Dibenzocrown ethers

Dibenzene chromium(O), physical properties, 6 528t Dibenzo-crown-6, 5 710 molecular formula, 5 713t Dibenzo[18]crown-6, 7 576 24 40, 41 Dibenzo[30]crown-10, 24 43 Dibenzocrown ethers, 24 50 Dibenzofurans, 27 152 Dibenzopyrenquinone dyes, 9 336 Dibenzothiophenes, 27 152 Dibenzoyl peroxide (BPO), 74 283-284 78 427... 

Stoddart has extensively investigated the interaction of dibenzocrown ethers with the dipyridinium dications, diquat and paraquat [19]. Dibenzocrown ether... 

Table 2. Association constants (K.assoc) for 1 1 complexes between diquat and dibenzocrown ethers 4 in acetone at 25.5 °Ca...

Lastly, such a trimerization reaction - until now specific for orthodialkoxy-benzenes - could be applied [11] to the polymerization (as polytriphenylenes) of dibenzocrown ethers leading to resins supported by conducting materials. The ionophoric properties of such products have been used for the extraction of heavy metal cations from water when the concentrations of these cations are extremely small. 

Polymeric crown ethers are prepared by condensation, polymerization, or substitution [37]. Above all, condensation polymers based on monobenzo- and dibenzocrown ethers are immobilized on the surface of a solid substrate, and are used in chromatographic applications. They are distinguished by chemical and thermal stability and exhibit a relatively high capacity. Modified and non-modified silicas are used preferentially as support materials. 

In 1967 Charles J. Pedersen, then 2 years away from retirement as a research chemist with Du Pont, published an extensive paper detailing the preparation of 33 cyclic polyethers [1], His thorough investigation of these macrocycles was the culmination of several years work initiated by the accidental preparation of dibenzo[18]crown-6 [2], The compound formed as a result of trace amounts of catechol that had contaminated 2-(hydroxyphenoxy)tetrahydropyran used in the synthesis of the original target compound, bis[2-(hydroxyphenoxy)ethyl]ether. The dibenzocrown ether thus became the first of the crown ethers, as Pedersen called them, to be isolated. 

More preorganized macrocycle 9 (Structure 4) forms more stable complexes with [DQT] " than that of the corresponding dibenzocrown ether [28],... 

Several different synthetic approaches have been used for the synthesis of fluorinated macrocycles. The simplest one relies on the introduction of a fluorinated substituent into hydrocarbon macrocycle. For example, the preparation of dibenzocrown ethers 128 is based on the reaction of the corresponding 4,4 - or 4,5 -diaminodibenzo-18-crown-6 ethers bearing amino groups on the phenyl ring with fluorinated lithium... 

Organomercury crown ether derivatives have been structurally characterized as threaded host-guest complexes of bis(trifluoromethyl)mercury with dibenzocrown ethers [394, 395]. Other threaded diorganomercury host-guest complexes of crown ethers have been studied in solution [396-398]. Internally complexed organomercury compounds (with Hg-Me and other groups) and l,3-xylyl-18-crown-5, e.g. 102, are also known [399]. 

The first stationary phases were prepared by packing columns with polymeric particles where benzo- or dibenzocrown ethers were cross-linked with formaldehyde in formic acid. The single crown ether molecules are bridged by methylene groups [71]. Dibenzo-18-crown-6 is a preferred starting material. Igawa et al. [76] also developed a polyamide crown ether resin to separate inorganic anions. 

Nakamura, Y., Asami, A., Ogawa, T., Inokuma, S. and Nishimura, J. Regioselective synthesis and properties of novel [60]fullerene bisadducts containing a dibenzocrown ether moiety. 7. Am. Chem. Soc. 124, 4329-1335, 2002. 

Monobenzo- and dibenzocrown ethers are chlorosulfonated by reaction with a large excess of chlorosulfonic acid. Monobenzo-12-crown-4, -15-crown-5 and -18-crown-6-ethers, when treated dropwise with chlorosulfonic acid (10 equivalents) in chloroform solution at —10 to —5 C and the reaction mixture left at RT (five to six hours), gave the corresponding sulfonyl chlorides in 65-75% yield. For instance, monobenzo-12-crown-4-ether 498 afforded the chlorosulfonyl derivative 499. The orientation of sulfonation is, as expected, p to the electron-donating oxygen atom. 

Dibenzocrown ethers, namely dibenzo-18-crown-6 and -24-crown-8 by similar treatment with a larger excess of the reagent (20 equivalents) gave the corresponding disulfonyl chlorides. For example, dibenzo-18-crown-6 ether 500 afforded the disulfonyl chloride 501 as a mixture of stereoisomers, showing that chlorosulfonation of the dibenzocrown ethers does not occur regioselectively. The chlorosulfonyl and dichlorosulfonyl derivatives were converted into sulfonamides by reaction with ammonia and amines. 

Ammonium-binding crownophanes Crownophanes 38a and 38b strongly complexed dibenzylammonium cation than the corresponding dibenzocrown ethers ... 

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