Stannic tetrachloride

Si, and stannic tetrachloride. An effective smoke agent, whether it be mechanically dispersed from an aircraft spray tank or vaporized thermally, is a mixt of S trioxide and chlorosulfonic acid (FS smoke agent) which upon hydrolysis forms sulfuric and hydrochloric acid dispersions. Of course, all such formulations are highly corrosive, and, if not outright toxic, then conducive to pulmonary edema... 

Nitroalkenes are also reactive Michael acceptors under Lewis acid-catalyzed conditions. Titanium tetrachloride or stannic tetrachloride can induce addition of silyl enol ethers. The initial adduct is trapped in a cyclic form by trimethylsilylation.316 Hydrolysis of this intermediate regenerates the carbonyl group and also converts the ad-nitro group to a carbonyl.317... 

These early workers polymerized propenylbenzene and anethole with stannic tetrachloride and boron trifluoride catalysts in toluene diluent between 0° and —78° C. Anethole polymerized more readily than propenylbenzene. Medium molecular weight products were obtained and the physical appearance of the materials resembled polystyrene. The products were soluble in benzene and their melting or softening points increased with molecular weights. 

In laboratory experiments we opted, for convenience reasons, for the use of stannic tetrachloride, which dissolves in EDC, cyclohexane, and nitrobenzene, possesses sufficiently high activity at elevated temperatures, and at the same time initiates a rather smooth beginning of the reaction. 

Presumably the reactive abhity of methylal (dimethoxymethane) is lower than that of MCDE. This is why methylal produces in the presence of 1 mol of stannic tetrachloride hypercrosshnked networks with smaher... 

The first represents the direct interaction of polystyrene with, for example, 0.5 mol of monochlorodimethyl ether (MCDE) [230]. In this case, however, the reaction medium proves to be extremely dduted with respect to aU reacting components, including the crosslinking reagent and the catalyst (stannic tetrachloride), and completing the process requires approximately 100 h. Also, smaU traces of impurities in the large amount of the solvent can deactivate the catalyst. These factors result in poor reproducibdity of the reaction product, especiaUy at very low concentrations of about 0.05% (Table 8.1). 

This material was obtained [132] by self-condensation of p-XDC in ethylene dichloride solution in the presence of stannic tetrachloride ... 

Stannic ammonium chloride Stannic chloride, aqueous Stannic tetrachloride Stannous bromide Stannous chloride, aqueous Stannous fluoride Stannous sulfate... 

Lewis acids are defined as molecules which act as electron pair acceptors. The proton is an important special case, but many other species can play an important role in the catalysis of organic reactions. The most important in organic reactions are metal cations and covalent compounds of metals. Metal cations which play prominent roles as catalysts include the alkali metal monocations Li", Na" , K", Cs", and Rb", the divalent ions Mg, Ca, and many of the transition metal cations. The most commonly employed of the covalent compounds include boron trifluoride, aluminum trichloride, titanium tetrachloride, and stannic tetrachloride. Various other derivatives of boron, aluminum, and titanium also are employed as Lewis acid catalysts. 

The situation is somewhat different in the case of chloromethylation of the same type of low cross-linked polymer in its shrunken state (nonsolvated) in n-hexane. This solvent coats but does not solvate the polymer beads. When the reactive complex of chloromethyl methyl ether/stannic tetrachloride is added, the macromolecules on the surface zone of the polymer pellets are immediately solvated due to much higher concentration of reactants at reactive phenyl moities, in contrast to the highly diluted state of the Friedel-Crafts alkylation in the first example. On the other hand, the relatively small amount of chloro-methyl-methylether/SnCl4 added in n-hexane is only sufficient to solvate and functionalize most exposed outer parts of the macromolecular thread in the shell zone of the polymer, depending on the accidental distribution of cross-links in that area of the macromolecule. 

Nitroparaffins afford an unique reaction medium for Friedel-Crafts reactions since these solvents will dissolve Lewis acid catalysts such as anhydrous aluminum chloride (AICI3), boron trifluoride (BF3), titanium tetrachloride (TiCl4), and stannic tetrachloride (SnC ). The role of nitromethane as a metal stabilizer for various chlorinated and fluorinated solvents involves its ability to complex with metal salts like aluminum chloride from the solvent-metal reaction. 

Friedel-Crafts reaction catalysts like anhydrous aluminum chloride are readily soluble in the nitroalkanes. Solutions containing up to 50% aluminum chloride are easily prepared in nitroalkane solvents. These catalytically active complexes, AICI3-RNO2, can be isolated and used in solvents other than the nitroalkane. The reactants in the Friedel-Crafts reaction are often soluble in the nitroalkane reaction medium. Other catalysts like boron trifluoride (BF3), titanium tetrachloride (TiCl4), and stannic tetrachloride (SnCl4) are also soluble in the nitroalkane solvents. Reaction types which use nitroparaffins as solvents include alkylation of aromatics, acetylation of aromatics, halogenations, nitrations, and the reaction of olefins and hydrogen sulfide to yield mercaptans. 

Similarly, titanium tetrachloride or stannic tetrachloride induces addition of silyl enol ethers to nitroalkenes. The initial product is a complex of the aci tautomer of the nitro group. Hydrolysis of this complex generates the new carbonyl group. ... 

Appreciable cyclization accompanies the cationic polymerization of o-divinylbenzene (11-53) (5). The relative magnitudes of x and y depend on the catalyst employed. At 0°C, in toluene as solvent, there was 19 % cyclization with boron trifluoride etherate. Under the same conditions as much as 47.8 % cyclization occurred when stannic tetrachloride was used. 

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