import evs
analytes = ("Trichloromethane" , "1,2-Dichloroethane",  "Carbon tetrachloride", 
            "Benzene", "Perchloroethylene", "Ethylbenzene", 
            "1,4-Dichlorobenzene", "1,2-Dichlorobenzene")
find = analytes[int(N1)]
replace = analytes[int(N2)]

for mod in evs.get_modules():
    if mod.find(find) > -1:
        newName = mod.replace(find, replace)
        evs.rename_module(mod, newName)