Pyridine water removal

To a solution of 10 g of 2-N-methyl-aminoacetamido-3-o-chlorobenzoyl-5-ethylthiophene in 50 ml of pyridine are added 20 ml of benzene and 1.9 g of acetic acid. The resulting mixture is refluxed with stirring for 10 hours in a flask provided with a water-removing adaptor. The reaction mixture is concentrated, and the residue is extracted with chloroform. The chloroform layer is washed with water and then with a sodium hydrogen carbonate solution, then dried over magnesium sulfate. The chloroform is distilled off under reduced pressure, and toluene is added to the residue. Thus is precipitated white crystalline-5-o-chloropheny -7-ethyl-1 -methyi-1,2-dihydro-3H-thieno-[2,3-e] [ 1,4] diazepin-2-one, MP 105°C to 106°C. 

A disaccharide is added to a pyridine SO3 complex solution, which is prepared by reacting 5 to 6 times the molar amount of liquid SO3 as much as that of disaccharide with 5 to 10 times the amount of pyridine as that of the disaccharide at 0°C to 5°C, for sulfation at 50°C to 70°C for 3 to 7 hours. After the completion of sulfation, the greater part of pyridine Is removed by decantation. The obtained solution exhibits an acidity that is so strong that it is improper to apply the reaction with aluminum ion and, therefore, sodium hydroxide is added for neutralization. After the remaining pyridine is removed by concentration, 100 unit volumes of water per unit volume of the residue is added thereto. To the solution is then added aluminum ion solution mainly containing aluminum dihydroxychloride, the pH of which is 1.0 to 1.2, in such an amount that the aluminum ion Is present in an amount of 4 to 6 molar parts of the amount of disaccharide to provide a pH of 4 to 4.5. The mixture is reacted under stirring at room temperature and the formed disaccharide poly sulfate-aluminum compound is allowed to precipitate. After filtration, the residue is washed with water and dried. 

To a freshly prepared solution of 11.3 g. (0.10 mole) of hydrox-ylamine-O-sulfonic acid (Note 1) in 64 ml. of cold water there is added 24 ml. (24 g., 0.30 mole) of pyridine (Note 2). The mixture is heated at about 90° on a steam bath for 20 minutes. It is then cooled to room temperature with stirring, and 13.8 g. (0.10 mole) of potassium carbonate is added. The water and excess pyridine are removed from the mixture by heating it at 30-40° in a rotatory evaporator in conjunction with a water aspirator. The residue is treated with 120 ml. of ethanol, and the insoluble precipitate of potassium sulfate is removed by filtration. 

SAMPLE PREPARATION. Dry Illinois No. 6 (Herrin seam, -60 mesh) was used in the sorption studies. Analysis Found C, 74.37 H, 4.83 N, 1.76 S, 1.76 O (by difference), 8.74 Ash, 8.33 (duplicate). Approximately 10 g of the sample was exhaustively Soxhlet extracted with pyridine. Extractability was 18.7% (wt). The pyridine solution was then filtered through a 0.4 /xm filter to insure removal of particulates and colloidal material. The filter did not plug. Most of the pyridine was removed by rotovaporization under reduced pressure at 70-80 C. Approximately 200 mL of a methanol/water (80/20 vol) mixture and 2 mL of cone. HCl were added to the flask and the mixture was stirred under nitrogen for two days. The solid extract was then filtered and dried under vacuum at 105 "C for 24 hours. Analysis Found C, 80.0 H, 5.64 N, 1.85 S, 0.70 Ash, 0.30 (duplicate). 

Method. The carbohydrates are chromatographed on Whatman No. 1 filter paper with n-butanol-pyridine-water (6 4 3) for 10 h. The chromatogram is removed from the chamber and sprayed with a 10% solution of ethylenediamine sulfate in water. The paper is then heated in an oven at 120-130 °C for 10 min. The spots appear violet on a dark background when observed under UV light at 394 nm. The limits of visual detection of a number of carbohydrates are given in Table 4.17. In some cases, 50 ng of carbohydrate may be detected. 

The impact of electron donor ligands in NdX3-systems has already been discussed in Sect. 2.1.1.1. ligands such as alcohols, trialkyl phosphates, alkyl sulfoxides, alkyl amides, THF, N-oxides, pyridine etc. are added in order to facilitate water removal from NdCl3 6H20 by azeotropic distillation and in order to increase solubility and activity of NdCl3-based catalyst systems in organic solvents. 

A solution of (dichloroiodo)benzene (5.5 g, 20 mmol) in anhydrous pyridine (10 ml) was added dropwise at — 40° C to a stirred solution of the sulphide (10 mmol) in 20% (v/v) aqueous pyridine (15 ml). The mixture was kept at - 40°C for 1 h, away from direct sunlight and then at room temperature overnight. Chloroform (50 ml) was added and pyridine was removed with aqueous sulphuric acid the organic solution was washed with water, dried and concentrated to give the crude product, which was purified by column chromatography on silica gel (ether-light petroleum). Several a-chlorosulphoxides were prepared in this way in 40-70% yield. 

A mixture of 37 g. (0.25 mole) of dry dihydroxymaleic acid (p. 121) and 92 ml. of pyridine is agitated and warmed to 50-55°. If complete solution does not take place, the mixture is filtered. The clear filtrate is placed in an apparatus for vacuum distillation using an efficient water pump, and the distillation vessel is placed in a bath at 30-35°. The distillation temperature, initially at 22°, rises to 25-27° as the pyridine is removed, and the bath temperature is raised to complete removal of the pyridine. The bath temperature is then raised to 150°, and the syrupy distillate which comes over is freed of pyridine by being allowed to stand in a vacuum desiccator over concentrated sulfuric acid. The compound crystallizes on seeding and standing overnight, and the solid is triturated with a small amount of acetone and filtered. The yield of glycolic aldehyde is 9 g., or 75%. 

A solution of 100 g. (0.58 mole) of 2-nitro-4-chlorotoluene in 500 ml. of pyridine and 390 ml. of water is heated on a steam bath under a reflux condenser while 6 portions of 43 g. each of potassium permanganate are added at intervals of 1 hour. After another 1-hour heating period, the mixture is filtered and the water and pyridine are removed from the filtrate by evaporation under reduced pressure. The residue is treated with excess aqueous sodium hydroxide solution, any oil present is removed by use of a separatory funnel, and the resulting aqueous solution is acidified with hydrochloric acid. The precipitated 2-nitro-4-chlorohenzoic acid is collected hy filtration, washed with water, and dried to give 56A g. (48%) of product melting at 138-140°. 

Acetamides. Reflux about 0.5 millimole of the unknown with 0.2 mL of acetic anhydride for 5 min, cool, and dilute the reaction mixture with 2.5 mL of water. Initiate crystallization by scratching, if necessary. Remove the crystals by filtration and wash thoroughly with dilute hydrochloric acid to remove unreacted amine. Recrystallize the derivative from alcohol-water. Amines of low basicity, e.g., p-nitroaniline, should be refluxed for 30 to 60 min with 1 mL of pyridine as a solvent. The pyridine is removed by shaking the reaction mixture with 5 mL of 2% sulfuric acid solution the product is isolated by filtration and recrystallized. 

Ion-exchange method [6]. 6 g of NaY were added to 100 ml of IN FeS04 7 H2O solution and were refluxed in argon atmosphere for 3 hours. The zeohte was filtered, washed with deionized water and dried. The iron exchanged zeolite was mixed with 6 g of 1,2-dicyanoben-zene in argon atmosphere. The mixture was heated to 473 K. The molten slurry was stirred for 4 hours and then cooled to room temperature. The product was washed with acetone and methanol to remove the excess 1,2-dicyanobenzene. After this procedure the catalyst was sox-hlet extracted with pyridine to remove the portion of the metal complex which formed on the external surface of the zeolite particles. The pyridine extraction was followed until a colorless extract was obtained. The blue-green material was washed extensively by acetone to remove the excess of pyridine. Finally, the catalyst was dried at 343 K. 

Barium 4Z- and 4 -2-Sulfo-2,3,4,6-tetrahydroxyhexa-2,4-dienoate-8-lac-tone. The procedure of Cousins et al. (36) was used to prepare L-ascorbyl 6-valerate (mp 89-92°C). The valerate ester (15 g, 57.6 mmol) was dissolved in pyridine (250 mL) at 25°C and pyridine-sulfur trioxide complex (25 g, 2.5 equivalents) was added. After stirring 18 h at room temperature, water (500 mL) was added, and the mixture was placed in a water bath at 70°C. The pH of the mixture was maintained at 9-9.5 by periodic addition of saturated barium hydroxide solution. The elimination reaction at 65°C was complete in 4-6 h, as evidenced by the constancy of the reaction pH. The reaction mixture was adjusted to pH 10 by addition of saturated barium hydroxide, and at that point the total volume of the mixture was 1.5 L. Pyridine was removed by evaporation under vacuum to 300 mL, and the evaporation step repeated twice after addition of water (250 mL). The mixture was adjusted to pH 2 by addition of sulfuric acid (1 M), and barium sulfate was removed by filtration. The filtrate was extracted with ethyl ether (3 X 500 mL) to remove valeric acid, and the aqueous layer (300 mL) was adjusted to pH 7 by addition of barium hydroxide. After evaporation to 50 mL, barium sulfate was removed, and an equal volume of acetonitrile was added to the filtrate. The desired compound crystallized in the cold to give 12.0 g (55% ) of crude material with mp 215-225°C. The crystals were dissolved in water (30 mL) and were decolorized with charcoal after addition of acetonitrile, analytically pure crystals were obtained [yield, 5 g with mp 220-225°C (decomposed)]. 

The pyridine is removed by rotary evaporation and 6.25 ml of deionized water is then added to the solution. Then the solution is filtered through a syringe filter having 0.22 pm PTFE membrane to remove insoluble by-products. 

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