Monsanto adiponitrile process

The Monsanto adiponitrile process, first commercialized in 1965 (65—67), involves the dimerization of acrylonitrile at the cathode in an electrolytic cell (eq. 7) ... 

Monoterpenoid ketones, 24 536-541 Monoterpenoids, 24 468, 470, 472, 484-541 Monothiocarboxylic acids, 23 739 Monotropic phase transitions, 15 101 Monounsaturated fatty acids, 10 830 Monounsaturated olefins, hydrogenation of, 26 879-880 Monovinylacetylene, 1 230 Monsanto acetic acid process, 19 646 Monsanto adiponitrile process, 17 236 Monsanto aluminum chloride-based Alkylation process, 23 333 Monsanto Prism separator, 16 21 Monsanto process (Lummus-UOP Classic process), 16 74 23 339, 341 Monsanto-Washington University collaboration, 24 390, 400-401 Montanic acid... 

Figure 19.16. Basic designs of electrolytic cells, (a) Basic type of two-compartment cell used when mixing of anolyte and catholyte is to be minimized the partition may be a porous diaphragm or an ion exchange membrane that allows only selected ions to pass, (b) Mercury cell for brine electrolysis. The released Na dissolves in the Hg and is withdrawn to another zone where it forms salt-free NaOH with water, (c) Monopolar electrical connections each cell is connected separately to the power supply so they are in parallel at low voltage, (d) Bipolar electrical connections 50 or more cells may be series and may require supply at several hundred volts, (e) Bipolar-connected cells for the Monsanto adiponitrile process. Spacings between electrodes and membrane are 0.8-3.2 mm. (f) New type of cell for the Monsanto adiponitrile process, without partitions the stack consists of 50-200 steel plates with 0.0-0.2 ram coating of Cd. Electrolyte velocity of l-2 m/sec sweeps out generated Oz.

During fhel970s, bofh a larger plant and a second plant were built. These expansions employed a second-generation, undivided cell design, with an emulsified reaction medium composed of 7% acrylonitrile in an aqueous solution of 15% disodium hydrogen phosphate with a low concentration (0.4%) of a quaternary ammonium salt. More information on the Monsanto adiponitrile process are found in [28-30, 42 (Part III), 65, 66]. 

The history of the Monsanto adiponitrile process demonstrates well the development of a synthetic process[1,23-25]. The first electrolytic process for the hydrodimerization of acrylonitrile was introduced on a 14,000 tons/year scale in 1965. The late 1970 s saw a large expansion of this process both in the UK and USA and it now produces some 200,000 tons adiponitrile/year. At least the recent cell houses are based on quite different technology to that used in the first plant and this has allowed large reductions in both capital investment and energy consumption. 

Danley, D.E. (1984) Development and commerciahsation of the Monsanto adiponitrile process. Journal of the Electrochemical Society, 135, 435C 142C. 

The application of electrochemistry in organic synthesis had already served to bring on stream in the United States in 1965 Monsanto s first industrial adiponitrile process from acrylonitrile. This was followed in 1977 by a similar installation in Seal Sands, England, which was later bought up by BASF. 

Ever since Monsanto commercialized their adiponitrile process in 1965 by electrolytic reductive coupling of acrylonitrile, a number of attempts at the commercialization of electrochemical reductions have been made. None of these attempts has succeeded in producing the tonnages involved in the adiponitrile process of approximately 100 000 tonne p.a. on plants both in the U.K and the U.S.A. However a number of significant tonnage production operations have been built and are outlined below. 

Like in the first example of the BASF acetal process, a unique feamre of organic electrochemistry is employed. In this case the desired product is elegantly generated at the cathode in one step with only one substrate and water as proton source. The first main developments have been conducted at Mmisanto by M. M. Baizer and his colleagues [24, 25]. Therefore, this adiponitrile process is often referred to as Monsanto process. As the electrohydrodimerization appeals by its atom efficiency, the realization of this efficiency has not been easy. The electrohydrodimerization takes place at quite negative potential [26]. In addition the needed proton source delivers at the... 

Adiponitrile is made commercially by several different processes utilizing different feedstocks. The original process, utilizing adipic acid (qv) as a feedstock, was first commercialized by DuPont in the late 1930s and was the basis for a number of adiponitrile plants. However, the adipic acid process was abandoned by DuPont in favor of two processes based on butadiene (qv). During the 1960s, Monsanto and Asahi developed routes to adiponitrile by the electrodimerization of acrylonitrile (qv). 

A.sahi Chemical EHD Processes. In the late 1960s, Asahi Chemical Industries in Japan developed an alternative electrolyte system for the electroreductive coupling of acrylonitrile. The catholyte in the Asahi divided cell process consisted of an emulsion of acrylonitrile and electrolysis products in a 10% aqueous solution of tetraethyl ammonium sulfate. The concentration of acrylonitrile in the aqueous phase for the original Monsanto process was 15—20 wt %, but the Asahi process uses only about 2 wt %. Asahi claims simpler separation and purification of the adiponitrile from the catholyte. A cation-exchange membrane is employed with dilute sulfuric acid in the anode compartment. The cathode is lead containing 6% antimony, and the anode is the same alloy but also contains 0.7% silver (45). The current efficiency is of 88—89%, with an adiponitrile selectivity of 91%. This process, started by Asahi in 1971, at Nobeoka City, Japan, is also operated by the RhcJ)ne Poulenc subsidiary, Rhodia, in Bra2il under Hcense from Asahi. 

EHD [Electrohydrodimerization] Also known as Electrodimerization. An electrolytic process for converting acrylonitrile to adiponitrile. See Monsanto. 

Monsanto (1) A process for making adiponitrile, an intermediate in the manufacture of Nylon 66, by the electrolytic hydrodimerization (EHD) of acrylonitrile ... 

The original process used aqueous tetraethylammonium ethylsulfate as the electrolyte, a lead cathode, and a lead-silver alloy anode. The Mark II process, commercialized in the mid-1970s, uses an emulsion of acrylonitrile in aqueous sodium phosphate containing a salt of the hexamethylene-bis-(ethyldibutylammonium) cation. The process was invented in 1959 by M. M. Baizer at Monsanto Corporation, St. Louis, MO. It was commercialized in 1965 and has been continuously improved ever since. The process is also operated in Japan by Asahi Chemical Industry Company. In 1990, the world production of adiponitrile by this process was over 200,000 tonnes per year. 

UCB-MCI [Union Chimique—Chemische Bedrijven and Ministry of Chemical Industry for the USSR] An EHD process for making adiponitrile, differing from the Monsanto process in using an emulsion of acrylonitrile and in not using a membrane. 

Baizer, working at the Monsanto Company, showed that good yields of adiponitrile are obtained from aqueous solutions by reduction at mercury or lead in the presence of a high concentration of quaternary ammonium salt [62]. Tetraethyl-ammonium toIuene-4-sulphonate was favoured as electrolyte. The first commercial plant operating the process was commissioned in 1965. It used a divided cell system with a lead cathode and aqueous tetraethylammonium ethylsulphate as electrolyte, with the addition of acid to regulate the pH. A lead anode with an anolyte of dilute sulphuric acid was employed. 

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