Made by aldehyde + K2Cr2O7/H2SO4 under reflux
Made by ester + dilute acid and heat
Made by nitrile + H2O and HCl and heat
Made by hydroxynitrile + H2O and HCl and heat
Made by acyl chloride + H2O
Makes acyl chloride with SOCl2
Makes ester with alcohol and conc H2SO4