Rate coeffcients for the gas-phase reactions of Cl atoms with (CH3)(2)C=CHC(O)H and CH3CH=CHC(O)OCH3 were determined to be (in units of 10(-10) cm(3) molecule(-1) s(-1)): 2.48 +/- 0.71 and 2.04 +/- 0.56, respectively. The experiments were performed by the relative technique in an environmental chamber with FTIR detection of the reactants at 298 K and 760 Torr. Structure activity relationships were developed for the reactions of Cl with a series of unsaturated esters and aldehydes. In addition, a comparison between the experimentally determined kCl with kCl predicted from k vs. HOMO correlations is presented. The atmospheric persistence of these compounds was calculated taking into account the measured rate coefficients. (C) 2010 Elsevier B. V. All rights reserved.