Vanillic acid, methyl ester

CAS 3943-74-6 EINECS/ELINCS 223-525-9 Synonyms Benzoic acid, 4-hydroxy-3-methoxy-, methyl ester 4-Hydroxy-3-methoxybenzoic acid methyl ester Methyl 4-hydroxy-3-methoxybenzoate Methyl 3-methoxy-4-hydroxybenzoate Vanillic acid, methyl ester Empirical C9H10O4... 

Vanillic acid, methyl ester. See Methyl vanillate... 

Veratraldehyde 3 and veratric acid methyl ester 4 were isolated from vanillic aldehyde 5 and vanillic acid methyl ester 6 in the original reaction mixture. Silica gel chromatography of this reaction mixture was used to isolate small amounts of these primary oxidation products. These compounds had lost two carbon atoms from the origind propenoidic chain. A further component isolated from the methylated mixture was 2-methoxyhomoveratric aldehyde 7, which suggested the presence of 2-hydroxyhomoveratric aldehyde 8 in the oxidation reaction mixture. Its structure was confirmed by independent synthesis. Treatment of the reaction mixture from the catalytic oxidation of E-ferulic acid 1 with 1,3-dithiane followed by methylation formed the thioketal 9, which was also prepared by reaction of veratraldehyde 3 with 1,3-dithiane carbanion 10 followed by methylation. 

After 72 h at room temperature with a substrate catalyst ratio (R) of 10, the reaction mixture was methylated with dimethylsulphate and potassium carbonate and analyzed by GLC-MS. Veratric acid methyl ester 4 and 1,2-dimethoxybenzene 22 were recognized, indicating that the oxidation reaction mixture contained vanillic acid methyl ester 6 and ortho-methoxyphenol 20. Also, 3,4-dimethoxyacetophenone 21 was found, indicating the presence of 3-methoxy-4-hydroxyacetophenone 19 in the oxidation reaction mixture. 

The second P-0-4 dimer submitted to reaction with dioxygen (10 bar) at room temperature in the presence of Co(II) salen as the catalyst was l-(3,4-dimethoxyphenyl)-(2-methoxyphenoxy)ethane-l-ol 23, also prepared according to Landucci (22). In the same reaction conditions, again, veratric add methyl ester 4 was recognized after methylation, derived from vanillic acid methyl ester 6 present in the oxidation reaction mixture. The other component of the methylated mixture was 1,2-dimethoxy-benzene 22, derived from ortho-methoxyphenol 20. 

For lignin substructures containing a carbon substituent in the aromatic C-5 position, or for stilbenes originating from phenylcoumaran structures, the oxidative degradation leads to the formation of isohemipinic acid methyl ester (4) (Fig. 6.3.2, R=CH3). However, Gellerstedt and co-workers have shown that model compounds of the biphenyl type also give rise to isohemipinic acid in addition to the expected bis-vanillic acid structure (7). The reason seems to be incomplete alkylation (pH 11, 24 h) with the result that the substrate is alkylated at only one of the available positions. To achieve a more complete alkylation, it is necessary to increase the pH to 13 or alternatively, to extend the alkylation time to 84 h. In both cases, the yield of the bis-vanillic acid structure is substantially increased as shown in Table 6.3.1 nevertheless, the concomitant formation of isohemipinic acid cannot be completely avoided. 

Hydroxy-3,5-dimethoxy-benzeneacetic acid, methyl ester (methyl homosyringate) 4-Hydroxy-3,5-dimethoxy-benzoic acid (syringic acid) 4-Hydroxy-3,5-dimethoxy-benzoic acid ethyl ester (ethyl syringate) 4-Hydroxy-3,5-dimethoxy-benzoic acid methyl ester (methyl syringate) 4-Hydroxy-3,5-dimethoxybenzaldehyde (syringaldehyde) 4-Hydroxy-3-methoxy-benzeneacetic acid methyl ester (methyl homovanillate) 4-Hydroxy-3-methoxy-benzoic acid (vanillic acid)... 

Hydroxy-3-methoxy-benzoic acid ethyl ester (ethyl vanillate) 4-Hydroxy-3-methoxy-benzoic acid ethyl ether (vanillyl ethyl ether) 4-Hydroxy-3-methoxy-benzoic acid methyl ester (methyl vanillate) 4-Hydroxy-3-methoxy-benzoic acid methyl ether (vanillyl methyl ether) 4-Methyl-2-(2 -methyl-l-propenyl)-phenol 4-Methyl-2,6-dimethoxyphenol (methylsyringol)... 

The methyl ester fraction of the alkaline nitrobenzene reaction, shown in Figure 8, contained, in addition to the expected methyl ether esters of />-hydroxybenzoic, vanillic, and syringic acids (Table II), the methyl esters of the di-, tri-, tetra-, and hexacarboxybenzenes. The individual esters of polycarboxybenzene isomers could not be resolved, as previously noted. Dehydrodivanillic acid or pentacarboxybenzene or both are present as an unmarked, secondary peak at approximately 25 minutes. Other acids reported in the literature—5-formylvanillic acid and 5-carboxyvanillin— may be present, but qualitative identification has not been completed. 

Similarly, the methyl ester fraction of the alkaline oxygen reaction contained the methyl esters of benzoic acid, the di-, tri-, and tetracarboxy-benzenes, and the methyl ether ester of vanillic acid. The methyl ether ester of syringic acid was also found. With regard to other acids reported... 

In the methyl ester fraction of the spent acid from the nitric acid reaction (Figure 10), the methyl ether esters of p-hydroxybenzoic, vanillic, and syringic acids and the methyl esters of benzoic acid and the di- and tricarboxybenzenes have been found. These compounds are also present in the chromatogram of the basic extract, as are the methyl esters of the tetracarboxybenzenes and mellitic acid. In addition, dehydrodivanillic acid or pentacarboxybenzene or both are present in both chromatograms... 

The ratio of vanillin to vanillic acid and the yields of these two products, expressed as percentages of wood lignin, are the most significant data available to judge the severity of an alkaline nitrobenzene oxidation of a coniferous wood. The yields of vanillin and vanillic acid reported in Tables IV and V as methyl ether and methyl ether ester are only approximately 8 and 50%, respectively, of amounts that might be expected based on previous work. The ratio of vanillin to vanillic acid has been found to be 8 1 whereas in the reaction reported here it is 1 2. Furthermore, Leopold 32) reported vanillin vanillic acid oxalic acid as 6 1 2 whereas... 

Among the derivates of HBAs, further compounds have been identified. GUntert et al. (1986) identified ethyl esters of vanillic acid and p-hydroxybenzoic acid, and methyl esters of vanillic acid and protocatechuic acid. Ethyl esters of protocatechuic acid and vanillic acid, as well as the glucose ester of vanillic acid, were isolated from a German Riesling wine (Baderschneider and Winterhalter 2001). Analytically, HBA are mostly determined as trimethylsilane derivatives by using... 

Main components During fermentation, vanillin (up to app. 2.5%) is formed from the odourless glucovanillin by enzymatic hydrolysis. Its aroma is rounded-off and modified by p-hydroxybenzoic acid, p-hydroxybenzaldehyde, p-hydroxybenzyl methyl ether, vanillyl alcohol, vanillic acid, cinnamic acid ester and various other trace constituents [291, 292], Also the resins, gums, amino acids and other organic acids contribute to the typical flavour of the cured beans [293[. For further constituents and characterisations of fruits from different growing areas see [294[. 

Fig. 14. Separation of several aromatic acids as methyl esters (A) before and (B) after acetylation, with a 7% F-60/1% Z at 170°C. VAN = vanillic acid VER = veratric acid HOMOVAN = homovanilUc acid HIPP = hippuric acid VMA = 4-hydroxy-3-methoxymandelie acid Ac = acetylated. Reproduced from Brooks and Horning (B24) with permission.

Hydroxybenzoic and vanillic acids are also present in numerous fruits and vegetables [1], and the native forms are frequently simple combinations with glucose (Table 1). Other derivatives have been detected in certain fruits [1,2] the methyl ester of />-hydroxybenzoic acid in passion fruit, 3,4-dihydrox-ybenzoic aldehyde in banana, a phenylpropene benzoic acid derivative in fruits of Jamaican Piper species, and benzoyl esters and other derivatives in the fruits of Aniba riparia. Different new glycosides of HBA showing radical-scavenging activity [e.g., a new guaiacylglycerol-vanillic acid ether (Fig. 1)] have been identified in the fruits of Boreava orientalis [20]. 

B. Narasin methyl ester detected with 3% vanil-lin-0.5% sulfuric acid spray, I00°C... 

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