Evaporation rate aqueous mixtures

Assuming that the evaporation rate coefficient, is constant over the entire length of the slick, a streamwise variation in the concentrations of compounds within the slick can be caused in only two ways. First, a variation in slick composition could be caused by spilling a mixture of compounds into one end of a slick while compounds rapidly and selectively evaporate and dissolve from the slick. In such a case, the composition of Ae slick near the spilling point would resemble the composition of the spilled product, while the portions of the slick farther downstream from the spilling point could contain less of the more volatile compounds. Second, a variation in slick composition may be caused by variations in the aqueous concentration of a compound beneath the slick. If toe aqueous concentration beneath the slick varies significantly from one end of the slick to the other, the dissolution rate, which is driven by the difference between the actual water concentration and the equilibrium concentration in the water, would also vary from one end of the slick to the other. Over time, the variation in dissolution rate could create a variation in slick composition. 

The reaction was carried out in a 22 L reactor with EDTA (3.35 g), mercaptoethanol (1.41g), ammonium formate (908 g), and sterile water (18.0 L), which was degassed prior to addition of keto acid sait 58 (800 g). The solution was filtered through a 0.2 p,m filter and transferred to a clean 22-L reactor. NAD+ (23.88 g) was added and the pH adjusted to 6.3 by adding 1 N HCI. This substrate solution was then fed into a membrane reactor with ultrafiltration membrane for enzymatic reduction. The reactor was previously filled with an aqueous mixture of enzymes (d-LDH, 400 units mL-1 with activity 20 units mg-1 and FDH, 20 units mL-1 with activity 76 units mL-1). An appropriate feed rate was used to maintain a conversion of > 90%. The circulation rate was kept between 15 and 30 times that of the feed rate. The aqueous effluent solution thus obtained was adjusted to pH 3.0 with 2 N HCI and extracted with MTBE (5 L). The organic layer was evaporated to obtain 972 g of acid 56 as an off-white solid in a yield of 88%, >90% purity and >99.9% ee. In this process a total of 14.5 kg of 56 was prepared with a productivity of approximately 560 gram per liter per day with good overall 72% yields [113]. To evaluate the optical purity, 56 was converted to methylester by esterification and the ee of methylester was found to be >99.9%. 

Purification of C q from a C(,q/C-,q mixture was achieved by dissolving in an aqueous soln of y (but not p) cyclodextrin (0.02M) upon refluxing. The rate of dissolution (as can be followed by UV spectra) is quite slow and constant up to lO M of C o- The highest concn of C o in H2O obtained was 8 x 10 M and a 2 y-cyclodextrin C q clathrate is obtained. C ) is extracted from this aqueous soln by toluene and C oof >99 purity is obtained by evaporation. With excess of y-cyclodextrin more C g dissolves and the complex precipitates. The ppte is insol in cold H2O but sol in boiling H2O to give a yellow soln. [J Chem Soc, Chem Commun 604 7922.]... 

Preparation of l9-Norandrost-A-ene-3, l-dionef A solution of 1.1 g of 10y5-cyano-19-norandrost-5-ene-3,17-dione bis-ethylene ketal in a mixture of 15 ml of ethanol and 15 ml of toluene is carefully added to a vigorously stirred suspension of 10 g of sodium in 150 ml of boiling toluene. The addition is regulated to maintain the reaction mixture at the boiling point of the solvent. Another 40 ml of anhydrous ethanol is then added at the same rate. The solution is cooled and the excess of sodium is decomposed by addition of 95% ethanol. The reaction mixture is then diluted with water, the toluene layer separated and the aqueous phase extracted twice with ether. The organic solution is washed with water, dried and evaporated to yield 1 g of an amorphous mixture of the bis-ethylene ketals of 19- norahd-rost-5- and -5(10)-ene-3,17-dione (Note 1). 

The dropping funnel is charged with a solution of 7.7 g (0.05 mole) of 4-/-butylcyclo-hexanone (Chapter 1, Section 1) in 50 ml of dry ether. The solution is slowly added to the mixed hydride solution at a rate so as to maintain a gentle reflux. The reaction mixture is then refluxed for an additional 2 hours. Excess hydride is consumed by the addition of 1 ml of dry t-butyl alcohol, and the mixture is refluxed for 30 minutes more. 4-/-Butylcyclohexanone (0.3 g) in 5 ml of dry ether is added to the reaction mixture, and refluxing is continued for 4 hours. The cooled (ice bath) reaction mixture is decomposed by the addition of 10 ml of water followed by 25 ml of 10% aqueous sulfuric acid. The ether layer is separated, and the aqueous layer is extracted with 20 ml of ether. The combined ether extracts are washed with water and dried over anhydrous magnesium sulfate. After filtration, the ether is removed (rotary evaporator), and the residue... 

Cyclooctane Sulfide To 12.5 g (0.06 mole) of the dichlorosulfide in 150 ml of ether is added 1.2 g (0.03 mole) of lithium aluminum hydride in 60 ml of ether at a rate so as to maintain a gentle reflux (about 20 minutes). The mixture is allowed to stand overnight and is then cautiously treated with water to decompose the excess hydride. The mixture is mixed with fuller s earth (Floridin) and is filtered, and the filtrate is dried over anhydrous magnesium sulfate. Filtration of the solution and evaporation of the solvent (rotary evaporator) gives about 7 g of the colorless crystalline solid, mp 170-171°. It may be recrystallized from aqueous methanol, mp 172-173°. 

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