Celanese process

On the other hand, the catalytic oxidation of a n-butane, using either cobalt or manganese acetate, produces acetic acid at 75-80% yield. Byproducts of commercial value are obtained in variable amounts. In the Celanese process, the oxidation reaction is performed at a temperature range of 150-225°C and a pressure of approximately 55 atmospheres. ... 

The high concentration of LiOAc in the medium was proposed to induce the formation of a [Rhl2(CO)2(OAc)] " pentacoordinated dianionic species, which would activate the methyl iodide more rapidly than would the [Rhl2(CO)2]" species [19]. The net result of the Hoechst Celanese process is a better selectivity with regards to CO, since the WGS reaction is reduced by one order of magnitude [17]. 

In the BHC (Boots-Hoechst Celanese) process about 3500 tons of ibuprofen per annum are produced by Pd/PPh3-catalysed carbonylation of IBPE (Figure 9) in the presence of HC1, in organic media.446 447,459 461 However, a shortcoming of this process is the cumbersome separation of the Pd/PPh3 catalyst from the... 

Boots-Hoechst-Celanese process More recently, a shorter three-step catalytic route has been developed and is illustrated in the following scheme. Here, a Pd catalyzed carbonylation reaction is employed in the final step to introduce the carboxyl group. 

Scheme 65 Synthesis of paracetamol, Hoechst-Celanese process.

Because ibuprofen has been a successful drug on the market for almost 30 years with no patent protection since 1985, there is a widespread competition for commercial production of this product throughout the world. As a result, several practical and economical industrial processes for the manufacture of racemic ibuprofen (14) have been developed and are in operation on commercial scales.38 Most of these processes start with isobutylbenzene (15) and go through an isobutylstyrene3 4 or an acetophenone intermediate.42 The most efficient route is believed to be the Boots-Hoechst-Celanese process, which involves 3 steps from isobutylbenzene, all catalytic, and is 100% atom-efficient (Scheme 6.1).43 44... 

Celanese process for the manufacture of ibuprofen on a 3500-ton scale has been operating since 1992. In this process isobutyl benzene is acylated and then hydrogenated over a heterogeneous catalyst to give the appropriate precursor alcohol. This alcohol is then carbonylated. The overall synthetic scheme is shown by reaction 4.14. The conventional process for ibuprofen manufacture was based on six synthetic steps and generated a large amount of salt as a solid waste. 

The Boots-Hoechst-Celanese Process for Ibuprofen Synthesis... 

In 1997, the developers of the Boots-Hoechst-Celanese process were awarded the Presidential Green Chemistry Award, sponsored by the U.S. Environmental Protection Agency. 

The main promoters of this technology are Celanese, whose fust plant at Pampa, Texas (230,000 t/ycar) dates from 1952, and Huls, whose Marl plant (40,000 t/year) is now shut down. The Celanese process involves oxidation in the presence of cobalt or manganese salts, and in the Huls process conversion takes place without catalyst. Other process licensors include Distillers. Umon Carbide, etc. 

The para isomer is a key intermediate in the Hoechst Celanese process for the manufacture of paracetamol (p-acetaminophenol) [2] the ortho isomer can be used for the synthesis of salicylic acid. Other hydroxyarylketones of commercial importance also result from the Fries rearrangement, e. g. 2,4-dihydroxybenzophe-none, an intermediate in the preparation of UV absorbents [3], and diphenol monomers which can be used for the manufacture of advaneed polymers [4], etc. 

A striking example of this is the manufacture of ibuprofen using the Boots Hoechst-Celanese process based on homogeneous catalytic carbonylation of p-isobutylphenyl-ethanol as a key step. 

In 1960, quickly after the introduction of the Celanese process, Wacker-Chemie commercialized a liquid phase vinyl acetate process which represented and extension of its earlier acetaldehyde process wherein acetic acid was simply substituted for water. (See equation [19]. This chemical transformation is also referred to as oxidative acetoxylation.) As shown in Figure 2, wherein R=Ac, the liquid phase oxidative acetoxylation of ethylene utilized the same catalytic cycle as the Wacker-Chemie acetaldehyde process. 

M.J. Sansone (Celanese). Process for the production of polyhenzimidazole ultrafiltration membranes. US Patent 4693824, September 1987. 

Celanese process Wacker process BASF process Monsanto... 

CO loss due to the water-gas shift reaction. Thus, advantages of the more recent Celanese process compared to the conventional Monsanto process are lower raw material consumption, an increase in productivity, and lower capital costs per ton of product. 

The Hoechst-Celanese process for the manufacture of ibuprofen on a 3500-ton scale has been operating since 1992. In this process. 

---