Vanillic acid preparation from vanillin

Vanillic acid has been prepared from vanillin in small amounts by action of moist air, exposure to sunlight and nitrobenzene, reaction with soil bacleria," ozone, and by caustic fusion. High yields of vanillic acid have been obtained from vanillin by con-... 

Benzoic aldehydes mainly cover syringaldehyde and vanillin. Natural vanilla is prepared from the seeds (beans) of Vanilla planifolia, which may contain about 21 mg/ 100 g FW total phenols, including the major components vanillin (19.4 mg/100 g FW), 4-hydroxybenzaldehyde (1 mg/100 g FW), and vanillic acid (0.4 mg/100 g FW) (Clifford 2000b). In mango, vanillin has been found as free as well as vanillyl glu-coside (Sakho and others 1997). It has also been found in lychees (Ong and Acree 1998) and wines (Moreno and others 2007). For analysis of both brandy and wine aged in oak barrels, the limits of detection were found to be 27.5, 14.25, 14.75, and... 

A specific description of a preferred practice of the invention with vanillin as the aromatic compound is as follows. Vanillin is dissolved in water with one molar equivalent of sodium hydroxide while the solution is warmed to 50°-100° C. One molar equivalent of iodine and two molar equivalents of sodium iodide are added to water to prepare one molar equivalent of NalS.Nal. This sodium triiodide solution is added to the sodium vanillate solution along with a catalytic amount of sulfuric acid--preferably from 5 to 10 mole %. The mixture is stirred about one hour at a temperature of 50°-100° C., then sodium hydroxide is added to make the solution alkaline (from 1 to 5N). The copper catalyst is then added and the mixture heated at reflux until the iodovanillin is consumed, about 12 hours. The excess hydroxide is then neutralized and the 5-hydroxyvanillin extracted with a water-immiscihle organic solvent. The aqueous phase bearing the sodium iodide is then subjected to oxidizing conditions and the resultant iodine precipitates from solution. The solid element is filtered out, and a sodium triiodide solution prepared by reducing a portion of the iodine to sodium iodide and dissolving the iodine in the iodide to make the sodium triiodide solution. 

Ferulic acid is the major cinnamic acid found in a variety of plant cell walls. Com fiber contains about 3% femlic acid. Wheat bran is another source of ferulic acid (0.5-1%). Faulds et al. 226) developed a laboratory scale procedure to produce free femlic acid (5.7 g) from wheat bran (1 kg) by using a Trichoderma xylanase preparation and A, niger femlic acid esterase. Using filamentous fungi, a two-stage process for vanillin formation was developed in which a strain of A. niger was first used to convert femlic acid to vanillic acid, which was then reduced to vanillin by a laccase-deficient strain of Pycnoporus cinnabarinus 227). 

Schuerch C (1948) Preparation of vanillonitrile and vanillic acid from vanillin. J Am Chem Soc 70(6) 2293-2294... 

The reduction of carboxylic acids to aldehydes is of preparative interest and a number of microbial carboxylic acid reductases (CARs) (aldehyde oxidoreductases) have been found since the discovery of the tungsten-containing CAR that reduced nonactivated carboxylic acids to the corresponding aldehydes with no further reduction of the aldehydes to alcohols [83]. The reduction of vanillic add to the aldehyde vanillin has been achieved in vitro with the CAR from Nocardia sp. [84] and as part of a de novo biosynthesis in yeast [85]. A CAR from Mycobacterium marinum has been discovered that can convert a wide range of aliphatic fatty acids (C6-C18) into corresponding aldehydes [86]. 

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