| 摘要 |
The invention comprises three isomers of 4, 5, 6, 7, 8, 8-hexachloro-3a, 4, 7, 7a-tetrahydro-4, 7-methanoindene, the latter being the 1:1-adduct of hexachlorocyclopentadiene and cyclopentadiene and having m.p. 210-211 DEG C. under nitrogen. The new isomers, which are characterised by distinct melting-ranges and infra-red spectra are prepared by heating the adduct in presence of ultra-violet radiation or a free-radical initiating catalyst and separating if desired by chromatography. The Specification lists suitable catalysts which are preferably but not exclusively organic peroxy compounds such as benzoyl peroxide.ALSO:Herbicidal compositions, stated to be particularly suitable for control of crabgrass, comprise an inert carrier and one or both of two specific isomers of 4,5,6,7,8,8-hexachloro-3a,4,7,7a-tetrahydro - 4,7 - methanoindene; a further inactive isomer and/or the starting material may also be present, provided that at least 20% of one or both active isomers are present. The compositions may be in the form of e.g. dusts, granules or emulsifiable concentrates. |
