Distillation reduced pressure

D 1160 Method for reduced pressure distillation of high-boiling... 

Figure 10.1 presents the part of the refining diagram that includes the atmospheric and reduced pressure distillations. 

Reduced pressure distillation of a mixture of chlorine octahydrate and HgO provides a distillate with about 25% HOCl (55,129). Chloride-free aqueous solutions of up to 76% HOCl can be obtained by dissolving Hquid CI2O, prepared by reaction of CI2 and HgO, in the appropriate amount of water (3). Alternatively, the gaseous CI2O can be absorbed in cold water to give lower concentrations of HOCl In addition, a CI2O solution in CCl can be extracted with H2O to give CU and Cl2-free HOCl solutions of up to 5 M (51). 

A 250-ml flask is charged with 28 g (0.20 mole) of 2-acetyIcyclohexanone and 25 g (0.22 mole) of 30% hydrogen peroxide in 100 ml of /-butyl alcohol. The solution is refluxed for 3 hours, cooled, and a pinch of palladium on charcoal (10%) is cautiously added. The mixture is refluxed for an additional hour to decompose excess peroxide. The cooled mixture is then filtered through celite, and the volume is reduced by removal of /-butyl alcohol and water at reduced pressure. Distillation of the residue affords about 85% of cyclopentanecarboxylic acid, bp 59-6271 rnm, 123727 mm, 215-21671 atm. 

Fig. A3.17. Capillary bleed tube for reduced pressure distillation.

Nc>tc 5). The mixture is stirred for 30 minutes to ensure complete hydrolysis. The upper organic layer is separated, and the aqueous layer is extracted with three 25-ml. portions of ethyl acetate. The organic extracts are combined, washed with sodium chloride solution, dried with anhydrous magnesium sulfate, and evaporated under reduced pressure. Distillation of the residual liquid under reduced pressure through a 10-cm. Vigreux column affords a... 

Trimellitic anhydride acid chloride was purified by reduced pressure distillation. 

To overcome this issue Kureshy et al. [55, 56] reported dimeric form of Jacobsen s catalysts 3, 4. They used the concept of solubility modification by altering the molecular weight of the catalyst so that in a post catalytic work-up procedure the catalyst is precipitated, filtered and used for subsequent catalytic runs. The complexes 3, 4 (0.2 mol % of Co(lll)-salen unit) (Figure 2) were effectively used for HKR of racemic epoxides, e.g., styrene oxide, epichlorohydrin, 1,2-epoxypropane, 1,2-epoxyhexane, 1,2-epoxyoctane, and 1,2-epoxydodecane to achieve corresponding epoxides and 1,2-diols in high optical purity and isolated yields. In this process, once the catalytic reaction is complete the product epoxides were collected by reduced pressure distillation. Addition of diethylether to the residue precipitated the catalyst which was removed by filtration. However, the recovered catalyst was required to be reactivated by its treatment with acetic acid in air. The catalysts were reused 4 times with complete retention of its performance. 

A solution of 13.8 gm (0.10 mole) of phosphorus trichloride in 30 ml of ethyl ether is added dropwise over a 3-4 hr period at —20°C to a stirred solution of 16.8 gm (0.3 mole) of propargyl alcohol, 30.0 gm (0.3 mole) of triethylamine, and 100 ml of ether. After the addition, the mixture is stirred for an additional hour at 0°-5°C, warmed slowly to room temperature overnight, water is added, the ether separated, and the resulting water layer extracted with two 100 ml portions of ether. The combined ether layer is washed with two 100 ml portions of dilute hydrochloric acid, two 100 ml portions of 10% aqueous sodium carbonate, dried, and concentrated under reduced pressure distillation of the residue affords 18.0 gm (92%), b.p. 115°-115°C (0.25 mm). 

The traditional way to free water of dissolved solids is to distil it, either at atmospheric pressure or by multistage flash evaporation at reduced pressure. Distillation removes virtually all solutes but is wasteful of energy unless the low grade heat can be economically recovered from the condensers. Flash evaporation is attractive in countries such as Saudi Arabia where energy is inexpensive and the only plentiful source of water is the sea, but problems usually arise with deposition of CaC03, Mg(OH)2, and CaS04 scales. 

Chlorocyclohexene (20 g. 0.17 mol) was added to BF3 OEt2 (24 g, 0.17 mol) and HF (3.4 g, 1.7 mol) dissolved in anhyd Et20. After neutralization with i-PrNH2 in anhyd Et20 the solid formed was filtered and the solvent was evaporated under reduced pressure. Distillation then gave I -chloro-l-fluorocyclohexane (18) yield 3g (13%) bp 6(TC. 

The reaction mixture is cooled to ambient temperature, filtered through a sintered glass funnel to remove inorganic salts, and the cake is washed with toluene (75 mL). The combined filtrate and wash are washed with water (150 mL). The organic layer is separated, and placed in a 500-mL, three-necked flask equipped with a mechanical stirrer. The toluene solution is concentrated by reduced pressure distillation with mechanical stirring (45-50°C, 25-30 mm) to a volume of approximately... 

Pivalonitrile (33.2 g) and t-butyl chloride (44.4 g) were added under nitrogen over 1 h to a well-stirred suspension of sodium sand (18.4 g) in a mixture of light petroleum (80 ml), THF (20 ml) and methanol (1ml), keeping the reaction temperature between 15 and 20°C during addition. The mixture was stirred for 3h. Chlorobenzene (2 g) in THF (5 ml) was added dropwise over 10 min, and stirring continued (1 h). Methanol (20 ml) was cautiously added over 0.5 h, followed by water, until clear phases separated. The aqueous phase was extracted with ether (3 X 50 ml). The combined organic phases were dried and concentrated under reduced pressure. Distillation afforded the pure imine (63%), b.p. 62-63°C/19 torr. 

Formamide is an excellent solvent for many polar organic compounds and for a selection of inorganic salts. It is very hygroscopic and readily hydrolysed by acids or bases. The commercial product frequently contains formic acid, water and ammonium formate. Purification may be effected by passing ammonia gas into the solvent until a slight alkaline reaction is obtained addition of dry acetone then precipitates the ammonium formate. The filtered solution is dried over magnesium sulphate and fractionally distilled under reduced pressure distillation at atmospheric pressure causes decomposition. Pure formamide has b.p. 105 °C/11 mmHg. 

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