Trihydroxy Benzenes

Beilstein Handbook Reference) AI3-08848 Benzene, trihydroxy Benzene, 1,3,5-trihydroxy- Benzene-1,3,5-triol Benzene-s-triol 1,3,5-Benzenetriol BRN 1341907 CCRIS 4147... 

Dihydroxy-5-[(ZZZZ)-heptadec-5,8,11,14-tetraenyl]benzene 1,3,5-Trihydroxy-2- [(ZZZZ)-octadec-1 -oxo-6,9.12,15-tetraenyl]benzene Alkenylhydroquinone... 

Alkylphenols, -chlorophenols, dihydroxy benzene, trihydroxy benzenes, biphenols [132]... 

A mixture of 10 g of the glyoxylic acid, 100 ml of acetic anhydride, and 0.5 g of 2,4-dinitrobenzenesulfonic acid is stirred at 25° for 2 hr. Sodium acetate (0.5 g) is added and the mixture concentrated in vacuum at 50°. The residue is taken up in 100 ml of benzene and washed with two portions of 2.5 N sodium hydroxide to remove the remaining acetic anhydride. The benzene solution is washed with water, dried and concentrated in vacuum to dryness. Crystallization from 40 ml of absolute ethanol gives 9.8 g (85%) of 3a,20,23-trihydroxy-16a-methyl-11 -oxo-21 -norchola-17(20),22-dienoic acid-24(20)-lactone 3,23-diacetate mp 165-175°. 

The enol lactone (12.7 g) is added to 157 ml of 0.5 M perbenzoic acid in benzene and allowed to stand at 25° for 140 hr. The solution is cooled to 15° and 15% sodium bisulfite solution is added to neutralize the excess peracid. The organic layer is separated and washed with saturated sodium bicarbonate solution and water. The benzene solution is dried over anhydrous sodium sulfate, filtered and concentrated to 30 ml. The product is crystallized by adding 80 ml of petroleum ether, filtered and washed with petroleum ether to yield 12.8 g (98%) of 3a,20,23-trihydroxy-16a-methyl-17(20)-oxido-ll-oxo-21-norchol-22-enoic acid-24(20)-lactone 3,23-diacetate mp 225-227°. 

The residue (12 g) which contains the 18-iodo-18,20-ether is dissolved in 200 ml of acetone, 5 g of silver chromate is added Note 3) and after cooling to 0°, 11.8 ml of a solution of 13.3 g of chromium trioxide and 11.5 ml of concentrated sulfuric acid, diluted to 50 ml with water is added during a period of 5 min. After an additional 60 min, a solution of 112 g of sodium acetate in 200 ml of water is added and the mixture diluted with benzene (400 ml), filtered and the benzene layer separated. The aqueous phase is reextracted with benzene, washed with half-saturated sodium chloride solution, dried and evaporated to yield 11.2 g of a crystalline residue. Recrystallization from ether gives 7.2 g (72%) of pure 3/5, 1 la, 20/5-trihydroxy-5a-pregnan-18-oic acid 18,20 lactone 3,11-diacetate mp 216-218°. 

The crude product obtained above is dried in high vacuum and then dissolved in 4 cc of pyridine. About 3 cc of acetic anhydride is added. The mixture is then heated on the steam bath for about 15 minutes and then evaporated to dryness in vacuo. About 20 cc of water is added. The product is then extracted into 150 cc of ethyl acetate, washed with saturated sodium bicarbonate solution and water, and dried over sodium sulfate. The solvent is removed in vacuo to give a residue which is crystallized from ethyl acetate-benzene to yield about 250 mg of 11/3,17a,21-trihydroxy-6,16a-dimethyl-20-oxo-2 -phenyl-4,6-pregnadieno-[3,2-c] pyrazole 21-aCetate, as described in U.S. Patent 3,300,483. 

J/3,5a,6(3- Trihydroxy-6oi, 17a-Dimethyl-17 -Carbometboxyandrostane (IV) 3(3-Acetoxy-5a-hydroxy-17a-methyl-17/3-carbomethoxyandrostan-6-one (III, 1.004 g) is dissolved in dry benzene (25 ml) and methyl magnesium bromide solution in ether (3M, 10 ml) is added. 

Phloroglucinol (1,3,5-Trihydroxy benzene, 1,3,5-Trioxy-benzol in Ger). C6H3(OH)3,mw 126.11, white to yellowish crysts mp 200—209° when heated slowly 212—217° when heated rapidly bp, sublimes with decompn. SI sol in w, sol in ale and eth. Combustible. Can be prepd by fusion of resorcinol with caustic soda, or by reduction of trinitrobenzene. It is highly toxic. by ingestion, inhalation and skin absorption, and is a strong irritant to skin and mucous membranes Refs 1) Beil 6,1092, (545) [1075]... 

Kresge et a/.498 have drawn attention to the fact that detritiation of [3H]-2,4,6-trihydroxy- and [3H]-2,4,6-trimethoxy-benzenes by concentrated aqueous perchloric acid gives correlations of log rate coefficient with — H0 with slopes of 0.80 and 1.14 respectively. Protonation to give the carbon conjugate acids is, however, governed by h0lA0 and h0l 9S, respectively, which suggests that the difference in kinetic acidity dependence is a property of the substrate and should not be interpreted as a major difference in mechanism. The kinetic difference can be eliminated by an appropriate comparison of kinetic and equilibrium acidity dependencies. In equation (230)... 

The reaction mixture from acidified dihydroxyacetone also included a series of seven di- and tri-hydroxybenzenes (see Scheme 4), namely, 2,3-dihydroxytoluene (16), pyrocatechol (17), 3,4-dihydroxy toluene (19), 3,5-dimethyl-l,2-benzenediol (20), 1,2,3-trihydroxybenzene (pyrogallol) (21), 1,2,4-trihydroxy benzene (22), 3,4,5,6-tetrahydroxy-2-methy 1-acetophe-none, and 2,3-dihydroxy-5,6-dimethyl-p-benzoquinone. Many of these same phenolic compounds are present after hexoses are similarly treated... 

PYROGALLIC ACID 1.2.3- Benzenetriol, Pyrogaliol, 1.2.3- Trihydroxy-benzene NL 1 1 0 ... 

SAMPLE SOLUTION (a) Like the dihydroxybenzenes, the isomeric trihydroxy-benzenes have unique names. Pyrogallol, used as a developer of photographic film, is 1,2,3-benzenetriol. The three hydroxyl groups occupy adjacent positions on a benzene ring. 

In the initial stages of this analytical method the proanthocyanidins are cleaved by acid catalysis into their constitutive subunits. Proanthocyanidin extension subunits, upon cleavage, form unstable electrophilic intermediates. Phloroglucinol (1,3,5-trihydroxy-benzene) is added to the reaction mixture as a nucleophile, where it combines with extension subunit intermediates to form analyzable adducts. 

De la Hoz et al. have studied the microwave-assisted synthesis of substituted coumarins by the condensation of phenol, 1,3-dihydroxybenzene/l,3,5-trihydroxy-benzene and propynoic/propenoic acids55. The examples illustrate that the application of heterogeneous supported catalysts can eliminate the production of acidic waste streams, associated with conventional Lewis acid catalysts. This synthetic approach constitutes an interesting alternative to the Pechman reaction (Scheme 3.34). 

For phenol one can compare the effects of hydroxy and methoxy substituents. Scheme 19 shows effects of O-methyl substitution on pATas for protonation of a benzene ring containing one, two, and three hydroxy substituents. The pK s for di- and trihydroxy-substituted and methoxy-substituted benzenes were measured directly by Kresge et al.68 Again the stabilities of the hydroxy-substituted cations in water are consistently greater than methoxy. The importance of solvation in controlling these effects is demonstrated by the inversion of relative pK s of trihydroxy and trimethoxy benzene in concentrated solutions of perchloric acid.68 Thus the difference in p/fas is matched by a... 

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