Naphthalene benzoic acid mixture

Figure 7.63. Phase diagram of the naphthalene-benzoic acid mixture il74. 175). Points on phase diagram taken from eight DTA curves.

A simple equation for calculating the solubilities of solid substances in gaseous mixtures of a supercritical fluid with another supercritical one or an inert gas was derived. This equation involves only the solubilities of the solid in the individual constituents of the gaseous mixture and the molar volumes of the latter. The equation was tested for the solubilities of naphthalene, benzoic acid, caffeine, cholesterol, and soybean oil in gaseous mixtures containing at least one supercritical fluid. In all cases good agreement with experimental data was found. 

Entrainer as a SC Fluid. The predicted and experimental solubilities of naphthalene, benzoic acid, and cholesterol in the mixture of SC CO2 and SC C2H6 are presented in Figures 1-3, respectively. For the solubility of cholesterol, the calculations were carried out at T = 328.1 K (because experimental data were available only for this temperature). However, no data on the solubility of cholesterol in pure SC CO2 at this temperature were found, and we used the solubility at... 

Kurnik and Reid described the solubility behavior for a number of binary solid mixtures consisting of combinations of phenanthrene, naphthalene, benzoic acid, and 2,3- and 2,6-dimethylnaphthalene extracted with supercritical carbon dioxide and ethylene. They found that for a binary solid mixture, the presence of one of the solid components solubilized in the SCF-rich phase enhances the solubility of the other solid component in the SCF-rich phase. They suggest that the first solid component acts as an entrainer, or so-called cosolvent, to enhance the solvent power of the pure SCF. For example, they... 

As mentioned earlier, the control of properties in a supercritical fluid can allow separation to be incorporated into a recrystallisation process. This uses the so-called crossover effect, which arises when the isotherms of solubility versus pressure for two compounds at the same temperature can cross, i.e. the solubility of one compound is greater at a lower temperature, whereas that of the other compound is higher at a higher temperature, and they are equal at an intermediate temperature. Chimowitz et al. [103], by expansion of the solution from an extraction vessel down to 1 bar, measured solubility of 1 10 w/w decanediol-benzoic acid mixture in supercritical carbon dioxide. They experimentally defined the crossover behaviour for the two compounds, and subsequently achieved the separation of almost pure benzoic acid [104] from the 1 10 w/w decanediol-benzoic acid mixture. In a subsequent study, Sako et al separated phenanthrene and naphthalene to 97 wt% purity from a 1 1 w/w mixture using a similar technique [105]. 

Problem 20.3 Assume you have a mixture of naphthalene and benzoic acid that you want to separate. How might you take advantage of the acidity of one component in the mixture to effect a separation ... 

Although significant improvements have been made in the synthesis of phenol from benzene, the practical utility of direct radical hydroxylation of substituted arenes remains very low. A mixture of ortho-, meta- and para-substituted phenols is typically formed. Alkyl substituents are subject to radical H-atom abstraction, giving benzyl alcohol, benzaldehyde, and benzoic acid in addition to the mixture of cresols. Hydroxylation of phenylacetic acid leads to decarboxylation and gives benzyl alcohol along with phenolic products [2], A mixture of naphthols is produced in radical oxidations of naphthalene, in addition to diols and hydroxyketones [19]. 

The acidic or basic properties of these functional groups can also be used to advantage to separate them from neutral compounds. For example, suppose we desire to separate a mixture of naphthalene and benzoic acid ... 

Dissolve the mixture in an organic solvent, and extract with a dilute aqueous solution of sodium hydroxide or sodium bicarbonate, which will neutralize benzoic acid. Naphthalene will remain in the organic layer, and all the benzoic acid, now converted to the benzoate salt, will be in the aqueous layer. To recover benzoic acid, remove the aqueous layer, acidify it with dilute mineral acid, and extract with an organic solvent. 

This is an example of an acid-base extraction. The solid mixture (e.g. 4.0 g for the solvent volumes used below) of benzoic- acid and naphthalene is soluble in dichloro-methane but benzoic acid will dissolve in dilute aqueous sodium hydroxide (2IV ) by forming the sodium salt (sodium benzoate). Naphthalene is insoluble in water. 

Three ternary mixtures (a) CO2 (1) + naphthalene (2) + ethane (3) (b) CO2 (1) + benzoic acid (2) + ethane (3) and (c) CO2 (1) + phenanthrene (2) + ethane (3) will be considered. The information [22-26] available regarding the solubilities of the above solids in ternary and binary mixtures (references, pressure range and temperature) is summarized in Table 1. 

The predictive method suggested in this paper allows one to calculate the solubility of a solid in a binary mixture of SC fluids. The solubilities of three solids were predicted using only experimental data regarding the solubilities in the constituent binary mixtures (solid/SC fluid and solid/SC entrainer). Very good agreement was found between the experimental and predicted solubilities. For the solubilities of naphthalene and benzoic acid, the prediction of Eq. (42) provided even better agreement than the correlation [2] of experimental data based on the Peng-Robinson EOS with parameters determined from ternary data. 

Solute/solute interactions are also important in SCF solutions, as observed by Kurnik and Reid and Kwiatkowski and coworkers (27,28), in the synergistic effects on the solubilities of mixed solutes. When a physical mixture of naphthalene and benzoic acid is extracted with SCF COj the solubilities of both components is greater than the solubility of either pure component. This phenomenon occurs at concentrations as low as 10 to 10" mol fraction. Frequently, equation of state models assume infinite dilution of the solutes due to the low solubilities. Clearly, recognition and a better understanding of these solute/solute interactions are important for the prediction of SC phase equilibria. 

The use of electricity in reactions is clean and, at least in some cases, can produce no waste. Toxic heavy metal ions need not be involved in the reaction. Hazardous or expensive reagents, if needed, can be generated in situ where contact with them will not occur. The actual oxidant is used in catalytic amounts, with its reduced form being reoxidized continuously by the electricity. In this way, 1 mol% of ruthenium(III) chloride can be used in aqueous sodium chloride to oxidize benzyl alcohol to benzaldehyde at 25°C in 80% yield. The benzaldehyde can, in turn, be oxidized to benzoic acid by the same system in 90% yield.289 The actual oxidant is ruthenium tetroxide. Naphthalene can be oxidized to naphthoquinone with 98% selectivity using a small amount of cerium salt in aqueous methanesulfonic acid when the cerium(III) that forms is reoxidized to cerium(IV) electrically.290 Substituted aromatic compounds can be oxidized to the corresponding phenols electrically with a platinum electrode in trifluoroacetic acid, tri-ethylamine, and methylene chloride.291 With ethyl benzoate, the product is a mixture of 44 34 22 o/m/fhhy-... 

Naphthalene and phthalic anhydride in benzene, o-dichlorobenzene, or tetrachloroethane reacted with A1C1S -> mixture of 60-70% a- and 30-40% / -naphthoyl-o-benzoic acid (Y 91-93%) with HB02 and H2S04 warmed at 60° for 6 hrs. 1,2-benzanthraquinone (Y 84%). —In nitrobenzene and CS2, the Friedel-Crafta reaction with A1C13 also gives a mixture of isomers, but in lower yields.—The ring closure with A1C13 is not uniform. (A. Eitel and R. Fialla, M. 79, 112 (1948) cf. Synth. Meth. 2, 746 5, 604.)... 

Application of this technique to the identification of methyl esters of the organic acids obtained by the controlled oxidation of bituminous coal allowed the more volatile benzene carboxylic acid esters to be identified (Studier et al., 1978). These were esters of benzene tetracarboxylic acid, tere-phthalic acid, toluic acid, and benzoic acid. Decarboxylation of the total acid mixture was shown to afford benzene, toluene, Cj-benzenes (i.e., ethylbenzene or xylenes), Cj-benzenes, butylbenzenes, Cj-benzenes, Cybenzenes, naphthalene, methylnaphthalene, C2-naphthalene, biphenyl, methylbi-phenyl, C3-biphenyl, indane, methylindane, Cj-indane, phenanthrene, and fluorene. 

The values of log (Sn,/S n,) for naphthalene, benzocaine, and benzoic acid in selected binary solvent mixtures are presented in Figures 14.21.2.2-a, -b, and -c, respectively. 

As crystalline drugs generally have very low vapor pressure at room temperature, almost no drugs noticeably sublime except for volatile drugs such as naphthalene. However, when the drugs are mixed with porous powder, the capillaries can provide a sink condition for the diffusion of the drug molecules in the mixture. The rate of diffusion of benzoic acid was calculated for a mixture of 50 mg benzoic acid and 950 mg CPG at 300 K. The diffusion equation... 

It has been found by experiment that substances of the type RX, containing two different haptenic groups, do not form precipitates with either anti-R serum or anti-X serum Alone, but do form precipitates with a mixture of the two specific antisera. This provides proof of the effective bivalence of the dihaptenic precipitating antigen, and thus furnishes further evidence for e framework theory of antigen-antibody precipitation. In these experiments tiie anti-R serum and anti-X serum were made by injecting rabbits with sheep serum coupled with diazotized p-arsanilic add and diazotized p-aminobenzoic acid, respectively, and the RX substances used were l-amino-2-/>-(p-azophenylazo)-phenylarsonic acid-3,6-disul-fonic add 7-p-(p-azophenylazo)-benzoic acid-8-hy-droxynaphthalene and l,8-dihydroxy-2-/>-azo-phenylarsonic acid-3,6-disulfonic acid-7-p-(p-azo-phenylazo)-benzoic acid-naphthalene. 

In the experimental procedures that follow, three types of separations of neutral, acidic, and basic compounds are described. The first involves separating a mixture of benzoic acid (5) and naphthalene (7), using aqueous hydroxide for the extraction. The flow chart for this separation corresponds to that of Figure 5.1. The second procedure involves separating a mixture of 5,7, and 2-naphthol (11). In this case, 5 is first selectively removed from the solution by extraction with aqueous bicarbonate, which does not deprotonate 11. A second basic extraction using aqueous hydroxide removes 11 from the organic solution. The flow chart for this sequence is depicted in Figure 5.3. 

Dissolution Obtain 2 g of a mixture of benzoic acid and naphthalene, Dissolve the mixture by swirling it with 30 ml of diethyl ether in an Erlenmeyer flask, If any solids remain, add more diethyl ether to effect complete dissolution. Transfer the solution to the separatory funnel. 

---