Vanillic acid, vanillin

B) percent b-alanine plus g-aminobutyric acid (%(BALA+GABA)) versus the vanillic acid vanillin ratio (Ad/Al)v. Symbols are as in Fig. 15.13. 

Aromatic acids and aldehydes (c.g., vanillic acid/vanillin)... 

Vanillic acid + vanillin + acetovanillone. Syringic acid + syringaldehyde + acetosyringone. /j-Coumaric acid + ierulic acid. y7-Hydroxybenzoicacid +y7-hydroxybenzaldehyde + /)-hydmxyacetophenone. S + C + V... 

The main drawback of the acid hydrolysis processes is the formation of undesirable by-products. This not only lowers the yield of sugars, but several of the by-products severely inhibit the formation of ethanol in the fermentation process. Potential inhibitors are furfural, 5-hydro ethylfiirfural (HMF), levulinic acid, acetic acid, formic acid, uronic acid, 4-hydroxybenzoic acid, vanillic acid, vanillin, phenol, cinnamaldehyde, formaldehyde, etc. (I, 36). Some inhibitors, such as terpene compounds, are initially present in the wood, but apparently most of the inhibitors are formed in the hydrolysis process. 

On distillation at atmospheric pressure, vanillin undergoes partial decomposition with the formation of pyrocatechol. This reaction was one of the first to be studied and contributed to the elucidation of its stmcture. Exposure to air causes vanillin to oxidize slowly to vanillic acid. When vanillin is exposed to light in an alcohoHc solution, a slow dimerization takes place with the formation of dehydrodivanillin. This compound is also formed in other solvents. When fused with alkaU (eq. 3), vanillin (I) undergoes oxidation and/or demethylation, yielding vanillic acid [121 -34-6] (8) and/or protocatechaic acid (2). 

It is possible to replace the vanillin in the reagent by 4-dimethylaminobenzaldehyde, 4-hydroxybenzaldehyde, salicylaldehyde, /n-anisaldehyde, cinnamaldehyde, 4-hydioxy-benzoic acid or vanillic acid [3]. However, the range of colors obtained is not so broad. 

The total phenolic content in XRPP was 1.10%. The major components were found to be p-hydroxybenzoic acid (0.44%), vanillin (0.19%), syringic acid (0.13%), and syringaldehyde (0.13%). The contents of p-hydroybenzaldehyde, vanillic acid and ferulic acid were 0.032, 0.015 and 0.020%, respectively. Gallic acid, protocatechuic acid and cinnamic acid were detected in trace amounts. 

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... 

Valeraldehyde, p28 Valeric acid, p38 Valeronitrile, p35 Valeryl chloride, p45 Vanillic acid, hi43 Vanillin, hl42 Vanillyl alcohol, hl45 Veratraldehyde, d492 Veratric acid, d496 Veratrole, d493 Veronal, d330... 

The biocatalytic reduction of carboxylic acids to their respective aldehydes or alcohols is a relatively new biocatalytic process with the potential to replace conventional chemical processes that use toxic metal catalysts and noxious reagents. An enzyme known as carboxylic acid reductase (Car) from Nocardia sp. NRRL 5646 was cloned into Escherichia coli BL21(DE3). This E. coli based biocatalyst grows faster, expresses Car, and produces fewer side products than Nocardia. Although the enzyme itself can be used in small-scale reactions, whole E. coli cells containing Car and the natural cofactors ATP and NADPH, are easily used to reduce a wide range of carboxylic acids, conceivably at any scale. The biocatalytic reduction of vanillic acid to the commercially valuable product vanillin is used to illustrate the ease and efficiency of the recombinant Car E. coli reduction system." A comprehensive overview is given in Reference 6, and experimental details below are taken primarily from Reference 7. 

The HPLC system used a mobile phase consisting of CH3CN/H2O/HCOOH (20 80 1, v/ v/v). Quantitation of standards and samples was achieved by isocratic elution over a C18,5 pm, Econosil HPLC column at a flow rate of 0.4 mL min. HPLC retention volumes and detection wavelengths for standards were as follows vanrllyl alcohol, 1.7 mL and 277 nm vanillic acid, 2.5 mL and 260 nm and vanillin, 4.1 mL and 284 nm. 

TLC analysis of samples was conducted on silica-gel plates carefully spotted with 10-20 pg of standard compounds, and 30 pL of bioconversion reaction samples. Plates developed with 75 25 1 (v/v/v) CH2CI2/CH3CN/HCOOH solvent may be visualized with a 254 nm UV lamp and/or by spraying with a 30 % w/v phosphomolybdic acid/ 95% ethanol spray reagent followed by gentle heating. Rf values of standards are vanillyl alcohol, 0.8 vanillic acid, 0.5 and vanillin 0.4. 

Most of the vanillic acid was reduced by E. coli containing Car in 2 h to vanillin (80 %) and vanillyl alcohol (20 %). Car does not reduce aldehydes to alcohols. However, E. coli s endogenous aldehyde reductase/dehydrogenase reduces vanillin to vanillyl alcohol. The broad substrate specificity of Car enables the wide application of this biocatalyst to other important applications, such as enantiomeric resolution of isomers such as ibuprofen and the reductions of many other natural and synthetic carboxylic acids. 

Methamidophos, see Acephate Methane, see Acetaldehyde, Benzoic acid, 7 Bromobenzoic acid. 3-Bromobenzoic acid. 4-Bromobenzoic acid. Bromoform, Carbatyl, Catechol, 2-Chlorobenzoic acid. 3-Chlorobenzoic acid. Chloroform, Dibromochloromethane, 2,5-Dichlorobenzoic acid. 1,2-Dichloroethane, Ethylamine, Ethyl bromide. Ethylene dibromide, Ethylenimine, Formic acid, Hydroqninone, 4 Hvdroxvbenzoic acid. Indole, 2-Iodobenzoic acid. 3 lodobenzoic acid. Methyl bromide, 4-Iodobenzoic acid. 2-Methylphenol, 4-Methylphenol, Phenol, Prorocatechuic acid. Svringic acid. Svringaldehvde. TCDD, Tetrachloroethylene, Toluene, Trichloroethylene, Vanillin. Vanillic acid. Vinyl chloride... 

Reduction. The reductive capacity of P. chrysosporium has been known for a long time. For example, veratraldehyde, veratric acid, vanillin, vanillic acid and analogous structures were converted into the corresponding... 

It should be noted that if the non-phenolic Ca-carbonyl compound contains an aromatic ring without Ca-carbonyl group (i.e., the structure should contain at least two aromatic rings), then the compound will be a substrate for lignin peroxidase and will be degraded according to the mechanisms discussed above. Degradation of this type of compounds can result, for example, in the formation of vanillin and vanillic acid derivatives (see compounds 7a and 8). As has been shown by Eriksson and coworkers... 

The trifluoroactate group can protect aromatic rings against oxidation by RuO generated from RuO /aq. Na(IO )/CCl. Thus isoeugenyl trifluoroacetate gave vanillin and vanillic acid (Table 3.6) [213]. Oxidation of various substituted... 

Properties. Vanillin is a colorless crystalline solid mp 82-83 °C) with a typical vanilla odor. Because it possesses aldehyde and hydroxyl substituents, it undergoes many reactions. Additional reactions are possible due to the reactivity of the aromatic nucleus. Vanillyl alcohol and 2-methoxy-4-methylphenol are obtained by catalytic hydrogenation vanillic acid derivatives are formed after oxidation and protection of the phenolic hydroxyl group. Since vanillin is a phenol aldehyde, it is stable to autoxidation and does not undergo the Cannizzarro reaction. Numerous derivatives can be prepared by etherification or esterification of the hydroxyl group and by aldol condensation at the aldehyde group. Several of these derivatives are intermediates, for example, in the synthesis of pharmaceuticals. 

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