Ethyl acetate chloroformate

Sodium acetate reacts with carbon dioxide in aqueous solution to produce acetic anhydride and sodium bicarbonate (49). Under suitable conditions, the sodium bicarbonate precipitates and can be removed by centrifugal separation. Presumably, the cold water solution can be extracted with an organic solvent, eg, chloroform or ethyl acetate, to furnish acetic anhydride. The half-life of aqueous acetic anhydride at 19°C is said to be no more than 1 h (2) and some other data suggests a 6 min half-life at 20°C (50). The free energy of acetic anhydride hydrolysis is given as —65.7 kJ/mol (—15.7 kcal/mol) (51) in water. In wet chloroform, an extractant for anhydride, the free energy of hydrolysis is strangely much lower, —50.0 kJ/mol (—12.0 kcal/mol) (51). Half-life of anhydride in moist chloroform maybe as much as 120 min. Ethyl acetate, chloroform, isooctane, and / -octane may have promise for extraction of acetic anhydride. Benzene extracts acetic anhydride from acetic acid—water solutions (52). 

Pyrrohdinone (2-pyrrohdone, butyrolactam or 2-Pyrol) (27) was first reported in 1889 as a product of the dehydration of 4-aminobutanoic acid (49). The synthesis used for commercial manufacture, ie, condensation of butyrolactone with ammonia at high temperatures, was first described in 1936 (50). Other synthetic routes include carbon monoxide insertion into allylamine (51,52), hydrolytic hydrogenation of succinonitnle (53,54), and hydrogenation of ammoniacal solutions of maleic or succinic acids (55—57). Properties of 2-pyrrohdinone are Hsted in Table 2. 2-Pyrrohdinone is completely miscible with water, lower alcohols, lower ketones, ether, ethyl acetate, chloroform, and benzene. It is soluble to ca 1 wt % in aUphatic hydrocarbons. 

Figure 10.16 Densitograms obtained for four subsequent developments of the extract from Radix rhev. (a) first development, 10% (vol/vol) ethyl acetate/chloroform, distance 9 cm (b) second development, 50% (vol/vol) ethyl acetate/chloroform, distance 9 cm (c) tliird development, 100% ethyl acetate, distance 8 cm (d) fourth development, 15% (vol/vol) methanol/ethyl acetate, distance 5 cm. Reprinted from Chromatographia, 43, G. Matysik, Modified programmed multiple gradient development (MGD) in the analysis of complex plant exti acts , pp. 39-43, 1996, with permission from Vieweg Publishing.

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]. 

Isolation of Sesquiterpene Lactones. The ether extract was evaporated and dissolved in 952 ethanol. Then an equal volume of 42 aqueous lead acetate was added. After 1 hour the mixture was filtered to remove precipitated chlorophyll and phenolic products and the ethanol removed under vacuum. The aqueous layer was extracted with chloroform giving a dark colored oil from which the sesquiterpenes were isolated by a combination of chromatographic procedures, i.e., LH-20 gel permeation, silica gel using both packed columns and thin layer plates. A variety of solvents were also used to purify the individual sesquiterpene lactones, e.g., benzene-acetone (1 1), ethyl acetate, chloroform-methanol (9 1). On thin layer chromatographic plates, spots were visualized by spraying with 22 aqueous KMn04 solution. 

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>. 

Kojic acid is readily soluble in water, ethanol, and acetone sparingly soluble in ether, ethyl acetate, chloroform, and pyridine and difficultly soluble in most other liquids.4-T It has been purified by recrystallization from acetone,7 ethanol-ether,20 and methanol-ethyl acetate26 also, by sublimation under diminished pressure at8-26-64 150-200°C. The m. p. (in °C.) has been given as 151-152,20-42 152,3-21-64 152.6,37 152-153,43 153-154,29 -31 and 154.6-6 The molecular weight was determined by the cryo-scopic method,4- 7-31 and the values obtained agreed well with the calculated value of 142. 

The 3,7-dicarboxylic acid metabolite was also measured fluorimetrically by extraction with ethyl acetate chloroform 1 1 at pH=l and re-extraction into aqueous solution. The fluorescence was determined at 350/435 nm there was no cross interference with the nalidixic acid determination.(8)... 

The solubility is generally improved by the introduction of fluorine atoms into aromatic condensation polymers. Poly(carbonate)s containing hexafluoroisopropylidene units are much more soluble than Bisphenol A poly(carbonate) (3). All of the hexafluoroisopropylidene-unit-containing poly(carbonate)s become soluble in acetone, ethyl acetate, chloroform, and dimethyl sulfoxide (DMSO) in addition to the solvents of Bisphenol A poly(carbonate) (3). Colorless, transparent, and flexible films are prepared from hexafluoroisopropylidene-unit-containing poly(carbonate)s by casting or pressing. 

For the extraction from water of a dissolved substance, ethyl acetate, chloroform, benzene, amyl alcohol are also used occasionally instead of ether. Since water dissolves about 10 per cent of its volume of ether, unnecessary dilution is to be avoided, already for the sake of economy. 

Mobile phase composition 1 = toluene-ethyl acetate-formic acid (30 10 10, v/v) 2 = toluene-ethyl acetate-formic acid (55 20 25, v/v) 3 = toluene-acetone-formic acid (7 6 1, v/v) 4 = benzene-ethyl acetate-formic acid (30 15 5, v/v) 5 = chloroform-methanol-formic acid (15 3 2, v/v) 6 = chloro-form-methanol-formic acid (147 30 23, v/v) 7 = Toluene-chloroform-acetone-formic acid (8 4 3 3, v/v) 8 = chloroform-methanol-formic acid (37 8 5, v/v) 9 = chloroform-methanol-formic acid (36 9 5, v/v) 10 = ethyl acetate-chloroform-formic acid (24 21 5, v/v) 11 = ethyl acetate-chloro-form-formic acid (23 21 6, v/v). 

These compounds were analyzed by using normal phase silica columns operated at ambient temperature. Mobile phase constituents included diethylene dioxide/ethyl acetate/chloroform/hexane-pyridine... 

Poly(ethyl methacrylate) (Cellomer Associates) was vacuum dried at 50 C. The molecular weight (M ) was determined to be 3.3 X 10 from its intrinsic viscosity in ethyl acetate.— Chloroform (spectral grade) and deuterochloroform (MSD Isotopes) were used as received. Prior to sample preparation the solvent was degassed using five freeze-thaw cycles. The solvent was vacuum distilled onto the polymer In a 12 nm NMR tube, and sealed. 

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). 

The pyrido[2,3- ]- and pyrido[3,4- ]-l,2,3,4-tetrazines 9-11 are new heterocyclic systems since the appearance of CHEC-II(1996) <1996CHEC-II(7)785> and are reported as stable yellow solids which recrystallize from ethanol and melt without decomposition in the range 180-230 °C. These three compounds are stable to chromatographic separation on silica with ethyl acetate-chloroform as eluent. 

Nitric acid, Urea, Sulfuric acid, Nitronium tetrafluoroborate. Anhydrous ammonia. Acetonitrile, Ethyl acetate. Chloroform Acetonitrile, Ammonium carbonate. Isopropyl alcohol, Nitronium tetrafluoroborate. Anhydrous ammonia. Diethyl ether. Acetone, Butanol, Ethyl acetate... 

After hydrolyzate acidification with hydrochloric acid at pH values lower than 1, quinoxaline-2-carboxylic acid is quantitatively extracted into ethyl acetate, chloroform, or dichloromethane, since at these strongly acidic conditions the ionization of their carboxylate moiety is suppressed (pK, 2.88), and then back-extracted into aqueous buffered solutions at pH 6.0 or higher. These liquid-liquid partitioning procedures isolate quinoxaline-2-carboxylic acid from a complex mixture of tissue hydrolysates, and provide an aqueous extract suitable for further purification by solid-phase extraction. This has been accomplished either with the strong cation-exchange resin AG MP-50 (419, 420) or with a polar silica column (422). 

A three-necked flask, fitted with a dropping funnel, thermocouple lead, and serum stopper, was thoroughly flame-dried and was charged with 2,66 g (7.75 mmol) of methoxy-methyltriphenylphosphonium chloride (recrystallized from ethyl acetate-chloroform and dried at 100°C/1 mm) and 40 mL of anhydrous THE The mixture was cooled to -20°C, and from a dropping funnel 4.75 mL of 1.6M n-butyl lithium in hexane was added. After all the... 

Method. The corticosteroid is dissolved in 0.1 ml of dry acetone. A 0.2-ml volume of a solution of EDTN (S mg/ml in dry acetone) is added followed by 0.025 ml of 0.1 M sodium carbonate. The tube is stoppered and incubated at 45 °C for 2 h. The contents of the tube are cooled, and 2 ml of water, 0.7 g of sodium chloride and 5 ml of methylene chloride are added. The steroid derivative is extracted into the methylene chloride phase. An aliquot portion of this layer is used for TLC on plates of silica gel G with acetone-chloroform or ethyl acetate-chloroform as solvent. The composition of the solvent used is dependent on the nature of the primary alcohol. The developed plates are observed under UV light at 366 nm. The excitation and emission of the derivatives in alcohol solution occurs at 352 nm and 419 nm respectively. Amounts of less than 100 ng per spot can be detected. 

Dissolves in water, forming maleic acid. Very soluble in acetone, ethyl acetate, chloroform, benzene, toluene, and xylene soluble in dioxane slightly soluble in carbon... 

After further working up there is obtained an oily crystalline residue which is subjected to chromatography on silica gel. The 16a-methyl-6a,9a-difluoro-SM-pregnadien-lip l-diol-S O-dione is eluated with ethyl acetate-chloroform (1 2), it is recrystallized from ethyl acetate/ether and then formed to melt at 240°/242°-244°C. The yield is 60% of the theoretical. The product is reacted with valeric acid chloride to give the valerate ester. 

Wood etal. (1988) developed the reversed-phase high-performance liquid chromatographic (HPLC) method for piperine determination in black pepper and its oleoresins. ft employs bonded C18 stationary phase (ODS-2) and acetonitrile-aqueous acetic acid mobile phase with UV detection. As the spectropho-tometric method which invariably yields higher results because of the contributions from other alkaloids such as piperyline and piperettine, the HPLC method relates more to piperine. Utilizing the UV absorption property of piperine, spectrophotometric estimation methods were developed by different groups using solvents such as benzene, ethanol, ethylene dichloride, acetone, ethyl acetate, chloroform and cyclohexane. Sowbhagya et al. (1990) proved that extractability with acetone was very efficient. 

For a long time (and also currently), drug discovery programs have typically used organic solvents such as methanol, butanol, ethyl acetate, chloroform, or hexane for... 

Thin-layer Chromatography. Dissolve the residue in chloroform and apply to a silica gel plate. At the same time apply a solution containing 1 mg/ml of 5a-androstane-3a,17(3-diol in methanol as a reference solution. Develop the plate in a mobile phase consisting of ethyl acetate chloroform (1 1). Spray the reference solution only with a 10% solution of molybdophosphoric acid in methanol. The reference substance appears as a blue-grey spot on a yellow background. 

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