Solvent complexation

Economic considerations in the 1990s favor recovering butadiene from by-products in the manufacture of ethylene. Butadiene is a by-product in the C4 streams from the cracking process. Depending on the feedstocks used in the production of ethylene, the yield of butadiene varies. Eor use in polymerization, the butadiene must be purified to 994-%. Cmde butadiene is separated from C and C components by distillation. Separation of butadiene from other C constituents is accomplished by salt complexing/solvent extraction. Among the solvents used commercially are acetonitrile, dimethyl acetamide, dimethylform amide, and /V-methylpyrrolidinone (13). Based on the available cmde C streams, the worldwide forecasted production is as follows 1995, 6,712,000 1996, 6,939,000 1997, 7,166,000 and 1998, 7,483,000 metric tons (14). As of January 1996, the 1995 actual total was 6,637,000 t. 

CeUulose is soluble only in unusual and complex solvent systems. The subject has been reviewed (84—87). Commercially, dissolving pulps, which have lower molecular weights, are used along with strong alkaU and derivatization. CeUulose subjected to high temperature and pressure during the steam explosion process can be dissolved in strong base (88). 

Mohamed, A.A., Mayer, A., Abdou, H.E., Irwin, M.D., Perez, L. and Fackler, J.P. Jr (2007) Dinuclear and tetranuclear gold-nitrogen complexes. Solvent influences on oxidation and nudearity of gold... 

A considerable explosion resulted from preparation of this compound (which presumably exists with several tightly complexed solvent molecules) in limited tetrahydrofuran under reflux. Investigation showed that there is an exotherm at 130°C, giving 440 J/g, followed by a more violent one at 300°C giving 690 J/g. Using a large excess of solvent no problems are observed. 

Polymerization of Ethylene in the Dark with Sigma-Bonded Metal Complexes, Solvent Toluene at 80°C, Partial Pressures of Ethylene 10 atm [catalyst] = 0.003 M... 

Complex Solvent Aniline (mmol) mol aniline/mol complex per day... 

An example is provided by the work of Valtasaari39 on solutions of cellulose in the coloured complex solvent FeTNa, which necessitates this correction even though the transmittance maximum of this solvent lies conveniently at X0 = 546 nm. In the absence of an absorption correction the molecular weight obtained will be lower than its true value. 

Table 8. Survey of existing complex solvents for cellulose122)...

As cyclic polyethers (polyethylene oxides), some of this group of aprotic complexing solvents may be subject to peroxidation, though no reports have been so far noted. 

Since the difference in entropy between the two redox couples is difficult to ascribe to different complex-solvent interactions, as the charges of the complexes are identical in the two cases, other causes of the entropy difference must be considered. 

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