Liotta

D. Liotta, ed.. Advances in Molecular Modeling, Vols. 1—2, JAI Press, Inc., Greenwich, Coim., 1988—1990. 

C. M. Starks and C. Liotta, Phase Transfer Catalysis, Academic Press, Inc., New York, 1978. 

Submitted by Geoboe W. Gokei., Donald J. Cbam, Chables L. Liotta, Hbnby P. Habbis, and Fred L. Cook ... 

C. M. Starks, C. L. Liotta, and M. Halpem, Phase Thmffer Catalysis Fundamentals, Applications and Perspectives, Chapnhin and Hall, New kbik, 1994. 

Phase transfer catalysis processes (Starks and Liotta, 1978 Starks, 1987) for the synthesis of many organic materials use less, or sometimes no, organic solvent may use less toxic solvent may allow use of less hazardous raw materials (for example, aqueous HCl instead of anhydrous HCl) and may operate at milder conditions. Some types of reactions where phase transfer catalysis has been applied include ... 

Starks, C. M., and C. Liotta (1978). Phase Transfer Catalysis Principles and Techniques. New York Academic Press. 

Chastrette and Chastrette showed that the cyclocooligomerization of furan and acetone was improved by the presence of lithium salts. Liotta and co-workers reported the synthesis of 12-crown-4 by a double Williamson approach in the presence of LiC104. They mention in a footnote that A run performed as detailed but without UCIO4 gave no product . Other inferential evidence has accumulated as well. 

Shortly after the publication of the 18-crown-6 procedure, Liotta and his coworkers applied a similar approach to the synthesis of 12-crown-4 and 15-crown-5 . They were able to realize yields of 13% and 15%, respectively, using a modification of the procedure illustrated in Eq. (3.9), above. 

In 1976, Johns, Ransom and Reese reported improvements in the previously reported syntheses of 18-crown-6 and 15-crown-5. By using tetraethylene glycol rather than triethylene glycol and the correspondingly shorter dichloride (2.5 equivalents of the latter) in concert with KOH (no water added), they were able to realize a 6% yield improvement in the synthesis of 18-crown-6 over the previously published method . The improvement in the yield of 15-crown-5 was of somewhat greater interest, being 38% compared to Liotta s previous report of 15% . ... 

Starks, C M, Liotta, C Phase Transfer Catalysis, Principles and Techniques Academic Press New York, 1978... 

Other measures of nucleophilicity have been proposed. Brauman et al. studied Sn2 reactions in the gas phase and applied Marcus theory to obtain the intrinsic barriers of identity reactions. These quantities were interpreted as intrinsic nucleo-philicities. Streitwieser has shown that the reactivity of anionic nucleophiles toward methyl iodide in dimethylformamide (DMF) is correlated with the overall heat of reaction in the gas phase he concludes that bond strength and electron affinity are the important factors controlling nucleophilicity. The dominant role of the solvent in controlling nucleophilicity was shown by Parker, who found solvent effects on nucleophilic reactivity of many orders of magnitude. For example, most anions are more nucleophilic in DMF than in methanol by factors as large as 10, because they are less effectively shielded by solvation in the aprotic solvent. Liotta et al. have measured rates of substitution by anionic nucleophiles in acetonitrile solution containing a crown ether, which forms an inclusion complex with the cation (K ) of the nucleophile. These rates correlate with gas phase rates of the same nucleophiles, which, in this crown ether-acetonitrile system, are considered to be naked anions. The solvation of anionic nucleophiles is treated in Section 8.3. 

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