Tetraglyme

The second method involves the direct reaction ofbromo- or lodofluoroolefinx with zinc powder [110] (equation 81) in solvents such as DMF, NJV-dimethyl-acetamide (DMAC), tnglyme, tetraglyme, THF, and CH3CN. In all cases, the stereochemistry is retained Table 4 shows some typical examples of this method ology Similar results are obtained with l-chloro-2 lodotetrafluorocyclobutene [III] and l-iodo-2-chlorohexafluorocyclopentene [112]... 

Several high-boiling, inert solvents have been reported in various steps of the Gould-Jacobs reaction. Dowtherm, f Ph20, cumene, tetraglyme, diphenyl methane, ... 

Compounds which produce a complex with Li+ ions have been investigated. The compounds examined were N,N,N, N tetramethylethylenediamine (TMEDA), eth-ylenediamine, crown ethers, cryptand [211], diglyme, triglyme, tetraglyme, eth-ylenediamine tetraacetic acid (EDTA) and EDTA-Li+ (n=l, 2, 3) complexes [59]. The cycling efficiency was improved by adding TMEDA, but the other additives did not show distinct effects. 

The infrared spectrum of a solution of rhodium dicarbonyl acetylacetonate with either 2-hydroxypyridine or piperidine (4 molar excess over rhodium) in tetraglyme at 210°C under a CO/H2 pressure of either 714 or 1225 bar contained bands consistent with the existence of the above equilibria [Eq. (12)]. The concentration of [Rh12(CO)34]2 was found to increase as the CO/H2 pressure was increased. In the absence of either 2-hydroxypyridine or piperidine, a higher pressure (ca. 1700 bar) was... 

Rhodium losses can also be reduced by using a two-phase system to separate the polyol products from the catalyst solution (64). In this modification the reaction is carried out in a production solvent (e.g., tetraglyme). In order to separate the products, water and an essentially water-immiscible organic extraction solvent (e.g., dichloromethane or chloroform) are added. The resulting two-phase system then consists of a water phase containing the alcohol products and an organic phase containing essentially all the rhodium complex. 

Tetraethyl titanate(IV), tl63 Tetrafluoromethane, cl5 Tetraglyme, b212 1,2,3,4-Tetrahydrobenzene, c368... 

The characteristics of homogeneous crown-ether catalysis were nicely demonstrated by Thomassen et al. (1971) who studied the rate of alkylation of potassium phenoxide with 1-bromobutane in dioxan at 25°C. By measuring the initial consumption of phenoxide (r, in M s-1), any effect of the bromide ion was neglected. The results (Table 21) show hardly any effect of tetraglyme... 

The behaviour of the dibenzo-18-crown-6 derivative is similar, yet the highest attainable rate is only one eighth of that observed with dicyclohexyl-18-crown-6, which points to an important difference in reactivity between crown ether-separated ion pairs. Compared to tetrabutylammonium phenoxide, the dicyclohexyl-18-crown-6/K+ phenoxide was 2.6 times less reactive. The addition of 0.05 M dicyclohexyl-18-crown-6 to dioxan resulted in the alkylation rate constant becoming the same as that observed in pure tetraglyme. 

The log K value for the formation of the Na+-fluorenyl complex with tetraglyme, CHs(OCH2CH2)40CH3, is reported to be over 3 log units lower than that of the corresponding complex with 4 -methylbenzo-15-crown-5 in tetrahydrofuran (18, 36). 

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