Methylacetate, solvent

An excellent example of PLC applications in the indirect coupling version is provided by the works of Miwa et al. [12]. These researchers separated eight phospholipid standards and platelet phospholipids from the other lipids on a silica gel plate. The mobile phase was composed of methylacetate-propanol-chloro-form-methanol-0.2% (w/v) potassium chloride (25 30 20 10 10, v/v). After detection with iodine vapor (Figure 9.2), each phospholipid class was scraped off and extracted with 5 ml of methanol. The solvent was removed under a stream of nitrogen, and the fatty acids of each phospholipid class were analyzed (as their hydrazides) by HPLC. The aim of this study was to establish a standardized... 

The micellization behavior of copolymers containing two hydrophobic blocks, or double-hydrophobic block copolymers, has been shown to be mainly controlled by the solvent and its interaction with the copolymer blocks. It is thus possible to tune the micellization of these copolymers by changing the organic solvent. In this respect, large differences in Z, i h, Rc, etc. are expected whenever the interaction parameter between the polymer and the solvent is varied. This is illustrated by, e.g., the work of Pit-sikalis et al. [87] for PS-PSMA diblock copolymers dissolved in either ethyl-or methylacetate. The effect of temperature has been studied by Quintana et al. [88,89], who have clearly shown that CMC decreases with increasing temperature for PS-PEB copolymers in alkanes. 

Thermodynamic association constants for the two solvents, calculated from the potentials of mean force for association of two A -methylacet-amide molecules, agreed closely with experiments. An important point is that, in water, the amide dimers are not hydrogen bonded, but rather are stacked with favorable dipole alignment so as to minimize the loss of hydrogen bonding with water. In chloroform the dimers are hydrogen bonded. This unexpected picture of the dimer in water perhaps explains difficulties that have been found in applying the iV-methylacetamide model to protein processes. 

In biotechnology, the products concerned are removed from aqueous solution by extraction with methylacetate, butylacetate, isobutyl methyl ketone etc. The remaining aqueous substrate is saturated with the extraction solvents. Sometimes this causes problems with regard to environmental regulations. Table V shows that the solvents can be remored almost entirely by reverse osmosis. The concentrate consists of two phases, namely, the solvent saturated with water and the water saturated with solvent. These can be separated by means of a settler. The water phase is recirculated to the reverse osmosis. The saturated solubility in Water at room temperature is 19 OOO mg/litre for isobutyl methyl ketone, 3300 mg/litre for butyl acetate and 9 500 mg/litre for methyl acetate. As the results in table V show, the retention for isobutyl-methyl ketone increases with increasing concentration. This result is remarkable, as generally a decrease in retention is observed with increasing concentration. 

Electrophilic catalysis of the departure of halogens in the century-old Koenigs-Knorr reaction is implicit in the use of heavy metal bases such as silver oxide and mercuric cyanide, but the first demonstration of electrophilic catalysis in water (in the hydrolysis of the p-glucoside of 8-hydroxyquinoline by first-row transition metals (Cu Np > C")) was by Clark and Hay in 1973. The observations were expanded to the more conveniently followed (because more labile) benzaldehyde methylacetals or tetrahydropyranyl derivatives of 8-hydroxyquinoline, whose hydrolysis is now known to give solvent-equilibrated oxocarbenium ions (Figure 3.19). Surprisingly, however, the observation of electrophilic catalysis of glycoside hydrolysis itself was not picked up by paper... 

Process 2 - Process Description. The impurities in the raw material form azeotropes with tetrahydrofuran and ethylacetate. All the azeotropes had to be separated by a combination of counter current extraction and rectification. The aim was to recover ethylacetate and THF. The following major problems had to be solved by a solvent recovery unit 1) separate the THF/ methanol and the THF/ ethanol azeotropes, 2) dewater the THF and ethylacetate (azeotropes), 3) separate THF (Atmospheric boiling point (Tb) = 65.7°C) from ethylacetate (Tb= 77°C) and methylacetate (Tb = 57.1°C). 

The third column (118) was a simple rectification column in which decane was separated from THF/ ethylacetate. Decane was recycled into the extraction column 116. Compared to different alternatives, which were simulated, this process has the following advantages. Water was eliminated from the ethylacetate/ THF-mixtures before their rectification. This approach takes advantage of the fact that the VLE-data of ethylacetate/ THF are more favorable than the ones of ethylacetate/ THF/ water. The counter current extraction with decane allows an efficient separation of the polar impurities such as methanol, ethanol, and acetic acid. Furthermore decane eliminated the water from the recovered solvent mixture (extractive rectification in column 117). Methylacetate posed a further problem and a rectification column was necessary to separate it from THF. The stripping column 117 combined the dewatering and the elimination of methylacetate. 

An efficient separation of apple procyanidins (oligomeric catechins) was performed by high-speed counter-current chromatography (HSCCC) in a one-step operation from an apple condensed tannins fraction using a hydrophilic two-phase solvent system composed of methylacetate-water (1 1, v/v). In further matrix-assisted laser desorption initiation-time-of-flight mass spectrometry (MALDI-TOF-MS) analyses of the solute oligomers, the elution order of the procyanidins in the HSCCC was coincident with their degree of polymerization. 

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