The products following Cl atom initiated reactions of FC(O)OOC(O)OCH3 in 50-760 Torr of N-2 at 296 K were investigated using FTIR. Reaction of Cl atoms with methyl fluoroformyl peroxycarbonate proceeds mainly via attack at the methyl group, forming FC(O)OOC(O)OCH2 center dot radicals. Further reaction of this kind of radical with Cl, forms three new compounds: FC(O)OOC(O)OCH2Cl, FC(O)OOC(O)OCHCl2, and FC(O)OOC(O)-OCCl3, whose existence was characterized experimentally by FTIR spectroscopy assisted by ab initio calculations at the B3LYP/6-31++G(d,p) level. Relative rate techniques were used to measure k((Cl+FC(O)OOC(O)OCH3)) (4.0 +/- 0.4) X 10(-14) cm(3) molecule(-1) s(-1) and k((Cl+FC(O)OOC(O)OCH2Cl) = (3.2 +/- 0.3) X 10(-14) cm(3) molecule(-1) s(-1). When the reaction is run in the presence of oxygen, the paths giving chlorinated peroxide formation are suppressed, and oxidation to (mainly) CO2 and HCl takes place through highly oxidized intermediates with lifetimes long enough to be detected by FTIR spectroscopy.