Formic methanol, carbonylation

Although the term methanol carbonylation is usually associated with acetic acid manufacture, an alternative carbonylation pathway involves base-catalyzed addition of CO to alkoxide ions to provide a simple route to formate esters (see also the section Direct Synthesis of Methanol from CO/H2). In the case of methanol as the alkanol, the reaction is carried out industrially on a large scale to produce formic acid. The reaction proceeds at ca 30 bar and 80°C using sodium or potassium methoxide as the catalyst and involves nucleophilic attack of methoxide on CO ... 

Carbonylation and decarbonylation reactions of alkyl complexes in catalytic cycles have been reviewed . A full account of the carbonylation and homologation of formic and other carboxylic acid esters catalysed by Ru/CO/I systems at 200 C and 150-200 atm CO/H2 has appeared. In a novel reaction, cyclobutanones are converted to disiloxycyclopentenes with hydrosilane and CO in the presence of cobalt carbonyl (reaction 4) . The oxidative addition of Mel to [Rh(CO)2l2] in aprotic solvents (MeOH, CHCI3, THF, MeOAc), the rate determining step in carbonylation of methyl acetate and methyl halides, is promoted by iodides, such as Bu jN+I", and bases (eg 1-methylimidazole) . A further kinetic study of rhodium catalysed methanol carbonylation has appeared . The carbonylation of methanol by catalysts prepared by deposition of Rh complexes on silica alumina or zeolites is comparable with the homogeneous analogue . 

Hydrocarbon oxidation, for example, butane, butene, naphtha Methanol carbonylation None/Co-acetate 150-230 50 n-Butane 50, naphtha 40 Propanoic add, formic add (15-30)... 

The Seientific Design/Bethlehem Steel process for formic acid production is based on the methanol carbonylation route to methyl formate [87,98,99]. The methyl formate is subsequently hydrolyzed and the products separated to yield pure formic acid and methanol The methanol is recycled to the carbonylation reactor, and overall methanol usage is about 2 kg per 100 kg product [99]. The reaction of methyl formate and water to form formic acid is an equilibrium reaction performed at 0.3 MPa and 80°C, with a residence time of about Ih [87]. The overall process stoichiometry yields formic acid from CO and H2q according to the reactions... 

Formic acid is currently produced iadustriaHy by three main processes (/) acidolysis of formate salts, which are ia turn by-products of other processes (2) as a coproduct with acetic acid ia the Hquid-phase oxidation of hydrocarbons or (3) carbonylation of methanol to methyl formate, followed either by direct hydrolysis of the ester or by the iatermediacy of formamide. 

The carbonylation of methanol [67-56-1] to methyl formate ia the presence of basic catalysts has been practiced iadustriaHy for many years. Ia older processes for formic acid utili2ing this reactioa, the methyl formate [107-31-3] reacts with ammonia to give formamide [75-12-7] which is hydroly2ed to formic acid ia the preseace of sulfuric acid ... 

Coproductioa of ammonium sulfate is a disadvantage of the formamide route, and it has largely been supplanted by processes based on the direct hydrolysis of methyl formate. If the methanol is recycled to the carbonylation step the stoichiometry corresponds to the production of formic acid by hydration of carbon monoxide, a reaction which is too thermodynamicaHy unfavorable to be carried out directly on an iadustrial scale. 

Formic acid is made by the oxidation of formamide or by the liquid-phase oxidation of butane to acetic acid. The by-product source is expected to dry up in the future, and the most promising route to replace it is through carbonylation of methanol. 

In 1970 the transition metal catalyzed formation of alkyl formates from CO2, H2, and alcohols was first described. Phosphine complexes of Group 8 to Group 10 transition metals and carbonyl metallates of Groups 6 and 8 show catalytic activity (TON 6-60) and in most cases a positive effect by addition of amines or other basic additives [26 a, 54-58]. A more effective catalytic system has been found when carrying out the reaction in the supercritical phase (TON 3500) [54 a]. Similarly to the synthesis of formic acid, the synthesis of methyl formate in SCCO2 is successful in the presence of methanol and ruthenium(II) catalyst systems [54 b]. 

The Reppe hydrocarboxylation of acetylenes was initially carried out in the presence of an acid, but little was known about the function of the acid or the nature of the carbon monoxide transfer agent. Sternberg et al. found that diphenylacetylene can be hydrocarboxylated in alkaline solution and that in this case a nickel carbonyl anion is the source of carbon monoxide. When the hydrocarbon was shaken with a saturated solution of sodium hydroxide in methanol in the presence of excess nickel carbonyl under helium the reaction mixture turned dark red. After 80 hrs., acidification and workup aiforded a-phenyl-rru/is-cinnamic acid and 1,2,3,4-tetraphenyl-butadiene in the yields indicated. Note that the ciimamic acid results from cis addition of the elements of formic acid. 

Formic acid is produced as a by-product when acetic acid is manufactured by the oxidation of n-butane. This has been the primary source of the material in the United States since its introduction shortly after the end of World War II. In Europe, however, where the production of formic acid has a much longer history, it is produced by a variety of methods. These include acetic acid by-product by oxidation of hydrocarbons, but also by the acidolysis of formamide by sulfuric acid, acidolysis of alkali metal formates, and decomposition of sodium formate. It is also produced by a two-step process involving the carbonylation of methanol at moderate temperature and pressure. The temperature is 150°C (300 F) and the required pressure is 15-25 bars (215-365 psig). In this process, methanol is carbonylated in the presence of a sodium methoxide catalyst to form methyl formate. This is followed by hydrolysis of the methyl formate to form formic acid and methanol [15]. The chemistry is shown in Eqs. (25) and (26) ... 

In fact, over the last 30 years, the market as well as the supply situation for formic acid has been very dynamic. It has been affected by the development of several other major technologies. The commercialization of acetic acid by the carbonylation of methanol and the development of the Propylene ammoxidation process for acrylonitrile which replaced the cyanohydrin process both had a large impact on formic acid. 

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