Light petroleum soluble, separation

After adjustment of the saponified mixture with water to contain 50 per cent of ethanol, heat the mixture nearly to boiling, transfer to a separator, wash in with hot 50 per cent ethanol and extract immediately with light petroleum. After separation, which is almost instantaneous, run off the aqueous layer and repeat the extractions two or three times. If the solution cools meanwhile it must be reheated. Wash the mixed light petroleum first with 50 per cent ethanol and finally with water, avoiding much agitation. Filter off any flocculent precipitate, which consists of soap soluble with difficulty in ethanol and water, evaporate the petroleum and weigh the insoluble matter. 

Amines, (a) Picrates The most versatile derivative from which the free base can be readily recovered is the picrate. This is very satisfactory for primary and secondary aliphatic amines and aromatic amines and is particularly so for heterocyclic bases. The amine, dissolved in water, alcohol or benzene, is treated with excess of a saturated solution of picric acid in water, alcohol or benzene, respectively, until separation of the picrate is complete. If separation does not occur, the solution is stirred vigorously and warmed for a few minutes, or diluted with a solvent in which the picrate is insoluble. Thus, a solution of the amine and picric acid in ethanol or benzene can be treated with benzene or light petroleum, repectively, to precipitate the picrate. Alternatively, the amine can be dissolved in alcohol and aqueous picric acid added. The picrate is filtered off, washed with water, ethanol or benzene, and recrystallised from boiling water, ethanol, methanol, aqueous ethanol or methanol, chloroform or benzene. The solubility of picric acid in water, ethanol and benzene is 1.4, 6.23 and 5.27% respectively at 20°. 

If the substance is found to be far too soluble in one solvent and much too insoluble in another solvent to allow of recrystallisation, mixed solvents or solvent pairs may frequently be used with excellent results. The two solvents must, of course, be completely miscible. Recrystallisation from mixed solvents is carried out near the boiling point of the mixture. The compound is dissolved in the solvent in which it is very soluble, and the hot solvent, in which the substance is only sparingly soluble, is added cautiously until a slight turbidity is produced. The turbidity is then just cleared by the addition of a small quantity of the first solvent and the mixture is allowed to cool to room temperature crystals will separate. Pairs of liquids which may be used include alcohols and water alcohols and toluene toluene and light petroleum acetone and light petroleum diethyl ether and pentane glacial acetic acid and water dimethyl-formamide with either water or toluene. 

The products from these hydrogenations were separated into gases (analyzed by G.C.), water (analysed by azeotropic distillation), insolubles (CH2CI2 insolubles), asphaltene (CH2CI2 soluble/X4 insoluble) (Shell X4 40-60 C b.p. light petroleum), oils (CH2CI2 soluble/X4 soluble). Hydrogen transferred from the donor solvent was determined by G.L.C. analysis of the ratio of tetralin to naphthalene in the total hydrocarbon liquid product. 

Tri-u-phenylenediarsine crystallises from benzene in small, almost colourless plates, M.pt. 295° to 296° C., soluble in acetone, light petroleum, and chloroform, sparingly soluble in alcohol or ether, insoluble in water. It can be sublimed without decomposition. Its crystallographic constants are as follows—System, monoclinic (holohedral) a b e = 1"589 1 - j8 = 113° 15 forms present a(lOO), c(OOl), m(llO) angles observed am 55° 35, ac 66° 45. It yields a mercuricMoride, consisting of short, colourless needles, M.pt. 285° to 286° 0., readily decomposed by dilute sodium hydroxide. When the diarsinc is boiled with concentrated nitric acid and the solution poured into water, the oxide is precipitated. This separates from dilute alcohol in short, thin, colourless needles, unmelted below 360° C. 

Phthaloylleucylvaline ethyl ester 710 DL-Valine ethyl ester hydrochloride (1.82 g, 10 mmoles) in dry tetrahydrofuran (20 ml) is treated at 0° with triethylamine (1.38 ml). The triethylamine hydrochloride is filtered off after an hour and washed well with tetrahydrofuran. Phthaloyl-leucine (2.57 g, 10 mmoles) is dissolved in the filtrate, and then at —8° dicyclohexylcarbo-diimide (2.26 g, 11 mmoles). The mixture is left for 2 h at — 5° and then at room temperature overnight. The separated 1,3-dicyclohexylurea is filtered off and the filtrate is evaporated in a vacuum, leaving a syrup which is dissolved in ethyl acetate (25 ml) and washed with 2n-hydrochloric acid (25 ml) and water (two 25-ml portions). The solution is dried over sodium sulfate, filtered, and evaporated in a vacuum, the residue (3.5 g, 90%) solidifying to a glass on storage this product is very soluble in alcohols, chloroform, ethyl acetate, pyridine, or dimethylformamide, moderately soluble in benzene or toluene, but insoluble in ether, light petroleum, or water. 

Methylphenyl-p-tolylbenzylphosphonium iodide, (CH3)(C6H5) (CeH4.CH3)(C6H5.CH2)PI, occurs when potassium iodide is added to any of the three foregoing salts in aqueous solution. It separates from alcohol in colourless, glistening plates, M.pt. 215° to 216-5° C., soluble in methyl alcohol, less soluble in hot ethyl alcohol and practically insoluble in ether, benzene or light petroleum. 

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