Alcohols from aqueous solution

Selective Sorption of Alcohols from Aqueous Solution... 

IV. Penetration of Non-Electrolytes (Alcohols) From Aqueous Solutions and From Pure Liquids, ]. Invest. Dermatol. (1973) 60, 286-296. 

Gibbs monolayers are widespread. The simplest system is that of the surface of a fully miscible binary liquid. More complex ones are monolayers of uncharged molecules adsorbed from dilute solutions (example aliphatic alcohols from aqueous solution) electrolytes surfactants (non-ionic or ionic) polymers and polyelectrolytes and yet more. On the other hand, the methods for characterizing... 

Scheuplein, R. J., and I. H. Blank. 1973. Mechanism of percutaneous absorption. IV. Penetration of nonelectrolytes (alcohols) from aqueous solutions and lfompure liquids./. Invest. Dermatol. 60 286-296. 

The present study reports the measurements of intracrystalline diffusion and adsorption equilibrium for ethanol, propanols and butanols from aqueous solution in silicalite using a modified HPLC technique. The unique feature of the present work is the use of a mathematical model with a nonlinear adsorption isotherm equation to obtain the intracrystalline diffusivity and adsorption isotherm parameters. The adsorption equilibrium data for alcohols from aqueous solution in silicalite measured by the conventional batch method are also reported and compared with the results measured by the HPLC technique. 

The batch measurement for the equilibrium adsorption of alcohols from aqueous solution in silicalite was conducted in air-tight bottles which were immersed in a thermal bath at 30°C (12). Amounts of activated silicalite sample, solute (alcohols) and solvent (water) in each bottle were measured gravimetrically. The bottles in the thermal bath were intermittently shaken to hasten the equilibrium. After the bottles had been kept in the thermal bath for over 10 hr, the equilibrium solution was withdrawn and analyzed by gas chromatography. 

An examination of the results reported in the previous studies on adsorption equilibrium for alcohols from aqueous solution in different silicalite samples (3,, 21) shows considerable differences in equil-... 

The intracrystalline diffusivities reported here for alcohols from aqueous solution in silicalite are found to decrease in the following order ... 

Isolation of water soluble materials from an aqueous solution is very costly and much problematic in an industrial scale. The isolation of ethanol from an aqueous solution obtained by the fermentation of biomass is one of the most important problems relating to a cheap energy source which may take the place of oU in future. If the crystal inclusion method can be appHed to such an isolation process cheap ethanol is available which might cause a revolution in the utilization of energy. This Section deals with the isolation of ethanol and some other alcohols from aqueous solution. 

In addition to ethanol, a wide variety of other alcohols are included by the host compounds shown in Table 6. X-Ray crystal structures of the 1 2 methanol and 1 1 butanediol inclusion compounds of 5 and of the 1 1 butanediol crystal inclusion of 6c have been reported. By using inclusion crystal formation, it is possible to separate the corresponding alcohols from aqueous solution. 

I. Fujita, K. Kuroda, M. Ogawa, Adsorption of alcohols from aqueous solutions into a layered silicate modified with octyltrichlorosilane, Chem. Mater., 17, ilYl-lslTl (2005). 

TABLE 2. Salting out of Amyl Alcohol from Aqueous Solutions... 

X 10 J/T (5.71 //g) at room temperature. It is air stable at 25°C, but is slowly converted to Fe202 and bromine at 310°C. The light yellow to brown hydroscopic sohd is soluble ia water, alcohol, ether, and acetonitrile. Iron(II) bromide forms adducts with a wide range of donor molecules. Pale green nona-, hexa-, tetra-, and dihydrate species can be crystallized from aqueous solutions at different temperatures. A hydrate of variable water content,... 

Succinic acid is absorbed from aqueous solutions by anion-exchange resins or active carbon (9—11). Succinic anhydride forms rhombic pyramidal or bipyramidal crystals. It is relatively insoluble in ether, but soluble in boiling chloroform and ethyl acetate. Succinic anhydride reacts with water and alcohols, giving the acid and monoesters, respectively. 

Oxo Ion Salts. Salts of 0x0 ions, eg, nitrate, sulfate, perchlorate, hydroxide, iodate, phosphate, and oxalate, are readily obtained from aqueous solution. Thorium nitrate is readily formed by dissolution of thorium hydroxide in nitric acid from which, depending on the pH of solution, crystalline Th(N02)4 5H20 [33088-17 ] or Th(N02)4 4H20 [33088-16-3] can be obtained (23). Thorium nitrate is very soluble in water and in a host of oxygen-containing organic solvents, including alcohols, ethers, esters, and ketones. Hydrated thorium sulfate, Th(S0 2 H20, where n = 9, 8, 6, or 4, is... 

The alcohol sulfate salts of monovalent metals, such as sodium and potassium, crystallize as anhydrous salts from aqueous solutions, whereas salts of bivalent alkaline earth metals form hydrates with 1 mol of water less than that of the equivalent inorganic sulfate [68]. 

However, when considering the use of acid or base in organic solvents for sample extraction, care must be taken to avoid potential artifacts that may arise from side reactions. For example, methylation of active hydroxyl groups or acidic functions on the analyte may sometimes occur when acidic methanol is used as the extractant. Another example is acetylation of an active alcohol on the analyte following partition of the analyte into ethyl acetate from aqueous solution acidified with glacial acetic acid. 

Derivatives are prepared from the appropriate acid anhydride, or occasionally the acid chloride, usually in the presence of a base such as pyridine, triethylamine, or N,N-dimethyl-4-amlnopyridine at elevated temperatures [474-482]. Acylation of amines and phenols (not alcohols) in aqueous solution in the presence of potassium carbonate has been demonstrated (448,483,484), but does not constitute m l practice as reactions are generally performed under i Arous conditions. 

Diao, L. Yang, C. Wan, P. Quinone methide intermediates from the photolysis of hydroxybenzyl alcohols in aqueous solution. J. Am. Chem. Soc. 1995, 117, 5369-5370. 

A large number of polyfructosans that have been reported from time to time by different authors have been investigated by Schlubach and his associates. In order to obtain polysaccharides of constant optical rotation, 100 to 300 precipitations from aqueous solution by the addition of alcohol were necessary. Fifty to 150 precipitations from chloroform solution with petroleum ether were required for purification of the acetate derivatives. These were methylated according to the procedure of Haworth and Straight,24 and upon hydrolysis partially methylated fructoses were obtained. 

The pure product is produced by dissolving the gum from the seeds in hot water. Diatomaceous earth filtration is then used to purify the solution. As the gum is less soluble in alcoholic than aqueous solutions it is precipitated by adding propan-2-ol. The pressed filter cake is then washed in pure alcohol to dehydrate it. The alcohol is then recovered by pressing again. The pressed product is then milled to the required final size. 

The selective separation of water from aqueous solutions of isopropanol or the dehydration of isopropanol can be carried out with different membranes, which contain polar groups, either in the backbone or as pendent moieties. For the dehydration of such a mixture, poly(vinyl alcohol) (PVA) and PVA-based membranes have been used extensively. PVA is the primary material from which the commercial membranes are fabricated and has been studied intensively for pervaporation because of its excellent film forming, high hydrophilicity due to -OH groups as pendant moieties, and chemical-resistant properties. On the contrary, PVA has poor stability at higher water concentrations, and hence selectivity decreases remarkably. 

Finally, the action of acid chlorides on alcohols and phenols is also used to separate them from solutions or to characterise them. For this purpose benzoyl chloride is usually employed. Methyl alcohol, for example, gives with p-nitrobenzoyl chloride the beautifully crystalline methyl ester and small amounts of the alcohol can thus be separated from aqueous solution. 

On account of their great lability the diazonium salts of the simple primary amines cannot be isolated from aqueous solution. On the other hand, they crystallise from alcohol when ether is added. Since the metallic salts of nitrous acid are insoluble in alcohol, its esters are used instead for diazotisation in alcohol. These esters are hydrolysed by acid with extraordinary rapidity and therefore behave almost like salts (see p. 147). 

Inorganic extractions seem to have come into practical use without any great notice. Although Peligot in 1842 reported that uranyl nitrate could be recrystalhzed from ether, he never mentioned extraction of this salt from aqueous solutions. In textbooks after 1870, however, it is stated briefly that ether can even withdraw sublimate (HgCy from aqueous solution. It was also reported, for example, that cobalt thiocyanate is weakly extracted by ether, better by amyl alcohol, and even better by a mixture of both. 

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