Pyro gallol

The addition of celite or HyfloSupercel to increase the contact surface with the extraction solvent and help filtration is often utilized during extraction. In case of interaction of such filter aids with the food, treated sand can be employed instead. Weak bases such as NaHCOj, MgC03, or CaC03 (1 g/10 g sample) to neutralize acids liberated from tissues and antioxidants (0.1% BHT, 5% pyro-gallol, ascorbic acid, and sodium ascorbate) to avoid oxidation can be added during extraction. ... 

Figure 1 Chemical structure of (A) lophine (2,4,5-triphenylimidazol) and (B) pyro gallol.

HTAB has been used, on the one hand, to increase the CL intensity of the reaction of 2,6,7-trihydroxy-9-(4 chlorophenyl)-3-fluorene with hydrogen peroxide in alkaline solution, in the presence of traces of Co(II) as a catalyst [43]. As a consequence, a CL method has been established for determination of ultratraces of Co(II). On the other hand, HTAB micelles sensitize the CL oxidation of pyro-gallol with A-bromosuccimide in an alkaline medium [44], while anionic and nonionic surfactants inhibit the CL intensity of this reaction (Table 3). This sensitized process allows the determination of pyrogallol by flow injection in an interval of 5 X 10 7-3 X 10 5 M. 

The enzyme catalyzes the intradiol cleavage of catechol with the insertion of 2 atoms of molecular oxygen to form e/s.c/s-muconic acid. The enzyme also catalyzes the oxidation of various catechol derivatives, including 4-methylcatechol, 4-chloro-catechol, 4-formylcatechol (protocatechualdehyde), 4,5-dichlorocatechol, 3,5-di-chlorocatechol, 3-methylcatechol, 3-methoxycatechol, and 3-hydroxycatechol (pyro-gallol). All of these substrates give products having an absorption maximum at around 260 nm characteristic of t7s-c/s-muconic acid derivatives. However, when 3-methylcatechol is used as a substrate, the product formed shows an absorption maximum at 390 nm besides that at 260 nm. These two absorption maxima are found to be attributable to two different products, 2-hydroxy-6-oxo-2,4-heptadienoic acid (7), and 5-carboxy-2-methyl-2,4-pentadienoicacid(2-methylmuconic acid), (2) [Eq. (19)]96. ... 

Figure 8. Molecular weight of the caffeine-pyro-gallol complex determined by optical density measurement after sample was equilibrated at various relative humidities...

CCA preservatives interfere with the curing of any phenolic adhesive, but particularly so with tannin cold-sets. This is due to the higher capability of complexation Cu and Cr with ortho-diphenols (such as the catecholic and pyro-gallolic B rings of flavonoids). The problem is not grave under normal ambient gluing conditions, but it becomes more evident at ambient temperatures of 30 °C or higher. The problem, of course, lies with CCA as a wood preservative rather... 

The reaction is not practical for the preparation of phenol itself, but is used in the case of the tri-hydroxy benzene pyro-gallol or pyro-gallic acid, which is obtained by heating gallic acid, which is tri-hydroxy benzoic acidj as above. 

Compounds of this class are mostly of little character as dyestuffs. They are colourless and only form coloured salts. Keal dyestuffs are only obtained from phenols which contain two hydroxyl groups in the meta position, such as resorcin and pyro-gallol. Probably here also the condensation takes place in a para position to one hydroxyl group, and is therefore ortho to the... 

Uranium salts have been used as mordants for both silk and wool,4 as well as in calico printing. Uranium salts also produce a pleasing brown dye on textiles when the fabric is first heated with solutions of uranium salts, and then the color is fixed by reduction with potassium ferrocyanide, gallic acid, or pyro-gallol,... 

Roy, B.K. and Moulik, S.P. (2002) Functions of hydrotropes (sodium salicylate, proline, pyro-gallol, resorcinol and urea) in solution with special reference to amphiphile behaviors. Colloid Surf. A, 203, 155-166. 

Atwood and coworkers have extensively explored the interactions of pyrogal-lol[4]arene tetramers with each other in the self-assembly mode. They have shown that the hydroxyl groups along the aromatic perimeter of the six pyro-gallol[4]arene tetramers can interact to form essentially octahedral capsules, as illustrated in Fig. 8.5 [18]. These compounds form in a variety of solvents and they can enclose significant amounts of space. They can encapsulate guests such as the solvents from which they form [19]. These remarkable capsules comprise an early example of molecules that enclose specific volumes and in principle could be used as nanoreactors [20]. 

If the nanotubes hexameric doughnuts retained their structural integrity on the aqueous surface, their presence would leave void spaces on the aqueous surface at the close-packed state, hi fact, this was observed and the phenomenon is illustrated schematically in Fig 8.17. The hexagons superimposed on the circles indicate the void spaces leading to larger-than-expected estimated areas. The presence of these void spaces contrasts with the surface behavior of other pyro-gallol[4]arenes studied. 

Naturally occurring phenolic compounds such as catechol, resorcinol, pyro-gallol, salicylic, gallic, ferulic, caffeic, and coumaric acids all serve as germination inhibitors. Indeed, some of the selective herbicides such as the substituted phenols and cresols also serve as germination inhibitors. Because of the widespread occurrence of coumarin in plants and its demonstrated inhibitory effects at levels found in fruits and some seeds, it is considered to be a natural germination inhibitor (Lerner et al. 1959). In time, of course, coumarin is metabolized in resting seeds to a level below inhibition. 

CjjHjgNgO, /J.4(oder 5).Benzolazozy-pyro gallol-tribenzoat 16 II333. 

Vinyl- phenol Pyro- catechol Resor- cinol Hydro- quinone pyro- gallol Phloro- ghidnol Gallic acid class... 

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