Solvent, solvents ethyl acetate

The solubility of commercial poly(methyl methacrylate) is consistent with that expected of an amorphous thermoplastic with a solubility parameter of about 18.8 MPa. Solvents include ethyl acetate (8 = 18.6), ethylene dichloride (8 = 20.0), trichloroethylene (8 = 19), chloroform (8 = 19) and toluene (8 = 20), all in units ofMPa. Difficulties may, however, occur in dissolving cast poly(methyl methacrylate) sheet because of its high molecular weight. 

Examples of mono-layer adsorption isotherms obtained for chloroform and butyl chloride are shown in Figure 5. The adsorption isotherms of the more polar solvents, ethyl acetate, isopropanol and tetrahydro-furan from -heptane solutions on silica gel were examined by Scott and Kucera [4]. Somewhat surprisingly, it was found that the experimental results for the more polar solvents did not fit the simple mono-layer... 

Bromo-4-methoxy-A-homo-estra-2,4,5(10)-trien-17-one (44 0. 2g), is dissolved in formic acid, 2 ml of boron trifluoride etherate is added and the mixture is stirred vigorously at 0° for 2 hr. A brown mass ca. 0.12 g) is obtained after evaporation of the solvents at reduced pressure. This material is diluted with water and extracted with chloroform. The chloroform extracts are washed successively with water and saturated salt solution, dried over anhydrous magnesium sulfate and evaporated at reduced pressure to give 95 mg of a product which is purified by filtration through a column of neutral alumina and crystallization of the residue after evaporation of the solvent from ethyl acetate-petroleum ether. The resulting A-homo-estra-l(10),2,4a-triene-4,17-dione (45), mp 143-146°, is identical to the tropone (45) prepared from monoadduct 17-ketone (43a). 

Triturating with hexane is necessary to remove trace amounts of solvents (ethyl acetate and ether) in the product. 

The Diels Alder reactions of maleic anhydride with 1,3-cyclohexadiene, as well the parallel reaction network in which maleic anhydride competes to react simultaneously with isoprene and 1,3-cyclohexadiene [84], were also investigated in subcritical propane under the above reaction conditions (80 °C and 90-152 bar). The reaction selectivities of the parallel Diels-Alder reaction network diverged from those of the independent reactions as the reaction pressure decreased. In contrast, the same selectivities were obtained in both parallel and independent reactions carried out in conventional solvents (hexane, ethyl acetate, chloroform) [84]. 

Fortunately, as the reaction is transferred from a purely organic solvent system to mixed organic-aqueous media, which are employed in most RP-HPLC separations, the apparent multiplicity of maxima in the time profile of the intensity dependence seems to be suppressed or to collapse to a reasonably simple biexponential-like dependence. As shown in Figure 11, simply changing the solvent from ethyl acetate to 95% aqueous acetonitrile and the catalyst from triethylamlne to imidazole produces a single maximum profile, one that is more easily modeled mathematically, as defined in Equation 4 ... 

Vitamin Bg and related compoimds (Figure 10.2) were quantitatively separated by preparative TLC on silica gel H. After elution, the pyridoxic acid lactone method was employed for fluorimetric determination of the concentration of the vitamin forms involved [8]. Table 10.2 shows Revalues obtained for various forms of vitamin Bg, using several solvent systems. The solvent selected, ethyl acetate/pyridine/water (2 1 2, v/v), gave excellent separation of pyridoxamine, pyridoxic acid, and pyri-doxine together with pyridoxal. 

Note System layer silica gel 60 F254 (0.25 mm, Merck Art. 5716) developing solvent ethyl acetate-formic acid-acetic acid-water (100 11 11 27). 

After the identification of the suitable compound bands, silica gel is scraped off the plates, placed in short glass columns, Pasteur pipettes, or sintered filter funnels, and fractions are recovered with such volatile solvents as ethyl acetate or dichloromethane. 

For the extraction of rubber and rubber compounds a wide variety of solvents (ethyl acetate, acetone, toluene, chloroform, carbon tetrachloride, hexane) have been used [149]. Soxtec extraction has also been used for HDPE/(Tinuvin 770, Chimassorb 944) [114] and has been compared to ultrasonic extraction, room temperature diffusion, dissolution/precipitation and reflux extraction. The relatively poor performance of the Soxtec extraction (50% after 4h in DCM) as compared with the reflux extraction (95% after 2-4 h in toluene at 60 °C) was described to the large difference in temperature between the boiling solvents. Soxtec was also used to extract oil finish from synthetic polymer yam (calibration set range of 0.18-0.33 %, standard error 0.015 %) as reference data for NIRS method development [150]. 

On intuition, a minute amount of water was added to the solvent (ethyl acetate) in the first crystallization experiment containing a molar excess of imidazole corresponding to 1, Regularly shaped crystals were formed within one hour. Such a crystal, subjected to X-ray analysis, has the structure as shown in Fig. 41 U1). Apart from the formation of the expected salt-type associate (carboxylate-imidazolium ion pair, cf. Sect. 4.2.2), two water molecules are present in the asymmetric unit of the crystal structure. This fact called our attention again to the family of serine protease enzymes, where water molecules are reported as being located in the close vicinity of the active sites 115-120),... 

In 1979 the bieyclic diol exo-2,ejco-6-dihydroxy-2,6-dimethylbicyclo[3.3.1]nonane (i) was prepared and observed to co-crystallise with various solvents, including ethyl acetate, chloroform, toluene, dioxane, and acetone. A crystal structure determination of the ethyl acetate compound revealed the occurrence of a helical canal host structure, containing ethyl acetate as guest (with 3 1 diol ethyl acetate stoichiometry), and that spontaneous resolution had occurred on crystallisation of the multimolecular inclusion compound 6>. 

Our first experiments were performed with benzene as solvent, which generally provides very good yields.3 Use of the less hazardous solvent ethyl acetate gives inferior yields if the silyl enol ether contains triethyiamine. Ethyl acetate was distilled from potassium carbonate. 

The purpose of this experiment is to test four organic solvents of varying polarity to determine which solvent is more effective in extracting chlorophyll from spinach leaves. The solvents are ethyl acetate, dichloromethane, acetone, and ethanol. 

The solvent sublation procedure of Wickbold [18] is another method that has been used for the analysis of LAS present in seawater [19,20], The solvent sublation technique (gaseous stripping into organic solvent, often ethyl acetate) has also been used to isolate and concentrate nonionic surfactants, e.g. AEs and APEO in aqueous samples [21,22], The co-extracted interferences can be eliminated by cation/anion ion-exchange and alumina chromatography [23,24]. 

The next step is to determine the solubility of the substrate (or its salts) in different solvents. This can also be performed by an automated liquid handling system. Depending upon the solubility of the substrate in water-miscible solvent (alcohols, acetone, tetrahydrofuran, etc.) and water-immiscible solvents (ethyl acetate, methyl-tert-butyl ether, heptane, etc.) the process chemist can identify one or many solvent systems from which the substrate (or its salts) could be ciystallized using the antisolvent addition strategy. 

Olsen and co-workers used a solution of nitronium tetrafluoroborate in acetonitrile for the V-nitration of acetamides and urethanes at —30°C. The following nitramides were obtained by this method V-nitroacetamide (13 %), V-nitro-2-chloroacetamide (55 %), V-nitro-n-butylacetamide (40 %), V-nitrobenzamide (53 %), ethyl V-nitro-n-butylcarbamate (91 %) and V-nitrosuccinimide (43 %). The low yield of V-nitroacetamide, a primary nitramide, is attributed to competing hydrolysis due to the release of tetrafluoroboric acid as the reaction progresses. The scope of the reaction is improved by moving to more basic solvents like ethyl acetate, 1,4-dioxane and trimethyl phosphate. ... 

The crude product (10 g) is diluted with 4 mL of a solvent mixture (ethyl acetate/cyclohexane = 9 1). This solution is poured onto a column (75-mm diameter) filled with 120 g of silica gel (Merck 230-400 mesh) for flash chromatography. Elution is performed under gravity and requires 200 mL of the above solvent system, followed by 200 mL of ethyl acetate. 2-Phenyl-2-propanol mixed with methyl p-tolyl sulfide is eluted in the first fraction ( 150 mL, monitored by TLC). The subsequent fractions are collected ( 300 mL)... 

The aerial parts were leached by soaking 100 g of fresh plants in 100 mL of distilled water. Soil extracts were prepared in a 2 1 proportion. The organic extracts of leaves were obtained with the following solvents hexane, ethyl acetate, chloroform, benzene, acetone, and methanol. The essential oils were obtained by steam distillation and the pure substances with several extraction techniques (11, 12, 13, 14). 

Solvent 2 ethyl acetate containing 0.1% (v/v) acetic acid Solvents 1-butyl chloride... 

Solvent ethyl acetate/hexane. b Solvent diethyl ether/pentane. 

Polymer and precursors (FeCl3, iron(III) acetate, titanium isopropoxide, silicon tetraethoxide, and copper(II) chloride) dissolved in organic solvent (acetone, ethyl acetate) and cast onto microscopic slides precursors in situ hydrolyzed... 

In a typical experiment, a Fischer Porter 2.5 x 25 cm column containing 55 g of silica gel (70-230 mesh) which had been treated with 2.75 mL of water, was equilibrated with the eluting solvent, hexanes/ethyl acetate (2/1). Five hundred milligrams of the methanolic fraction was adsorbed on 5 g of silica gel and carefully poured on the preequilibrated column. The eluting solvent was then forced (using nitrogen pressure) through the column at the flow rate of 25-35 mL/min and 100 mL fractions were collected. 

Sample extraction and deproteinization is usually accomplished with organic solvents including ethyl acetate (182-187, 189-192), acetone (193-196), methanol (177,197-200), acetonitrile (201,202), and ethanol (188). To optimize the extraction efficiency, acidification of the sample has been suggested by many workers (177, 188, 192, 197-199). In acidic conditions (pH 3), quinolones, being zwitterions, are fully protonated and, therefore, are becoming less bound by the matrix and more soluble in organic extraction solvents. Extraction of quinolones from food samples can also be accomplished using water (203), phosphate buffer, pH 9 (204), or trichloroacetic acid (205). 

The discovery and development of route 3 met all of the pre-determined criteria (quahty, robustness, safety, cost) and was significantly more environmentally acceptable than route 1. The chemistry was carried out predominantly in a single solvent, ethyl acetate, thereby improving the viabihty and ease of recovery and re-use of the solvent. Overall, route 3 offered several cost benefits owing to a reduction in solvent (down from a total of 232 kg/kg of API for route 1 to -54 kg/kg of API ) mass intensity, reduced by -75% compared to route 1. A more detailed environmental assessment of the chemistry is given in Section 10.4. 

The solvents 1, ethyl acetate-2-propanol-water (126 70 35) 2, 2-propanol-water (90 10) 3, benzene-methanol (10 3) 4, chloroform-acetone (1 7) 5, 1-butanol-acetic acid-ether-water (0 6 3 1) 6, chloroform-2,2,4-trimethylpentane-methanol (50 15 5) 7, chloroform-methanol (10 2). 

Solvent 3. Ethyl acetate-methanol-acetic acid, 2 1 1 (v/v/v) Standard mixture of dansyl amino acids in acetone, 1 mg/mL each Phe, Leu, Gly, Ala, Val. 

By Reduction of Unsaturated Precursors The method of choice for labeling with tritium is the reduction of a suitable unsaturated precursor (containing a double bond, carbonyl group, etc.) with carrier-free tritium gas or tritiated metal hydrides. The major limitation of this method is the availability of a suitable unsaturated precursor of the desired compound. It is essential to carry out the synthesis in a non-hydroxylic solvent (dioxane, ethyl acetate, etc.). Reductions carried out in alcohol or water will lead to almost complete exchange of the tritium gas with the solvent. 

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