The reaction mechanism of alkyl halides with carbon dioxide catalyzed by 5,10,15,20,-tetraphenyl porphyrin cobalt (CoTPP)

Abstract Benzyl chloride and butyl halide each react with CO 2 catalyzed by 5,10,15,20-tetraphenylporphyrin cobalt (CoTPP) to form phenylacetic acid (in the form of benzyl phenylacetate, the product of electrocarboxylation) or oxalic acid (the direct reduction product of CO 2 , in the form of dibutyl oxalate), respectively. The data show that electrocarboxylation of benzyl chloride reacting with CO 2 can occur, but butyl halide in the presence of CO 2 cannot produce the electrocarboxylation product amylic acid. The reasons for the different mechanisms are examined through the reaction of alkyl halide with CoTPP studied by electrochemistry and spectroelectrochemistry. The intermediate N-alkyl CoTPP is detected by spectroelectrochemistry in situ . The reasons that they form different products with different N-alkyl CoTPP are discussed in detail.