Formation water fractional crystallization

The exact order of the production steps may vary widely in addition, some parts of the process may also vary. Metal formate removal may occur immediately after the reaction (62) following formaldehyde and water removal, or by separation from the mother Hquor of the first-stage crystallization (63). The metal formate may be recovered to hydroxide and/or formic acid by ion exchange or used as is for deicing or other commercial appHcations. Similarly, crystallization may include sophisticated techniques such as multistage fractional crystallization, which allows a wider choice of composition of the final product(s) (64,65). 

When an aqueous solution of the A-fraction is cooled in contact with butyl alcohol, it satisfies its associative tendencies through the formation of an alcoholate. Since butyl alcohol is probably adsorbed via its hydroxyl group, the alcoholate then presents a hydrophobic surface to the medium and precipitates from solution." The crystalline precipitate can be washed with cold water saturated with butyl alcohol, since this will not dissolve alcohol from the alcoholate and therefore does not disturb the crystal lattice. When the crystals are dried in the absence of water, the crystal structure is frozen without the establishment of intermolecular bonding. Consequently, the product can be dissolved in hot water. With cold water, the molecules immediately associate to give an insoluble gel. 

A mixture of 150 g (0.89 mol) of ( —)-e (fo,e.vo-2-hydroxy-2,6,6-trimethylbicyclo[3.1.1]hcptan-3-one [( — )-l-hy-droxypinocamphone], freshly distilled 150 g (0.73 mol) of AI(0-i -Pr)3 and 150 g (2.5 mol) of /-PrOH is heated in a 2 L flask with distillation column. A gentle reflux is maintained so that 30 g of the acetone/ -PrOH mixture distills per hour, which is replaced by the same volume of fresh i-prOH. When the formation of acetone ceases (ca. 3-4 h), the excess /-PrOH is distilled off and the residue is stirred for 1 h with weakly alkaline water. The mixture is filtered and the residue extracted with Ft.O. The extract contains ca. 15% of starting material which is removed by fractional crystallization (hydroxylamine method) to afford the crude diol yield 75 g (49%) mp 35 40 JC. Purification via the phenylurethane gives mp 55.5-56X [a]f,° -J-3.3 (EtOH). 

Many alkaloids may be only sparingly soluble in ether but, with the exception of pentane and hexane, their purification is more readily effected from this solvent than from any other. It is possible to prepare ether solutions of these bases of a concentration far in excess of their equilibrium value which then often yield a crystalline solid in reattaining a state of equilibrium. A supersaturated ethereal solution of these bases is readily prepared as follows The relatively dilute aqueous acid solution of the alkaloids, in a separatory funnel, is covered with a layer of ether, and a layer of water interposed between the two layers by the cautious addition of water down the side of the funnel. Aqueous ammonia is run in, in a like manner, the stopper inserted in the funnel, and the mixture shaken very vigorously. Often the more insoluble alkaloids will crystallize from the ether layer before it can be separated. In any case the wet turbid ethereal solution can be brought to brilliant clarity by treatment with charcoal. Removal of the ether leaves a residue which is now amenable to fractional crystallization from other solvents, to fractional distillation, or to salt formation. 

---