Phase water-ethanol-ethyl acetate

The phase regions for micellar solutions and lyotropic liquid crystals form a complicated pattern in water/amphlphile/hydrocarbon systems. The present treatment emphasizes the fact that they may be considered as parts of a continuous solubility region similar to the one for water/short chain amphiphilic systems such as water/ethanol/ethyl acetate. 

It is essential to realize that any thermodynamic evaluation of this solubility "maximum" with standard reference conditions in the form of the three pure components in liquid form is a futile exercise. The complete phase diagram. Fig. 2, shows the "maximum" of the solubility area to mark only a change in the structure of the phase in equilibrium with the solubility region. The maximum of the solubility is a reflection of the fact that the water as equilibrium body is replaced by a lamellar liquid crystalline phase. Since this phase.transition obviously is more. related to packing constraints — than enthalpy of formation — a view of the different phases as one continuous region such as in the short chain compounds water/ethanol/ethyl acetate. Fig. 3, is realistic. The three phases in the complete diagram. Fig. 2, may be perceived as a continuous solubility area with different packing conditions in different parts (Fig. 4). 

A new HP-TLC method has been applied for the quantitative analysis of flavonoids in Passiflora coerulea L. The objective of the experiments was the separation and identification of the compound(s) responsible for the anxiolytic effect of the plant. Samples were extracted with 60 per cent ethanol or refluxed three times with aqueous methanol, and the supernatants were employed for HPTLC analysis. Separation was performed on a silica layer prewashed with methanol and pretreated with 0.1 M K2HP04, the optimal mobile phase composition being ethyl acetate-formic acid-water (9 1 l,v/v). It was established that the best extraction efficacy can be achieved with 60 - 80 per cent aqueous methanol. The HPTLC technique separates 10 different flavonoids, which can be used for the authenticity test of this medicinal plant [121],... 

Fig. 16.32 Ternary solubility diagram showing the temperature dependence of the phase behaviour of ethyl acetate/ water/ethanol, indicating that the ternary azeotrope is two phase at 20 °C and single phase at 70 °C.

Griswold, Chu, and Winsauer [Ind, Eng, Chem, 41, 2352 (1949)] provide very complete data on the liquid-liquid and vapor-liquid equilibria in the system ethanol-ethyl acetate-water. Design a plant and solvent-recovery system for the recovery of 99.8% ethanol from 50,000 gal./day of a 5% solution in water, using ethyl acetate as extracting solvent. Solvent concentration in the raffinate phase is to be no greater than 0.001%. 

An example of a reversible reaction in the liquid phase is afforded by the esterification reaction between ethanol and acetic (ethanoic) acid forming ethyl acetate and water. Since, however, ethyl acetate undergoes conversion to acetic acid and ethanol when heated with water, the esterification reaction never proceeds to completion. 

This method, although described for indoles, probably also worlds with 5-OH-tryptamine (serotonin), and 5-OH-DMT (bufotenin) with compounds of the latter type, orally active psilocybin analogs will be obtained in one step. Dissolve 5 g 5-OH-indole (or analog) in 25 ml ethanol. Add 5.5 g 33% aqueous dimethylamine (or other amine, e.g., piperidine) and add slowly dropwise with stirring 3.5 g 38% aqueous formaldehyde. Two minutes after the end of the addition shake with water and CHCI3 dry and evaporate in vacuum the CHClj phase to get 5 g oily 4-dimethyl-aminomethyl-5-OH-indole (1) (can chromatograph on 100 g alumina and elute with ethyl acetate). It has been claimed that this method does not work. 

A simple TLC method has been developed for the separation and identification of flavons and flavon glycosides in the extract of Phillyrea latifolia L. The leaves (100 g) were defatted in 11 of chloroform for 24 h and then extracted with 2 X 11 of ethanol-water (80 20, v/v). The collected extracts were concentrated and extracted again with n-hexane to remove chlorophylls and other apolar constituents. Analytes were extracted with ethyl acetate. Both normal phase and RP-TLC have been used for the separation of flavonoids. The results are compiled in Table 2.36. It was concluded from the data that TLC can be successfully applied for the quality control of plant extracts containing various flavone derivatives [124],... 

The step 1 product (0.583 mol) was dissolved in 500 ml of ethyl acetate, cooled to 0°C, and treated with A -hromosuccinimide (0.583 mol) and then warmed to ambient temperature and stirred for 1 hour. The organic phase was washed three times with water, dried, concentrated, and recrystallized using ethanol. The product was isolated in 85% as a colorless solid that had a >99% purity. 

Solid-phase extraction for milk, urine, and feces samples is carried out by washing the loaded Cig cartridge successively with 5 ml water, 5 ml acetone/ water (20 80), 5 ml methanol/water (20 80), 5 ml dichloromethane/hexane (20 80), and 5 ml ethyl acetate/hexane (10 90). The corticosteroids are eluted with 3 ml ethyl acetate. The eluate is evaporated, and the residual is reconstituted in 0.5 ml ethanol and 5 ml phosphate-buffered saline, pending subsequent immunoaffinity column cleanup. The solid-phase extraction procedure differs for liver samples. In that case, washing of the cartridge is performed with 5 ml water, 5... 

Remove the guard column before washing the analytical column, so that impurities from the guard column are not washed into the analytical column. Bare silica and cyano- and diol-bonded phases are washed (in order) with heptane, chloroform, ethyl acetate, acetone, ethanol, and water. Then the order is reversed, using dried solvents, to reactivate the column. Use 10 empty column volumes of each solvent. Amino-bonded phases are washed in the same manner as silica, but a 0.5 M ammonia wash is used after water. C18 and other nonpolar phases are washed with water, acetonitrile, and chloroform, and then the order is reversed. If this is insufficient, wash with 0.5 M sulfuric acid, and then water. 

The paper-chromatographic properties of the common deoxy and dideoxy sugars have been treated in several reviews,2 28 a book,829 and individual publications. Common solvent-systems are 6 4 3 1-butanol-pyridine-water (Solvent A) 4 1 5 1-butanol-acetic acid-water (Solvent B) and 1-buta-nol-ethanol-water (4 1 5, upper phase, Solvent C or 3 1 1, Solvent D). The four 2-deoxy-D-hexoses and the 2,6-dideoxyhexoses may be separated as their borate complexes. 0 The use of 1-butanol-water on the one hand, and of 2-butanone-borate buffer on the other, usually provides adequate separation and, by use of a combination of solvents, these deoxy sugars may be identified. 80 The use of buffered systems has proved highly advantageous in the separation and identification of the isomeric 6-deoxy-hexoses.8 1 Other systems, such as Solvent A and 2 1 2 ethyl acetate-... 

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