Solids purification

The mixture is allowed to warm up over 20 minutes and is poured into a 2-1. separatory funnel. The purplish solution is washed with a saturated ammonium sulfate solution (about 1.5 1.) containing ferrous ammonium sulfate until the rust-brown ferric color is no longer produced. The organic layer is dried over magnesium sulfate and concentrated, leaving a dark solid. Purification of the solid by high-vacuum short path distillation gives 127-142 g. (73-81%) of a pinkish or tan-colored product, b.p. 148-150° (0.15 mm.), m.p. 145-147°. It may be further purified by sublimation, or recrystallization from benzene-hexane, m.p. 148-149°. 

Triphenylphosphine (342 mg, 1.30 mmol) was added in one portion to a solution of 4-acethylamino-5-azido-3-(l-ethyl-propoxy)-cyclohex-l-ene-l-carboxyllic acid ethyl ester (272 g, 0.80 mmol) in THF (17 ml) and water (1.6 ml). The reaction was then heated at 50°C for 10 h, cooled and concentrated in vacuo to give a pale white solid. Purification of the crude solid by flash chromatography on silica gel (50% methanol in ethyl acetate) gave 242 mg (96%) of the 4-acethylamino-5-amino -3-(l-ethyl-propoxy)-cyclohex-l-ene-l-carboxyllic acid ethyl ester as a pale solid. 

Molybdenum catalyst SI (9 mg, 0.01 mmol) was weighed in a glove box in a 10-mL round-bottom three-necked flask equipped with a reflux condenser and a rubber septum. The reaction vessel was subsequently removed from the glove box and maintained under an atmosphere of argon. The catalyst was then dissolved in anhydrous benzene (6.0 mL), and diene 1 (20 mg, 0.04mmol) was added as a solution in anhydrous benzene (0.60 mL). The reaction flask was immersed in an oil bath that was previously warmed to 50 °C, and the mixture was allowed to stir for 14h. After this period, the reaction vessel was allowed to cool to 22 °C. The mixture was stirred in the presence of air (septum was removed) for approximately 2 h. Removal of solvent in vacuo afforded a black solid. Purification through silica gel chromatography (10 1 hexanes/ethyl acetate followed by 4 1 hexanes/ethyl acetate) delivered 3 as a white solid (18.1 mg, 90% yield). 

If the purity of the reagent is not up to the level required, standard solid purification techniques (chromatography, recrystallization, sublimation) should be used to purify it (see Chapter 11 for more details). 

A mixture of CuCN (5.0 g, 55 mmol) and dry pyridine (100 mL) was heated under reflux until all the CuCN dissolved. The solution was cooled to rt as 6-iodo-9-( -D-ribofuranosyl)purin-2-amine (5.0 g, 12.7 mmol) was added, and the mixture was heated at 130-135 °C for 10 min. The mixture was evaporated to dryness, and the black residue was extracted with hot MeCN (3x250mL). The combined MeCN extracts were evaporated, and the residual solid was reextracted with hot i-PrOH (3 x 200 raL). The i-PrOH extract was evaporated to yield 6.0 g of tan solid. Purification by column chromatography (silica gel) gave a pure sample yield 2.6 g (70%). Crystallization (EiOH) gave light yellow crystals mp 131 -132 C. 

The alkali metal cyantrimethylsilylamides may be prepared in an inert organic solvent like n-hexane or toluene. Alternatively, an excess of the liquid BTSC can be used. In all cases the alkali metal compound is obtained as a white solid. Purification was performed by washing with hexane, drying in vacuum, and/or re-crystallization fl om THF or pyridine. 

Solvent extraction (leaching) Preferential dissolution of one solid Purification of penicillin. Recovery of sugar from crushed cane or beat... 

Farha, O. K., Mulfort, K. L., Thorsness, A. M., and Hupp, J. T. Separating solids purification of metal-organic framework materials. Journal of the American Chemical Society, 130, 8598-8599 (2008). 

---