hexabromocyclohexane ('a-benzene hexabromide') are reported. ... hexabromocyclohexane, a compound available by direct bromination of benzene.
Short Communications
Aust. J. Chem., 1994, 47, 1395-1399
Raymond M. Camnan,A A. Christopher GarnerA and Ward T. RobinsonB A
Department of Chemistry, The University of Queensland, Brisbane, Qld. 4072. Department of Chemistry, University of Canterbury, Christchurch, New Zealand.
Abstract The X-ray crystal structure determination (130 K) and n.m.r. analysis of a-1,2,3,4,5,6hexabromocyclohexane ('a-benzene hexabromide') are reported.
Introduction I n connection with other studies,l we required a compound with cis vicinal bromines on a cyclohexane ring, a n d we were attracted t o a-1,2,3,4,5,6hexabromocyclohexane, a compound available by direct bromination of benzene. This compound has had its structure determined as ( 1 ) only indirectly from infrared a n d dipole moment measurements together with elimination studies and early (1928)X-ray diffraction d a t a for t h e P-isomer (2).2-7 T h e compound (Chem. Abstr. Registry Number [87-82-11 or [30105-41-01)has been explored in various insecticidal a n d flame retardant trials, b u t no n.m.r d a t a have been reported.
Results and Discussion T h e compound (1) is available by prolonged reaction of bromine with benzene i n t h e presence of light. Yields are low a n d variable, b u t t h e compound crystallizes o u t essentially pure from the reaction mixture a s t h e reaction proceeds, a n d so isolation is facile.
Carman, R. M., and Garner A. C., unpublished work directed toward the cis vicinal bromination of olefins. Hendricks, S. B., and Bilicke, C., J. Am. Chem. Soc., 1928, 48, 3007. Zbinden, R., Helv. Phys. Acta, 1953, 26, 129. Reimschneider, R., 2. Naturforsch., Teil B, 1953, 8, 701. Reimschneider, R., 2. Naturforsch., Teil B, 1954, 9, 751. Cornubert, R., and Rio, A., Bull. SOC.Chirn. Fr., 1955, 60. Bolton, R., Bhangar, M. I., and Williams, G. H., J. Chem. Soc., Perkin Trans. 1 , 1984, 893. Manuscript received 16 December 1993
0004-9425/94/071395$05.00
Short Communications
The compound has limited solubility in suitable n.m.r. solvents, but showed only three different carbon peaks, each of approximately equal area. The lH n.m.r. spectrum provided three independent multiplets, each of equal area, consistent with the symmetry of structure (1). This spectrum could be completely analysed as an AA'BB'CC' system. Iterative simulation of the spectrum, adjusting both chemical shifts and coupling constants to provide a least-squares minimization between calculated and observed frequencies for 105 transitions, provided the coupling constants and chemical shifts listed in Table 1. The root-mean-square difference between calculated and observed frequencies over 105 transitions was then
