Recrystallization drying

Note 1. Experimental gives reagents, solvents, quantities, times, yields, etc., and sufficient detail for the experiment to be repeated by a proficient chemist. Details of standard techniques such as weighing liquids, setting up apparatus, recrystallization, drying the product, etc., are understood by the experimentalist from experience and training. 

It is cooled to 20 C, and about 90% of potassium chlorate is obtained as crystals, which are recrystallized, dried in a revolving drier by hot air or by vacuum drier and crushed to powder[Handbook of potassium salt industry p.126(I958 ) 1. 

The NaCl produced in the solution is collected and used again by re-cycling Except for the preparation of the electrolyte in the beginning, the supplement of sodium chloride is almost unnecessary only potassium chloride is required. The solution is electrolysed using graphite anodes and steel plate cathodes as in the case of (a) and adding a small amount of potassium bichromate. The pH value is adjusted to about 6.5 6.8, the bath voltage 3 1 3 5 and the temperature about O O C. When potassium chloride is added to the electrolyte, the potassium chlorate crystallizes out The crystals are recrystallized, dried, crushed to powder and sieved to requirements. This process has one more double decomposition step than (a), but needs less electric power than (a). 

The crystalline material is obtained by evaporation of a solution of HgO in aqueous HCN. The product is recrystallized, dried at 50°C, ground and redried. 

The active material is produced by dissolutimi of pure iron in sulfuric acid. The FeS04 is recrystallized, dried, and roasted at high temperature to produce Fc203. The materials are washed free of the sulfate, dried, and partiaUy reduced in H2 to produce a mixture of Fe304 and iron. The resulting mixture is blended with small amounts of FeS, sulfur, and HgO for use in negative plate assembly. 

N-Bromoacetyl p-jy-Galactopyranosylamine. y8-Galactosylamine, 2 mmoles, is suspended in 2 ml of dimethylformamide and 2.5 mmoles of the anhydride are added. After 3 hr at 25°, ethyl ether is added and the precipitated product is filtered and washed well with ethyl ether. For recrystallization, dry product is dissolved in a minimal volume of cold water. To this mixture are added 10 volumes of methanol, followed by ethyl ether to turbidity. 

Phenylacetic acid. Use 5 0 g. of magnesium, 25 g, (23 ml.) of redistilled benzyl chloride (Section IV,22) and 75 ml. of sodium-dried ether. Allow the reaction mixture to warm to 15° and then decompose it with dilute hydrochloric or sulphuric acid. Filter off the crude acid and recrystallize it from water. The yield of pure phenylacetic acid, m.p. 76-77°, is 11 g. 

Bromo-2-nitrophenylacetic acid (26 g, 0.10 mol) was dissolved in a mixture of 50% HjSO (400 ml) and ethanol (600 ml) and heated to 90°C. Over a period of 1 h, zinc dust (26.2 g, 0.40 mol) was added. slowly and then heating was continued for 2 h. The excess ethanol was removed by distillation. The solution was cooled and filtered. The filtrate was extracted with EtOAc. The filtered product and extract were combined, washed with 5% NaCOj and brine and then dried (MgSO ). The solvent was removed in vacuo and the residue recrystallized from methanol to give 20.5 g (97% yield) of the oxindole. 

Sodium hydride (9.3 g, 0.22 mol) was washed with petroleum ether and DMSO (200 ml) was added and the mixture was heated to 100°C. A solution of diethyl malonate (35.2 g, 0.22mol) in DMSO (50 ml) was then added and stirred for 10 min to give a clear solution. A solution of 4-bromo-3-nitrobenzophenone (30.6 g, 0.10 mol) in DMSO (100 ml) was added and the resulting dark solution kept at 100 C for 1 h. The solution was poured into water (3 1) and extracted (2x) with ether. The extract was washed with water, dried (NajSOj and concentrated in vacuo to give an oil which crystallized. The solid was recrystallized from isopropyl alcohol to give 35.4 g (92% yield) of the product. 

A stirred solution of o-methylpivalanilide (50 mmol) in dry THE (100 ml) was maintained at 15°C under a nitrogen atmosphere. A 1.5 M solution of n-butyllithium in hexane (3 equiv.) was added dropwise. The solution was then maintained at room temperature for 16h. The solution was cooled in an ice-bath and treated with 2 N HCl (60 ml). The organic layer was separated and the aqueous layer was further extracted with benzene. The combined layers were dried (MgS04). The product was obtained in 87% yield and recrystallized from ether-cyclohexane. 

Phenyl-3-oxopropanoic acid (25 mmol) and EtjN (87.5 mmol) were dissolved in THF (150 ml) and cooled to —40°C. Ethyl chloroformate (27.5 mmol) was added dropwise to this solution and then the reaction mixture was stirred for 30 min at —20°C. Di-n-hexylamine (27.5 mmol) was added to the suspension and it was stirred at room temperature for an additional hour. The reaction mixture was diluted with water (100 ml) and extracted with ether (400 ml). The extract was washed with aq. 5% HCl (100 ml) and brine (2 X 100 ml) and dried over NajSO. The crude amide was obtained by removal of the solvent in vacuo and phenylhydrazine (25 mmol) was added. The mixture was heated to 100°C for 30 min. The residue was held in vacuo to remove the water formed and then powdered ZnCl2 (125 mmol) was added. The mixture was heated at 170"C with manual stirring for 5 min. The cooled residue was dissolved in acetone (100 ml) and diluted with ether (500 ml). Water (100 ml) was added. The organic layer was separated and washed successively with 5% aq. HCl (100 ml) and brine (2 x 100 ml) and dried over NajSO. The solvent was removed in vacuo, and the residue was recrystallized from EtOAc-hexane. The yield was 79%. 

A solution of 2,3-dibromo-5-methoxyaniline (32 g, 0.17 mol) in CHjClj (300 ml) was stirred and cooled in an icc bath. Boron trichloride (1 M in CH2CI2, 180 ml, 0.18 mol), chloroacetonitrile (14.3 g, 0.19 mol) and TiC (1 M in CH CIj, 190ml, 0.19 mol) were added. The resulting mixture was refluxed for 1.5 h. The solution was cooled to room temperature and poured carefully on to a mixture of icc and 20% aq. HCl (700 ml). The organic layer was separated and the CH Clj removed by distillation. The residue was heated to 90°C on a water bath for 30 min. The solution was cooled and the solid collected by filtration. It was partitioned between ether (1.41) and 1 N NaOH (500 ml). The ether layer was washed with brine, dried over Na2S04 and evaporated. The residue was recrystallized from ethanol to give 2-amino-3,4-dibromo-6-methoxy-a-chloroacetophenone (55 g) in 90% yield. 

The above product (24 g, 0.067 mol) was dissolved in 90 10 dioxane-water (300 ml) and sodium borohydride (92.5 g, 0.067 mol) was added. The mixture was refluxed for 4h. The cooled solution was poured into 0.1 N HCl (1.11). A solid precipitated and was collected by filtration, dried and recrystallized from ether hexane to give 6,7-dibromo-4-methoxyindole (18.5 g, 90%). 

Phenylmagnesium bromide (2.8 mol) was prepared in anhydrous ether (21) from bromobenzene (440 g, 2.9 mol) and magnesium turnings (68.0 g 2.8 g-atom). To this solution was added dropwise a solution of indole (328 g, 2.8 mol) in benzene (8(X)ml). The resulting solution was stirred for 10 min and then a solution of cyclopentanoyl chloride (322 g, 2.4 mol) in benzene (800 ml) was added dropwise. The solution was stirred for 1 h and then water (11) was added carefully. The precipitate which formed was collected by filtration and dried to give 169 g of crude product. Additional product (97 g) was obtained by evaporation of the organic layer of the filtrate. The combined products were recrystallized from toluene to give 250 g (49% yield) of pure product. 

A solution of 6-bromoindole (O.lOmol) in toluene (200 ml) was treated with Pd(PPh3)4 (5mol%) and stirred for 30 min. A solution of 4-fluorophenyl-boronic acid (0.25 M, 0.15 mol) in abs. EtOH was added, followed immediately by sal aq. NaHCOj (10 eq.). The biphasic mixture was refluxed for several hours and then cooled to room temperature. The reaction mixture was poured into sat. aq. NaCl (200 ml) and the layers separated. The aq. layer was extracted with additional EtOAc (200 ml) and the combined organic layers dried (Na2S04), filtered and concentrated in vacuo. The solution was filtered through silica gel using hexane-CHjCl -hexanc for elution and evaporated. Final purification by recrystallization gave the product (19 g, 90%). 

A solution of 1.05 M diborane in THF (25 ml, 26 mraol) was added slowly to a stirred suspension of 3-acetyl-5-hydroxy-2-methylindole (1.0 g, 5.3 mmol) in THF (10 ml). After hydrogen evolution ceased, the mixture was heated at reflux for I h, cooled and poured into acetone (75 ml). The mixture was heated briefly to boiling and then evaporated in vacuo. The residue was heated with methanol (50ml) for 20min. The solution was concentrated and 3NHC1 (40ml) was added. The mixture was extracted with ether and the extracts dried (MgSO ) and evaporated to yield a yellow oil. Vacuum sublimation or recrystallization yielded pure product (0.76 g, 82%). 

Spray drying Spray lay-up Spray painting Spray pyrolysis Spray recrystallization Sprays... 

The first stage crystals are rich in pentaerythritol linear formal and may be treated (60,61) to convert this species to pentaerythritol and formaldehyde, which can then be recovered. The concentrated Hquors obtained after redissolving are then recrystallized and filtered prior to drying of the final product. 

DAG is treated with ethanol and hydrochloric acid in the presence of inert solvent, eg, chlorinated solvents, hydrocarbons, ketones, etc. The L-ascorbic acid precipitates from the mixture as it forms, minimising its decomposition (69). Cmde L-ascorbic acid is isolated through filtration and purified by recrystallization from water. The pure L-ascorbic acid is isolated, washed with ethanol, and dried. The mother Hquor from the recrystallization step is treated in the usual manner to recover the L-ascorbic acid and ethanol contained in it. The cmde L-ascorbic acid mother Hquor contains solvents and acetone Hberated in the DAG hydrolysis. The solvents are recovered by fractional distillation and recycled. Many solvent systems have been reported for the acid-catalyzed conversion of DAG to L-ascorbic acid (46). Rearrangement solvent systems are used which contain only the necessary amount of water required to give >80% yields of high purity cmde L-ascorbic acid (70). 

North American Chemical Co. produces borax pentahydrate and decahydrate from Seades Lake brines in both Trona and West End, California (see Chemicals frombrines). The 88 km dry lake consists of two brine layers, the analyses of which are given in Table 11. Two distinct procedures are used for the processing of upper and lower lake brines. Borax is produced in Trona from upper lake brines by an evaporative procedure involving the crystallization of potash and several other salts prior to borax crystallization as the pentahydrate (104). A carbonation process is used in West End, California to derive borate values from lower lake brines (105). Raw lower stmcture brine is carbonated to produce sodium bicarbonate, which is calcined and recrystallized as sodium carbonate monohydrate. The borate-rich filtrate is neutralized with lake brine and refrigerated to crystallize borax. 

Ethyl 4,5-Dlbenzamldopent-4-enoate (2) Ethyl 3-lmidazol-4(5)-ylpropanoale 1 (9.2 g, 54 mmol) In ElOAc (140 mL) was treated with benzoyl chloride (15 7 g, 112 mmol) In ElOAc (40 mL) and 1M NaHCOa (380 mL) added simultaneously In 1 h under Ice-cooling. The reaction mixture was stirred for 1 h, then a further portion of benzoyl chloride (IS 7 g, 112 mmol) in ElOAc) and iM NaHCOa (280 mL) was added m the same manner, followed by an additional portion o( 1M NaHCOa (200 mL) The reaction mixture was stirred for 24 h, then the organic layer was separated, concentrated, and the residue dissolved in THF (300 mL) The THF solution was stirred with 10% NaHCOa (600 mL) for 24 h to decompose any N-lormyl intermediate and to remove benzoic acxl Extraction with EtOAc, drying (Na2S04), solvent evaporation and recrystallization of the residue from EtOAc hexane afforded 16 24 g of 2 (84%), mp 128-129°C... 

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