FUNNELLING TECHNIQUE

A semi-structured interviewing technique was used to allow interviewees sufficient flexibility in articulating their responses while ensuring sufficient topic coverage for the subsequent analysis. Interview questions acted as guides or probes, based on a funnelling technique (see [294]) ... 

The inverted filter funnel technique described above reduces contact of the reactive solid with moist air and thus lowers the chances of deterioration, and also the risk of fire. In some instances the less reactive powders, such as sodium hydride, can be safely weighed in the atmosphere if you are quick and careful. However, it is recommended that an inert atmosphere blanket is always used for weighing more reactive reagents, such as potassium hydride. 

We also draw attention to a funnel techniqu in which a hydrophobic funnel is moved across a LG surface in order to compress or expand its area isotropically. A counter-body compensates for the displaced liquid by moving in the opposite direction. In this way the meniscus level remains constant. Relaxation processes, induced by the funnel movement are monitored through a Wilhelmy plate. In this... 

Using a Pasteur pipette, transfer the reaction mixture to a 10-mL Erlenmeyer flask. Add 1 mL of water and heat the mixture almost to boiling for about 2 minutes. Allow the flask to cool slowly to room temperature in order to crystallize the product. Then place the flask in an ice-water bath for several minutes to complete crystallization. Collect the crystals by vacuum filtration, using a small Hirsch funnel (Technique 8, Section 8.3). Wash the crystals with three 1.0-mL portions of an ice-cold mixture of 80% methanol and 20% water. After the crystals are dry, weigh them and determine their melting point (literature, 153-154°C). 

Once the solid is dissolved, cork the flask and allow the contents of the flask to cool slowly to room temperature. Pure acetaminophen should crystallize out of the solvent. If solid does not form, scratch the inside of the flask with your microspatula. Place the flask in an ice bath to complete the crystallization for at least 10 minutes. Transfer the solid from the flask to a Hirsch funnel (Technique 8, Section 8.3, and Figure 8.5). Rinse the flask with about 0.5 mL of ice-cold solvent (50% methanol/50% water) and transfer this mixture to the Hirsch funnel. Repeat this rinsing with an additional 0.5-mL portion of ice-cold solvent. Dry the crystals for 5-10 minutes by allowing air to be drawn through them while they remain on the Hirsch funnel. Transfer the product to a watch glass or a day plate and allow the crystals to dry in air. Let the crystals dry until the next laboratory period. 

Cool the alkaline solution and precipitate the benzoic acid by adding 5 mL of 6M hydrochloric acid with stirring. Cool the mixture in an ice bath. Collect the solid by vacuum filtration on a Hirsch funnel (Technique 8, Section 8.3, and Figure 8.5). The transfer may be aided and the solid washed with several small portions of cold water (total volume, 4 mL). Allow the crystals to dry thoroughly at room temperature at least overnight in an open container. Weigh the solid and calculate the percentage yield of benzoic acid (MW = 122.1). 

The reaction requires about 1 week for completion (3 hours with a sunlamp). If the reaction has occurred during this period, the product will have crystallized from the solution. Observe the result in each test tube. Collect the product by vacuum filtration using a small Buchner or Hirsch funnel (Technique 8, Section 8.3) and allow it to dry. Weigh the product and determine its melting point and percentage yield. At the option of the instructor, obtain the infrared spectrum using the dry film method (Technique 25, Section 25.4) or as a KBr pellet (Technique 25, Section 25.5). Submit the product to the instructor in a labeled vial along with the report. 

Alkane monosulphonates cannot be extracted from an acid medium by a simple separating-funnel technique because they are not sufficiently soluble in hydrocarbon solvents, the distribution coefficient between pentane and aqueous alcohol being only 0.08-0.09. Extraction with diethyl ether, which is effective for other monosulphonates, has apparently not been reported, but may be practicable. 

The constraint limits in Eqs. 20-59 to 20-62 can vary with time as a result of changes in process equipment or instrumentation. However, it can also be beneficial to allow the limits to change in a specified manner over the control or prediction horizons. For example, in the limit funnel technique, the output limits in (20-61) or (20-62) gradually become closer together over the prediction horizon (Maciejowski, 2002 Qin and Badgwell, 2003). 

The technique of the filtration of hot solutions has already been described in Section 11,28. The filtration of cold solutions will now be considered this operation is usually carried out when it is desired to separate a crystalline solid from the mother liquor in which it is suspended. When substantial quantities of a solid are to be handled, a Buchner funnel of convenient size is employed. The ordinary Buchner fimnel (Fig. 11,1, 7, a) consists of a cylindrical porcelain funnel carrying a fixed, flat, perforated porcelain plate. It is fitted by means of a rubber stopper or a good cork into the neck of a thick-walled filtering flask (also termed filter flask, Buchner flask or suction flask) (Fig. 11,1, 7, c), which is connected by means of thick-walled rubber tubing (rubber pressure tubing) to a similar flask or safety bottle, and the latter is attached by rubber pressure tubing to a filter pump the safety bottle or trap is essential since a sudden fall in water pressure may result in the water sucking back. The use of suction renders rapid filtration possihle... 

If preferred, a 1 5 litre three-necked flask. equippedropping funnel, mechanical stirrer and leflux condenser, may be used and the obvious modifications of technique introduced. This proaadure is recommended. 

The technique used here has been described previously by the checkers. Instead, the submitters used a dry 500-mL, three-necked flask equipped with a variable speed mechanical stirrer, a IQQ-mL pressureequalizing dropping funnel topped by a gas inlet and a Claisen head containing a low temperature thermometer (-70 C to +35°C), and a bubbler. A stream of nitrogen followed from the gas inlet. 

Filtration. Filtration removes particulate impurities rapidly from liquids and is also used to collect insoluble or crystalline solids which separate or crystallise from solution. The usual technique is to pass the solution, cold or hot, through a fluted filter paper in a conical glass funnel. 

Proteins (BSA or ovomucoid, OVM) have also been successful in the preparative resolution of enantiomers by liquid-liquid extraction, either between aqueous and lipophilic phases [181] or in aqueous two-phase systems (ATPS) [123, 180]. The resolution of d,l-kynurenine [180] and ofloxacin and carvediol [123] were performed using a countercurrent extraction process with eight separatory funnels. The significant number of stages needed for these complete resolutions in the mentioned references and others [123, 180, 189], can be overcome with more efficient techniques. Thus, the resolution of d,l-kynurenine performed by Sellergren et al. in 1988 by extraction experiments was improved with CCC technologies 10 years later [128]. 

Liquid-liquid extraction is a technique in which a solution (usually aqueous) is brought into contact with a second solvent (usually organic), essentially immiscible with the first, in order to bring about a transfer of one or more solutes into the second solvent. The separations that can be performed are simple, clean, rapid, and convenient. In many cases separation may be effected by shaking in a separatory funnel for a few minutes. The technique is equally applicable to trace level and large amounts of materials. 

Fick s law 592 Filter funnel 102 Filter papers 115 folding of, 116 incineration of, 120, 121 macerated, 450 quantitative, (T) 116 Filter pulp 450 Filtering crucibles 102 Filters, optical 661 Filtration 102, 106, 115 accelerated, 450 technique of, 116, 117 with filter papers, 116 with filtering crucibles, 117 Flame emission spectroscopy 779, 797 background correction, 795 elementary theory of, 780 D. of alkali metals by, 812... 

As the initial and final states are set by the problem under study, their important phase space relationship could be any one of the cases illustrated in Fig. 6.1. For cases Fig. 6.1c, d, it is impossible to construct a funnel path from 0 to 1 directly. To satisfy the funnel requirement, similar to the MFEP calculation, a staged NEW calculation can be performed. For example, in the case Fig. 6.1c, one can first construct an intermediate in the common region of / ,[ and /), then perform two separate NEW calculations following the paths 0 —> M and 1 —> M, respectively. This NEW-overlap sampling (NEW-OS) technique will be discussed in detail in Sect. 6.6. 

Liquid-Liquid extraction is a versatile and dependable separation technique wherein an aqueous solution is usually brought into contact with another organic solvent, exclusively immiscible with the former, so as to affect a legitimate and actual transfer of either one or more solutes into the latter. The normal-feasible separations which can thus be achieved are found to be rather easy, fast, convenient and effective resonably. Invariably such separations may be performed by shaking the two liquids in a separatory funnel for a few minutes and may be extended either to large quantities of pharmaceutical substances or trace levels. 

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