Catechol 3-methyl

In the case of low temperature tar, the aqueous Hquor that accompanies the cmde tar contains between 1 and 1.5% by weight of soluble tar acids, eg, phenol, cresols, and dihydroxybenzenes. Both for the sake of economics and effluent purification, it is necessary to recover these, usually by the Lurgi Phenosolvan process based on the selective extraction of the tar acids with butyl or isobutyl acetate. The recovered phenols are separated by fractional distillation into monohydroxybenzenes, mainly phenol and cresols, and dihydroxybenzenes, mainly (9-dihydroxybenzene (catechol), methyl (9-dihydtoxybenzene, (methyl catechol), and y -dihydroxybenzene (resorcinol). The monohydric phenol fraction is added to the cmde tar acids extracted from the tar for further refining, whereas the dihydric phenol fraction is incorporated in wood-preservation creosote or sold to adhesive manufacturers. Naphthalene Oils. Naphthalene is the principal component of coke-oven tats and the only component that can be concentrated to a reasonably high content on primary distillation. Naphthalene oils from coke-oven tars distilled in a modem pipe stiU generally contain 60—65% of naphthalene. They are further upgraded by a number of methods. 

For the studied catechol methylation reaction the catalyst structure and surface properties can explain the catalytic behaviour As mentioned above, the reaction at 260-350°C has to be performed over the acid catalysts. Porchet et al. [2] have shown, by FTIR experiments, the strong adsorption of catechol on Lewis acid/basic sites of the Y-AI2O3 surface. These sites control the reaction mechanism. 

MDB 2-(Ethoxy methoxy) phenol 3-Methyl catechol Methyl -MDB ... 

Catechol methyl transferases require the catechol function to be present to bind to the Mg ion. In the search for p2-adrenoceptor selectivity to produce potent bron-chodilators with low cardiovascular effects, changing the 3,4-hydroxy grouping of the catechol to 3,5- or 3-hydroxyl, 4-methyl-hydroxy, proved to be important (Figure 7.25). These compounds now have much improved bioavailability and pharmacokinetics due to their resistance to catechol methyl transferases. 

Scheme 1. Reaction scheme in catechol methylation with strongly acid catalysts.

The reaction of catechol methylation by methanol in gas-phase over modified y-alumina was studied with the aim to correlate catalytic activity and selectivity to acid/base properties of the catalysts. Catalytic activity and selectivity towards guaiacol formation (0-alkylation) was found to increase with surface acidity. A 20-fold change in the O/C-methylation ratio was achieved by varying the catalyst acid/base properties, keeping constant the other reaction parameters. 

This work intends to correlate the catalytic activity and selectivity of catechol methylation to catalyst acid-base properties under constant reaction operating conditions. The work also aims at the study of the reaction selectivity towards O- or C-alkylated product formation through suitable catalyst modification. 

During the catechol methylation under the conditions used, three parallel reactions take place (see Figure 2). The rates of these pathways (R,) can be easily calculated from the data of Table 1, since Rj = Si (-Ri), where Si is the selectivity towards the monomethylated product Ai. The rise of acidity affects differently the rates of the reaction pathways for the phosphated alumina the rate of guaiacol formation (R2, O-methylation ) doubled and the rate of C-methylation pathways simultaneously decreased 1.5 times, if compared to pure Y-AI2O3. 

The reaction of catechol methylation in gas phase at temperatures below 300°C is seen to proceed efficiently over modified y-aluminas with moderate acid sites. At low catechol conversion (X < 0.05), O- and C-methylated products are formed in parallel reaction pathways. The 0/C methylation ratio has been regulated by varying acid/base properties of the catalyst. Modification of Y-AI2O3 by phosphoric acid was observed to increase the selectivity towards guaiacol formation (O-methylation) up to 82=0.89. The catalyst Mg (7.5 at.% )/ Y-AI2O3 showed the maximum selectivity towards 3-methyl catechol formation (C-methylation) to be 3=0.65. It means that a 20-fold change in the O/C methylation ratio was achieved, when the catalyst acidity was modified, keeping constant other reaction conditions. 

Guaiacol (Catechol methyl ether, o-hydroxy-aniaole, o-methoxyphenol)... 

Ashton, P.R., Odell, B., Reddington, M.V., Slawin, A.M.Z., Stoddart, J.F. and Williams, D.J. (1988) Isostructural Alternately-charged Receptor Stacks. The Inclusion Complexes of Hydroquinol and Catechol Methyl Ethers with Bisparaquat(l,4)cyclophane Angew. Chem. Int. Ed. Engl. 27,1550. 

Fig. 4. Protected catechol-methyl ethers and methylenedioxy analogs...

Catechol methyl ether, see M-00102 Catechol sulfonephthalein, see P-00433 Catechol violet, see P-00433 4-CatecholyIazo-4 -acetylaminobiphenyl, in... 

METHOD 4 [115]-80% phenol in aqueous H2SO4 soiution of pH 3 is brought to 50 C. 30% H2O2 is then added causing an exothermic reaction and a temperature of 15 C over 3-4 minutes time. 6% aqueous H2SO3 is added after 4.5 minutes, the solution quickly cooled and extracted with isopropyl acetone (Strike would think that another solvent like methyl ethyl ketone could be used) to give 60% catechol. 

Methyl Vinyl Ketone. Methyl vinyl ketone [78-94-4] (3-buten-2-one) is a colorless Hquid with a pungent odor. It is stable only below 0°C, and readily polymerizes on standing at room temperature. It can be inhibited for storage and transportation by a mixture of acetic or formic acid and hydroquinone or catechol (266). This ketone is completely soluble in water, and forms a binary azeotrope with water (85 MVK 15 H2O vol %) at 75.8°C. 

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. 

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). 

Both methyl aryl and methyl alkyl ethers are cleaved under these conditions. A methylenedioxy group, used to protect a catechol, is cleaved under similar conditions in satisfactory yield methyl and ethyl esters are stable (0-20°, 2 h). °... 

The cyclohexylidene ketal, prepared from a catechol and cyclohexanone (AI2O3/ TsOH, CH2CI2, reflux, 36 h), is stable to metalation conditions (RX/BuLi) that cleave aiyl methyl ethers. The ketal is cleaved by acidic hydrolysis (coned. HCl/ EtOH, reflux, 1.5 h, 20°, 12 h) it is stable to milder acidic hydrolysis that cleaves tetrahydropyranyl ethers (1 AHCl/EtOH, reflux, 5 h, 91% yield). ... 

Kondo maintained his interest in this area, and with his collaborators [62] he recently made detailed investigations on the polymerization and preparation of methyl-4-vinylphenyl-sulfonium bis-(methoxycarbonyl) meth-ylide (Scheme 27) as a new kind of stable vinyl monomer containing the sulfonium ylide structure. It was prepared by heating a solution of 4-methylthiostyrene, dimethyl-diazomalonate, and /-butyl catechol in chlorobenzene at 90°C for 10 h in the presence of anhydride cupric sulfate, and Scheme 27 was polymerized by using a, a -azobisi-sobutyronitrile (AIBN) as the initiator and dimethylsulf-oxide as the solvent at 60°C. The structure of the polymer was confirmed by IR and NMR spectra and elemental analysis. In addition, this monomeric ylide was copolymerized with vinyl monomers such as methyl methacrylate (MMA) and styrene. 

Catechol O-methyltransferase (COMT) is a widespread enzyme that catalyzes the transfer of the methyl group of S-adenosyl-l-methionine (AdoMet) to one of the phenolic group of the catechol substrate (Fig. 1). High COMT activity is found in the liver, kidney and gut wall... 

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