Several　polar　molecules,　such　as　alcohols,　ketones,　esters　and　acids,　were　used　as　co-catalysts　for　the　cyclohexane　oxidation　catalyzed　by　manganese　porphyrins,　and　the　catalytic　activity　was　found　to　be　closely　related　to　polarity　of　co-catalysts.　The　results　indicated　that　the　total　selectivity　of　products　was　as　high　as　96.3%　and　glutaric　acid　selectivity　was　up　to　50.9%.　Thus,　the　proposed　method　provides　a　new　approach　for　preparing　glutaric　acid.　(C)　2015　Elsevier　B.V.　All　rights　reserved.