Pressure through

Streaming potentials, like other electrokinetic effects, are difficult to measure reproducibly. One means involves forcing a liquid under pressure through a porous plug or capillary and measuring E by means of electrodes in the solution on either side [6, 23, 71-73]. 

We can now calculate the Donnan contribution to film pressure through the use of Eq. III-113 in the approximate form ... 

The aolventa, enumerated under 10 and 11, may contain traces of peroxides. These can be removed either by refiuxing over anhydrous stannous ofiloride (see concluding paragraph of Section VI, 12) or by filtration under slight pressure through a column of activated alumina. 

The ester and catalj st are usually employed in equimoleciilar amounts. With R =CjHs (phenyl propionate), the products are o- and p-propiophenol with R = CH3 (phenyl acetate), o- and p-hydroxyacetophenone are formed. The nature of the product is influenced by the structure of the ester, by the temperature, the solvent and the amount of aluminium chloride used generally, low reaction temperatures favour the formation of p-hydroxy ketones. It is usually possible to separate the two hydroxy ketones by fractional distillation under diminished pressure through an efficient fractionating column or by steam distillation the ortho compounds, being chelated, are more volatile in steam It may be mentioned that Clemmensen reduction (compare Section IV,6) of the hj droxy ketones affords an excellent route to the substituted phenols. 

The aqueous layer was extracted with diethyl ether. The combined ethereal solutions were dried over potassium carbonate, after which the greater part of the diethyl ether was distilled off at normal pressure through a 40-cm Vigreux column (bath temperature < 90°C). Careful distillation of the remaining liquid afforded the bis-ether, b.p. 47-49°C/18 mmHg, Op 1.4469, in 78% yield. 

The greater part of the pentane was distilled off at normal pressure through a... 

After vigorous shaking the layers were separated and three extractions of the agueous layer with diethyl ether were carried out. The combined solutions were washed twice with saturated NaCl solution and then dried over magnesium sulfate. The greater part of the solvents was distilled off at normal pressure through a... 

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