MAGNETIC STIRRERS PREPARATION

The specificity of the MIP will be evaluated from competitive binding assays, as follows. Based on the [PJso (Img polymer per mL), a 10 mg/mL stock suspension (5 mL) is prepared in binding solvent. Keep the polymer in suspension by agitating the mixture with a small magnetic stirrer. Prepare competitor solutions containing 100 and 1 pg/mL of each theophylline, caffeine, or theobromine in binding solvent. Pipette these stock solutions into Eppendorf tubes according to the scheme in Table 8 (see pg. 46). 

The oxidizing agent is prepared in a 500-ml flask equipped with a magnetic stirrer and cooled in an ice bath as follows In the flask are placed 60 ml of concentrated sulfuric acid and 20 ml of water, and the solution is cooled to 10°. Potassium persulfate (42 g, 0.15 mole) is added slowly to the stirred solution while maintaining the temperature below 10°. The solution is diluted with an additional 65 ml of water maintaining the temperature below 15°. The solution is now cooled to about 7° and 0.08 mole of the ketone is added over 40 minutes. After the addition has been completed, the solution is allowed to come to room temperature and stirring is continued for 20 hours. The solution is diluted carefully with 150 ml of water and extracted twice with 75-ml portions of ether. The ether is washed with sodium bicarbonate solution, followed by water, and the ethereal solution is dried. Removal of the solvent, followed by fractional distillation, affords the product ester. 

Preparation of Ruthenium Tetroxide (/5) In a 250-ml flask equipped with a magnetic stirrer and cooled in an ice-salt bath is placed a mixture of 0.4 g of ruthenium dioxide and 50 ml of carbon tetrachloride. A solution of 3.2 g of sodium metaperiodate in 50 ml of water is added and the mixture is stirred 1 hour at 0°. The black ruthenium dioxide gradually dissolves. The clear yellow carbon tetrachloride layer is separated and filtered through glass wool to remove insoluble materials. The solution may be used immediately or stored in the cold in the presence of 50 ml of sodium metaperiodate solution (1 g/50 ml). As prepared above, the solution is about 0.037 M in ruthenium tetroxide and contains 0.3 g/50 ml. 

A dry 5(X)-mI flask equipped with a thermometer, pressure-equalizing dropping funnel, and magnetic stirrer is flushed with nitrogen and then maintained under a static pressure of the gas. The flask is charged with 50 ml of tetrahydrofuran and 13.3 ml (0.15 mole) of cyclopentene, and then is cooled in an ice bath. Conversion to tricyclo-pentylborane is achieved by dropwise addition of 25 ml of a 1 M solution of diborane (0.15 mole of hydride see Chapter 4, Section 1 for preparation) in tetrahydrofuran. The solution is stirred for 1 hour at 25° and again cooled in an ice bath, and 25 ml of dry t-butyl alcohol is added, followed by 5.5 ml (0.05 mole) of ethyl bromoacetate. Potassium t-butoxide in /-butyl alcohol (50 ml of a 1 M solution) is added over a period of 10 minutes. There is an immediate precipitation of potassium bromide. The reaction mixture is filtered from the potassium bromide and distilled. Ethyl cyclopentylacetate, bp 101730 mm, 1.4398, is obtained in about 75% yield. Similarly, the reaction can be applied to a variety of olefins including 2-butene, cyclohexene, and norbornene. 

The vinyl ether prepared above (4.5 g) is dissolved in 30 ml of ether and mixed with 60 ml of 1 A sulfuric acid in a 250-ml flask equipped with a magnetic stirrer and a condenser. The mixture is gently refluxed with stirring for 2.5 hours, and the cooled... 

Step C Preparation ofthebase-A 300 ml one-necked, round-bottomed flask, equipped with a water-cooled condenser, calcium chloride tube and magnetic stirrer is charged with anhydrous methanol (150 ml) and sodium metal (5.75 g,0.25 g atom). When the reaction is complete, the solution is treated with dry guanidine hydrochloride (26.3 g, 0.275 mol) and stirred for 10 minutes. The sodium chloride that forms is removed by filtration. The solution is concentrated in vacuo to a volume of 30 ml and the residue treated with the product of Step B, heated one minute on a steam bath and kept at 25°C for 1 hour. The product is filtered, washed well with water, dissolved In dilute hydrochloric acid and the free base precipitated by addition of sodium hydroxide to give the amllorlde product base, a solid which melts at 240.5°-241.5°C. 

Because hydrolytic reactions are reversible, they are seldom carried out in batch wise processes [26,28,36,70]. The reactor is usually a double jacket cylindrical flask fitted with a reflux condenser, magnetic stirrer, and thermometer connected with an ultrathermostat. The catalyst is added to the reaction mixture when the desired temperature has been reached [71,72]. A nitrogen atmosphere is used when the reactants are sensitive to atmospheric oxygen [36]. Dynamic methods require more complicated, but they have been widely used in preparative work as well as in kinetic studies of hydrolysis [72-74]. The reaction usually consists of a column packed with a layer of the resin and carrying a continuous flow of the reaction mixture. The equilibrium can... 

An initial solution was prepared by the hydrofluoride method, i.e. melting of a mixture of ammonium hydrofluoride and tantalite, followed by the digestion of soluble components with water and separation of the solution by filtration. The prepared initial solution contained no free HF or any other acid, and had a pH 3. In order to obtain an optimal acidity level, sulfuric acid was added to the solution. Concentrations of Ta2Os (50-60 g/1) and Nb205 ( 30 g/1) were kept approximately constant during the preparation of the solutions. Extraction was performed using a polypropylene beaker and a magnetic stirrer. 

Pipette 25 mL of solution B into a 100 mL beaker mounted on a magnetic stirrer and add an equal volume of TISAB from a pipette. Stir the solution to ensure thorough mixing, stop the stirrer, insert the fluoride ion-calomel electrode system and measure the e.m.f. The electrode rapidly comes to equilibrium, and a stable e.m.f. reading is obtained immediately. Wash down the electrodes and then insert into a second beaker containing a solution prepared from 25 mL each of standard solution C and TISAB read the e.m.f. Carry out further determinations using the standards D and E. 

B. Polymeric Urea [Benzene, diethenyl-, polymer with ethenylbenzene, [[[[(1 methylethyl)amino]carbonyt]amino]methyl] deriv.] A 10.0-g. portion of benzylamine polymer beads prepared as in Part A and 125 ml. of tetrahydrofuran (Note 6) are combined in a 300-ml., three-necked, round-bottomed flask equipped with a magnetic stirrer, a dropping funnel, and a condenser fitted with a gas-inlet tube A nitrogen atmosphere is established in the system, and the slurry is stirred while 1.35 g. (0.0159 mole) of isopropyl isocyanate [Propane, 2-isocyanato-] is added. This causes an exothermic reaction, which subsides after about 20 minutes. The mixture is then stirred at room temperature for 22 hours and at reflux for an additional 4 hours. The beads are collected by filtration, washed with 150-ml. portions of tetrahydrofuran (Note 6) and methanol, and dried under reduced pressure over calcium chloride to yield 9.09 g, of the isopropyl urea polymer. 

C. Polymeric Garbodiimide. The polymeric urea prepared above (9.09 g.) is combined with 100 ini. of dichloromethane in a 300-ml., thrce-ncckcd, round-bottomed flask equipped with a magnetic stirrer, a condenser fitted with a gas-inlet tube, and a stopper. Under a blanket of nitrogen, 5.76 g. (0.057 mole) of triethylamine [Ethanamine, N,N-... 

Diazomethane Follow essentially Aldrich Chemical Company s procedure for the Preparation of ethereal-alcoholic solution of diazomethane A 25-mL volume of ethanol is added to a solution of 5 g of potassium hydroxide in 8 mL of water in a 100-mL distillation flask fitted with a dropping funnel and a distillation condenser. The lower end of the condenser extends through and just below the neck of a 250-mL Erlenmeyer receiving flask, the latter being cooled in an ice-bath. The distillation flask containing the alkaline solution is heated in a water-bath to 65 °C and the contents of the flask are agitated with a magnetic stirrer. A solution of... 

A solution of 24.2 g. (0.15 mole) of hexamethylbenzene in 300 ml. of distilled methylene chloride is prepared in a 1-1. threenecked flask equipped with two ice-jacketed addition funnels (Note 5) and a thermometer. The solution is cooled to 5° in an ice-ethanol bath and is agitated by a magnetic stirrer. The cold peroxytrifluoroacetic acid solution is added at a constant rate to the hexamethylbenzene solution from one of the ice-jacketed... 

The membrane preparation is diluted to an appropriate final concentration in the incubation buffer and the mixture is stirred with a magnetic stirrer. Because multiple aliquots will be taken from the incubation mixture, it is important to start with an adequate total volume. To initiate association, the radioligand is added to the mixture under constant stirring. 

It is wise to use a mechanical or magnetic stirrer in order to induce rapid crystallization of the product. Prolonged contact of the product with water at this stage diminishes the yield markedly. The presence of anions, e.g., chloride, can lead to more rapid decomposition of the product, and it is best to use distilled water and ice prepared from distilled water at this point. If the oil cannot be induced to crystallize rapidly, more ice water should be added. 

Prepare citrate buffer as follows Dissolve 2.56 g citric acid and 2.36 g trisodium citrate in 50 mL double-distilled water stir with a magnetic stirrer for 15 min. The buffer may be stored at 4°C for approx 2 mo. 

Dimethylxylaramide 1- To a 250 mL round-bottom flask equipped with a magnetic stirrer was added methanol (50 mL) and the xylaric acid - methanol esterification product (6.7 mmol in 10 mL of methanol) prepared as described above. Triethylamine (6.5 mL, 46 mmol) and methylammonium chloride (1.0 g, 14.7 mmol) were then added to the methanol solution and the reaction mixture was refluxed with stirring overnight. The mixture was concentrated and the residue was washed several times with methanol. The... 

To prepare the initiator solution, 1.28 g (10 mmol) of very pure naphthalene are introduced into tube (1) through the joint (8), while passing a slow stream of nitrogen through stopcock (6). After inserting a magnetic stirrer, 100 ml of purified THE are run in... 

In a 100-mL Schlenk tube equipped with a magnetic stirrer, 10 equiv of 2-methylpropanethiol (3 mL, 33 mmol) are added at room temperature to the [NH2Me2] [Rh(CO)2Cl2] solution prepared as described in Section 27.A. After 30 min, the solution turns from light orange to brown, and an IR spectrum of the solution shows four vqo bands at 2062, 2050, 1999, and 1984 cm characteristic of Rh(p-S Bu)(CO)2 2- Then, a 1.5 molar equivalent of triphenylphos-phine per rhodium is added (1.5 g, 5.7 mmol). An immediate CO evolution is observed, and the reaction is completed within 5 min. The IR spectrum of the solution shows a single vqo band at 1977 cm Precipitation of the complex is achieved by adding slowly 50 mL of cold (20°C) distilled water. The product is collected by filtration on a Buchner funnel, washed with 150 mL of water, then dried under vacuum. Yield 1.51 g (82%). 

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