Synthesis from Melts

The Bridgman-Stockbarge melt growth technique. This method is named after P.W. Bridgman (United States) and D.C. Stockbarge (Germany) with the collaboration of three 

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Nylon-6 [25038-54-4] was first made in 1899 by heating 6-aminohexanoic acid (143), but its commercially feasible synthesis from caprolactam was discovered by Paul Schlack at 1. G. Farbenindustrie in 1938. Like nylon-6,6, it is a tough, white translucent, semicrystalline sofld, but melts at a lower temperature (T = 230° C. The physical properties and primary producers of nylon-6 are Hsted in Tables 9 and 10, respectively. 

PA-6,10 is synthesized from 1,6-hexamethylenediamine and sebacic acid, and PA-6,12 from 1,6-hexamethylenediamine and dodecanedioic acid. The melt synthesis from their salts is very similar to PA-6,6 (see Example 1). These diacids are less susceptible to thermal degradation.55 PA-6,10 can also be synthesized by interfacial methods at room temperature starting with the very reactive sebacyl dichloride.4 35 A demonstration experiment for interfacial polycondensation without stirring can be carried out on PA-6,10. In this nice classroom experiment, a polymer rope can be pulled from the polymerization interface.34... 

Figure 1. Schematic diagram of the cold metal crucible system used for synthesis, zone melting and crystal pulling crystal growth (from ref. 5).

Shell, H. R., J. E. Comoforo, and W. Eitel (1958). Synthetic Asbestos Investigations Synthesis of Fluoroamphiboles from Melts. U.S. Bureau of Mines RI No. 5417. Washington, DC. 

The UV spectrum (7max 235, 270 (sh), 279,301,312, and 378 nm) of 236 indicated a dihydropyrido[4,3-l7]carbazole framework. This assignment was supported by the IR spectrum (v ax 843, 1028, 1167, 1410, 1595, and 1615 cm ). The structure for 3,4-dihydroellipticine was confirmed by synthesis from ellipticine and comparison of the IR and UV spectra, melting points and Rf values. Additional support for this assignment derived from the transformation into derivatives of 3,4-dihydroellipticine (216). 

Kumada et al.359 prepared linear methylpolysilanes up to n = 12 by Wurtz synthesis from different chloromethyldisilanes and found by investigation of the physical constants that the melting points of the silanes up to n = 7 do not rise continuously but follow in a zigzag course since the polysilanes with an odd number of silicon atoms melt at a lower temperature, than those with an even number of silicon atoms, though this effect is less pronounced with higher n. 

By treatment of D-gulose (XVII) or D-idose (XVIII) with warm aqueous barium hydroxide solution Van Ekenstein and Blanksma were able to isolate D-sorbose (II) with a melting point of 165° and [< ]d + 42.9° in water. The aldoses were prepared from D-gulonic and D-idonic lactones obtained by the cyanohydrin synthesis from D-xylose. 

The conventional methods of mullite preparation are the following crystallization from melt, high-temperature sintering of oxides, high-temperature annealing of kaolin [32]. Mechanical activation of hydrated oxides brings to decrease of mullite synthesis temperature [32-39]. 

Sodium aluminum hydride can be synthesized by many different routes. The first preparation was performed by the reaction of NaH and AlBr3 in the presence of dimethyl ether as a solvent [92]. The direct synthesis from NaH and A1 under elevated hydrogen pressures and in various solvents is possible [59, 60]. However, sodium aluminum hydride can also be synthesized by melting the elements in the absence of any solvents (Eq. (5.22)) [93[. 

The presence of a miscibility gap at equilibrium interferes with the requirements for an absolute asymmetric synthesis from racemic (2). On the other hand, fast cooling of samples of racemate from the melt is associated with the formation of a new phase, almost isomorphous to the eutecticum, but with an internal composition of each crystallite being 50(/ ) 50(5 ) (Scheme 5, c). The existence and nature of this phase was confirmed by two independent routes by differential scanning calorimetry (Figures 2 and 4 a) and from product distribution studies. 

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