Vanillin anion

Hplc techniques are used to routinely separate and quantify less volatile compounds. The hplc columns used to affect this separation are selected based on the constituents of interest. They are typically reverse phase or anion exchange in nature. The constituents routinely assayed in this type of analysis are those high in molecular weight or low in volatility. Specific compounds of interest include wood sugars, vanillin, and tannin complexes. The most common types of hplc detectors employed in the analysis of distilled spirits are the refractive index detector and the ultraviolet detector. Additionally, the recent introduction of the photodiode array detector is making a significant impact in the analysis of distilled spirits. 

A general methodology for the construction of quaternary carbon atoms at the carbonyl carbon of ketones has been successfully exploited for the facile synthesis of ( )-lycoramine (299) (Scheme 30) (165). Thus, the O-allylated o-vanillin 322 was allowed to react with vinyl magnesium bromide followed by Jones oxidation, and the acid-catalyzed addition of benzyl IV-methylcarbamate to the intermediate a,(3-unsaturated ketone furnished 323. Wadsworth-Emmons olefination of 323 with the anion derived from diethyl[(benzylideneami-no)methyl]phosphonate (BAMP) provided the 2-azadiene 324. The subsequent regioselective addition of n-butyllithium to 324 delivered a metalloenamine that suffered alkylation with 2-(2-bromoethyl)-2-methyl-l,3-dioxolane to give, after acid-catalyzed hydrolysis of the imine and ketal moieties, the 8-keto aldehyde 325. Base-catalyzed cycloaldolization and dehydration of 325 then provided the 4,4-disubstituted cyclohexenone 326. The entire sequence of reactions involved in the conversion of 323 to 326 proceeded in very good overall yield and in one pot. 

The complexes of zinc and cadmium with Schiff bases derived from salicylaldehyde and propan-2-olamine or 2-aminomethylpropanol have been reported,57 as well as their complexes with ethanolamine and propan-2-olamine.58,59 Zinc complexes of stoicheiometry ZnL2X2 have been obtained where L = benzoyl- and salicyl-hydra-zones of vanilline. furfural, and cinnamaldehyde. Zinc complexes of several substituted o-bydroxybutyrophenones and their oximes have been reported.60-62 Complexes of stoicheiometery ZnL2U have been reported where L = the a-nitroketonato-anion obtained from nitroacetone, 3,3-dimethyl-l-nitrobutan-2-one or 3-nitrocam-phor and L — bipyridyl or 1,10-phenanthroline.63... 

As alkyl groups are added to benzene, A ax shifts from 255 nm for benzene to 261 nm for toluene to 272 nm for hexamethylbenzene. Substituents bearing nonbonding electrons also cause shifts of A ,ax to longer wavelengths, e.g., from 255 nm for benzene to 257 nm for chlorobenzene, 270 nm for phenol, and 280 nm for aniline (e = 6,200-8,600). That these effects are the result of interaction of the 7r-electron system with the nonbonded electrons is seen dramatically in the spectra of vanillin and the derived anion (Fig. 6). Addition of two more nonbonding electrons in the anion causes A. to shift from 279 nm to 351 nm and e to increase. 

FIG. 6 Ultraviolet spectrum of (1) neutral vanillin and (2) the anion of vanillin. 

The catalytically active cationic complex is preformed by reaction of complex 12 with the strong acid HCIO4 the phenolic oxygen is protonated and the coordinative bond of the bidentate vanillin ligand to platinum is cleaved at this end. In contrast to the treatment of 12 with HCl, which gives an inactive chloro-platinum complex, the non-coordinating anion [0104] leaves a vacant coordination site on the central metal, thus rendering it catalytically active. 

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