CONVERSION OF FREE-RADICALS UPON ANNEALING OF X-IRRADIATED SINGLE-CRYSTAL OF CHOLETS-4-EN-3-ONE

Single crystals of the steroid cholest-4-en-3-one were irradiated at 6 8 K and studied at 68 and 300 K using X-band ESR and ENDOR. At 68 K, t wo A- and B-types of radicals were detected. The A-type radical was id entified as the one formed by attachment of an electron to the O-3 oxy gen atom. The B-type was probably formed on the aliphatic part of the molecule. Upon heating in the temperatures ranging from 90-100 K both types of radicals undergo a conversion. The radical A converts into ne utral one and becomes like a radical formed in single crystal of chole st-4-en-3-one. Explanation of the radical B conversion would need more research. From ESR and ENDOR data collected for three planes of singl e crystal rotation, four proton hyperfine coupling tensors of the low- temperature radical A were obtained.