Solution distillation

Care must be taken in distilling solutions of lithium aluminum hydride. Explosions have been reported 4 toward the end of distillations of such solutions, especially if they contained carbon dioxide. It is therefore recommended that these distillations be carried out behind a shield and that not more than three-fourths of the solvent be removed. 

To explore the potential for loss of moderately volatile compounds during vacuum distillation, solutions of biphenyl (4 /zg/mL), phenanthrene (4 /zg/mL), and pyrene (0.14 /zg/mL) were freeze-dried or vacuum-distilled for varying times, and the amount of compound remaining in the flask was determined. The results (Table II) show that vacuum distillation resulted in greater losses than lyophilization and that the ease of loss varied considerably. Biphenyl was so readily lost that the mere degassing of its solution resulted in a loss of about two-thirds of the original compound (see Figure 2). 

Cautionl The following spectrophotometric analysis shovM he performed in a hood. To determine the concentration of diazomethane in the ether solution obtained in this preparation, a 5-ml. aliquot of the distilled solution is diluted to 25 ml. with ether, and a portion of this solution is placed in a cylindrical Pyrex cell with an internal diameter of 1.0 cm. The optical density of the solution is determined at 410 m/i with... 

This method is based on the titration of basic ammonia with standard sulfuric acid using methyl red-methylene blue indicator to pale lavender end point. Distill 100 mL sample into 50 mL boric acid mixed indicator solution. Titrate ammonia in this distillate solution with standard H2S04 (0.02 N) until the color turns to pale lavender. Perform a blank titration using distillate obtained from reagent grade water under similar conditions. Calculate the concentration of NH3-N in the sample as follows ... 

UVAE HERMETIS — Philosophical Water, Distillation, Solution, Sublimation, Calcination, Fixation. 

A certain amount of acid or of base becomes free, arid determined in any manner, will serve as measure of the hydrolysis. Dibbits, e. g., distilled solutions of acetates, and determined how strong a solution of acetic acid must be to give a distillate of the same character. 

Liquid scintillation counting. An 8 ml aliquot of the trap or distilled solution is mixed with 12 ml of Meridian Goldstar scintillant and counted in a Quantulus liquid scintillation counter against a reagent blank. 

Since our original publication,2 we have improved the method by conducting the cyclization at —78° in methylene chloride followed by flash distillation. Solutions of pure a-peroxylactone without decomposition products (checked by IR) can be obtained under optimized conditions.21 This method has served to prepare the dimethyl (2b) and di-terf-butyl (2c) systems. However, for relatively involatile derivatives as the adamantyl (2d) and adamantylidene (2e) derivatives, which have been prepared but not isolated,22 flash distillation is not feasible. For such cases we are developing22 polymer-supported carbodiimides24 as cyclants. 

Phenylcyclopropane 112 Freshly distilled styrene (20.8 g, 0.2 mole) is added to a distilled solution of diazomethane (about 0.3 mole) in ether (from 35 g of recrystallized methylnitroso-urea), and the mixture is kept for 2-5 days in a fume cupboard in the dark at room temperature. The solvent is then distilled off in a vacuum. At 35°/14 mm distillation of a very small... 

A distillation column with a partial reboiler and a total condenser is being used to separate a mixture of benzene, toluene, and 1,2,3-trimethylbenzene. The feed, 40 mol% benzene, 30 mol% toluene, and 30 mol% 1,2,3-trimethylbenzene, enters the column as a saturated vapor. We desire 95% recovery of the toluene in the distillate and 95% of the 1,2,3-trimethylbenzene in the bottoms. The reflux is returned as a saturated liquid, and constant molar overflow can be assumed. The column operates at a pressure of 1 atm. Find the number of equilibrium stages required at total reflux, and the recovery fraction of benzene in the distillate. Solutions of benzene, toluene, and 1,2,3-trimethylbenzene are ideal. 

The structure of minicondenser. A, inlet for water vapor B, outlet for water drop C, outlet for air D, rap E, inlet for cooling water F, outlet for cooling water G, outlet for overflow H, outlet for distillated solution. 

In the first two methods, described above, the distillate solutions were subjected to standard gas chromatography combined with mass spectrometry instrument. In the third method a quantitative mass spectrometric analysis of methylmercury was performed using the combined instrument supplied with an accelerating voltage alternator (AVA unit) >. ... 

A solution of propanol in water having 71.69% CH3CH2CH2OH by mass—an azeotrope—has a lower boiling point than any other solution of these two components. In fractional distillation, solutions having less than 71.69% of the alcohol yield the azeotrope and water as ultimate products. Solutions with more than 71.69% of the alcohol yield the azeotrope and propanol. 

Korzhev and Rossinska> a mea iired partial-pressure values for formaldehyde solutions at ordiumu temperatures by analysing the formaldehyde oouTcnt of the condensate obtained b.y distilling solutions of knovn concentrations at reduced pressures. Tlie A ahies they obtained at these temperatures are higher tlian those of Ledbury and Blair. 

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