Sulfolane solutions of acids

Figure 3. Specific conductance of sulfolane solutions of acids as. a function of water concentration at 30°C ( ), 0.54M HCFsCOt (A), 0.53M HCH3SOs (Q), 0.50M HCF SOs (O),...

Materials. Sulfolane (99%purity) (Aldrich) was treated with calcium hydride and distilled under reduced pressure. The freshly prepared solvent had a specific conductivity of 1.0 X 10 7 O"1 cm"1 and a residual water content of 8 X 10"3M as determined by Karl Fisher titration. Conductivity water and reagent grade ether (Baker) were used. Glacial acetic acid (CIL), trifluoroacetic acid (Baker), and trifluoro-methanesulfonic acid (3M) were used as received. All these acids had a minimum purity of 99.5% as determined by titration with standard sodium hydroxide. Methanesulfonic acid (Eastman), distilled under reduced pressure, had a purity of 99.6%. Sulfolane solutions of these acids were prepared by weight, and the acid concentrations were checked by acidimetry after the samples were flooded with water. The solutions... 

The calorimetric data obtained for the addition of water and ether to acid solutions are summarized in Tables I and II, respectively. The addition of water or ether (R20) to the solutions of acid (HA) in sulfolane gives rise to a series of reactions. We have considered the following... 

Activated tertiary amines such as triethanolamine (TEA) and methyl diethanolamine (MDEA) have gained wide acceptance for CO2 removal. These materials require very low regeneration energy because of weak CO2 amine adduct formation, and do not form carbamates or other corrosive compounds (53). Hybrid CO2 removal systems, such as MDEA —sulfolane—water and DIPA—sulfolane—water, where DIPA is diisopropylamine, are aqueous alkaline solutions in a nonaqueous solvent, and are normally used in tandem with other systems for residual clean-up. Extensive data on the solubiUty of acid gases in amine solutions are available (55,56). 

The physical solvent sulfolane provides the system with bulk removal capacity. Sulfolane is an excellent solvent of sulfur compounds such as H2S, COS, and CS2. Aromatic and heavy hydrocarbons and CO2 are soluble in sulfolane to a lesser degree. The relative amounts of DIPA and sulfolane are adjusted for each gas stream to custom fit each application. Sulfinol is usually used for streams with an H2S to CO2 ratio greater than 1 1 or where it is not necessary to remove the CO2 to the same levels as is required for H2S removal. The physical solvent allows much greater solution loadings of acid gas than for pure amine-based systems. Typically, a Sulfinol solution of 40% sulfolane, 40% DIPA and 20% water can remove 1.5 moles of acid gas per mole of Sulfinol solution. 

In the analogous studies of the photolysis of sulfolane (31), the work of Honda and coworkers66 was carried out in the gas phase at 70-130 °C and established the formation of S02, ethylene, cyclobutane and acetylene as the major products, on mercury-sensitized photolysis. In considerable contrast, photolysis of sulfolane at 185 nm in the liquid phase67 produced ethylene( = 0.22), the sultine (32) (parallel experiments on aqueous solutions of sulfolane, a sulfinic acid is also believed to be formed. The authors believe that both four-membered (33) and six-membered (32) sultines may be formed during these photolyses. Further work in this area would appear to be necessary to unravel the full mechanistic details. 

Alkyl esters are efficiently dealkylated to trimethylsilyl esters with high concentrations of iodotrimethylsilane either in chloroform or sulfolane solutions at 25-80° or without solvent at 100-110°.Hydrolysis of the trimethylsilyl esters serves to release the carboxylic acid. Amines may be recovered from O-methyl, O-ethyl, and O-benzyl carbamates after reaction with iodotrimethylsilane in chloroform or sulfolane at 50—60° and subsequent methanolysis. The conversion of dimethyl, diethyl, and ethylene acetals and ketals to the parent aldehydes and ketones under aprotic conditions has been accomplished with this reagent. The reactions of alcohols (or the corresponding trimethylsilyl ethers) and aldehydes with iodotrimethylsilane give alkyl iodides and a-iodosilyl ethers,respectively. lodomethyl methyl ether is obtained from cleavage of dimethoxymethane with iodotrimethylsilane. 

Nitronium salts are efficient and powerful nitrating agents. Nitronium tetrafluoroborate is the most commonly used nitronium salt for nitration and is commercially available as a solid or as a solution in sulfolane in which the ions are highly solvated and exist as an ion pair. Nitronium tetrafluoroborate shows poor solubility in most organic solvents and so the more soluble nitronium hexafluorophosphate is sometimes preferred for nitrations. Olah and co-workers - have studied the nitration of a vast array of aromatics with nitronium salts. Solutions of nitronium salts in aprotic organic solvents are useful for the nitration of acid sensitive or readily oxidized substrates. Nitronium tetrafluoroborate has been used for the... 

Calorimetry. Heats of solution were measured at 30°C using an LKB model 8725-2 isoperibol calorimeter. Details of the procedure have been given (5). The heats of mixing known weights of water or ether with 25 ml of 0.1-0.5M acid solutions in sulfolane were determined. Some of the acid solutions contained some known concentrations of water as well. In addition, the heats of solution of NEt4CF3S03 in sulfolane and in a 0.211M HSbCl6 solution in sulfolane were determined at three concentrations between 0.02 and 0.04M. 

Our work gives insight into the many problems that would be met in trying to account for the influence of the concentration of water and acid both on reactions and physicochemical processes that take place in a solvent such as sulfolane. Our results also indicate some possible methods for solving such problems. For example, our present vapor-liquid equilibrium data on solutions of water and acid in sulfolane were correlated with solution composition along lines previously used for the system NH3-Cu(II) salts in aqueous solution (35) in this latter system... 

A spirothietane sulfone-oxetane is a comonomer in the preparation of polyethers. A polymer obtained from this sulfone in a solution of bis(3,3-chloromethyl) oxetane with phosphorus pentafluoride can be spun to drawable filaments. Thietane sulfone spirocyclic carbonates may be polymerized via the carbonate group to high-molecular-weight solids said to be useful in laminating. Thietane 1,1-dioxide improves the dye receptivity of poly (acrylonitrile), viscose, cellulose acetate, and poly(vinyl chloride). It is also reported to be a stabilizer for nitric acid in oxidizer mixtures for rocket motors. 2-Methylthietane 1,1-dioxide is claimed to be superior to sulfolane (thiolane 1,1-dioxide) in the liquid extraction of aromatic hydrocarbons from mixtures with saturated hydrocarbons. " A number of bis(3,3-alkoxy) thietane 1,1-dioxides have been proposed as intermediates in the preparation of cyanine dyes useful as photographic sensitizers. " ... 

Table 1 in Chapter 15 shows that water extracted 2.8% of an H+-ex-changed organic histosol as fulvic acids. When the residual soil was sequentially extracted, exhaustively, with aqueous solutions of sulfolane. 

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