Fractional distillation under diminished pressure

PRECISION FRACTIONAL DISTILLATION UNDER DIMINISHED PRESSURE... 

An elementary account of the subject has been given in the previous Section. For the fractional distillation under diminished pressure of liquids diflfering only slightly in boiling point, a firactionating column (see Sections 11,15 and 11,17) must be used. Provision must, of course, be made for the insertion of a capillary tube into the fiask containing the mixture. This can be done by any of the following methods —... 

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. 

Fractional distillation under diminished pressure.—A 5-25 ml. Claisen flask (with pear-shaped bulb) provided with a fractionating side arm (Fig. II, 24, 4r-5) and attached to a Liebig s condenser and a Perkin triangle (Fig. II, 20, 1 or II, 20, 2 volume of receiver ca. 10 ml.) wUl be found to have wide apphcation. 

Oleic acid may be obtained from glycerol trioleate, present in many liquid vegetable and animal nondrying oils, such as olive, cottonseed, lard, by hydrolysis. The crude oleic acid after separation of the water solution of glycerol is cooled to fractionally crystallize the stearic and palmitic acids, which are then separated by filtration, and fractional distillation under diminished pressure. Oleic acid reacts with lead oxide to form lead oleate, which is soluble in ether, whereas lead stearate or palmitaie is insoluble, prom lead oleate oleic add may be obtained by treatment with IL 5 (lead sulfide, insoluble solid, formed). With sodium oleate, a soap is formed. Most soaps are mixtures of sodium stearate, palmitate. and oleate. 

Schimmel Co. have examined the oil obtain from cardamom roots from Indo-Ohina. They obtained 0 64 per cent, of oil having the following characters dif,o 0 9066 ao - 32 57 nD2o 1 48151 acid value 3 7 ester value 87 9 ester value after acetylation 96 7. e oil was soluble in 0 5 volumes of 95 per cent, alcohol, when more alcohol was added the mixture rapidly turned turbid, and did not. become clear again until the solvent had been increased to 4 volumes. Fractional distillation under diminished pressure (5 mm.) gave the following result —... 

After standing for about an hour, the reaction mixture is separated and the upper layer washed with dilute alkali and with water. After drying, the nfixture is fractionally distilled under diminished pressure in a modified Claisen flask, 52 g. (63%) of /5-cyclohexylnaphthalene (b.p. 190-195°/15 mm. 1.5973 1-020) is obtained. The... 

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