Ethylene sulfite

In alkylation, phenols and amines are alkylated by sulfites in high yield and quaternary salts readily form (67). Ethylene sulfite reacts yielding hydroxyethyl derivatives and SO2 elimination, corresponding to its activity as an ethylene oxide precursor (68). 

Hydrolysis of dialkyl sulfites under acidic and alkaline conditions, which is followed by the use of OH2, proceeds by attack at sulfur to give S—O cleavage (72). The rate of hydrolysis is generally faster for cycHc and aryl sulfites than for dialkyl sulfites (73). Activation parameters of hydrolysis are known for some sulfites, and the increased rate for ethylene sulfite results from a reduced entropy of activation which results from a rigid ring stmcture (74). 

Numerous research activities have focused on the improvement of the protective films and the suppression of solvent cointercalation. Beside ethylene carbonate, significant improvements have been achieved with other film-forming electrolyte components such as C02 [156, 169-177], N20 [170, 177], S02 [155, 169, 177-179], S/ [170, 177, 180, 181], ethyl propyl carbonate [182], ethyl methyl carbonate [183, 184], and other asymmetric alkyl methyl carbonates [185], vinylpropylene carbonate [186], ethylene sulfite [187], S,S-dialkyl dithiocarbonates [188], vinylene carbonate [189], and chloroethylene carbonate [190-194] (which evolves C02 during reduction [195]). In many cases the suppression of solvent co-intercalation is due to the fact that the electrolyte components form effective SEI films already at potential which are positive relative to the potentials of solvent co-intercalation. An excess of DMC or DEC in the electrolyte inhibits PC co-intercalation into graphite, too [183]. 

Ethylene sulfite is prepared from ethylene oxide, pyridine, and sulfur dioxide in excess to prevent polymerisation of ethylene oxide. Use of a deficiency of sulfur dioxide led to rupture of a reactor from that cause. 

Wrodnigg G. H., Besenhard J. O., Winter M., Ethylene sulfite as electrolyte additive for lithium-ion cells with graphitic anodes, J. Electrochem. Soc. (1999), 146 (2), 470-472. 

In most other cases the relationship will allow the approximate prediction of the half-wave potentials of a given ion in a solvent of given donicity by interpolation. It may be expected that E jy2 for a certain metal ion in tetramethylene sulfone (DN = 14.8) will be similar to that in PDC (DN = 15.1), benzylcyanide (DN = 15.1) or ethylene sulfite (DN = 15.3). Likewise, the half-wave potentials are expected to be similar in nitrobenzene (DN = 4.4) and nitromethane (DN = 2.7). In an analogous manner the half-wave potentials may be predicted in methyl acetate, diethylether, pyridine, and various other solvents. 

A sulfur analogue of EC, ethylene sulfite (ES), was proposed as an additive for PC-based electrolytes by Winter and co-workers,apparently because of its structural similarity to EC and its potential, under reductive conditions, to release SO2, a known additive that effectively suppresses PC decomposition. As the voltammetry in Figure 39 shows, ES in only 5% presence successfully eliminated the exfoliation of the graphite anode, whereas 10% SO2 failed. The irreversible process corresponding to the reduction of ES occurred at --"2.0 V, lower than that of SO2 by 0.80 V however, the quantity of charge associated was much lower. According to the authors, the above apparent gap between the reduction potentials of ES... 

Table 6 Raman Absorption Bands of Liquid 1,3,2-DioxathioIane 2-Oxide (Ethylene Sulfite)...

Scheme 9 Methods for preparing 1,3,2-dioxathiolane 2-oxide (ethylene sulfite)...

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