Seven p-nitrophenyl benzoate esters (p-nitrophenyl benzoate, p-nitrophenyl m-anisate, p-nitrophenyl p-anisate, p-nitrophenyl m-chlorobenzoate, p-nitrophenyl p-chlorobenzoate, p-nitrophenyl m-toluate, p-nitrophenyl p-toluate) were synthesized and characterized by students in a second-semester organic laboratory course. In a subsequent laboratory period, the rate constants for the base hydrolysis of these esters were measured by monitoring the formation of the p-nitrophenoxide ion by UV-vis spectrophotometry. The Hammett equation rho constant for this hydrolysis reaction was then determined. The two-experiment sequence was developed to demonstrate structure-reactivity relationships and pseudo-first-order reaction kinetics. The students gained experience in organic synthesis and characterization, performing kinetics studies by spectrophotometry, and carrying out data analysis using spreadsheet software. (Contains 3 schemes, 1 table, and 3 figures.)