Sulfur dioxide double metallation

The 65 to 70% sulfuric acid containing a residue of metal sulfates (3 to 5%) is either directly, or after further concentration to 80 to 90%, in admixture with 96% acid or oleum (from a double contact plant fed with sulfur dioxide from metal sulfate cracking) is further utilized in the digestion of titanium ore. 

Polymers for use in 193 nm lithography are co-, ter-, and tetra-polymers of 1) methacrylates, 2) norbornenes, 3) norbornene-maleic anhydride, 4) nor-bornene-sulfur dioxide, and 5) vinyl ether-maleic anhydride (Fig. 39). While 1), 3), 4), and 5) are prepared by radical polymerization, all-norbornene polymers 2) are synthesized by transition-metal-mediated addition polymerization [166-168].Norbornenes (Fig.40) are sluggish to undergo radical [168,169] and cationic [170] polymerizations. Their ring-opening metathesis polymerization (ROMP, Fig. 40) [ 171 ] has never produced worthy resist polymers. The C=C double bonds introduced in the ROMP polymer backbone must be hydrogenated to reduce the 193 nm absorption and the ROMP polymers tend to have low Tg. However, the major problem for the ROMP polymers was their unacceptable swelling in aqueous base development. While polymethacrylate systems contain etch-resistant alicyclic structures in the ester side chain, norbornene-based systems carry the alicyclic unit in the backbone. Essentially all the 193 nm re-... 

Silvery-white metal hexagonal dose-packed structure-Slowty oxidizes in moist air. Available as bars, ribbons, wire and powder, mp 651°. bp 1100°. dM 1,738. Sp heat (20°) 0.245 cal/g. Heat of fusion 88 cal/g. Electrical resistivity 4.46 fiohm-cm, E° (aq) MgJ + /Mg —2.37 V. Reads very slowly with water at ordinary temp, less slowly at 100°. Reacts readily with dil adds with liberation of hydrogen reacts with aq solns of ammonium salts, forming a double salt. Reduces carbon monoxide, carbon dioxide, sulfur dioxide, nitric oxide, and nitrous oxide at a red heat. Burns in air continues to bum in a current of steam. Combines directly with nitrogen, sulfur, the halogens, phosphorus, and arsenic, Reacts with methyl alcohol at 200° giving magnesium methylate. 

Silva and coworkers [120] reported the thermal characterization of double sulfites witii empirical formula Cu2S03-MS03 2H20 (where M is Cu, Fe, Mn, or Cd), obtained by saturation with sulfur dioxide gas of an aqueous mixture of M(n)-sulfate and copper sulfate at room temperature. The thermal behaviour of the double sulfites, evaluated by TG and DSC, showed that these salts are thermally stable up to 200 C, but the structures of sulfite ion coordination strongly influence the course of the thermal decomposition. The sulfite species coordinated to the metal through the oxygen was more easily oxidized to sulfate than the sulfur-coordinated species. 

Monomers with electron-rich double bonds produce one-to-one copolymers with monomers having electron-poor double bonds in reaction systems that also contain certain Lewis acids. These latter are halides or alkyl halides of nontransition metal elements, including AlCb, ZnCh, SnCL, BF3, AI(CH2CH3)Cl2, alkyl boron halides, and other compounds. The acceptor monomer generally has a cyano or carbonyl group conjugated to a vinyl double bond. Examples are acrylic and methacrylic acids and their esters, acrylonitrile, vinyl ketones, maleic anydride, fumaric esters, vinylidene cyanide, sulfur dioxide, and carbon monoxide. The variety of donor molecules is large and includes various olefins, styrene, isoprene, vinyl halides and esters, vinylidene halides, and allyl monomers [30]. 

Barium hydroxide decomposes to barium oxide when heated to 800°C. Reaction with carbon dioxide gives barium carbonate. Its aqueous solution, being highly alkahne, undergoes neutrahzation reactions with acids. Thus, it forms barium sulfate and barium phosphate with sulfuric and phosphoric acids, respectively. Reaction with hydrogen sulfide produces barium sulfide. Precipitation of many insoluble, or less soluble barium salts, may result from double decomposition reaction when Ba(OH)2 aqueous solution is mixed with many solutions of other metal salts. 

The formation of the sultone (160) probably involves addition of the complex across the alkene double bond, a 1,2-hydride shift and an intramolecular nucleophilic substitution reaction. The sultone (161) is formed by addition of sulfur trioxide to give the unstable p-sultone which rearranges to the more stable y-isomer (161). Another useful route to sultones is by metallation of alkanesulfonate esters for example, butane-1,3-dimethylsulfonate (162), prepared from butanel,3-diol, yields the 8-sultone, namely 6-methyl-l,2-oxathiin-2,2-dioxide (163) (Scheme 67). 

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