Samarium Diiodide Reduction of Cinnamic Acids

Abstract The method for measuring SmI2 reduction rates is expanded to a wider range of organic compounds by using not only GC or GC/MS, but also HPLC as the detecting tool. The reduced substrates are not only confined to water insoluble compounds or low boiling compounds only. Water soluble cinnamic acid derivatives of high boiling points are chosen for this application. The absolute rate constants of SmI2 reduction of cinnamic acid in the presence of hexamethylphosphoramide or t‐butanol is considered as a suitable proton source in this reaction. The rates are dependent on substrates and additives as: Rate ∞ [t‐BuOH][Cinnamic acid] and Rate ∞ [HMPA][Cinnamic acid] The reduction rates of α‐methylcinnamic acid, 2‐methylcinnamic acid, 4‐methylcinnamic acid, 2‐methoxycinnamic acid, 3‐methoxycinnamic acid, 4‐methoxycinnamic acid, 2‐hydroxycinnamic acid, 3‐hydroxycinnamic acid, 4‐hydroxycinnamic acid, 2‐chlorocinnamic acid, 3‐chlorocinnamic acid, 4‐chlorocinnamic acid were carefully measured to study the substituent effect.