Of catechols

That aqueous layer that was saved can be removed of most of its water by vacuum distillation, allowed to cool slightly then extracted with hot toluene. When the toluene cools, a few hundred more grams of catechol will crystallize out but will be contaminated with some heavy red bromo compounds. The crystals are filtered and vacuum distilled such that the pyrocatechol will distill over first, leaving the higher boiling bromo compounds behind. Yield is about 80% or 600g of catechol. 

METHOD 1 [112l-5g phenol in dH20 is stirred 5 hours at 20 C with some ferric sulfate (Fe2(S04)3, an additional 7mLs dH20, 13mLs 6% H2O2 and a pinch of aluminum oxide (AI2O3). Yield of catechol is 2.5g (50%). 

The best yield I ve achieved is 84g of benzodioxole from 110 of catechol. And to progress from here you ll probably need to do this reaction twice to get enough benzodioxole for the bromination."... 

Several oxygen- and sulfur-substituted boranes have been reported (125—130). 1,3,2-Benzodioxaborole [274-07-7] (catecholborane, CB) (15) is the one best studied. It is commercially available or can be prepared by the reaction of catechol with borane-THF (57,131), or by other procedures (132). The product is a Hquid existing as a monomer, remarkably stable to disproportionation. No... 

Conversion of Aromatic Rings to Nonaromatic Cyclic Structures. On treatment with oxidants such as chlorine, hypochlorite anion, chlorine dioxide, oxygen, hydrogen peroxide, and peroxy acids, the aromatic nuclei in lignin typically ate converted to o- and -quinoid stmctures and oxinane derivatives of quinols. Because of thein relatively high reactivity, these stmctures often appear as transient intermediates rather than as end products. Further reactions of the intermediates lead to the formation of catechol, hydroquinone, and mono- and dicarboxyhc acids. 

Dopamine. Dopamine (DA) (2) is an intermediate in the synthesis of NE and Epi from tyrosine. DA is localized to the basal ganglia of the brain and is involved in the regulation of motor activity and pituitary hormone release. The actions of DA are terminated by conversion to dihydroxyphenylacetic acid (DOPAC) by monoamine oxidase-A and -B (MAO-A and -B) in the neuron following reuptake, or conversion to homovanillic acid (HVA) through the sequential actions of catechol-0-methyl transferase (COMT) and MAO-A and -B in the synaptic cleft. 

A related homogeaous aqueous—alcohoHc system, composed of V(II) complexes of catechol and its derivatives, reduces N2 to ammonia and H2. Only catecholates are active ia this system, which is seasitive to pH. This system has beea likened to nitrogeaase by suggestiag that both use a sequeace of two four-electroa reductioas to evolve oae H2 for every N2 reduced (201). 

The dimethyl ethers of hydroquiaones and 1,4-naphthalenediols can be oxidized with silver(II) oxide or ceric ammonium nitrate. Aqueous sodium hypochlorite under phase-transfer conditions has also produced efficient conversion of catechols and hydroquiaones to 1,2- and 1,4-benzoquiaones (116), eg, 4-/-butyl-l,2-ben2oquinone [1129-21-1] ia 92% yield. 

The properties of 1,1-dichloroethane are Hsted ia Table 1. 1,1-Dichloroethane decomposes at 356—453°C by a homogeneous first-order dehydrochlofination, giving vinyl chloride and hydrogen chloride (1,2). Dehydrochlofination can also occur on activated alumina (3,4), magnesium sulfate, or potassium carbonate (5). Dehydrochlofination ia the presence of anhydrous aluminum chloride (6) proceeds readily. The 48-h accelerated oxidation test with 1,1-dichloroethane at reflux temperatures gives a 0.025% yield of hydrogen chloride as compared to 0.4% HCl for trichloroethylene and 0.6% HCl for tetrachloroethylene. Reaction with an amine gives low yields of chloride ion and the dimer 2,3-dichlorobutane, CH CHCICHCICH. 2-Methyl-l,3-dioxaindan [14046-39-0] can be prepared by a reaction of catechol [120-80-9] with 1,1-dichloroethane (7). 

The original commercial source of E was extraction from bovine adrenal glands (5). This was replaced by a synthetic route for E and NE (Eig. 1) similar to the original pubHshed route of synthesis (6). Eriedel-Crafts acylation of catechol [120-80-9] with chloroacetyl chloride yields chloroacetocatechol [99-40-1]. Displacement of the chlorine by methylamine yields the methylamine derivative, adrenalone [99-45-6] which on catalytic reduction yields (+)-epinephrine [329-65-7]. Substitution of ammonia for methylamine in the sequence yields the amino derivative noradrenalone [499-61-6] which on reduction yields (+)-norepinephrine [138-65-8]. The racemic compounds were resolved with (+)-tartaric acid to give the physiologically active (—)-enantiomers. The commercial synthesis of E and related compounds has been reviewed (27). The synthetic route for L-3,4-dihydroxyphenylalanine [59-92-7] (l-DOPA) has been described (28). 

The procedure described is similar to that of Dakin for the preparation of catechol. The reaction has been carried out using four times the quantities specified here the yield was 81% (C. F. H. Allen, private communication)... 

Wash with cone H2SO4, then Na2C03 soln, dry with anhydrous Na2C03, and finally pass through a 50cm column of activated alumina before distn. Alternatively, wash with 10% ferrous sulfate soln to remove peroxides, then H2O, dry with CaS04, and dist in vac. Add 0.2% of catechol to stabilise it. VERY TOXIC. 

Na2C03 soln, then fractionally distd in the presence of a small amount of catechol. 

Pedersen reasoned that there must have been a small amount of catechol present which had not been protected properly. This must have led to the formation of 1 in situ... 

The main product of the Elbs reaction is the 1,4-dihydroxybenzene (hydro-quinone). If the para position is already occupied by a substituent, the reaction occurs at an ortho position, leading to a catechol derivative although the yields are not as good as for a hydroquinone. Better yields of catechols 7 can be obtained by a copper-catalyzed oxidation of phenols with molecular oxygen ... 

An analogous sequence on the allyl ether of catechol (63) leads to oxyprenolol (64) in the same vein, ortbo-allylphenol (65) affords alprenolol (66). ... 

Azaloxan (12) is an antidepressant agent. Its synthesis can be accomplished starting with the reaction of catechol (7) and 3,4-dibromobutyronitrile (obtained by addition of bromine to the olefin) to give l,4-benzodioxan-2-ylacetonitrile (8). A series of functional group transformations ensues [hydrolysis to the acid (9), reduction to the alcohol (10) and conversion to a tosylate (11)] culminating in an SN-2 displacement reaction on tosylate 11 with l-(4-piperidinyl)-2-imidazolidi-none to give azaloxan (12) [3]. 

Catechol-O-Methyltransferase. Figure 3 Chemical structures of some inhibitors of catechol O-methylation. 

FIGURE 3-24 Electrophoretic separation of catechols with end-column detection. Detection potential, +0.8 V separation capillary, 20 kV The peaks correspond to 4.6 fmol dopamine (1), 4.1 fmol isoproterenol (2), and 2.7 fmol catechol (3). (Reproduced with permission from reference 60.)... 

Less is known about the mechanism than is the case for 19-3, but, as in that it seems to vary with the oxidizing agent. For oxidation of catechol with NaI04, it was found that the reaction conducted in H2 0 gave unlabeled quinone, " so the following mechanismwas proposed ... 

A solution of sodium methoxide (80 mmol) in methanol (40 mL) is added to silica gel (2.7 g, 45 mmol) followed by a solution of catechol (13.2 g, 120 mmol) in methanol (40 mL). The resulting mixture is stirred and heated under reflux for 18 h. The methanol is then evaporated and the solid residue washed with ether. The black sohd is dissolved in THF (400 mL) and the resulting solution is heated for 1 h in the presence of charcoal. After filtration and evaporation of the solvent the sodium tris(benzene-l,2-diolato)silicate 80 is isolated as a white powder (12.53 g, 70% Scheme 2.20) [93]. 

Pure cultures growing anaerobically with catechol and sulfate were isolated,and the carboxylation of catechol was proposed to be the initial reaction of anaerobic catechol degradation by Desulfobacterium sp. strain Cat2. Zhang and Young" proposed that the initial key reaction for anaerobic degradation of naphthalene and phenanthrene was also carboxylation. 

A 3,4-dihydroxybenzoate decarboxylase (EC 4.1.1.63) was purified from C. hydroxybenzoicum and characterized for the first time. The estimated molecular mass of the enzyme is 270 kDa. The subunit molecular mass is 57kDa, suggesting that the enzyme consists of five identical subunits. The temperature and pH optima are 50°C and pH 7.0, respectively. The Arrhenius energy for decarboxylation of 3,4-dihydroxybenzoate was 32.5 kJ mol for the temperature range from 22 to 50°C. The and for 3,4-dihydroxybenzoate were 0.6 mM and 5.4 X 10 min respectively, at pH 7.0 and 25°C. The enzyme catalyzes the reverse reaction, that is, the carboxylation of catechol to 3,4-dihydroxybenzoate, at pH 7.0. The enzyme does not decarboxylate 4-hydroxybenzoate. Although the equilibrium of the reaction is on the side of catechol, it is postulated that C. hydroxybenzoicum uses the enzyme to convert catechol to 3,4-dihydroxybenzoate. ... 

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