Sodium hydroxide emulsions, benzene

One can observe similar effects If the same surfactants are used as emulsifying agents. Table ill shows results obtained in benzene - aqueous two molar sodium hydroxide emulsions using different surfactants. AgAin It can be seen that the film forming cationic surfactant causes marked Increases In yields. 

Estrone methyl ether (100 g, 0.35 mole) is mixed with 100 ml of absolute ethanol, 100 ml of benzene and 200 ml of triethyl orthoformate. Concentrated sulfuric acid (1.55 ml) is added and the mixture is stirred at room temperature for 2 hr. The mixture is then made alkaline by the addition of excess tetra-methylguanidine (ca. 4 ml) and the organic solvents are removed. The residue is dissolved in heptane and the solution is filtered through Celite to prevent emulsions in the following extraction. The solution is then washed threetimes with 500 ml of 10 % sodium hydroxide solution in methanol to remove excess triethyl orthoformate, which would interfere with the Birch reduction solvent system. The heptane solution is dried over sodium sulfate and the solvent is removed. The residue is satisfactory for the Birch reduction step. Infrared analysis shows that the material contains 1.3-1.5% of estrone methyl ether. The pure ketal may be obtained by crystallization from anhydrous ethanol, mp 99-100°. Acidification of the methanolic sodium hydroxide washes affords 10-12 g of recovered estrone methyl ether. 

The extraction of the pyridone from the aqueous solution is difficult when benzene or ether is used as a solvent. i-Methyl-2-pyridone, when dry, is very soluble in ethyl ether, benzene, and most organic solvents. It is, however, practically insoluble in petroleum ether or ligroin. When a mixture of water, benzene, and a little pyridone is shaken together all the pyridone is found in the water layer. When the pyridone is salted out from water by adding a sufficient quantity of potassium carbonate, the oily layer does not dissolve when benzene or ethyl ether is added, but three layers are formed. The pyridone seems to be extracted by ether or benzene only when the aqueous solution is strongly saturated with sodium hydroxide or potassium hydroxide and then the tendency to form an emulsion is so great that separation of the layers is extremely difficult. 

A troublesome emulsion sometimes results after benzoyla-tion. This may be broken up usually by the addition of more strong sodium hydroxide solution. In case an emulsion is formed which cannot be broken it is possible to extract the product with benzene. 

Diamino-2-phenyltriazole and nitrosobenzene, stirred in an emulsion of benzene and 12 N sodium hydroxide, gave 4-amino-2-phenyl-5-phenylazotriazole (60°C, 10 min, 72%) (70BCJ3587). Potassium permanganate in dilute acetic acid oxidized 4-amino-3,5-diphenyltriazole to 3,3, 5,5 -tetraphenyl-4,4 -azotriazole (25 °C, 30%). This product, stirred with hydrazine hydrate and palladized carbon in chloroform, gave 4-amino-3,5-diphenyltriazole (25°C, 1 hr, 91%) (70JOC2215). 

Aldehydes that contain only one a-hydrogen atom may be alkylated in reasonable yields with reactive alkylating agents such as methyl iodide, allyl chloride or benzyl chloride in an emulsion of benzene and 50% aqueous sodium hydroxide in the presence of a catalytic amount of a tetra-n-butylammonium... 

The emulsion from the reactor was collected in a glass flask immersed in an ice bath here it separated by decanting into acid and hydrocarbon phases. The total acidity of the latter phase was measured by titrating a methanolic solution of it with standard sodium hydroxide to a methyl red endpoint. Part of the hydrocarbon phase was water washed, and it was then analyzed by gas chromatography using a Perkin Elmer Model 154 Vapor Fractometer for benzene and nitrobenzene. Certain by-products were also detected when and if they formed. 

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