In the presence of protosensitizer-benzophenone, ethyl diazoacetate was photolyzedand the resulting carboethoxylcarbene reacted with n-hexane. The result was compared withthat done without the sensitizer. It was revealed that the nature of the insertion products andtheir relative proportions remained the same, whether the sensitizer was presentor not. At the same time, the influence of oxygen on the sensitized and unsensitized inser-tion reaetions was also studied; these showed also no influence on the nature of insertionproducts and their relative proportions no matter whether the sensitizer or oxygen was pres-ent or not. Since oxygen ks a well-known seavenger for the triplet state carbene, the ex-perimental results indicate clearly that the insertion reactions are conducted by the carbenein singlet state. The photo-oxidation products of n-hexane sensitized by air in the presence of benzophe-none were carefully studied, showing that the primary hexyl radical seemed to be rearrang-ed to thermodynamicall The result was compared withthat done without the sensitizer. It was revealed that the nature of the insertion products andtheir relative proportions remained the same, whether the At the same time, the influence of oxygen on the sensitized and unsensitized inser-tion reaetions was also studied; these showed also no influence on the nature of Insertproducts and their relative proportions no matter whether the sensitizer or oxygen was pres -ent or not. Since oxygen ks a well-known seavenger for the triplet state carbene, the ex-perimental results indicate clearly that the insertion reactions are conducted by the carbenein singlet state. The photo-oxidation products of n-hexane sensitized by air in the presence of benzophe-none were carefully studied, showing that the primary hexyl radical seemed to be rearrang-ed t o thermodynamicall