Hydrogen methanol solution

The oxidative reaction of furan with bromine in methanol solution or an electrochemical process using sodium bromide produces 2,5-dimethoxy-2,5-dihydrofuran (19), which is a cycHc acetal of maleic dialdehyde. The double bond in (19) can be easily hydrogenated to produce the corresponding succindialdehyde derivative. Both products find appHcation in photography and as embalming materials, as well as other uses. 

Manufacture. The manufacture of 1,4-cyclohexanedimethanol can be accompHshed by the catalytic reduction under pressure of dimethyl terephthalate ia a methanol solution (47,65). This glycol also may be prepared by the depolymerization and catalytic reduction of linear polyesters that have alkylene terephthalates as primary constituents. Poly(ethylene terephthalate) may be hydrogenated ia the presence of methanol under pressure and heat to give good yields of the glycol (see Polyesters) (66,67). 

Solutions of NaBH in methanol, and to a lesser degree ethanol, are subject to a similar decomposition reaction that evolves hydrogen these solutions can be stabilized by alkaU. The solubiUty of NaBH in lower aUphatic alcohols decreases as the carbon chain length increases, but the stabiUty increases. Solutions in 2-propanol and /-butanol are stable without alkaU (22,24). 

Hydrogen peroxide has also been analy2ed by its chemiluminescent reaction with bis(2,4,6-trichlorophenyl) oxalate and perylene in a buffered (pH 4—10) aqueous ethyl acetate—methanol solution (284). Using a flow system, intensity was linear from the detection limit of 7 x 10 M to at least 10 M. 

Nitroso compounds are formed selectively via the oxidation of a primary aromatic amine with Caro s acid [7722-86-3] (H2SO ) or Oxone (Du Pont trademark) monopersulfate compound (2KHSO KHSO K SO aniline black [13007-86-8] is obtained if the oxidation is carried out with salts of persulfiiric acid (31). Oxidation of aromatic amines to nitro compounds can be carried out with peroxytrifluoroacetic acid (32). Hydrogen peroxide with acetonitrile converts aniline in a methanol solution to azoxybenzene [495-48-7] (33), perborate in glacial acetic acid yields azobenzene [103-33-3] (34). 

Nucleophilic aromatic substitutions involving loss of hydrogen are known. The reaction usually occurs with oxidation of the intermediate either intramoleculady or by an added oxidizing agent such as air or iodine. A noteworthy example is the formation of 6-methoxy-2-nitrobenzonitrile from reaction of 1,3-dinitrobenzene with a methanol solution of potassium cyanide. In this reaction it appears that the nitro compound itself functions as the oxidizing agent (10). 

Anhydro-bases derived from quaternary )S-carbolinium salts are reduced to p /r-A-substituted-l,2,3,4-tetrahydro-j8-carboline derivatives on hydrogenation over Adams catalyst in methanol solution made alkaline to ensure the presence of anhydro-base. ... 

Catalytic hydrogenation (Pd/C) of 2-chloro-3-nitro-l,5-naphthyridine (125, R = Cl) in methanolic solution afforded 3-amino-l,5-naphthyridine (126, R = H, 74%) isolated in the form of its trihydrochloride (40MI1). Similar Pd/C hydrogenation of 2-ethoxy-3-nitro-l,5-naphthyridine (125, R = OEt) gave 3-amino-2-ethoxy-l,5-naphthyridine (126, R = OEt, 47%) (80RTC83). Reduction with tin(II) chloride in hydrochloric acid also leads to 126, (R = OEt, 73%) (63RTC997). 

Electron transfer initiated photocyclization of a methanolic solution of 90 followed by catalytic hydrogenation gave a mixture of benzoindolizines 91 and tetrahydroquinoline. Hydrogenation is necessary to stabilize one of the proposed products (82TL919, 83JA1204) (Scheme 17). 

Substituted perhydropyrido[l,2-a]pyrazine-l,4-diones were obtained when methyl A-[2-(benzyloxycarbonylamino)acetyl]-4-substituted pipecoli-nates were hydrogenated over 10% Pd/C catalyst in MeOH, and then the methanolic solutions were refluxed (00JAP(K)00/86659). 

When addition is complete the mixture is heated under reflux during 5 hours and then the acetone is removed by distillation. The residue is dissolved in water, acidified with hydrochloric acid and the mixture extracted with chloroform. The chloroform extract is stirred with sodium hydrogen carbonate solution and the aqueous layer is separated. The alkaline extract is acidified with hydrochloric acid and filtered. The solid product is drained free from oil on a filter pump, then washed with petroleum ether (BP 40° to 60°C), and dried at 50°C. The solid residue, MP 114° to 116°C, may be crystallized from methanol (with the addition of charcoal) to give p-chlorophenoxyisobutyric acid, MP 118° to 119°C. 

On evaporation of the ethyl ether from the ethyl ether solution, the benzhydryl ether was recovered as a pale yellow oil. The benzhydryl ether was dissolved in 60 ml of isopropanol and the isopropanol solution acidified to a pH of 3 with dry hydrogen chloride-methanol solution. The acidic propanol solution was then diluted with ethyl ether until a faint turbidity was observed. In a short time, the crystalline hydrochloride salt of the benzhydryl ether separated from the propanol solution. The crystallized salt was recrystallized once from 75 ml of isopropanol with the aid of ethyl ether in order to further purify the material. A yield of the pure hydrochloride salt of 1-methylpiperidyl-4-benzhydryl ether of 24.5 grams was obtained. This was 39% of the theoretical yield. The pure material had a melting point of 206°C. 

A mixture of 1 gram of 2-hydroxymethylene-dihydrotestosterone, 10 cc of pyridine and 2 cc of propionic anhydride was allowed to react at room temperature for 16 hours and then poured into water. The resulting suspension was heated for 1 hour on the steam bath to hydrolyze the excess of propionic anhydride, cooled and extracted with methylene dichloride. The extract was consecutively washed with dilute hydrochloric acid, sodium bicarbonate solution and water, dried over anhydrous sodium sulfate and evaporated to dryness under vacuum. There was thus obtained the dipropionate of 2-hydroxymethylene-dihydrotestosterone which was treated with hydrogen, in methanol solution. 

A solution of 1.7 g of 2-hydroxymethyl-3-benzyloxy-(1-hydroxy-2-tert-butyl-aminoethyl)py-ridine in 30 ml of methanol containing 1.2 ml of water is shaken with 700 mg of 5% palladium-onatmospheric pressure. In 17 minutes the theoretical amount of hydrogen has been consumed and the catalyst is filtered. Concentration of the filtrate under reduced pressure provides 1.4 g of the crude product as an oil. Ethanol (5 ml) Is added to the residual oil followed by 6 ml of 1.75N ethanolic hydrogen chloride solution and, finally, by 5 ml of Isopropyl ether. The precipitated product is filtered and washed with isopropyl ether containing 20% ethanol, 1.35 g, melting point 182 (dec.). 

Fuel cells can run on fuels other than hydrogen. In the direct methanol fuel cell (DMFC), a dilute methanol solution ( 3%) is fed directly into the anode, and a multistep process causes the liberation of protons and electrons together with conversion to water and carbon dioxide. Because no fuel processor is required, the system is conceptually vei"y attractive. However, the multistep process is understandably less rapid than the simpler hydrogen reaction, and this causes the direct methanol fuel cell stack to produce less power and to need more catalyst. 

Hydrogenation of exocyclic, pyranoid vinyl ethers could afford a mixture of both possible 6-deoxy-D and L-hexoses. Our observations show that the proportion of each isomer is dependent upon the catalyst and the substituents on the vinyl ether. Thus, treatment of a methanol solution of l,2,3,4-tetra-0-acetyl-6-deoxy-/ -D-xylo-hex-5-eno-pyranose (12) with hydrogen in the presence of a palladium catalyst afforded a mixture which was shown by gas chromatography to contain 96% of the 6-deoxy-D-gluco isomer (11) and 4% of the 6-deoxy-L-ido isomer (13). In this... 

Whereas reduction of dimethyl 1,2,7-trimethyl-l T/-azepine-3,6-dicarboxylate (5) with platinum and hydrogen in cyclohexane yields the hexahydroazepine 6, hydrogenation in methanol solution results in loss of methylamine and formation of dimethyl 2,3-dimethylbenzene-1,4-dicar-boxylate (52% mp 66-67 C).239... 

A methanolic solution of a V-alkyl-2-nitroaniline (13.3 mmol) was hydrogenated at 20 C and atmospheric pressure in the presence of Raney nickel, filtered and treated with coned HCI (1.32 mL, 13.3 mmol), followed by sodium dicyanimide (1.17 g, 13.1 mmol) in H20 (5 mL). The mixture was heated in an open vessel on a steam bath for 1 h, by which time most of the McOH had evaporated. The resulting suspension of a black oil was treated with a solution of picric acid (6.0 g, 26.2 mmol) in MeOH, whereupon the dipicrate of the product separated as yellow crystals. 

Weiss et al. [75] have synthesized Na and Zn salt of sulfonated styrene(ethylene-co-butylene)-styrene triblock ionomer. The starting material is a hydrogenated triblock copolymer of styrene and butadiene with a rubber mid-block and PS end-blocks. After hydrogenation, the mid-block is converted to a random copolymer of ethylene and butylene. Ethyl sulfonate is used to sulfonate the block copolymer in 1,2-dichloroethane solution at 50°C using the procedure developed by Makowski et al. [76]. The sulfonic acid form of the functionalized polymer is recovered by steam stripping. The neutralization reaction is carried out in toluene-methanol solution using the appropriate metal hydroxide or acetate. 

The transient response of DMFC is inherently slower and consequently the performance is worse than that of the hydrogen fuel cell, since the electrochemical oxidation kinetics of methanol are inherently slower due to intermediates formed during methanol oxidation [3]. Since the methanol solution should penetrate a diffusion layer toward the anode catalyst layer for oxidation, it is inevitable for the DMFC to experience the hi mass transport resistance. The carbon dioxide produced as the result of the oxidation reaction of methanol could also partly block the narrow flow path to be more difScult for the methanol to diflhise toward the catalyst. All these resistances and limitations can alter the cell characteristics and the power output when the cell is operated under variable load conditions. Especially when the DMFC stack is considered, the fluid dynamics inside the fuel cell stack is more complicated and so the transient stack performance could be more dependent of the variable load conditions. 

FIGURE 10. Effects of addition of 200 pL of 30% hydrogen peroxide solution on methanol... 

The thermodynamic standard potential of the methanol electrode has a value of + 0.02 V (RHE) that is, it is quite close to the hydrogen electrode potential. The steady-state potential of a platinum electrode in aqueous methanol solutions is about + 0.3 V (RHE). 

Water insoluble tetrabutylammonium metaperiodate, which can be prepared from sodium metaperiodate and tetrabutylammonium hydrogen sulphate in aqueous solution, was found to be a useful reagent for the selective oxidation of sulphides in organic solvents . The reaction was generally carried out in boiling chloroform and gave dialkyl, alkyl aryl and diaryl sulphoxides in yields which are comparable with those reported for sodium metaperiodate in aqueous methanol solution (Table 4). In the case of diaryl sulphoxides, the yields decrease with prolonged reaction time. 

Jing, D., Zhang, Y., and Guo, L. (2005) Study on the synthesis of Ni doped mesoporous Ti02 and its photocatalytic activity for hydrogen evolution in aqueous methanol solution. Chemical Physics Letters, 415 (1-3), 74—78. 

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