Ethers, alkylation with titration

Originally it was believed that etherification with sulfuric acid proceeded through the intermediate formation of alkyl sulfuric acids (R0S03H), since these products sometimes could be isolated from the reaction mixture. It now seems clear, however, that alkyl sulfuric acids are formed only as by-products in the reaction and are not actually intermediates in the etherification process. Thus, ethyl ter -butyl ether was prepared in yields of 95 per cent by heating a mixture of tert-butyl and ethyl alcohols containing 15 per cent sulfuric acid at 70°, yet titration of the cooled reaction mixture showed no evidence of the formation of an alkyl sulfuric acid.4 Furthermore, the yield of diethyl ether was 95 per cent when ethanol was passed through concentrated sulfuric acid heated to 140°, but when the reaction was carried out with ethyl sulfuric acid at the same temperature, much sulfur dioxide was evolved and the yield dropped to 70 per cent.4 8 We can, therefore, conclude that the... 

Use the same method as for alkyl sulphates etc. (section 5.3.1), but use methyl red or bromocresol green as indicator, to avoid titrating the liberated fatty acid. Alternatively, extract the fatty acid with petroleum ether before titrating. The identity of the indicator will then have a negligible effect on the result. 

Contrary to probe 22, triazole-linked anthracene bearing calix[4]arene in the cone conformation 23a [50] (Fig. 28.6) showed selectivity for Co " ions, with a detection limit of 55 ppb (0.92 pM). The selectivity is favored by the hexa-coordination of Co " by two ether oxygens, two phenolate oxygens, and two triazole nitrogen atoms of probe 23a. Alkylation of 23a results in the triazolium-anthracenyl calix[4]arene probe 23b (Fig. 28.6) [51]. The fluorescence titrations with various nucleosides showed high selectivity for nucleoside triphosphates... 

In a dry flask, ZnCl2 (20 mL, 1.0 M in diethyl ether, Aldrich, 20 mmol) is diluted with diethyl ether (10 mL). A freshly prepared and titrated solution of an alkylmagnesium halide (2.2 m in diethyl ether, 40 mmol prepared via oxidative addition of magnesium turning to the respective alkyl halide) is added and the resulting suspension is stirred at 25 °C for 2 h. Dry 1,4-dioxane (12 mL) is added and the reaction mixture stirred for additional 45 min at 25 °C. Subsequent filtration under an inert atmosphere yields a clear solution of the dialkylzinc reagent 292. 

ISO 6843 specifies a variation of the extraction method for determination of PEG in nonionic surfactants. In this case, an aqueous salt solution of the surfactant is extracted with 9 1 ethyl acetate/l-butanol. Almost all of the ether sulfate goes into the organic phase, leaving behind PEG, PEG sulfate, and sulfate ion, as well as a small amount of the ether sulfate. Alkyl- or alkylphenol ethoxylate and alkyl- or alkylphenol sulfate are expected to partition primarily in the organic phase. The amount of anionic surfactant remaining in the aqueous phase is determined by two-phase titration, as is the equivalent weight of the extracted material (71). 

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