C-Metalation

Benzothiazoles undergo reactions similarly at the 2-position through deprotonation in the presence of a base such as w-butyl lithium.  

Florio et al. have found that 2-lithio-4-methylthiazole can be conveniently generated almost quantitatively by the deprotonation of 4-methyl-thiazole with lithium diisopropylamide (LDA) in THF at -78 °C. Addition of a-chloroacetone to the solution yields the corresponding chlorohydrins.  

Similarly, MyllymSki et al. have employed this concept in the synthesis of aryl ketones via the reaction of the lithio benzothiazole with an aryl acid chloride to produce the desired ketone. A series of such carbonyl compounds was synthesized and evaluated as potential fatty acid amide hydrolase (FAAH) inhibitors. 

Other metalated compounds such as silanes and stannanes can be derivatized likewise. For example, the corresponding stannanes of lithio benzothiazole can also be synthesized with relative ease by treating the lithiated species with organotin chlorides. 

Taunton and co-workers have reported a one-step racemization free organolithium-mediated diversification of peptide thiazoles. A mild procedure for the C5 lithiation of 2,4-disubstituted thiazoles has been described in this report, and an example is shown below. The method is compatible with A-Boc, A-trityl, carboxylic ester, and carboxamide protecting groups and has been used to functionalize directly the thiazole ring of cyclopeptide natural products. 

---

Nelson et al. [34] determined from void shapes that the ratio 7100/7110 was 1.2, 0.98 and 1.14 for copper at 600°C, aluminum at 550°C, and molybdenum at 2000°C, respectively, and 1.03 for 7100/7111 for aluminum at 450°C. Metal tips in field emission studies (see Section VIII-2C) tend to take on an equilibrium faceting into shapes agreeing fairly well with calculations [133]. 

Four possible mechanisms for solid-state extraction (a) adsorption onto a solid substrate (b) absorption into a thin polymer or chemical film coated on a solid substrate (c) metal-ligand complexation in which the ligand is covalently bound to the solid substrate and (d) antibody-antigen binding in which the receptor is covalently bound to the solid substrate. 

Coordination Compounds. A large number of indium complexes with nitrogen ligands have been isolated, particularly where Ir is in the +3 oxidation state. Examples of ammine complexes include pr(NH3)3] " [24669-15-6], prCl(NH3)] " [29589-09-1], and / j -pr(03SCF3)2(en)2]" [90065-94-4], Compounds of A/-heterocychc ligands include trans- [xCX py)][ [24952-67-8], Pr(bipy)3] " [16788-86-6], and an unusual C-metalated bipyridine complex, Pr(bipy)2(C, N-bipy)] [87137-18-6]. Isolation of this latter complex produced some confusion regarding the chemical and physical properties of Pr(bipy)3]3+ (167). 

An electrolytic process for purifying cmde vanadium has been developed at the U.S. Bureau of Mines (16). It involves the cathodic deposition of vanadium from an electrolyte consisting of a solution of VCI2 in a fused KCl—LiCl eutectic. The vanadium content of the mixture is 2—5 wt % and the operating temperature of the cell is 650—675°C. Metal crystals or flakes of up to 99.995% purity have been obtained by this method. 

For ring-opening reactions of C-metallated azoles, see Section 4.02.3.8. 

Stainless steel is susceptible to sensitization when it is heated to the range of 900 to 1550°F (480 to 850°C). Since any welding operation involving stainless steel will produce such temperatures in the metals being joined, it would appear that all welded stainless steel would sensitize. However, sensitization is a function of both time and temperature, occurring most rapidly at temperatures near 1250°F (675°C). Metals that cool rapidly through this temperature range will not sensitize. Consequently, thin metal sections, which cool rapidly, are less susceptible to sensitization than thick sections. 

A.C. metal enclosed switchgear and controlgear for rated voltages above IkV and up to and including 52kV 3427/1991 BSEN 60298/1996... 

Figure 1. A, Dewar flask B, sintered glass filter C, metal cooling coil D, water inlet E, water outlet F, reaction vessel < , quartz immersion well /f, pyrex filter /, lamp ...

BRADLEY, D. c., Metal-Orgonic Compounds, Advances in Chemistry Series Vol. 23, p. 10, American Chemical Society, Washington (1959)... 

Y. Shimomura. Point defects and their clusters in f.c.c. metals studied by computer simulations. Mater Chem Phys 50 139, 1997. 

The white cesium fluoroxy sulfate precipitates from the reaction medium and may be kept for several months in the cold (0 to -15 °C) Metal surfaces can cause detonation of the reagent. The reaction scope of cesium fluoroxysulfate seems narrower than that of acetyl hypofluorite because of its limited solubility in organic solvents Cesium fluoroxysulfate has not been prepared with a fluorine-18 label. 

The reaetion between Ha and the gently heated (300-350°C) metals produees blaek, reaetive and highly eondueting solids, LnHa. These hydrides have the fee fluorite strueture (p. 118) and are evidently eomposed of Ln , 2H , e , the eleetron being deloealized in a metallie eonduetion band. Further hydrogen ean be aeeommodated in the interstiees of the lattiee and, with the exeep-tions of Eu and Yb, whieh are the two lanthanides... 

A.C. metal enclosed switch gear and control gear between the voltages of 1 and 72.5 kV can be manufactured to three basic designs metal enclosed, metal clad and cubicle. 

The e.m.f. of a thermogalvanic cell is the result of four main effects (a) electrode temperature, (b) thermal liquid junction potential, (c) metallic thermocouple and (d) thermal diffusion gradient or Soret. 

Laidlaw, R. A. and Pinion, L. C., Metal Plate Fasteners in Trussed Rafters Treated with Preservatives of Flame Retardants-Corrosion Risks, IS 11/77, Building Research Establishment (1977)... 

M—C metal bonded with carbon in some organometallic compds... 

FIGURE 14.35 Carbon monoxide can bind to a c/-metal atom in two ways ... 

Lead azide, Pb(N,)2, is used as a detonator, i i) What volume of nitrogen at STP (1 atm, 0°Ci does 1.5, of It id azide produce when it decomposes into lead metal and nitrogen gas (b) Would 1.5 g of mercury(ll) azide, Hg(N which is also used as a detonator, produce a larger or smallei volume, given that its decomposition products i c elemental mercury and nitrogen gas (c) Metal azides in general are potent explosives. Why ... 

Wahrend die C—Al-Bindungen leicht hydrolysieren, sind die anderen C-Metall-Bin-dungen meist hydrolysebestandig und werden am einfachsten in gegebenem Falle durch Protonolyse mit niederen Fettsauren gespalten. 

Organo-silane werden durch Elektrolyse an der C-Metall-Bindung gespalten. So erhalt man z. B. aus Trimethyl-phenylathinyl-silan in Methylamin/Lithiumchlorid (s. a. S. 577) an Platin-Elektroden Phenyl-acetylen (38% d.Th.). Als Nebenprodukte fallen infolge Hydrierung Trimethyl-(2-phenyl-athyl)-silan (10% d.Th.) und A thy T benzol (30% d.Th.)... 

---