Manufacture of Acetic Acid

Some of the process parameters for methanol carbonylation processes are compared in Table 4.1. 

The main byproduct forming reactions in the BASF and Monsanto processes are different. In the former it is the liquid phase Fischer-Tropsch-type reaction, that leads to the formation of products such as such as alkyl acetates, methane etc. In the Monsanto process it is the homogeneous water-gas shift reaction that produces C02 and H2 as byproducts. Also note that the Monsanto process is superior in terms of selectivity, metal usage and operating conditions. 

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Acetonylacetone is available commercially as a by-product of the manufacture of acetic acid from acetylene. It may be prepared by condensation of chloroacetone with ethyl sodioacetoacetate the resulting ethyl acetonylacetoacetate when heated with water under pressure at 160° undergoes ketonic scission to give acetonylacetone. 

The fermentative fixing of CO2 and water to acetic acid by a species of acetobacterium has been patented acetyl coen2yme A is the primary reduction product (62). Different species of clostridia have also been used. Pseudomonads (63) have been patented for the fermentation of certain compounds and their derivatives, eg, methyl formate. These methods have been reviewed (64). The manufacture of acetic acid from CO2 and its dewatering and refining to glacial acid has been discussed (65,66). 

Anhydrous Acetic Acid. In the manufacture of acetic acid by direct oxidation of a petroleum-based feedstock, solvent extraction has been used to separate acetic acid [64-19-7] from the aqueous reaction Hquor containing significant quantities of formic and propionic acids. Isoamyl acetate [123-92-2] is used as solvent to extract nearly all the acetic acid, and some water, from the aqueous feed (236). The extract is then dehydrated by azeotropic distillation using isoamyl acetate as water entrainer (see DISTILLATION, AZEOTROPIC AND EXTRACTIVE). It is claimed that the extraction step in this process affords substantial savings in plant capital investment and operating cost (see Acetic acid and derivatives). A detailed description of various extraction processes is available (237). 

Catalysts. Iodine and its compounds ate very active catalysts for many reactions (133). The principal use is in the production of synthetic mbber via Ziegler-Natta catalysts systems. Also, iodine and certain iodides, eg, titanium tetraiodide [7720-83-4], are employed for producing stereospecific polymers, such as polybutadiene mbber (134) about 75% of the iodine consumed in catalysts is assumed to be used for polybutadiene and polyisoprene polymeri2a tion (66) (see RUBBER CHEMICALS). Hydrogen iodide is used as a catalyst in the manufacture of acetic acid from methanol (66). A 99% yield as acetic acid has been reported. In the heat stabiH2ation of nylon suitable for tire cordage, iodine is used in a system involving copper acetate or borate, and potassium iodide (66) (see Tire cords). 

Acetic Acid. Manufacture of acetic acid [64-19-7] by homogeneous catalytic methanol carbonylation has become the leading commercial route to acetic acid (eq. 8) (34,35). 

Jeffreys GV (1964) A Problem in Chemical Engineering Design — The Manufacture of Acetic Acid, The Institution of Chemical Engineers, UK. 

It is now nearly 40 years since the introduction by Monsanto of a rhodium-catalysed process for the production of acetic acid by carbonylation of methanol [1]. The so-called Monsanto process became the dominant method for manufacture of acetic acid and is one of the most successful examples of the commercial application of homogeneous catalysis. The rhodium-catalysed process was preceded by a cobalt-based system developed by BASF [2,3], which suffered from significantly lower selectivity and the necessity for much harsher conditions of temperature and pressure. Although the rhodium-catalysed system has much better activity and selectivity, the search has continued in recent years for new catalysts which improve efficiency even further. The strategies employed have involved either modifications to the rhodium-based system or the replacement of rhodium by another metal, in particular iridium. This chapter will describe some of the important recent advances in both rhodium- and iridium-catalysed methanol carbonylation. Particular emphasis will be placed on the fundamental organometallic chemistry and mechanistic understanding of these processes. 

Uses Manufacture of acetic acid, acetic anhydride, aldol, aniline dyes, 1-butanol, 1,3-butylene glycol, cellulose acetate, chloral, 2-ethylhexanol, paraldehyde, pentaerythritol, peracetic acid, pyridine derivatives, terephthalic acid, trimethylolpropane, flavors, perfumes, plastics, synthetic rubbers, disinfectants, drugs, explosives, antioxidants, yeast silvering mirrors hardening gelatin fibers. 

Acetic Acid. Although at the time of this writing Monsanto s Rh-catalyzed methanol carbonylation (see Section 7.2.4) is the predominant process in the manufacture of acetic acid, providing about 95% of the world s production, some acetic acid is still produced by the air oxidation of n-butane or light naphtha. n-Butane is used mainly in the United States, whereas light naphtha fractions from petroleum refining are the main feedstock in Europe. 

A Wacker catalyst is used in this process, similar to that for the manufacture of acetic acid. Since the acetic acid can also be made from ethylene, the basic raw material is solely ethylene. A liquid-phase process has been replaced by a vapor-phase reaction run at 70 to 140 psi and 175 to 200°C. Catalysts may be (1) carbon-palladium chloride-cupric chloride (C-PdCl2-CuCl2), (2) palladium chloride-alumina (PdCl2-Al203), or (3) palladium-carbon-potassium acetate (Pd-C-KOAc). The product is distilled into water, acetaldehyde that can be recycled to acetic acid, and the pure colorless liquid, which is collected at 72°C. The yield is 95percent. 

Manufacture of acetic acid from ethyl alcohol... 

On the scene of industrial chemistry, too, many sizable advances have occurred. Among them are processes for production of vinyl acetate from ethyl-ene/02/acetic acid over a heterogeneous Pd-catalyst the manufacture of acetic acid by carbonylation of methanol using a transition metal complex homoge-... 

Manufacture of acetic acid and numerous other chemicals. Synthetic flavors. 

The Wacker process reached a maximum production capacity of 2.6 Mt/a worldwide in the mid 1970 s. The cause of the decline in the following years (1.8 Mt/a in 2003) was the increase in the manufacture of acetic acid (the most important product made from acetaldehyde) by the carbonylation of methanol. In future new processes for chemicals, such as acetic anhydride and alkylamines (which were also made from acetaldehyde) will probably further decrease its importance. With the growing use of syngas as feedstock, the one-step... 

The main large-scale metal catalyzed reactions involving addition of CO (rather than CO + H2) to an organic substrate are the manufacture of acetic acid from methanol and the related production of acetic anhydride from methyl acetate. The syntheses of some other carboxylic acids and the conversion of a substituted benzyl alcohol to ibuprofen involve similar reactions. 

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