Isopropanol steam distillation

In 212 cc of water are mixed 21.2 grams (0.112 mol) of N-(benzylidene)-3-amino-2-oxa-zolidone, 8.93 grams of concentrated sulfuric acid, and 30.1 grams (0.124 mol) of 5-ni-tro-2-furaldehyde diacetate. This mixture is heated to effect the hydrolysis of N-(benzy-lidene)-3-amino-2-oxazolidone, steam distillation of the benzaldehyde and hydrolysis of 5-nitro-2-furaldehyde diacetate. Approximately IV2 hours are required for this reaction to take place. When the bulk of the benzaldehyde has been removed, 50 cc of 99% isopropanol are added, the reaction mixture is refluxed a short time, and the crystals of N-(5-nitro-2-furfurylidene)-3-amino-2-oxazolidone are filtered from the hot suspension. The product is washed with water and isopropanol and dried a yield of 23.3 grams, 92.8% based on N-(benzylidene)-3-amino-2-oxazolidone of MP 254° to 256°C is obtained, according to U.S. Patent 2,759,931. 

A preconcentration method that bears some resemblance to SDE consists of isolating the volatile phenols by steam distillation, followed by freeze-drying of the distillate. End analysis was by HPLC with ELD. The method was applied for determination of such phenolic components in foodstuffs and packing materials. Determination of phenolic antioxidants in polyolefins was carried out by dissolving the polymer sample in a hep-tane-isopropanol mixture (1000/5, v/v), at 160-170 °C, in an autoclave. The polymer precipitated on cooling the solution, and the dissolved antioxidant could be determined by LC with UVD. The advantage of the method is the relatively short time of analysis (about 2 h) and its reproducibility (RSD 3-5%) . 

Preferential formation of 1,2-nitrosochlorides. A soln. of coned. HCl in isopropanol and a coned, aq. soln. of NaNO added simultaneously below 10° to a soln. of (+)-limonene in isopropanol, stirred for an additional 15 min., and allowed to stand 1 hr. in the refrigerator limonene nitrosochloride (Y 80.7% the amount of acid, 33-50 ml. per 0.1 mole olefin, is critical) refluxed 30 min. with dimethylformamide in isopropanol until the rotation is constant carv-oxime (Y 83.5%) melted in a separatory funnel by means of an infrared lamp, added dropwise to boiling aq. H2SO4 at pH 0.8, the product steam-distilled out of the reaction mixture as rapidly as it is formed and isolated in a continuous separator while the condensate water is returned to the still pot and dil. H2SO4 added portionwise to maintain the pH at 0.7-0.9 carvon (Y 83%). R. H. Reitsema, J. Org. Chem. 23, 2038 (1958). 

The mixture was stirred for 2 hours, heated at 60° to 70°C for 1 hour and poured into 2 liters of H O. The resulting suspension was extracted with ether, the ether layer separated and the ether removed under vacuum. A gummy mass remained which was dissolved in decalin and the solution was partly distilled to remove excess chlorobromide. After removal of most of the decalin under vacuum, the residue was treated with a large excess of N-( -hydroxyethyl)-piperazine and heated on a steam bath for 2 hours. This material was extracted with dilute aqueous HCI, this acid layer neutralized with aqueous base and the resulting oil extracted into ether. The ether layer was washed with water until the washings were neutral and dried over anhydrous potassium carbonate. On treatment with maleic acid in ether a yellow solid separated which was recrystallized from isopropanol. This yellow solid had MP 175° to 177°C. 

The reaction mixture is then warmed on the steam bath for an additional two hours (90°C to 95°C). The excess hydrazine hydrate is removed in vacuo. The residue of viscous 1-hy-drazlno-3-morpholinyl-2-propanol Is not distilled, but is mixed with 10.16 g (0.0B6 mol) diethyl carbonate and a solution of 0.3 g sodium metal in 15 ml methyl alcohol. The mixture is refluxed about 2 hours under a 15 cm Widmer column, the alcohol being removed leaving a thick, green liquid residue, which is cooled and the precipitate which forms is removed by filtration and washed well with ether. Yield B2%, MP114°C to 116°C. Recrystallization from isopropanol gives purified 3-amino-5-(N-morpholinyl)-methyl-2-oxazolidone, MP 120°C as the intermediate. 

The azeotropic composition of a binary system is not only influenced by recycled third components added to the mixture and by the operating pressure, but also by the presence of an insoluble inert gas, which is favorable for the separation if the volatile components of the mixture diffuse at different velocities across the regions of inert gases. Figure 2-31 a shows an example using the binary isopropanol/water mixture. Steam diffuses faster across an air bolster than isopropanol vapor, and thus, the distillate of isopropanol mole fraction is more water-rich due to the presence of air between the liquid and the condensation surfaces (point A2), compared with the distillation under air exclusion (point A,). 

---