1.2- Dimethoxybenzene, pyridination

With the oxides which are nitrated as the cations the difficulties are much less serious for the use of an acidity function is not involved. Comparison of 2,6-dimethoxy- and 3,5-dimethoxy-pyridine i-oxide with wt-dimethoxybenzene (which is nitrated at the encounter rate)... 

Halophenols without 2,6-disubstitution do not polymerize under oxidative displacement conditions. Oxidative side reactions at the ortho position may consume the initiator or intermpt the propagation step of the chain process. To prepare poly(phenylene oxide)s from unsubstituted 4-halophenols, it is necessary to employ the more drastic conditions of the Ullmaim ether synthesis. A cuprous chloride—pyridine complex in 1,4-dimethoxybenzene at 200°C converts the sodium salt of 4-bromophenol to poly(phenylene oxide) (1) ... 

All the 3-diazoindazoles 2, irradiated in an aromatic solvent (benzene, p-chlorotoluene, benzonitrile, 1,2-dimethoxybenzene), gave by ring substitution the corresponding 3-arylindazoles in variable yields (66LA17). 3-Diazoindazole 2b, irradiated in pyridine and in thiophene, gave the 6-chloro-3-(2-pyridyl)-indazole and the 6-chloro-3-(2- or 3-thiophenyl)-indazole (66LA17). 

I. 4-methoxyacetophenone (30 //moles) was added as an internal standard. The reaction was stopped after 2 hours by partitioning the mixture between methylene chloride and saturated sodium bicarbonate solution. The aqueous layer was twice extracted with methylene chloride and the extracts combined. The products were analyzed by GC after acetylation with excess 1 1 acetic anhydride/pyridine for 24 hours at room temperature. The oxidations of anisyl alcohol, in the presence of veratryl alcohol or 1,4-dimethoxybenzene, were performed as indicated in Table III and IV in 6 ml of phosphate buffer (pH 3.0). Other conditions were the same as for the oxidation of veratryl alcohol described above. TDCSPPFeCl remaining after the reaction was estimated from its Soret band absorption before and after the reaction. For the decolorization of Poly B-411 (IV) by TDCSPPFeCl and mCPBA, 25 //moles of mCPBA were added to 25 ml 0.05% Poly B-411 containing 0.01 //moles TDCSPPFeCl, 25 //moles of manganese sulfate and 1.5 mmoles of lactic acid buffered at pH 4.5. The decolorization of Poly B-411 was followed by the decrease in absorption at 596 nm. For the electrochemical decolorization of Poly B-411 in the presence of veratryl alcohol, a two-compartment cell was used. A glassy carbon plate was used as the anode, a platinum plate as the auxiliary electrode, and a silver wire as the reference electrode. The potential was controlled at 0.900 V. Poly B-411 (50 ml, 0.005%) in pH 3 buffer was added to the anode compartment and pH 3 buffer was added to the cathode compartment to the same level. The decolorization of Poly B-411 was followed by the change in absorbance at 596 nm and the simultaneous oxidation of veratryl alcohol was followed at 310 nm. The same electrochemical apparatus was used for the decolorization of Poly B-411 adsorbed onto filter paper. Tetrabutylammonium perchlorate (TBAP) was used as supporting electrolyte when methylene chloride was the solvent. 

In a subsequent study using diphenylnitrenium ion, several intermediates were detected. With 1,3,5-trimethoxybenzene or 1,3-dimethoxybenzene, the decay of the nitrenium ion occurred concurrently with the appearance of sigma adducts (141, Fig. 13.69). These were characterized on the basis of their absorption maxima and their behavior toward pyridine bases. On the other hand, when readily oxidized arenes, such as AW-dimethylanihne were employed, the characteristic ion radicals were detected (Fig. 13.70). ... 

The following chemicals were obtained from Aldrich Chemical Company, Inc. and used without further purification 1,3-dimethoxybenzene (99%) butyl lithium (1.6 M in hexanes) 1-formylpiperdine (99%) boron trifiuoride-diethyl ether (purified, redistilled) 2,3-dichloro-5,6-dicyano-l,4-benzo-quinone (98%), and pyridine hydrochloride (98%). All solvents were reagent grade and were obtained from Fisher Scientific and used without further purification except where noted. Silica gel (230-400 mesh) was obtained from EM Scientific. Chloroform was stored over activated, 4-A molecular sieves for at least 24 h prior to use. Tetrahydrofuran (optima grade) was distilled from sodium benzophenone. Pyrrole (99%) was obtained from Aldrich Chemical Company, Inc. and distilled from calcium hydride. 

In all the aprotic solvents (with no proton donor admixtures), the superoxide ion generally cannot act as an oxidant, taking into account a wide range of functionally substituted compounds. For example, in dry pyridine, 07 does not oxidize 1,2-dimethoxybenzene (Sawyer Gibian 1979). This ion, however, reacts with 1,2-dihydroxybenzene. For the OH form, the first step consists of proton transfer from the hydroxyl group to the superoxide ion. Next, reactions proceed with the participation of HOO. The latter is formed according to the disproportionation of Scheme 1-70. 

A mixture of 21.2 g. of l-(l,l-dimethylheptyl)-3,5-dimethoxybenzene and 55 g. of pyridine hydrochloride was heated at reflux and stirred for 51/2 hours. The reaction mixture then was cooled to room temperature and added to 150 mL. of water. The aqueous solution was extracted several times with diethyl ether, and the ethereal extracts were washed with water and dried. Removal of the solvent by evaporation under reduced pressure provided the product as a solid residue. The solid was recrystallized from 40 mL. of n-hexane to afford 13.0 g. of 5-(l,l-dimethylheptyl)resorcinol. M.R 97°-99° C. 

The test molecules were 1,2-dimethoxybenzene [52] and benzo[b]pyridine (or quinoline) [53] in Ti02 aqueous suspensions. Added SOD markedly decreased the removal rates of these molecules and furthermore changed the distribution of the intermediate products. In particular, in the case of quinoline [53], it was very detrimental to the formation of the intermediate products attributed to the reaction of the quinolinium radical cation with superoxide. In addition, control experiments showed that the SOD effect was not due to a competition between SOD and the test molecules [52],... 

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