31. With a pK a near 2.5, it acid is almost 100x more acidic than benzoic acid . 32. Benzoic acid is also formed in apples after infection with the fungus " Nectria galligena ".33. In 1993, research showed how benzene can form from benzoic acid in the presence of vitamin C. 34. It is a derivative of benzoic acid . 35. Anyway, benzoic acid can also be conjugated to things as a benzoate, i . e . benzoyl. 36. I also have which is benzoic acid . 37. It is the sodium salt of benzoic acid and exists in this form when dissolved in water. 38. Typical levels of use for benzoic acid as a preservative in food are between 0.05 0.1 %. 39. This can be used, e . g . in the reaction with carbon dioxide to prepare benzoic acid . 40. Aromatic hydroxyaldehydes to divalent phenols ( Dakin reaction ) and gives under suitable conditions the corresponding benzoic acids .