Carbon to methanol

Recently, density functional computation on hydrogenation of dimethyl carbonate to methanol, catalysed by Ru(II)-PNN catalyst 2 supported a stepwise hydrogenation mechanism (Fig. 13) [83, 84]. A hydride/methoxide metathesis-based mechanism was suggested by DFT [85]. 

Scheme 9 Hydrogenation of cyclic carbonates to methanol and diols [86]...

Scheme 10 Catal5dic hydrogenation of (a) methyl and (b) benzyl carbonates to methanol...

Formaldehyde is readily reduced to methanol by hydrogen over many metal and metal oxide catalysts. It is oxidized to formic acid or carbon dioxide and water. The Cannizzaro reaction gives formic acid and methanol. Similarly, a vapor-phase Tischenko reaction is catalyzed by copper (34) and boric acid (38) to produce methyl formate ... 

In the early 1920s Badische Arulin- und Soda-Fabrik aimounced the specific catalytic conversion of carbon monoxide and hydrogen at 20—30 MPa (200—300 atm) and 300—400°C to methanol (12,13), a process subsequendy widely industrialized. At the same time Fischer and Tropsch aimounced the Synth in e process (14,15), in which an iron catalyst effects the reaction of carbon monoxide and hydrogen to produce a mixture of alcohols, aldehydes (qv), ketones (qv), and fatty acids at atmospheric pressure. 

Sodium iodide [7681-82-5] Nal, mol wt 149.92, mp 662°C, 84.66% I, forms colorless cubic crystals, which are soluble in water, ethanol, methanol, and acetone. It is used in photography, for the production of organic chemicals, and as an expectorant in cough medicines. Nal is separated by addition of sodium hydroxide or sodium carbonate to an acidic iodide solution (see also Expectorants, antitussives, and related agents). 

Because the synthesis reactions are exothermic with a net decrease in molar volume, equiUbrium conversions of the carbon oxides to methanol by reactions 1 and 2 are favored by high pressure and low temperature, as shown for the indicated reformed natural gas composition in Figure 1. The mechanism of methanol synthesis on the copper—zinc—alumina catalyst was elucidated as recentiy as 1990 (7). For a pure H2—CO mixture, carbon monoxide is adsorbed on the copper surface where it is hydrogenated to methanol. When CO2 is added to the reacting mixture, the copper surface becomes partially covered by adsorbed oxygen by the reaction C02 CO + O (ads). This results in a change in mechanism where CO reacts with the adsorbed oxygen to form CO2, which becomes the primary source of carbon for methanol. 

Fig. 1. Fquilihrium conversion of carbon oxides to methanol based on reformed natural gas composition of 73% H2, 15% CO, 9% CO2, and 3% CH ...

Equipment for storing and handling methanol may be made of carbon or stainless steel. Methanol is aggressive toward copper, zinc, magnesium, tin, lead, and alurninum, which should therefore be avoided. Gasket materials must also be chosen carefiiUy, because some elastomers swell and deteriorate when exposed to methanol. Similarly, the use of plastics for storage is not recommended. 

Magnesium methylate is sensitive to air and moisture, decomposing to magnesium hydroxide, carbonate, and methanol. It can be stored for one year in polyethylene bags under nitrogen or argon. 

Changing the atom bound to a methyl group from carbon to nitrogen to oxygen, as in going from ethane to methylamine to methanol, produces a decrease in the rotational barrier from 2.88 to 1.98 to 1.07kcal/mol. This closely approximates the 3 2 1 ratio of the number of H—H eclipsing interactions in these three molecules. 

Using cesium carbonate in methanol, Kellogg and coworkers were able to convert catechol and pentaethylene glycol into benzo-18-crown-6 in 74% yield. They found that the cesium salts in these reactions were usually equal or superior to the potassium salts. 

Alcoholic potassium hydroxide or sodium hydroxide are normally used to convert the halohydrins to oxiranes. Other bases have also been employed to effect ring closure in the presence of labile functional groups such as a-ketols, e.g., potassium acetate in ethanol, potassium acetate in acetone or potassium carbonate in methanol.However, weaker bases can lead to solvolytic side reactions. Ring closure under neutral conditions employing potassiunT fluoride in dimethyl sulfoxide, dimethylformamide or A-methyl-pyrrolidone has been reported in the patent literature. 

Mono-substitution occurs most readily in the stepwise replacement of the halogen substituents of 2,4,6-trichloro-s-triazine with aqueous methanol and sodium bicarbonate (30°, 30 min), the monomethoxy derivative (324) is obtained on heating (65°, 30 min), the disubstitu-ted derivative is formed and on brief heating (65°) with the more basic sodium carbonate or methanolic sodium hydroxide (25°, 3 hr) complete methoxylation (320) occurs. Ethanolic ethoxide (25°, 1 hr) or sodium carbonate (35°) is sufficient to give complete ethoxy-dechlorination. The corresponding phenoxy derivatives are obtained on treatment with one (0°), two (15°, 1 hr), or three equivalents (25-70°, 3 hr) of various sodium phenoxides in aqueous acetone. The stepwise reaction with phenols, alcohols, or thiols proceeds in better yield in organic solvents (acetone or chloroform) with collidine or 2,6-lutidine as acid acceptors than in aqueous sodium bicarbonate. ... 

For substituted lactones this method gave a low yield of the spiroketal 189 (<5%). For 5,6-dimethylvalerolactone a second scheme has been suggested involving treatment of ketoalcohol 190 with potassium carbonate in methanol to form enole ether acetal 191 in quantitative yield (90JOC5894). 

The third synthetic scheme is employed when the phenylthio substituent is in the a-position of the lactone function, which interferes with the cyclization (90JOC5894). Acetylenic ketone 194 (95% yield) is readily transformed to the acetal 195 (with potassium carbonate in methanol) however, under the above conditions neither its hydrolysis nor cyclization to the spiroketal occurs. The spirocyclic pyrone 197 is formed in quantitative yield on treatment of 195 with p-toluenesulfonic acid in a 4 1 THF-H2O mixture at reflux for 12 h. 

Aj Preparation of 3-Chloromethyl-6-Chloro-7-Sulfamyl-3,4-Dihydro-Benzothiadizine-1,1-Dioxide—Jo 8 ml of 40-50% chloroacetaldehyde aqueous solution and 7 ml of dimethyl-formamide are added 10 grams of 2,4-disulfamvl-5-chloroaniline. The mixture is heated on a steam bath for 2 hours after which it Is concentrated at reduced pressure. The residue Is triturated with water. The solid material is recrystallized from methanol-ether after-treatment with activated carbon to give 7.2 grams of product, MP 229°-230°C. 

The ethyl acetate solution is then washed with water, dried and evaporated. To remove any selenium still present, the residue is dissolved in 200 cc of methanol and mixed with 100 g of iron powder and 2 g of active carbon. The mixture is heated for 30 minutes with stirring under reflux, then filtered with suction, washed with methanol and the solution evaporated in vacuo. The residue is then chromatographed on 900 g of aluminum oxide. The residues of the evaporated benzene and ether fractions are treated with active carbon in methanol or acetone, evaporated again, and the residue recrystallized from a mixture of acetone and ether. There are obtained 17.5 g of pure 1-dehydro-17a-methyl-testosterone which melts at 163° to 164°C. 

Step C Preparation of 3-Morpholino-4-(3-tert-Butylamino-2-Oxopropoxy)-1,2,5-Thia-diazole — The 1-toluenesulfonyloxy-2-oxo-3-tert-butylaminopropane, prepared as described in Step B, (11 mols) is added to 0.80 N methanolic sodium methoxide (15 ml) at 0°C. The mixture is stirred for 15 minutes at 0° to 5°C, treated with 3-morpholino-4-hydroxy-1,2,5-thiadiazole (4.29 grams) and then refluxed for 16 hours. The solvent is evaporated in vacuo and the residue is treated with excess potassium carbonate to provide 3-morpholino-4-(3-butylamino-2-oxopropoxy)-1,2,5-thiadiazole. 

As an alternate to LNG, natural gas can be chemically converted to methanol, chemical feedstocks (such as ethylene), gasoline, or diesel fuel. Most processes start with the conversion of methane to synthesis gas, a mixture of carbon monoxide and hydrogen. This can be done partial oxidation, an exothermic reaction ... 

The C2-symmetric epoxide 23 (Scheme 7) reacts smoothly with carbon nucleophiles. For example, treatment of 23 with lithium dimethylcuprate proceeds with inversion of configuration, resulting in the formation of alcohol 28. An important consequence of the C2 symmetry of 23 is that the attack of the organometallic reagent upon either one of the two epoxide carbons produces the same product. After simultaneous hydrogenolysis of the two benzyl ethers in 28, protection of the 1,2-diol as an acetonide ring can be easily achieved by the use of 2,2-dimethoxypropane and camphor-sulfonic acid (CSA). It is necessary to briefly expose the crude product from the latter reaction to methanol and CSA so that the mixed acyclic ketal can be cleaved (see 29—>30). Oxidation of alcohol 30 with pyridinium chlorochromate (PCC) provides alde-... 

Cleavage of the acetate unit(s) in 5-acetoxy- and 3,5-diacetoxy-4-phenyl-l-benzothiepins 11 with potassium carbonate in methanol at room temperature does not stop at the diketone stage, but further undergoes ring contraction to the thiophene derivative 12 in 55-80% yield.90... 

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