Electrohydrodimerization process

HMDA) manufacturing processes. The two sets of metrics clearly show the tradeoffs for these processes. The hydrocyanation process has lower energy-intensity and greenhouse-gases metrics, but its material-intensity, water consumption and pollutants metrics are higher than those for the electrohydrodimerization process. 

The most powerful illustration to date of the ability of steady-state TG/SC measurements to identify short-lived intermediates in electrode processes comes from studies in which the radical anion of acrylonitrile (AN) was detected in the electrohydrodimerization reaction (8). Prior to these investigations, the mechanism of the AN electrohydrodimerization process was unclear. On the basis of SECM measurements, it was shown that the reaction proceeded analogously to other activated olefins, including those highlighted in Sec. III.B. Electrogeneration of the radical anion, R , is followed by dimerization and then protonation to yield the hydrodimer ... 

A series of electrolysis of pymvic acid were carried out at different fixed potentials in an undivided conventional three-electrode Pyrex cell (50 cm3). In sulfuric acid, the electrohydrodimerization process was favored (69%) when increasing the concentration of pymvic acid and the electrode potential ... 

Ethylene glycol can be produced by an electrohydrodimerization of formaldehyde (16). The process has a number of variables necessary for optimum current efficiency including pH, electrolyte, temperature, methanol concentration, electrode materials, and cell design. Other methods include production of valuable oxidized materials at the electrochemical cell s anode simultaneous with formation of glycol at the cathode (17). The compound formed at the anode maybe used for commercial value direcdy, or coupled as an oxidant in a separate process. 

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

As indicated, the reduction of an electron-deficient alkene renders a formally electropositive carbon center nucleophilic. The fields of electrohydrodimerization and electrohydrocyclization are a direct consequence of this realization [1, 2]. The former corresponds to the dimerization of an electron-deficient alkene via a process that couples the electron-deficient -carbons of the substrate. Overall, two electrons and two protons are consumed. Electrohydrocyclization is the intramolecular counterpart of this process. 

Like the electrohydrodimerization and electrohydrocyclizahon reactions, this process also requires the consumphon of two electrons and two protons. It has been shown to occur via a sequence consisting of electron transfer followed by a ratedetermining protonation of the resulting radical anion, addihon of a second electron to generate a carbanion, cyclization of the carbanion onto the carbonyl acceptor unit and the addition of the second proton [16]. Carbon acids like dimethyl malonate and malononitrile are often used as a proton source. The course of this and other... 

Without doubt, this is the best known cathodically-initiated cyclization. The transformation corresponds to the intramolecular variation of electrohydrodimerization [11-13], a process well known for its application to the preparation of adiponitrile [14]. 

The derivation of a similarly atypical rate expression is required for the simulation of the electrochemical behavior encountered in electrohydrodimerization studies. In these studies, the variation of the bulk concentration of the olefin (e.g., ethyl cinnamate, diethyl furmarate) reveals that there is a concentration dependence to the reaction order associated with the dimerization of the electrogenerated radical ion [33]. This variation in apparent reaction order with concentration can only be attributed to a two-step mechanism [25] involving two independent rate or equilibrium processes. A mechanism that meets this criterion and appears to fit the electrochemical data is the preequilibrium mechanism [36] in which the electrogenerated radical ions first engage in an equilibrium dimerization before the rate-determining ring closure of the dimer takes place. Symbolically, this mechanism may be written ... 

Baizer-Monsanto process — (also called Monsanto process) is the reductive electrohydrodimerization of acrylonitrile, ACN, to adipodinitrile, ADN, an intermediate in the manufacture of Nylon 66 ... 

The electrohydrodimerization of acrylonitrile was a milestone in the history of organic electrochemistry. The success of this process is associated with the name of Manuel M. Baizer. In 1960, he initiated the biggest success story of organic electrochemistry to date, namely, the Monsanto process for the hydrodimerization of ACN, acrylonitrile, to ADN, adipodinitrile (Scheme 3). 

Again the dimerization or coupling reactions will involve free radicals or radical ions, but the intermediates are generated cathodically. Suitable substrates are electrophiles such as activated olefins and carbonyl compounds. In this section, it is intended to focus only upon the electroreduction of activated olefins, partly because the electrode reactions of aldehydes and ketones has been discussed earlier. However, it is the electrohydrodimerization of an activated olefin that has become a successful, commercial electro-organic process, i.e., the electroreduction of acrylonitrile developed by Monsanto ... 

Intramolecular cyclization has been observed in several electrohydrodimerization reactions,another indication of the versatility of this type of electrode process. High yields of cyclopropanes, cyclopentanes, and cyclohexanes have been obtained from a,/8-unsaturated esters. 

The single most successful industrial process based upon organic electrochemistry is the electrohydrodimerization of acrylonitrile to yield adiponitrile, introduced commercially in 1965 by Monsanto. The discovery, development, and commercialization of this process have been described in detail in recent articles that provide excellent insight into the commitment that is required to bring a process to commercial success. 

Another large-scale industrial electrosynthesis process, first commercialized by Monsanto in 1965, is the electrohydrodimerization of acrylonitrile to produce adiponitrile (Grotheer et al., 2006 Sequeira Santos, 2009), used in the production of Nylon 66. 

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