Historical method

Urea (the diamide of carbonic acid) can be prepared by the historic method of Wohler. When an aqueous solution of ammonium cyanate is allowed to stand, the cyanate undergoes molecular rearrangement to urea, and an equilibrium mixture containing about 93% of urea is thus formed. Urea is... 

By far the most commonly used oxidation method is the corrected permanganate number test (26) in which the number of mL of 0.1 KMnO consumed by 1 g of oven-dried pulp under specified conditions (kappa number) is deterrnined (TAPPl Historical Method T236 hm-85). Typical kappa numbers for representative pulps are shown in Table 3. 

This chapter on analysis of methylxanthines is divided into three sections historical methods, current analytical methods for foods, and current methods for biological samples which can include plasma, blood, urine, cell extracts, and other potential samples of biological significance. 

The risk probability is assessed based on input from analysts at transferring site, experience of receiving site with methods and products, historical method performance, e.g. method/product process capability data, stability trends, OOS history, etc. (Raska et al., 2010). 

Irrational Approach This approach is the historical method of discovering and developing drugs. It involves empirical observations of the pharmacological effects from the screening of many chemical compounds, mainly those from natural products. The active component that gives rise to the observed effects is isolated. The chemical formula is determined, and modifications are made to improve its properties. This approach has yielded many drugs available today. 

Ginzburg, C. Clues, Myths, and the Historical Method. Baltimore Johns Hopkins, 1992. 

In Figure 15.1, some examples of different disciplines and methods relevant to organic research are placed in relation to two methodological dimensions. One is the complexity of the research world described above. The other is the degree of involvement of the researcher or the research unit in its research world. The triangular form illustrates that in simple and well-controlled research worlds, the detached and involved phases of research can be employed in close cooperation, whereas detached, descriptive, historical methods are widely different from involved, interactive, developmental action research methods though they both work with complex research worlds. 

Section 4.2 deals with the most useful hydrate equilibria—calculations of temperatures and pressures at which hydrates form from gas and free water. In this section, two historical methods, namely, the gas gravity method (Section 4.2.1) and the Kvs, value method (Section 4.2.2), for calculating the pressure-temperature equilibrium of three phases (liquid water-hydrate-vapor, Lw-H-V)1 are discussed. With the gas gravity method in Section 4.2.1.1, a method is given for limits to expansion, as for flow through a valve. In Section 4.2.2 a distribution coefficient (KVSi) method is provided to determine whether a component prefers residing in the hydrate or the vapor phase. These methods provide initial estimates for the calculation and provide a qualitative understanding of the equilibria. A statistical... 

The object of Chapter 4 was to provide an overview of phase equilibria concepts, which are more easily obtained through phase diagrams and the approximate, historical methods. With Chapter 4 as background, the subject of the present chapter is the phase equilibrium calculation method that is both most accurate and most comprehensive. 

Distillation is an important historical method for the separation of liquids. A mixture or solution of two liquids is heated until the vapor pressure of the lower boiling compound reaches the pressure of the surroundings. This may be ambient pressure or a lowered pressure caused by application of a vacuum. In either event, vaporization occurs, the vapors are condensed on a cold surface, and the condensed liquid is collected. If the boihng points of the two liquids are sufficiently different given the pressure and efficiency of the apparatus, separation may be achieved. A zeotrope is a mixture that can be separated by distillation. 

A historic method for 1,2,4-oxathiazolidine synthesis is based on 1,3-cycloaddition reactions, for example, addition of carbonyl compounds across the S-C=N groups of 5-imino-l,2,3,4-thiatriazolines <1996CHEC-II(4)453>. The thermally induced conversion of 677-1,3,5-oxathiazine A-oxides 119 in refluxing benzene results in 1,2,4-oxathiazo-lines 20 in high yields by intramolecular cyclization with extrusion of carboxaldehydes (see Section 6.03.8.2). Oxidative cyclization of A-acylthioureas 114 and iV-acylthiocarbamates 115 by Br2 gives 1,2,4-oxathiazolium hydrobromides 43 and 38, respectively (see Section 6.03.8.1). 

The remainder of this review is outlined as follows. The historical method development of EA use for global cluster geometry optimization is briefly recalled in Sect. 2. An overview of typical application work in recent years is provided in Sect. 3. In Sect. 4, we take a side glance at other methods to tackle the same and related problems, and briefly discuss advantages and disadvantages of some the prominent alternatives to EAs. Finally, in Sect. 5 recent method development work is summarized, and we try to give some (personal, biased) opinions on which open questions such developments should address in the future. 

Sheldon-Barnes s Studies in Historical Method. Suggestive studies for teachers and students. Cloth. 160 pages. 90 cents. 

Peter Griess, 1858.—Diazo compounds were discovered and first prepared by Peter Griess in 1858. The historical method used by him is the same in general as is now used widely in dyestuff manufacture. It has already been described and consists in the action of nitrous acid on an aromatic primary amine, e.g., aniline. When this reaction takes place, at ordinary or slightly raised temperatures, the same products are obtained as with aliphatic primary amines, viz., the hydroxyl compound of the hydrocarbon radical, free nitrogen and water. 

The Ziegler direct process technology far surpassed historical methods for synthesis of trialkylaluminum compounds. Excellent conversions and yields are obtained with relatively little waste, since all raw materials are incorporated into the product (3). Texas Alkyls was acquired by Akzo Chemicals (now Akzo Nobel) in 1992. 

Derivation From adrenal gland extract (usually from cattle) (historical method), syntheticahy from bile acids, from other steroids or sapogenins. 

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