Tetrabromobenzene

In the reaction of o-dibromobenzene, disubstitution is faster than monosubstitution, and the disubstituted product is obtained as a major product. Similarly, 1,2,4,5-tetrabromobenzene reacts with styrene to give the tetrasub-stituted product[29]. The bridged, annulated [2,2]paracyclophanedieiie 22 was... 

The novel, low-melting-point salt [N-pentylpyridinium][cJoso-CB11H12] has been used as solvent in several dehalogenations of mono- and polychlorides and -bromides, catalyzed by several Pd phosphine complexes [69]. The debromina-tion of hexabromo- and 1,2,4,5-tetrabromobenzene was accomplished quite rapidly, whereas the dechlorination of 1,2,4-trichlorobenzene proceeded more slowly, but with excellent selectivity to 1,2-dichlorobenzene. The system could be recycled at least seven times without noticeable decrease of activity. 

Miyazaki T, Yamagishi T, Matsumoto M. 1986. [Identification of 1,2,4,5-tetrabromobenzene and mirex in human milk by gas chromatography-mass spectrometry.] Journal of the Food Hygienic Society of Japan 27(3) 267-271. (Japanese)... 

Tetrabromobenzene used from sources other than Lancaster Synthesis contained trace amounts of an impurity that carried through the entire reaction scheme. This impurity gave a proton resonance at 1.58 ppm in the starting... 

The procedure given here is a modification of the first synthesis of the tetrahydroanthracene diepoxides.5 7 These compounds have also been prepared from another 1,4-benzadiyne equivalent, namely 1,5-diamino-1,5-dihydrobenzo[1,2-d 4,5-d ]bistriazole which, although it has certain advantages,12 is not as available as 1,2,4,5-tetrabromobenzene. 

Finally, it should be pointed out that the diaryne reactions of 1,2,4,5-tetrabromobenzene are stepwise. Thus the procedure described here, but using half the amounts of furan and butyllithium, can be used to prepare 6,7-dibromonaphthalene 1,4-endoxide (mp 115-117°C) in 70% yield.17 This versatile intermediate can then be used as a benzyne precursor, to make unsymmetric adducts 7 13 17 it also can be used as a dienophile.15 18... 

Chemical/Physical. 1,2,4,5-Tetrabromobenzene (150 mg in 250-mL distilled water) was stirred in the dark for 1 day. GC analysis of the solution showed 1,2,4-tribromobenzene as a major transformation product (Kim and Saleh, 1990). 

One of the major difficulties associated with the X-ray diffraction investigations of the polyhalogenobenzenes is that although the heavy atom positions may be determined with some precision, the same cannot be said for the lighter atoms. This is brought out clearly, for example, by Gafner and Herbstein s analysis of 1,2,4,5-tetrabromobenzene, where the standard deviations in positional parameters of the bromine atoms are 0-003 A compared with 0-026 A for the carbon atoms. This does not make detailed description of the molecular geometry any easier. 

In the mid 1980s, J. Fraser Stoddart and Franz Kohnke, then from the University of Sheffield, UK, developed another rather less studied curved building block 6.5, which is derived from the reaction of 1,2,4,5-tetrabromobenzene with furan (Scheme 6.4). Kohnkene (6.39), which was named after its creator, is a very rigid structure, and possesses a small elliptical cavity that is unsuitable for inclusion of molecular guest species. However, the molecule may be deoxygenated to give dideoxykohnkene... 

Chemical Name 1,2,4,5-tetrabromobenzene CAS Registry No 636-28-2 Molecular Formula C6H2Br4 Molecular Weight 393.696 Melting Point (°C) ... 

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