed when ground beef was canned. The mutagenicity decreased when the ground beef was washed with water prior to canning. The wash water (stock) apparently extracted precursors which could form mutagens upon heating the canned stock produced an MAR more than twice that of the canned untreated meat. 

Both the EBC and the ASBC describe methods for determining the original extracts of beers. The apparent extract ( % w/w) is determined from the specific gravity of the filtered beer. Then 100-0 g of beer is distilled and the alcoholic content (A % w/w) is determined from the specific gravity of the distillate diluted to 100-0 g and the real extract (E r% w/w) is determined from the specific gravity of the residue diluted to 100-0 g. 

The parameters discussed above have direct effects on extraction rates. In addition, several variables exist which, since they influence membrane stability, have secondary effects on rates. Unstable membranes which liberate some of their internal phase to the external phase, either by "leakage or rapture, show a significantly lower "apparent extraction rate. The most importam of these parameters are the viscosity of the emulsion, the amount and type of surfactam used in enmlsiott preparation, the size of the internal micro-subdroplets, and the operating conditions of the mixer. "- - Membranes of very low viscosity or with inadequate surfactant levels are unstable. Hochhauser and Cussler observed that a 50% increase... 

Table 3. Apparent extraction constants of tetrabutylammonium bromide...

---