Pyrocatechol derivatives

Mono- and polyl dric phenols and enols frequently form characteristically colored complexes with Fe + ions [4, 28, 29]. Here monohydric phenols usually produce reddish-violet colors, while pyrocatechol derivatives yield green chelates [4]. Detection of acetone using Legal s test is based on the formation of an iron complex [4]. The same applies to the thioglycolic acid reaction of the German Pharmacopoeia (DAB 9) [4, 30]. 

Compounds from Pyrocatechol, Resorcinol and Quinol.—These three phenols yield compounds of the type (C6H5)4Cr.O.C6H4OH. C6H4(OH)2 the pyrocatechol derivative consists of orange columns, M.pt. 153 5° C., the resorcinol compound is a microcrystalline product, M.pt. 180° to 181° C., and the quinol compound forms yellow needles, decomposing at 206° C. 

The chemistry of silicon oxygen compounds with SiOs and SiC>6 skeletons in aqueous solution is of special interest. It has been speculated that such Si(IV) complexes with ligands derived from organic hydroxy compounds (such as pyrocatechol derivatives, hydroxycarboxylic acids, and carbohydrates) may play a significant role in silicon biochemistry by controlling the transport of silicon. 

The relationship of structure to activity is discussed on the basis of measurements performed in the presence of 0.05 mole of antioxidant per kg. of polypropylene. The results obtained at lower concentrations (0.01 and 0.025 mole/kg.) showed some differences in details. On the other hand, almost identical relationships were found (45) in stabilizing polypropylene at higher antioxidant concentrations (0.1 mole/kg.). Analysis of those concentration relationships supports our assumption that the activity of pyrocatechol derivatives is influenced above all by reactions between the peroxidic bodies and antioxidants in the oxidation chain-breaking mechanism. 

Oxygen reacts very eagerly with radicals but it is not a good inhibitor, mainly because it leads to the production of labile peroxides. In addition, its concentration in the stored monomer is usually low. Antioxidants of the phenol or aniline type are themselves very inefficient inhibitors. However, they significantly reduce the rate of 02 consumption when the latter is present [71]. This probably occurs by way of ROO decomposition to non-radical products so that ROO propagation is prevented [72]. More recently, therefore, the kinetics and mechanism of the inhibition effects of antioxidants (hydroquinone, pyrocatechol derivatives, etc.) in radical polymerizations and copolymerizations have been studied mainly in the presence of oxygen [73, 74],... 

Besides the membrane materials described above, several other membrane materials have been investigated. Aminated [44,45] and carboxylated [46,47] PVC membranes were used for covalent attachment of ionophore to the matrix and showed to have improved adhesion to the gate oxide. These membranes were also used in ion-selective electrodes and showed to be ion-sensitive up to about 50 days, but had the disadvantage of being pH dependent. Membrane adhesion to the gate oxide can also be enhanced by using Urushi latex as membrane material. Urushi latex mainly consists of Urushiol which is a mixture of 3-substituted pyrocatechol derivatives... 

A few polysubstituted benzenes have been evaluated for their possible use in protozoal chemotherapy. RC-12 (57) is a pyrocatechol derivative, which was initially found to possess promising antimalarial activity. However, in clinical trials against P. vivax it failed to protect volunteers exposed to infected mosquitoes [16]. Another compound ethyl 4-acetamido-2-ethoxybenzoate (ethopabate, 58) has been found to exhibit anticoccidial activity [45,57]. Also some nitrobenzamides have been shown to have anticoccidial properties. The important drugs of this class are zoalene (59) [58], nitromide (60) [59] and alkomide (61) [45,60]. The detailed SAR on nitrobenzamides has been studied [59,61]. 

In addition to BF4 , other anionic boron complexes, also forming ion-associates with basic dyes, have been applied to determine boron, namely 2,4-dinitro-1,8-naphthalenediol and Brilliant Green (formula 4.26) (toluene, e = 1.0-10 at 637 nm [41 3], 2,6-dihydroxy-benzoic acid, and Malachite Green (chlorobenzene, e = 9.5-10 [5], 2,3-dihydroxy-naphthalene and Crystal Violet (benzene, e = 8.8-10 [44]), mandelic acid, and Malachite Green (benzene, e = 6.5-10 ) [45,46], pyrocatechol derivatives, and Ethyl Violet (toluene, e = 1.05-10 [47,48]. The ion-pair of the salicylate complex of boron with ferroin has also been proposed (CHCI3) [49]. 

Among a number of pyrocatechol derivatives being potential reducing agents we have found the compound which does not reduce silver. The complexation prevents t he r edox r eaction. Interaction o f s ilver i ons with (2,3-dihydroxy-4,6-di-tert-butylphenylthio)-acetic acid (L) results in formation of the Ag(L)2 complex. 

Pyrimidines la 266,438,439 lb 32,430 Pyrimidine nucleoside derivatives lb 290 Pyrocatechol lb 170,172,185 -, 4-rerr-butyl- lb 201 Pyrocatechol derivatives lb 119 Pyrocatechol violet reagent la 398 Pyrogallol lb 383,399,400 Pyrogallol derivatives lb 312 Pyrolysis of organic substances la 92,96 a-Pyrone derivatives la 288 lb 387,388 Pyrrole lb 268,270 Pyrrole alkaloids la 66 lb 279 Pyrrole derivatives la 266.269,270 lb 63 Pyrrolidine derivatives lb 290 Pynolizidine alkaloids lb 243,246,291... 

Urushiol yu- rii-she- 61, ii-, - ol [ISV, fr. Japanese urushi lacquer -f ISV -ol] (1908) n. A mixture of pyrocatechol derivatives with saturated or unsaturated side chains of 15 or 17 carbon atoms that is an oily toxic irritant principle present in poison ivy and some related plants (genus Rhus) and in oriental lacquers derived from such plants. Langenheim JH (2003) Plant resins chemistry, evolution ecology and ethnobotany. Timber Press, Portland, OR Paint pigment, drying oils, polymers, resins, naval stores, cellulosics esters, and ink vehicles, vol 3. American Society for Testing and Material, Conshohocken, PA, 2001. 

---