Systems, acetic acid-water acetone-chloroform

In other chemical systems, the molecules can attract instead of repulse. The results can be the formation of maximum-hoWing azeotropes because the molecular attraction reduces the effective vapor pressures of the components. Examples include nitric acid-water, acetone-chloroform, formic acid-water, and M, -dimethyl acetamide-acetic acid. 

The lower, chloroform-rich phase is separated carefully from the protein-containing interface, and then it is washed twice with methanol-water (10 9, v/v) and the washes are discarded. The chloroform layer contains the phosphatidic acid (as a sodium salt) and can be isolated by acetone precipitation. The yields can be of the order of 90-95%. One alternative route to identification of the chloroform-soluble material is to analyze it for total phosphorus and total fatty acid ester (see procedures described earlier). In the case of diacylphosphatidylcholine as the substrate, the fatty acid ester/P molar ratio should be 2.0. Another approach is to subject the chloroform-soluble fraction to preparative thin-layer chromatography on silica gel H (calcium ion free) in a two-dimensional system with a solvent system of chloroform-methanol-28% ammonium hydroxide (65 35 6, v/v) in the first direction and a solvent system of chloroform-acetone-methanol-glacial acetic acid-water (4.5 2 1 1.3 0.5, v/v) in the second direction. The phosphatidic acid will not migrate far in the basic solvent Rf 0.10) and will show an Rf value one-half of that of any remaining starting substrate (fyO.40) in the second solvent. Of course with a simple substrate system, one can use the basic solvent in one dimension only... 

Phospholipase A2 Action. Incubation of phosphatidylserine with phospholipase A2 obtained from Crotalus adamanteus or Naja Naja snake venom will show that the serine-containing phosphoglyceride was smoothly and completely converted to a lysophosphatidylserine with liberation of 1 mol of fatty acid per mole of lipid P. The experimental procedure was the same as the one described before in this and in the previous chapter. The products of the reaction can be recovered by thin-layer chromatography on Whatman K6 plates in a solvent system of chloroform-acetone-methanol-acetic acid-water (4.5 2 1 1.3 0.5, v/v). 

The 2-D TLC was successfully applied to the separation of amino acids as early as the beginning of thin-layer chromatography. Separation efficiency is, by far, best with chloroform-methanol-17% ammonium hydroxide (40 40 20, v/v), n-butanol-glacial acetic acid-water (80 20 20, v/v) in combination with phenol-water (75 25, g/g). A novel 2-D TLC method has been elaborated and found suitable for the chromatographic identification of 52 amino acids. This method is based on three 2-D TLC developments on cellulose (CMN 300 50 p) using the same solvent system 1 for the first dimension and three different systems (11-IV) of suitable properties for the second dimension. System 1 n-butanol-acetone -diethylamine-water (10 10 2 5, v/v) system 11 2-propanol-formic acid-water (40 2 10, v/v) system 111 iec-butanol-methyl ethyl ketone-dicyclohexylamine-water (10 10 2 5, v/v) and system IV phenol-water (75 25, g/g) (h- 7.5 mg Na-cyanide) with 3% ammonia. With this technique, all amino acids can be differentiated and characterized by their fixed positions and also by some color reactions. Moreover, the relative merits of cellulose and silica gel are discussed in relation to separation efficiency, reproducibility, and detection sensitivity. Two-dimensional TLC separation of a performic acid oxidized mixture of 20 protein amino acids plus p-alanine and y-amino-n-butyric acid was performed in the first direction with chloroform-methanol-ammonia (17%) (40 40 20, v/v) and in the second direction with phenol-water (75 25, g/g). Detection was performed via ninhydrin reagent spray. 

There have been very few quaternary systems which have been studied in detail because of the tediousness of the experimental problems. Clearly many combinations of ternary systems are conceivable, resulting in many possibilities for the quaternary equilibria. A system, chloroform-acetone-acetic acid-water at 25°C., which is of considerable interest because it parallels in form many of the petroleum-mixed solvent equilibria, has been determined in some detail by Brancker, Hunter, and Nash (7). This quaternary is made up of the following ternary systems ... 

There are many important industrial applications of azeotropic separations, which employ a variety of methods. In this book we discuss several of these chemical systems and demonstrate the application of alternative methods of separation. The methods presented include pressure-swing distillation, azeotropic distillation with a light entrainer, extractive distillation with a heavy entrainer (solvent), and pervaporation. The chemical systems used in the numerical case studies included ethanol-water tetrahydrofuran (THF)-water, isopropanol-water, acetone-methanol, isopentane-methanol, n-butanol-water, acetone-chloroform, and acetic acid-water. Economic and dynamic comparisons between alternative methods are presented for some of the chemical systems, for example azeotropic distillation versus extractive distillation for the isopropanol-water system. 

The purity of the 5 -p-fluorosulfonylbenzoyl adenosine can be assessed by thin-layer or descending paper chromatography. With EM silica gel F-254 (fast running) thin-layer plates on aluminum and a solvent system composed of methyl ethyl ketone acetone water (60 20 15), the Rf for 5 FSBA is 0.76, whereas that for 3 -FSBA is 0.80. With a solvent consisting of methanol chloroform (15 85) the Rf for 5 -FSBA is 0.56, whereas that for 3 -FSBA is 0.64. In descending paper chromatography (Whatman No. 3 MM), with n-butanol acetic acid water (4 1 5) as solvent, the 5 -FSBA exhibits an Rf of 0.76, whereas the 3 -FSBA has an Rf of 0.86. 

Two-dimensional systems are often used to separate complex phospholipid mixtures in plant and animal tissues. See reviews in Mangold (98) and Rouser et al. (99) for details. The first development is typically in chloroform-methanol-water (65 25 4), and development in the second direction is often in either n-butanol-acetic acid-water (60 20 20) or chloroform-acetone-methanol-acetic acid-water (5 2.1 1 0.5). Although 2-D procedures may increase the resolution of some spots, it often results in large spots with tails. Figure 6 shows a 2-D separation of phospholipids from snail tissue, and Fig. 7 shows a 2-D separation of serum lipids. Table 7 lists frequently used 2-D solvent systems for complex lipid mixtures. 

One key aspect of the sequence of Scheme 3.2 was the use of CeCla to effect selective carbonyl reductions, as pioneered by Luche and co-workers. The CeCls serves two purposes in the reduction of 1 to 8, most importantly, that of allowing selective reduction of the ketone group over the aldehyde. It also exerts a buffering action so that the ester group in 8 and in the alcohol precursor of 11 is not hydrolyzed by water in the solvent. Furthermore, it probably also serves to suppress 1,4-reduction in these conjugated systems. Another point of some interest was the surprising stability of die hemiacetal 8. Evaporation with benzene, benzene-acetic acid, chloroform, acetone, or water only slowly removed the methanol. But, fortunately, two or three evaporations with water—acetic acid—... 

Classification Primary aliphatic alcohol Empirical C10H22O Formula CH3(CH2)8CH20H Properties Colorless to It. yel. mod. vise, liq., sweet odor sol. in alcohol, ether, acetone, benzene, chloroform, acetic acid pract. insol. in water m.w. 158.32 sp.gr. 0.8297 (20/4 C) m.p. 7 C b.p. 232.9 C flash pt. (OC) 82 C ref. index 1.43587 surf. tens. 28.9 dynes/cm (20 C) Toxicology LD50 (oral, rat) 4720 mg/kg mod. toxic by skin contact mildly toxic by ing., inh. irritating to eyes, skin, respiratory system inh. may cause nose/throat irritation high cones. 

Properties Wh. cryst. solid odorless very sol. in ether sol. in benzene, acetone, chloroform, glac. acetic acid, HCI, CCU, oxygenated, chlorinated, and aromatic soivs. si. sol. in alcohol insol. in water m.w. 262.30 dens. 1.132 m.p. 79-82 C b.p. 377 C flash pt. (OC) 356 F Toxicology LD50 (oral, rat) 800 mg/kg LC50 (inh., rat, 4 h) 1135 ppm mod. toxic by ing. mildly toxic by inh. irritating to eyes, skin, respiratory system neurological hazard TSCA listed... 

The system is remarkable in the simplicity of the relationships between the quatenary and various ternary equilibria. Refer to Fig. 2.32. The binodal curve XGY represents the solubility data for chloroform-water-acetic acid, and the line LK is typical of the tie lines in this ternary. Similarly, in the ternary chloroform-water-acetone, the binodal curve is indicated by XEY, with tie lines such as RS, The three-dimensional surface formed by the two binodal curves and the sloping lines joining them enclose the quaternary heterogeneous region. Any mixture whose composition can be represented by a point underneath this surface exists as two liquid phases, while mix-... 

No solvent system resolves all the Dns-amino acids by ID chromatography. Also, 2D chromatography requires more than two runs for a complete resolution. The eluents most commonly used on polyamide layers are benzene-acetic acid (9 1), toluene-acetic acid (9 1), toluene-ethanol-acetic acid (17 1 2), water-formic acid (200 3), water-ethanol-ammonium hydroxide (17 2 1 and 14 15 1), ethylacetate-ethanol-ammonium hydroxide (20 5 1), n-heptane-n-buta-nol-acetic acid (3 3 1), chlorobenzene-acetic acid (9 1), and ethylacetate-acetic acid-methanol (20 1 1). On silica plates, acetone-isopropanol-25 % aqueous ammonia (9 7 1), chloroform-benzyl alcohol-ethyl acetate-acetic acid (6 4 5 0.2), chloroform-ethyl acetate-acetic acid (38 4 2.8 or 24 4 5), and dichloromethane-methanol-pro-pionic acid (21 3 2) are used. 

Nuttall and Bush (1971) analyzed biotin in multivitamin preparations. The fat-soluble vitamins were first extracted, and the water-soluble materials were separated in three TLC systems biotin was resolved using the mobile phase acetone-acetic acid-benzene-methanol (1 1 14 4) and detected by spraying the plate with o-toluidine-potassium iodide. Groningsson and Jansson (1979) determined biotin in the presence of other water-soluble vitamins using silica gel TLC and the mobile phase chloroform-methanol-formic acid (70 40 2) detection was by spraying with p-DACA. 

In this chapter, we explore the design and control of the maximum-boiling azeotropic acetone-chloroform distillation system as a typical example. Other systems that exhibit maximum-boiling azeotropes include formic acid-water, nitric acid-water, and acetic acid-DMAC (n,n-dimethyl acetamide). 

In the field of log P calculations, the free energy methodology was applied to the water/chloroform system using Monte Carlo simulations - and to water/carbon tetrachloride using molecular dynamics simulations. Because the computer resources necessary for such calculations appear enormous, only a few log P values for small organic compounds (methylamine, dimethylamine, methanol, ethanol, propanol, dimethyl ether, acetonitrile, acetic acid, methyl acetate, acetone) were examined even in organic solvents relatively simple to model. A major source of variation between experimental and calculated log P values may lie in the assumption of the immiscibility of the two solvent systems, an assumption which is not supported experimentally. 

This is the most common type of system in extraction, and typical examples are water (A)-chloroform (B)-acetone (C) and benzene (A)-water (B)-acetic acid (C). The triangular coordinates are used as isotherms, or diagrams at constant temperature. Refer to Fig. 10.3a. Liquid C dissolves completely in A and B, but A and B dissolve only to a limited extent in each other to give rise to the saturated liquid solutions at L (A-rich) and at K (B-rich). The more insoluble the liquids A and B, the nearer the apexes of the triangle will points L and A" be located. A binary mixture /, anywhere between L and K, will separate into two insoluble liquid phases of compositions at L and A, the relative amounts of the phases depending upon the position of J, according to the principle of Eq. (10.1). 

Ji et al. [182] investigated the condensation of 6-methyl-4-hydroxypyran-2-one with an aldehyde and primary amine or ammonium acetate in IL [BMIM][Br] to obtain bislactam systems 93 in less than 2h with high yield (Scheme 47). The reaction sequences involved an intermolecular condensation with associated transamidation of the lactone ring to form bislactam systems. It was observed that both the aromatic and aliphatic aldehydes efficiently form products. The IL used was recovered and reused five times with no appreciable decrease in yield. The reaction when carried out in methanol resulted in the formation of product only in traces while no reaction was observed in acetone, acetonitrile, chloroform, water, or acetic acid [182]. 

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