Soxhlet extractors

A solution of 2,3-dimethylindole (145 g, 1 mol) in dry dioxan containing hydroquinone (100 mg) was treated with JV,JV,JV-trimethylbenzylammonium ethoxide (5 ml of a 40% solution in MeOH) and warmed to 35 C. Freshly distilled acrylonitrile (150 ml, 2.5 mol) was added at a rate such that the temperature did not rise above 40°C. The solution was then stirred overnight and diluted with 10% aq. acetic acid (11). The solution was extracted with CH Clj and the extract was washed with water and dried (MgS04). extract was then mixed with silica gel (800 g) and the solvent removed in vacuo. The silica was placed in a Soxhlet extractor and extracted with cyclohexane. The extract deposited the product as colourless needles (125 g, 63% yield). 

In a solid-phase extraction the analytes are first extracted from their solution matrix into a solid adsorbent. After washing to remove impurities, the analytes are removed from the adsorbent with a suitable solvent. Alternatively, the extraction can be carried out using a Soxhlet extractor. 

Several standard methods for the quantitative analysis of food samples are based on measuring the sample s mass following a selective solvent extraction. For example, the crude fat content in chocolate can be determined by extracting with ether for 16 h in a Soxhlet extractor. After the extraction is complete, the ether is allowed to evaporate, and the residue is weighed after drying at 100 °C. This analysis has also been accomplished indirectly by weighing a sample before and after extracting with supercritical GO2. 

Ash is a measure of residual sodium acetate. A simple method consists of dissolving the PVA in water, diluting to a known concentration of about 0.5 wt %, and measuring the electrical conductivity of the solution at 30°C. The amount of sodium acetate is estabUshed by comparing the result to a cahbration curve. A more lengthy method involves the extraction of the PVA with methanol using a Soxhlet extractor. The methanol is evaporated and water is added. The solution is titrated using hydrochloric acid in order to determine the amount of sodium acetate. 

This modified Soxhlet extractor was devised by D. F. McFarland. 

For extraction of solid materials with a solvent, a Soxhlet extractor is commonly used. This technique is applied, for example, in the alcohol extraction of dyes to free them from insoluble contaminants such as sodium chloride or sodium sulfate. 

Benzamide [55-21-0] M 121,1, m 129.5", pK -2.16 (aq H2SO4), Crystd from hot water (about 5mL/g), EtOH or 1,2-dichloroethane, and air dried. Crystd from dilute aqueous ammonia, water, acetone and then benzene (using a Soxhlet extractor). Dried in an oven at 110° for 8h and stored in a desiccator over 99% H2SO4. [Bates and Hobbs y. 4m C/icm 73 2151 1951.]... 

Benzanilide [93-98-1] M 197.2, m 164", pK 1.26. Crystd from pet ether (b 70-90°) using a Soxhlet extractor, and dried overnight at 120°. Also crystd from EtOH. 

M 367.3, Cl 15670, Xma 501nm, pK 7.22 (OH), pK 13.39 (OH). Converted to the monosodium salt by pptn with NaOAc/AcOH buffer of pH 4, then purified by pptn of the free acid from aq soln with cone HCl, washing and extracting with EtOH in a Soxhlet extractor. The acid ppted on evaporating the EtOH and was reconverted to the sodium salt.as described for Chlorazole Sky Blue FF. Dried at 110°. It is hygroscopic. [Coates and Rigg Trans Faraday Soc 57 1088 7967.]... 

Phosphorus pentasulfide [1314-80-3] M 444.5, m 277-283 . Purified by extraction and crystallisation with CS2, using a Soxhlet extractor. Liberates H2S in moist air. HARMFUL VAPOURS. 

Sodium 2,2, 4-trihydroxyazobenzene-5 -sulfonate [3564-26-9] M 295.3. Purified by precipitating the free acid from aqueous solution using concentrated HCl, then washing and extracting with EtOH in a Soxhlet extractor. Evaporation of the EtOH left the purified acid. 

In a 5-1. three-necked flask, fitted with a ball-joint sealed stirrer and a Soxhlet extractor (70 mm. internal diameter X 300 mm. length of body) carrying a large-capacity condenser, are placed... 

If a Soxhlet extractor having a smaller capacity is employed, the cup will have to be recharged during the course of the reaction. 

Several pairs of reactants are possible. The aldol reaction between two molecules of the same aldehyde is generally quite successful, since the equilibrium lies far to the right. For the analogous reaction of ketones, the equilibrium lies to the left, and the reaction conditions have to be adjusted properly in order to achieve satisfactory yields (e.g. by using a Soxhlet extractor). 

Finally, the extraction of solid or semisolid masses into solvents can be carried out by use of a Soxhlet extractor (Fig. A3.1 lb). The. .ample is placed in a porous cup in the extractor. The boiling solvent condenses into the cup and accumulates until a siphon column is established in the adjacent tube. Then the saturated solvent returns to the boiling flask and fresh solvent distills again, repeating the process. 

The PVAc latex was cast 1.8 mm in thickness on a poly(-ethylene) plate and dried at room temperature. The latex film was dried further in a vacuum desiccator for 24 h, and extracted in Soxhlet extractor with acetone for 20... 

Under N2, clean Li metal (0.17 g, 25 mmol) was placed in a round-bottom flask with a solvent mixture of MeOH (3 mL) and pcntan-t-ol (17 mL). The mixture was heated under N, until the reaction with Li was complete. Then, naphthalene-2,3-dicarbonitrilc (2 g, 11 mmol) was added to the mixture which turned green-brown the mixture was refluxed for 3h. The brown powder, obtained after cooling and removal of the solvent under reduced pressure, was dissolved in anhyd acetone (20 mL) and then hexane (70 mL) was added. The green precipitate was separated from the brown solution by filtration. This purification by precipitation was repeated twice. The green precipitate was placed in a Soxhlet extractor and extracted for 3 h with acetone (200 mL) in order to separate the product from the insoluble metal-free species and LiOH. The acetone solution was evaporated down to a volume of 20 mL. The product precipitated after the addition of hexane (70 mL). This latter purification step was performed several times yield 1.29 g (64%). 

Sodium i-nitro-2-naphtholate, 13, 78 Sodium perbenzoate, 13, 86 Sodium succinate, 12, 72 Sodium sulfide, 12, 68, 76 16, 72 Soxhlet extractor, 16, 69 17, 74 Stannic chloride, 18,1 Stannous chloride, 17, 10, 11 Steam distillation, rapid, 17, 20 Stilbene, 17, 90... 

Copper(I) iodide, purchased from Fisher Scientific Company, was purified by continuous extraction with anhydrous tetrahydrofuran in a Soxhlet extractor for approximately 12 hours in order to remove colored impurities. The residual copper(I) iodide was then dried under reduced pressure at 25° and stored under nitrogen in a desiccator. 

Cleaning for fluorine service. It is important that materials that may contact elemental fluorine be thoroughly cleaned to remove any traces of grease or other substance that may ignite on contact with fluorine. Furthermore, it is important to passivate all surfaces that may contact fluorine. Refer to the manufacture s fluorine material safety data sheet for more information. The assembled anodes used in the laboratory were degreased by refluxing overnight with trichlorotrifluoroethane in an oversized Soxhlet extractor. 

Soxhlet extractor Visiprep SPE manifold Visiprep drying attachment... 

Flumetralin was extracted from tobacco using Soxhlet extraction. A 5-g amount of Florisil (5% deactivated) was transferred directly on to the filter disk of a Soxhlet extractor followed by another 5 g of Florisil mixed with 5 g of ground tobacco sample as an upper layer. A 60-mL volume of hexane and 3mL of a 4 agmL internal standard solution were placed in a 250-mL round-bottom flask prior to attaching the Soxhlet extractor. The unit was placed on a heating mantle and the hexane was refluxed through the extractor at the rate of about 250 mLh for 4.5 h. After cooling, 0.5 pL of the extract was injected directly into a GC/FCD or GC/MS system. 

Weigh a finely ground representative crop sample (20 g for grain or 10 g for straw) into a cellulose extraction thimble. Assemble a Soxhlet extractor using a 500-mL round-bottom flask containing 200 mL of acetone and boiling chips. Place the extraction... 

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.

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