Distillation experimental procedures

The experimental procedure to be followed depends upon the products of hydrolysis. If the alcohol and aldehyde are both soluble in water, the reaction product is divided into two parts. One portion is used for the characterisation of the aldehyde by the preparation of a suitable derivative e.g., the 2 4-dinitrophenylhydrazone, semicarbazone or di-medone compound—see Sections 111,70 and 111,74). The other portion is employed for the preparation of a 3 5-dinitrobenzoate, etc. (see Section 111,27) it is advisable first to concentrate the alcohol by dis tillation or to attempt to salt out the alcohol by the addition of solid potassium carbonate. If one of the hydrolysis products is insoluble in the reaction mixture, it is separated and characterised. If both the aldehyde and the alcohol are insoluble, they are removed from the aqueous layer separation is generally most simply effected with sodium bisulphite solution (compare Section Ill,74),but fractional distillation may sometimes be employed. 

The most common direct methods are the oven, the distillation, and the Fischer methods. They can be made precise by careful standardization of the experimental procedures their accuracy can be assured only by calibration against some accurate reference method. 

Pure di-2-propenylzinc2,8,9 10, bis(2-methyl-2-propenyl)zinc11 or di-2-butenylzinc11 are best prepared by the metal exchange between dimethylzinc and the appropriate triallylborane, which is produced in situ from the Grignard reagent and boron trifluoride-diethyl ether complex. The purification is accomplished by distillation, for experimental procedure, see ref 2, p619. 

The experimental procedures were essentially the same as reported (Figure 1, (16, 17)). Reagents other than those described in (16. 17) were as follows. Acrylic acid(Wako Pure Chemicals) was distilled once under reduced pressure under a nitrogen stream. Solvents(acetonitrile, n-hexane, and benzene) were purified by accepted procedures. 

A 30-mL ethanolic solution of K[FeH(CO)4] (11 mmol) is prepared in a 100-mL Schlenk flask under argon as described in Section 30.A. The equipment and the experimental procedure are the same as those described in Section 30.D, using triethyl phosphite (Fluka > 97%, distilled under argon and stored under argon) (5.48 g, 33 mmol). The reflux time is 8 h. The isolated Fe(CO)2[P(OC2H5)3]3 is an off-white solid which melts at 51-52°C. Yield 6.5 g, 96% (Note 4). 

Acetophenone (99 %) and cyclohexane (HPLC grade) were distilled before use. In addition Raney nickel was soaked in the cyclohexane used as a solvent in order to remove any sulfur compounds. HPLC grade alcohols were used. Experimental procedures... 

Pyruvic acid may be obtained by the distillation of tartaric acid or glyceric acid.7 Better results are obtained, however, by the distillation of tartaric acid in the presence of a dehydrating agent such as potassium bisulfate.8 This method has been adopted after a study of a variety of dehydrating agents and various experimental procedures. 

In the vast majority of cases, the equilibrium in Oppenauer oxidations is shifted to the right by employing an excess of oxidant. When aldehydes or ketones with a certain volatility are formed during Oppenauer oxidations, it is possible to shift the equilibrium by removing the product by distillation under reduced pressure, while oxidants with a low volatility, such as benzaldehyde, cinnamaldehyde or piperonal, are used.5 This experimental procedure, although very suitable for multigram scale reactions, is seldom employed because of the inconvenience of running a reaction while a distillation under vacuum is performed. 

When reasonable amounts of liquid components are available (> 5 ml) the boiling point is readily determined by slowly distilling the material from a pear-shaped flask in an apparatus assembly shown in Fig. 2.98, and recording the temperature at which the bulk of the compound distils. Due attention should be paid to the experimental procedure which was discussed in detail in Section 2.24. 

Experimental procedures are given in Expt 6.107 for o- and p-hydroxy-propiophenones (R = Et). The ortho-para ratio in the product is influenced by the nature of the alkyl residue, the temperature, the solvent and the amount of aluminium chloride used generally low temperatures favour the formation of p-hydroxyketones. It is usually possible to separate the two hydroxyketones by fractional distillation under reduced pressure through an efficient fractionating column or by steam distillation the ortho isomers, being chelated, are more steam volatile. It may be mentioned that Clemmensen reduction (cf. Sections 5.1.3, p. 476 and 6.1.1, p. 826) of the hydroxyketones affords an excellent route to alkyl phenols. 

General Experimental Procedure. A mixture of the amine, 0.1 mole in 250 cc. of absolute alcohol, with 10 g. of sulfuric acid and 28 g. of arseni-ous chloride, cooled to 0°, is diazotized with a saturated aqueous solution of the calculated amount of sodium nitrite (starch-iodide end point). Then, and not before, 1 g. of cuprous bromide is added the mixture is thoroughly stirred, warmed to 60° until no more nitrogen is evolved, and then distilled with steam. The separated arsonic add is recrystallized. 

Exploratory experiments could test hypotheses, see whether popular beliefs were well founded, or involve the invention of instruments, which could produce new phenomena by reducing nature to alter her course. The same experimental procedures in different contexts could be either exploratory or probatory distillation, for example, could determine whether a drug was pure or could be used to discover the drug s chemical constituents. 

Experimental Procedure. The coal and solvent were mixed together and the moisture content of the coal was removed by distillation in glassware at atmospheric pressure. The water-free slurry was then added to AC1 with the stirrer on by applying a vacuum to the system through the vent lines. This insured that the coal did not settle out. The preheater temperature was 200 °C. 

The enthalpies of solution were measured with a LKB 8700-1 precision calorimetry system. The experimental procedure and test of the instrument have been given before (6,7). EC (Fluka, purissimum) was distilled under reduced pressure and the middle fraction was stored over molecular sieves (4 A) for at least 48 hr. ACN (Merck, pro analysis) was dried over molecular sieves and used without further purification. The purity of both solvents (determined shortly before use), as deduced from GLC, was always better than 99.8%. The volume fraction of water, determined by K. Fischer titration (8) was always less than 3.10-4. The mixed solvents were prepared by weight as shortly as possible before the measurements. AH° of Bu4NBr in W-ACN mixtures have been measured at 25°C while those in W-EC are at 45°C, which is above the melting point of pure EC. 

The apparatus and experimental procedures are similar to those used for the tetrafluoride (synthesis 66), except for the use of the heavier-walled vessel H instead of the vessel F. In order to add the required amount of fluorine, it will be necessary either to use a larger vessel G or to repeat the measuring and condensing procedures. The xenon-to-fluorine mol ratios used are about 1 20 [0.689 g. (0.00525 mol) of xenon and 4.18 g. (0.110 mol) of fluorine]. The gas mixture is heated to 300° for 16 hours. The hexafluoride is purified by distillation, the less volatile fraction of lower fluorides being discarded. The purity may be checked by examination of the infrared spectrum, noting the presence of bands at 520 and 612 cm. and the absence of peaks for the difluoride and the tetrafluoride. The spectrum should also be studied in the 900- to 1000-cm. region, where oxyfluorides have fundamentals, for e.xample, XeOF4 at 928 cm. h... 

Schematic experimental procedure is shown in Figure 1. All the chemicals used were of analytical grade, and ion-exchanged distilled water was used for aU the procedure. Amberhte IRC-76 (Organo K.K.) was used for cation exchange reactions. Its cation exchange capacity for 1 dm of wet resin is 200 g of CaCOs. The resin was treated in the diluted HCl solution to displace Na by H , and then treated in saturated CaCOs solution to displace H+ by Ca . After washing with the distilled water, 1 cm of wet Ca +-resin was dispersed in the 300 cm of the distilled water. Pure CO2 gas was introduced into the resin-dispersed solution at the constant flow rate (10 cm min i). Time variation of the pH value and Cs concentration of the resin-dispersed solution was analyzed by using pH / ion meter (Horiba K.K. model F-23 with pH and calcium ion electrodes).

Gum arable, CoCb 6 H2O, cooking salt, water-insoluble dyes, distilled water. Experimental Procedure... 

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