Summary: A comparison of the reaction products from the title photolytilc reactions allows the preclusion of signifi- cant carboethoxycarbene participation in the carboethoxy- methyne reaction. ... Sir: Photolytic decomposition of diethyl mercurybisdia- zoacetate2 (1) at wavelengths shorter than 290 nm has been shown to be a complicated but useful source of carboethox- ymethyne (A).3 ... We have studied the photolysis reaction of 1 in several chloroalkanes and ...