on G.L.C. with compounds produced by UV irradiation of pure dieldrin in the 
laboratory. The main dieldrin irradiation product, prepared in the labora- 
tory, had a m.p. 195-196°C and corresponded on G.L.C., T.L.C., and I.R. with 
that obtained in field trials. U.V. spectra showed the absence of a conju- 
gated chromophore or a carbonyl group. I.R. spectra showed no absorption 
around 1600 cm), the region ascribed to -CCl = CCl- bonding in spectra of 
dieldrin, aldrin, and heptachlor. There was no absorption corresponding to 
carbonyl (1540-1900 em-l) or hydroxyl (360 cm-!) groups. The most prominent 
new peak at 870 cm-l) was consistent with an oxygen atom attached to a 
tertiary carbon atom. The peak at 990 cm-l corresponded with the absorption 
band of a 4-membered ring containing oxygen; and the two peaks at 1030 and 
1070 cm-! corresponded to absorption bands of 5-membered rings containing 
oxygen. NMR spectrometry showed the absence of the methano bridge present 
in the non-chlorinated ring in dieldrin. However, the M.W. and mass spectrum 
are the same as for dieldrin. One of the several isomeric forms (VII) was 
proposed (618). 
Exposure of aldrin to sunlight and UV light produced two decomposition 
products which were isolated but not identified. Recrystallization from ben- 
zene-methanol gave crystalline compounds with m.p. of 178-9°C and 187-9°C (771). 
In the absence of air, ultra-violet irradiation of aldrin gave rise to two 
compounds whose suggested structures are those of compounds X and Xa. When 
aldrin was exposed to ¥Y-radiation, dieldrin plus about eleven other compounds 
were observed (1678). 
In other studies, gas chromatograms of herbage treated with dieldrin 
displayed an unknown peak in addition to dieldrin. UV irradiation of dieldrin 
at 2537 A gave rise to the same compound (1228). Subsequently, on the basis 
of I.R. spectra, G.L.C. and T.L.C. behavior, mass spectra, NMR spectra, 
molecular weight and elemental analyses, this ultraviolet irradiation product 
was shown to be 10-oxa-3,6-exo0-4,5,13, 13-hexachlorohexacyclo (6.3.1.1 On 
19911,9257,95°12) tridecane (VIII), mp. 188°C. (1226, 1227, 1237, 1570). 
Hexane solutions of dieldrin and aldrin were irradiated with UV light 
having a peak intensity of 2537 A. Elemental analysis indicated an empirical 
formula of C 15H {C1.0 and C)5H,Cl, for the respective photo-products, suggest-— 
ing that dieldrin and aldrin had undergone monodechlorination during photol- 
ysis. Because of the similarity in chemical activity between the photo- 
products and dieldrin and aldrin, principal reliance was placed on spectro~ 
photometric procedures for structure elucidation. On the basis of I1.R., 
mass and NMR spectra, the photodecomposition product of dieldrin was assigned 
Structure (IX) and that of aldrin was assigned structure (X) (645). High 
concentrations, in solution, or in the solid state, apparently favored the 
intramolecular reaction of carbon 2 with the adjacent hydrogen on the 
methylene bridge. In dilute solutions, with very large molar excess of 
hydrogen donor such as hexane, the replacement of chlorine by hydrogen 
appeared to predominate. From flies (Musca domestica L.) treated with photo- 
dieldrin(¥III) or photoaldrin (Xa), compound XI was obtained (1790). 
28 

