Distillation procedure

By far the best method I have tried to produce benzodioxole in terms of yields and simplicity. In comparison to other processes, this is in fact quite fun and I ll explain It in a fashion that can be followed by a complete novice, like I was when I started a while ago. What we do is react and reflux the ingredients first, then use a simple distillation procedure to extract the product with water as an azeotrope. Once extracted we wash until the product is clear, and then separate. From start to finish it will take about six hours. 

Heating mantles are particularly designed for the heating of flasks and find wide application in distillation operations. For details of the distillation procedure and description of the apparatus employed a textbook of practical organic chemistry should be consulted.9... 

Careless Workmanship. One laboratory operator combined a variety of equipment for a distillation procedure and finally came up with something that met his needs. In other words, it worked —but he had a tangle of wires, water hoses, and blocks of scrap wood for support. With less than one day s additional work, he could have improved both performance and safety features. 

Beer Samples. The beer samples were examined as part of the American Society of Brewing Chemists (ASBC) and Association of Official Analytical Chemists (AOAC) collaborative studies of NDMA in beer. Duplicate samples were analyzed by the column extraction procedure and the ASBC distillation procedure (35). The AOAC procedure (36) was similar, except that a larger sample (50 vs. 25 g) was examined and sulfamic acid was added to minimize artifactual formation of nitrosamines. Both methods utilize N-nitrosodipropylamine (NDPA) as an internal standard. 

Column Extraction. Results obtained by the standard ASBC distillation procedure and by Celite column extraction are compared in Table III. The ASBC method included... 

EMA is volatile. During the hydrolysis/distillation procedure, the delivery tip of the hydrolysis unit must remain below the surface of the liquid in the receiving funnel at all times. Procedures that involve generation of heat must be performed carefully to minimize losses. 

The actual isolation of zinc metal on an appreciable scale seems to have occurred first in China in the 10th Century AD (Xu, 1990), using an upwards distillation procedure from secondary (oxidized) zinc minerals. Earlier finds of metallic zinc (such as that at the Agora, noted above) are possibly explained by the chance condensation of small quantities of zinc in the furnace during the production of lead and silver from mixed ores. Much attention has been focused in recent years on northern India, particularly the Zawar region,... 

Wagner et al. used the reaction procedure shown in Fig. 4.2.5, and variations thereof, to yield the monodisperse oligoethoxylate monomethyl ether oligomers (n = 3-9). The trisiloxanes were then produced by hydrosilylation as in step b of Fig. 4.2.4 [72]. Distillation procedures were used to purify the intermediates and resulting trisiloxane alkylethoxylate products, and structural characterisation was performed by GC-MS and NMR. Purities for the n = 3-9 oligomers of 99, > 99, 99, 97.5, 96, 95 and 90%, respectively, as determined by GC-MS, were reported. 

PODanalysis analychem A precision laboratory distillation procedure used to separate low-boiling hydrocarbon fractions quantitatively for analytical purposes. Also known as Podblelnlak analysis. pe o de 3,nal 3 S3s )... 

Nitrogen, Ammonia (Colorimetric Titrimetric Potentiometric - Distillation Procedure)... 

Diazinon begins to decompose at a temperature of 100 °C. During distillation procedures at this temperature, <0.5% is decomposed to 2-isopropyl-4-methyl-6-hydroxypyrimidine. When technical diazinon is dissolved in 20% hydrochloric acid, 0,0,0-triethyl thiophosphate is formed (Gysin and Margot, 1958). Above 120 °C, diazinon decomposes and emits toxic fumes of phosphorus, nitrogen, and sulfur oxides (Sax and Lewis, 1987 Lewis, 1990 Wlndholz et al, 1983). 

The submitters had originally distilled the volatile products from this mixture, containing mainly polymeric material, by a more conventional procedure. However, the checkers found the problems from foaming during the distillation so severe that the alternative low-temperature distillation procedure was adopted. 

In the classical Willard-Winter [167] distillation procedure introduced in 1933, decomposition of compounds and separation of resulting fluoride from interfering substances take place concurrently. This technique and its modifications [168-170] have provided a wealth of information through the middle decades of the 20th century but, mostly because of its cumbersome procedure, have been replaced by simpler methods. 

M.A. Wade, S.S. Yamamura, Microdetermination of fluoride using an improved distillation procedure. Anal. Chem. 37 (1965) 1276-1287. 

After the amalgam is cooled, 400 mL of tetrahydrofuran (THF) distilled from lithium tetrahydridoaluminate is added to the flask, followed by 50.0 g (142 mmole) of W(CO)6. "Caution. The THF should be checked for peroxide and high water content before LiAlH4 is added. The distillation procedure is given in Reference 6. 

CH3CSCCH2SH, njj(20") 1.5104, is obtained by a similar work-up and flash distillation procedure (raising the bath temperature to above 100 C). The compound is obtained in a good (-80%) yield. 

Heat of Explosion Determination (1286—88) Hygroscopicity of Propellants (1288—89) Moisture by the Carbon Tetrachloride Distillation Procedure (1289—90)... 

The procedure is as follows. After application of high vacuum (approximately 5 mPa) to the apparatus, the distillation procedure is started by dropping aliquots of the sample into distillation flask no. 4 (Fig. 16.1). The volatiles, includ-... 

For total sulfur dioxide determination, distillation procedures are preferred (3, 4, 6, 22). Careful attention to details is necessary since the methods are empirical (16, 36, 37). Automated analysis (38) also can be used (up to 20 samples per hr). For a summary of investigations on sulfur dioxide determination see Wucherpfennig (39). 

The precipitation as barium sulfate requires boiling in the absence of air to remove sulfur dioxide. (The residue from the distillation procedure for sulfur dioxide may be used.) Some skill in handling the precipitate is required for accurate results. Complexometric titration after precipitation as lead sulfate (4) is possible. By using three solutions containing different amounts of barium chloride, it is possible to rapidly determine from the clouding whether a wine contains more or less than 0.7, 1.0, or 2.0 grams/liter of potassium sulfate. 

Design. When the vapor-liquid equilibria are known, in the form of UNIQUAC parameters for instance, the calculation of azeotropic distillation may be accomplished with any of the standard multicomponent distillation procedures. The Naphthali-... 

Described a new extraction methodfor determining TBA values for meat during storage. Unlike the classical distillation procedure, this method involves an aqueous extraction of the sample with trichloroacetic acid prior to reaction with TBA. It also described a similar way of calculating the K value so that absorbance readings could be expressed as TBA values. This technique is faster and easier to perform than the distillation method and the authors recommended its employment for rapid analyses of large numbers of samples. 

To assess the level of sulphur dioxide in a fruit juice, or a soft drink containing juice, a steam distillation procedure is generally used. Here sulphur dioxide is driven out of acidified solution by heating. Acidification displaces any sulphur dioxide that was bound to other food materials. As sulphur dioxide is carried over by the steam it passes through a trap containing a hydrogen peroxide solution, where it is oxidised to sulphuric acid. The acidity contained in the trap is then measured by titration against sodium hydroxide. 

A 750-ml. portion of this suspension of crude adamantanone is transferred to a 2-1. round-bottomed flask, equipped for steam distillation (Notes 7 and 8), which is placed in a heating mantle. The contents of the distillation flask are heated to 70° then the external heating is turned off (Note 9) and steam is introduced carefully through both inlet tubes (Note 10). The two layers of distillate are separated, and the aqueous layer is extracted with two 75-ml. portions of methylene chloride. This steam distillation procedure is then repeated with the second half of the suspension of crude adamantanone. The organic extracts are combined, washed with 100 ml. of aqueous, saturated sodium chloride, and dried over anhydrous sodium sulfate, and the solvent is evaporated under reduced pressure. The yield of adamantanone is 52-53 g. (47-48%) (Notes 11, 12, and 13). 

Should the temperature rise steadily, instead of remaining virtually constant, it is then clear that this simple distillation procedure is unsuitable for the purification of the sample and some form of fractional distillation (Section 2.26) will have to be used. 

Wade, M. A., and S. S. Yamamura Microdetermination of Fluoride Using an Improved Distillation Procedure. Anal. Chem. 37, 1276 (1965). 

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