Cyanation of Aryl Halides

A cyanation process of aryl halides with K4[Fe(CN)6]3H2O as the cyanation reagent in the presence of Pd(OAc)2 and Na2CO3 was studied.Factors affecting the reaction such as the ratio of reactants,time,temperature,amount of catalyst on the cyanation was investigated.Optimal reaction conditions were determined to be:130 ℃,n(K4[Fe(CN)6]·3H2O):n(ArBr):n(Pd(OAc)2)=200:1 000:1,and 1.5 h.The conversion of the bromobenzene could reach 99% and cyanobenzene could be obtained with a yield of 95%.Compared with the traditional cyanating agents,potassium hexacyanoferrate(Ⅱ) is non-toxic,affordble and readily available without the need of complicated pre-processing.The protocol is proceeded in the presence of small amounts of palladium catalyst and is easy to operate.It is not necessary to add any expensive ligand,and is less environment polluting and apparently is economically beneficial.Cyanation of other aryl halides was also performed.Both active aryl bromides and aryl iodides gave the corresponding benzonitriles with 91%～96% yields.