Williamson -, modified

Table 7.3. Shock-modified powders Crystallite size, strain, and static magnetization data on hematite (after Williamson et al. [86W03]).

The modified Williamson synthesis with NaOH and chloroacetic acid or monochlorosodium acetate for the preparation of ether carboxylates is very old [3-8] and is suitable for batch production of different types of ethercarboxylates. 

With the modified Williamson reaction the molecule grows longer, but by the oxidation reaction just the molecule becomes shorter. The advantage of the oxidation reaction is that generally conversion to the ether carboxylate is almost 100%. However, the oxidation reaction for the production of ether carboxylates is economically possible only if high amounts of the same type of ether carboxylate are produced. 

Figure 7.1. Site map. Snake Hill. The well-preserved specimen. Burial 8, is to the left of the septic pipe. Other burials sampled in this study are marked with circles. The Lake Erie shore line is to the right, ca. 25 m. (Modified from Pfeiffer and Williamson 1991).

C. D. Williamson. Chemically modified lignin materials and their use in controlling fluid loss. Patent GB 2210888, 1989. 

Tphe original objectives of this work were to determine how much the relative reactivity of two hydrocarbons toward alkylperoxy radicals, R02, depends on the substituent R—, and whether there are any important abnormalities in co-oxidations of hydrocarbons other than the retardation effect first described by Russell (30). Two papers by Russell and Williamson (31, 32) have since answered the first objective qualitatively, but their work is unsatisfactory quantitatively. The several papers by Howard, Ingold, and co-workers (20, 21, 23, 24, 29) which appeared since this manuscript was first prepared have culminated (24) in a new and excellent method for a quantitative treatment of the first objective. The present paper has therefore been modified to compare, experimentally and theoretically, the different methods of measuring relative reactivities of hydrocarbons in autoxidations. It shows that large deviations from linear rate relations are unusual in oxidations of mixtures of hydrocarbons. 

Phenols do not undergo intermolecular dehydration. Although aryl halides cannot be used as substrates in typical Williamson syntheses, they do undergo a modified Williamson-type synthesis at higher temperature in the presence of Cu. 

The second method involves substitution reactions on a preformed polymer with a stiff backbone. The advantage of this method is that it provides better control over the MW of the starting polymer. However, the substitution may not be 100%. The first example involved the substitution on a poly( 1,1,1-propellane) copolymer [116]. A copolymer with 80% functionalizable units has been successfully modified with a [G-1]-Br poly(benzyl ether) dendron (see Scheme 13a). Further studies exploring the feasibility and steric limitations of the substitution route have been performed on poly(p-phenylene) [113, 116]. The Williamson substitution reaction on... 

Materials.—Xenon diffuorlde was obtained by the method of Streng and Streng and Holloway as modified by Williamson.u... 

Methyl cellulose and hydroxyalky methyl cellulose manufacture involves in part Williamson synthesis with methyl chloride and alkoxylation. The various ethers are used primarily in building materials and in industrial applications (O Table 13). Higher grades with greater purities consist of modified vegetable gums, and they find uses in controlled release applications in pharmaceuticals, and in food products and cosmetics where they serve as emulsifiers and texture agents. 

T. H. McWaid and E. Marschall, Applications of the Modified Greenwood and Williamson Contact Model for Prediction of Thermal Contact Resistance, Wear, Vol. 152, pp. 263-277,1992. 

Crown-4 (I) and 15-crown-5 (2). Liotta et al have published preparations of these crown ethers by modified Williamson syntheses from readily available starting materials. 12-Crown-4 is useful for complexing lithium ions 15-crown-5 resembles 18-crown-6 in ability to complex potassium and sodium... 

A. Jaleel, P. Halvatsiotis, B. Williamson, P. Juhasz, S. Martin, and K. S. Nair, Identification of Amadori-modified plasma proteins in type 2 diabetes and the effect of short-term intensive insulin treatment, Diabetes Care, 28 (2005) 645-652. 

The Graham-Liebig work on polybasic acids added a fifth strand to the four interconnected developments discussed in the last section—chlorine substitution, type theory, a modified radical theory, and the hydrogen theory of acidity—all of which worked against electrochemical-dualist theory. A molecule of a polybasic acid, in Liebig s hands, was depicted as a molecular entity that could hold together additional molecular components it formed the hub, as it were, of a more complex molecule. It appears that Williamson likewise saw Graham s work on phosphoric acids in this way, for in an obituary of... 

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