Dates, phenolic acids

Both the free and the combined forms of phenolic acids in date fruit (Phoenix dactylifera L.) were analyzed by HPLC (19). The elution rate of phenolic acids increased with the degree of hydroxylation by isocratic elution using dioxane-acetic acid (15 85) on a /zBondapak C,8 column. Ferulic acid was the most abundant in the free form, and p-coumaric, vanillic, p-hydroxy-benzoic, protocatechuic, and syringic acid were also identified in dates. 

Eventually, several hydroxyphenyl alcohols and hydroxy-benzyl alcohols were identihed in tobacco and tobacco smoke by Hecht et al. (1561). These identifications were soon followed by the identification of a series of phenolic acids from tobacco by Snook et al. (3749, 3751). Table IX.A-5 summarizes the studies on phenols in tobacco smoke up to 1964. In Table IX.A-9, studies on phenols in tobacco smoke from 1964 to date are summarized. 

Some phenolic acid decarboxylases [60, 62-65] which catalyze the conversion of hydroxycinnamic acids into styrenes are also of interest. Considering the structural data available to date, both enzymes work with different mechanisms ... 

Figure 7.31 Among the compounds found in dates are phenolic acids and uncharacterized anthocyanins and carotenoids. Dates also contain procyanidin oligomers and polymers as well as luteolin, quercetin and apigenin glycosides.

To date, effecting the subsequent reaction chemistry (as hypothesized in Fig. 12.9) has not been possible in our laboratories. There have been indications that reaction of the epoxide quinone methide QM24 in chloroform with acetic acid may have opened the epoxide before rearomatizing the quinone methide moiety, but this is not well authenticated. However, all attempts to add phenols to this epoxide, particularly aimed at producing 8-0-4-ethers PI, have been unsuccessful. Similar reactions using QM25 have also failed. 

This preparative scheme leads to only 30% yield due to the side reactions between the meto-astatoaniline diazonium salt and astato-phenol, which cannot be eliminated even by continuous extraction of the product with n-heptane (167). All the astatophenols synthesized to date have been identified by either HPLC (99,104) or TLC (160,166,167). Their dissociation constants (KJ have been established from extraction experiments by measuring the relative distribution of compounds between aqueous borax buffer solutions and n-heptane as a function of acidity. On the basis of these derived values, the Hammett a-constants and hence the field (F) and resonance (R) effects have been estimated for these compounds (167) (see Table VI). The field effect for astatine was found to be considerably weaker than that for other halogens the resonance effect was similar to that for iodine (162). 

Duosol Process. The Duosol process developed by the Max B. Miller Co. (28) is an outstanding example of commercial adoption of a double solvent extraction process. Patents (27) for this process date from May 1933 and cover numerous aspects of the problem including a variety of paraffinic solvents (ethane, propane, butane, petroleum ether) and naphthenic solvents (wood tar acids, cresols, creosote, and phenol). Present commercial application utilizes propane and Selecto (a mixture of phenol and cresylic acid, normally ranging in composition from 20 to 80% phenol). 

The history of inclusion compounds (1,2) dates back to 1823 when Michael Faraday reported the preparation of the clathrate hydrate of chlorine. Other early observations include the preparation of graphite intercalates in 1841, the 3-hydroquinone H2S clathrate in 1849, the choleic acids in 1885, the cyclodextrin inclusion compounds in 1891, and the Hofmann s clathrate in 1897. Later milestones of the development of inclusion compounds refer to the tri-o-thymotide benzene inclusion compound in 1914, phenol clathrates in 1935, and urea adducts in 1940. 

Organosolv. Organosolv lignins are obtained as relatively low-molecular-weight entities by treatment of plant tissue with aqueous solutions of organic solvents, normally containing trace amounts of mineral acids (44) Solvents include ethanol, methanol, butanol, acetic acid, ethyl acetate, phenol, etc. To date, this approach has not been commercialized due to the quantities of organic solvents consumed and the low quality of the pulp fiber obtained. 

Manthey, J.A. Perkins-Veazie, P. 2009. Influences of harvest date and location on the levels of /i-carotene, ascorbic acid, total phenols, the in vitro antioxidant capacity, and phenolic profiles of five commercial varieties of mango (Mangifem indica L.). J. Agric. Food Chem. 57 10825-10830. 

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