Chloranilic acid, salts

A. Mercury(II) chloranilate method Discussion. The mercury(II) salt of chloranilic acid (2,5-dichloro-3,6-dihydroxy-p-benzoquinone) may be used for the determination of small amounts of chloride ion. The reaction is ... 

Mahrous et al. reported the use a spectrophotometric method for the determination of dipyridamole and other cardiovascular drugs using p-chloranilic acid [30]. Tablets, or aqueous solutions containing salts of dipyridamole and the other drugs, were rendered alkaline with aqueous... 

Chloranilic Acid.—Hydroxyl substitution products of quino e are important as they yield salts with bases which are intensely colored and therefore valuable as dyes. The most important one of these compounds is a di-hydroxyl product of a quinone related to anthracene and known as alizarin. A mixed chlorine and hydroxyl substitution product is the di-chlor di-hydroxy quinone. It is chloranil in which two of the chlorine atoms have been replaced by hydroxyl groups, and is known as chloranilic acid. 

With a, -dichloroketones such as chloranil or 2,3-dichloro-1,4-naphthoquinone, dithiocarbamic acid salts yield compounds 108 and... 

Derivatives of ubiquiaones are antioxidants for foodstuffs and vitamins (qv) (217,218). Ubichromenol phosphates show antiinflammatory activity (219). Chroman o1 compounds inhibit oxidation of fats and can be used ia treatment of macrocytic anemias (220). Monosulfate salts of 2,3-dimethoxy-5-methyl-6-substitutedhydroquiaone have been reported to be inhibitors of Hpid oxidation ia rats (221). Polymers based on chloranilic and bromanilic acid have been prepared and contain oxygenated quiaones (63), which are derived from 1,2,3,4-benzenetetrol (222). 

In extension of this work, Sugasawa and Yoshikawa have shown that d/- omolaudanosoline (XIII), on oxidation by chloranil in presence of acetic acid, also gives rise to a dehydro-product, which on methylation furnishes 2 3 11 12-tetramethoxy-8-methyl-6 7 15 16-tetrahydro-5 18 9 14-dibenzopyridocolinium salts (XIV). 

The much simpler steroid, 253, was fortuitously found to fulfill this role when injected into animals. Its lack of oral activity was overcome by incorporation of the 7a-thioacetate group. Reaction of the ethisterone intermediate, 77b, with a large excess of an organomagnesium halide leads to the corresponding acetylide salt carbonation with CO2 affords the carboxyllic acid, 251. This is then hydrogenated and the hydroxy acid cy-clized to the spirolactone. Oppenauer oxidation followed by treatment with chloranil affords the 4,6-dehydro-3-ketone (254). Conjugate addition of thiolacetic acid completes the synthesis of spironolactone (255), an orally active aldosterone antagonist. ... 

An alternative new synthetic approach to chrysene 1,2-dihydro-diol based on Method IV has recently been developed (60). This method (Figure 12) entails synthesis of 2-chrysenol via alkylation of 1-1ithio-2,5-dimethoxy-1,4-cyclohexadiene with 2-(1-naphthyl) e-thyl bromide followed by mild acid treatment to ge nerate the diketone 12. Acid-catalyzed cyclization of 12 gave the unsaturated tetracyclic ketone 13 which was transformed to 2-chrysenol via dehydrogenation of its enol acetate with o-chloranil followed by hydrolysis. Oxidation of 2-chrysenol with Fremy s salt gave chrysene... 

More recently, an environmentally benign method using air as oxidant has been developed for the oxidative cyclization of arylamine-substituted tricarbonyl-iron-cyclohexadiene complexes to carbazoles (Scheme 19). Reaction of methyl 4-aminosalicylate 45 with the complex salt 6a affords the iron complex 46, which on oxidation in acidic medium by air provides the tricarbonyliron-complexed 4a,9a-dihydrocarbazole 47. Aromatization with concomitant demetalation by treatment of the crude product with p-chloranil leads to mukonidine 48 [88]. The spectral data of this compound are in agreement with those reported by Wu[22j. 

If nitrogen and/or sulphur is present, acidify 3-4 ml of the fusion solution with dilute nitric acid and evaporate to half the original volume in order to expel any HCN and/or H2S which may be present. If nitrogen and sulphur are absent, proceed directly with 2 ml of the sodium fusion filtrate. Render the solution just neutral to litmus by the addition of dilute (5 m) aqueous ammonia solution, then add 5 drops of 5 m acetic acid and 20 mg of lanthanum chloranilate (2,5-dichloro-3,6-dihydroxy-p-benzoquinone, lanthanum salt) and shake intermittently for 10-15 minutes. Filter. A pink-violet coloration of the filtrate is a positive test for fluorine. 

Dithioacetic acid derivatives add to 1,4-benzo- or 1,4-naphthoquinones to give, after oxidation of the adduct with silver oxide or chloranil, the quinones 217 and 218 (69LA103). Quinones 218 were prepared also from 2,3-dichloro-1,4-naphthoquinone and salts of dithiocarbamic acids (51JA3459) and those of type 219 by oxidation of the corresponding hydroquinones. From reduction potentials and the semiquinone formation constants, it was concluded that their anion radicals are thermodynamically stable (86CC1489). 

Bisbenzene chromium reacts with good 77-acceptor Lewis acids to form complexes (CgHg)2Cr L" (L = tetracyanoethylene, trinitrobenzene, -quinone, chloranil) in which electron transfer from the (CgHg)2Cr to the Lewis acid has taken place. The complexes are best described as bisbenzene chromium cation salts of radical anions (765). The crystal structure of one such compound [(MeCgHg)2Cr] (TCNQ) (TCNQ = 7,7,8,8-tetracyanoquinodimethane) has been determined and consists of Stacks of TCNQ anions and bisbenzene chromium cations with interplanar spacings of 3.42 A (577). 

The micFobiologically important 4-oxoquinoline-3-carboxylic acid skeleton is formed by applying Dieckmann conditions to the diester (70.9) in which the NH is protected as its acyl derivative. Dehydrogenating agents such as chloranil do not always give good results when applied to the dihydroquinolinones thus produced. Better yields are obtained by electrolysis in acetic acid-t-butanol with a quaternary ammonium salt as electrolyte. With careful choice of conditions, a high yield of the deacylated quinolinone may be obtained. 

Some other reported curing agents are quinone [81], chloranil [81], anhydroformaldehyde aniline [82], methylolureas and melamines [83], ethylenediamine-formaldehyde products, and paraformaldehyde. Resorcinol novolac resins can be cured with paraformaldehyde [84] and the mildly acid nature of resorcinol helps to catalyze the curing reaction [84]. Ammonium salts have also been reported as accelerators for the curing of phenolic resins [85]. 

The ptdymer XXX in the Fe(II) state has a low ccmductivity (10 —10 crfun" cm ) but subsequent to partial oxMation with picric acid, benzoquinone, chloranil TCNQ produces intensely cdouied salts with maximum conductivities at 70% oxidaticm of lO times that of tiie parent Such increases also occur with poly(ferrocenylene) (XXXI) polymer (XXXII) ptdj ethynyl-ferrocene) (XXXIV) and pdy(3-vinylbisfulvalenedi-iron) (XXXIIl) upcm partial oxidation. Polymer XXXIV incorporates both a conjugated n and redox tems. 

Application of the oxygen-flask combustion method to the determination of fluorine in organic combination has now been made by a number of workers. The fluoride in solution after combustion may be determined by thorium nitrate titration or colorimetrically as the alizarin complexan chelate or with a chloranilate (see Halogen Acids and Salts, p. 302). A method based upon the alizarin complexan chelate is given in Appendix IV. 

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