Extraction with solvents, continuous liquids

Extraction thimble, 153 Extraction with solvents, continuous, of liquids, 152, 153, 223t, 224 Continuous, of solids, 153, 154, 222t, 223t... 

Natural Products. Various methods have been and continue to be employed to obtain useful materials from various parts of plants. Essences from plants are obtained by distillation (often with steam), direct expression (pressing), collection of exudates, enfleurage (extraction with fats or oils), and solvent extraction. Solvents used include typical chemical solvents such as alcohols and hydrocarbons. Liquid (supercritical) carbon dioxide has come into commercial use in the 1990s as an extractant to produce perfume materials. The principal forms of natural perfume ingredients are defined as follows the methods used to prepare them are described in somewhat general terms because they vary for each product and suppHer. This is a part of the industry that is governed as much by art as by science. 

APPARATUS FOR THE CONTINUOUS EXTRACTION OF SOLIDS OR LIQUIDS BY SOLVENTS Solids by solvents. The various forms of Soxhlet apparatus illustrated in Section 11,44 can be purchased with groimd glass joints. A simplified form, in which the fragile side tubes are absent, is shown in Fig. 77,58,1. The material to be extracted, if of granular form, may rest upon a sintered glass disc or upon a removable septum ... 

Figure 8.6 Apparatus used for saeple preparation involving solvent extraction. A, heavier-than-water continuous liquid-liquid extractor B, pressurized Soxhlet extractor for use with supercritical fluids C, Kudema-Danlsh evaporative concentrator 0, autonated evaporative concentrator.

Applications Simultaneous steam distillation-solvent extraction has been in use for many years [163]. Steam distillation combined with continuous liquid extraction is an efficient technique for the removal and isolation of volatile compounds in various matrices (environmental,... 

The product workup consisted of continuously extracting the filter cake with tetrahydrofuran (THF) and combining the THF and filtrate to make up a sample for distillation. In some experiments the THF extracted filter cake was extracted with pyridine and the pyridine extract was included in the liquid products. Extraction with pyridine increased coal conversion to soluble products by an average of 1.6 weight percent. The hot filtrate-THF-pyridine extract was distilled. Distillation cuts were made to give the following fractions, THF (b.p. <100 C), light oil (b.p. 100-232 C), solvent (b.p. 232-482), and SRC (distillation residue, b.p. >482 C). 

Nitrobenzene oxidation was carried out by adding 50 mg of dry soda lignin into a mixture of 7 mL of 2 M NaOH and 4 ttiL of nitrobenzene in a 15 ttiL steel autoclave. Then, the antoclave was heated to 165°C for 3 hours in a preheated thermostat oil bath. After the autoclave was cooled to room temperature, the mixture was then transferred to a liqnid-hquid extractor for continuous extraction with chloroform (5 x 20 mL) in order to remove any nitrobenzene reduction product and excess nitrobenzene. The oxidation mixtnre was then acidified by concentrated HCl to pH 3 and further extracted with chloroform (5x15 mL). The solvent from the second chloroform solution was then removed using a rotary evaporator at 40°C under reduced pressure in order to obtain the nitrobenzene oxidation mixture. The mixture was then dissolved into dicloromethane and made up to 10 luL. This mixture was then used as a stock solution for high performance liquid chromatography (HPLC) analysis [6]. 

A. Ethyl a-(hydroxymethyl)aotylate, (Note 1). A 1000-mL, four-necked, round-bottomed flask is fitted with a mechanical stirrer, 250-mL pressure-equalizing funnel, condenser, and thermometer. Paraformaldehyde (48 g, 1.6 mol), 1 N phosphoric acid (4 mL) and water (110 mL) are heated at 90°C for 1.5 hr to form a clear aqueous formaldehyde solution. This solution is cooled to room temperature. Triethyl phosphonoacetate (89.6 g, 0.4 mol) is added to the flask and the solution is stirred at room temperature at 1000 rpm. A solution of potassium carbonate (60.7 g, 0.44 mol) in water (60 ml) is added at room temperature (first slowly 10 mL in 10 min) and then more rapidly (40 min). The temperature reaches 35-40 C and must be maintained at this level (with a water bath if necessary). Stirring is continued for 5 min at 40 C after the end of the addition then the mixture (liquid-liquid heterogenous mixture) must be cooled rapidly to room temperature using an ice bath (Note 2) while diethyl ether (200 mL) and brine (150 mL) are added. After decantation, the mixture is extracted with ether (three 100-mL portions). The combined organic layers are washed with brine (two 100-mL portions) (Note 3) and dried over magnesium sulfate the solvents are evaporated under reduced pressure and the... 

Laboratory studies of the rearrangement process began with semi-continuous operation in a single, 200-mL, glass reactor, feeding 1 as a liquid and simultaneous distillation of 2,5-DHF, crotonaldehyde and unreacted 1. Catalyst recovery was performed as needed in a separatory funnel with n-octane as the extraction solvent. Further laboratory development was performed with one or more 1000-mL continuous reactors in series and catalyst recovery used a laboratory-scale, reciprocating-plate, counter-current, continuous extractor (Karr extractor). Final scale-up was to a semiworks plant (capacity ca. 4500 kg/day) using three, stainless steel, continuous stirred tank reactors (CSTR). 

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