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Butadiene hydrogen cyanide addition

Hexamethylenediamine is now made by three different routes the original from adipic acid, the electrodimerization of acrylonitrile, and the addition of hydrogen cyanide to butadiene. Thus, the starting material can be cyclohexane, propylene, or butadiene. Currently, the cyclohexane-based route from adipic acid is the most costly and this process is being phased out. The butadiene route is patented by DuPont and requires hydrogen cyanide facilities. Recent new hexamethylenediamine plants, outside DuPont, are based on acrylonitrile from propylene, a readily available commodity. [Pg.136]

In an extension of an early work on the nickel-catalyzed addition of hydrogen cyanide to unsaturated compounds, a basic reaction in various large-scale processes in the polymer industry, the hydrocyanation of butadiene (equation 15) and the efficiency of catalysis of this reaction by low-cost copper salts has been studied extensively by Belgium researchers47,48. [Pg.556]

Copper-catalyzed monoaddition of hydrogen cyanide to conjugated alkenes proceeded very conveniently with 1,3-butadiene, but not with its methyl-substituted derivatives. The most efficient catalytic system consisted of cupric bromide associated to trichloroacetic acid, in acetonitrile at 79 °C. Under these conditions, 1,3-butadiene was converted mainly to (Z )-l-cyano-2-butene, in 68% yield. A few percents of (Z)-l-cyano-2-butene and 3-cyano-1-butene (3% and 4%, respectively) were also observed. Polymerization of the olefinic products was almost absent. The very high regioselectivity in favor of 1,4-addition of hydrogen cyanide contrasted markedly with the very low regioselectivity of acetic acid addition (vide supra). Methyl substituents on 1,3-butadiene decreased significantly the efficiency of the reaction. With isoprene and piperylene, the mononitrile yields were reduced... [Pg.556]

Hexamethylenediamine is discussed in Chapter 10, Sections 1 and 8. It is produced from adiponitrile by hydrogenation. Adiponitrile comes from electrodimerization of acrylonitrile (32%) or from anti-Markovnikov addition of 2 moles of hydrogen cyanide to butadiene (68%). [Pg.226]

Hydrogen cyanide can be added across olefins in the presence of Ni, Co, or Pd complexes (Scheme 56) (123). Conversion of butadiene to adiponitrile is a commercial process at DuPont Co. The reaction appears to occur via oxidative addition of hydrogen cyanide to a low-valence metal, olefin insertion to the metal-hydrogen bond, and reductive elimination of the nitrile product. The overall reaction proceeds with cis... [Pg.288]

Hydrogen cyanide smoothly adds to butadiene (BD) in the presence of zero-valent nickel catalysts to give (3PN) and (2M3BN) [1,4- and 1,2-addition products, respectively, Eq. (7)]. A variety of Ni[P(OR)3]4 (R = alkyl or aryl) complexes are suitable as catalysts. The reaction may be carried out neat or in a variety of aromatic or nitrile solvents at temperatures from 50-120°C. Whereas in many olefin hydrocyanations it is desirable to keep the HCN concentration very low to protect the nickel from degradation, with butadiene HCN may be added batchwise as long as the HCN concentration is kept near the butadiene concentration. In the case of batch reactions one must be cautious because of possible temperature rises of 50°C or more over a period of a few minutes. Under typical batch conditions, when Ni[P(OEt)3]4, butadiene, and HCN are allowed to react in a ratio of 0.03 1.0 1.0 at 100°C for 8 hr, a 65% conversion to 3PN and 2M3BN (1.5 1) is observed (7). [Pg.14]

Several reviews compile general aspects of the applications of transition metal catalyzed hydrocyanation of alkenes and alkynes1-6. This method is synthetically interesting since, starting from nonactivated alkenes. access is achieved not only to nitriles, but also to carboxylic acid derivatives, amines and isocyanates. Of industrial importance is the double addition of hydrogen cyanide to butadienes yielding adipodinitrile7,8. [Pg.389]

Hydrogen cyanide may, however, be added directly to alkenes e.g., butadiene gives adiponitrile (for Nylon) in the presence of palladium or zerovalent nickel phosphite catalysts25 which operate by oxidative-addition and transfer reactions (Chapter 24). [Pg.300]

In 1893, the French chemist Moreau described two routes for the synthesis of acrylonitrile that were based on the dehydration of either acrylamide or ethylene cyanohydrin [10]. There was very little interest in acrylonitrile until 1937 when synthetic rubber based on acrylonitrile-butadiene copolymers was first developed in Germany. A process based on the addition of hydrogen cyanide to acetylene was developed at that time and in the 1950s, the acrylic fiber industry provided the stimulus for further process developments. Today acrylonitrile is made commercially by one of three possible methods (a) from propylene, (b) from acetylene and hydrogen cyanide, and (c) from acetaldehyde and hydrogen cyanide. [Pg.816]

The hydrocyanation of alkenes and dienes has similarly provided an exceptionally useful process for the conversion of simple feedstocks into more complex structures. [Caution Hydrogen cyanide is a highly toxic gas.] The process is best known as a key step in the DuPont adiponitrile process, which involves the dihydrocyanation of 1,3-butadiene (Scheme 3-95). The overall sequence first involves butadiene hydrocyanation to afford a mixture of 3-pentenenitrile and 2-methyl-3-butenenitrile. The unwanted branched isomer 2-methyl-3-butenenitrile is isomerized to 3-pentenenitrile under different conditions, and then 3-pentenenitrile is isomerized to 4-pentenenitrile in a subsequent nickel-catalyzed process in the presence of Lewis acidic additives. Finally, hydrocyanation of the remaining alkene generates the desired product adiponitrile, which serves as a precursor for nylon. A vast number of studies describing the optimization and mechanistic study of this process has appeared, and the interested reader is referred to the many excellent studies describing the details of this process. " ... [Pg.404]

The 16-electron complex NiLj (L = tris-o-tolylphosphite) catalyses the addition of hydrogen cyanide to ethene and to 1,3-butadiene below 25°C. A catalytic cycle for ethene based on the alternant formation of 16- and 18-electron intermediates is shown in Fig. 12.3. The inner route is considered to be the more likely, but the outer one cannot be excluded. If DCN is used instead of HCN, deuterium appears at both the a and positions in the resulting GHjCH CN. This shows that the addition of Ni—H (Ni—D) to is reversible. [Pg.364]

Hydrogen cyanide is a large volume-hazardous chemical that serves diverse functions. DuPont is the single largest manufacturer of HCN in the world, producing 500 million pounds each year, both for internal use in synthesis and for external sales. The majority of HCN manufactured at DuPont is used internally, primarily for adiponitrile synthesis en route to production of nylon. In that case, HCN is reacted with butadiene to produce adiponitrile, an intermediate in the manufacture of nylon polymer. In addition, over one million lbs per year are shipped out in gas cylinders (approximately 4000 cylinders/year). [Pg.48]

The catalyst is similar for all three steps, and consists of a zero valent nickel phosphite complex, promoted with zinc or aluminium chlorides. The direct addition of hydrogen eyanide to butadiene is particularly attractive with the availability of by-product hydrogen cyanide form the manufactnie of acrylonitrile by the ammoxidation of propylene. [Pg.287]

Cases in which allyl radicals display sufficient reactivity to participate successfully in radical chain reactions include the addition of bromotrichloromethane to butadiene the reaction of cyclopentadiene with tosyl cyanide, the addition of thiols , stannanes " and hydrogen halides . All these reactions follow the simple two-step radical chain mechanism depicted in Scheme 1, and the low reactivity of the intermediate allyl radicals can be compensated by using the trapping agent in excess or even as the solvent. In chain reactions with three or more chain-carrying radicals, this compensation is not possible anymore, because the concentration of the reaction partners has to be chosen such that the selectivity requirements for all intermediate radicals are satisfied. Complex radical chain reactions with polyenes as one of the reactants are therefore not known. [Pg.627]


See other pages where Butadiene hydrogen cyanide addition is mentioned: [Pg.549]    [Pg.68]    [Pg.963]    [Pg.224]    [Pg.555]    [Pg.119]    [Pg.180]    [Pg.489]    [Pg.2]    [Pg.42]    [Pg.258]    [Pg.489]    [Pg.555]    [Pg.555]    [Pg.16]    [Pg.963]    [Pg.287]    [Pg.438]    [Pg.209]    [Pg.567]    [Pg.1578]    [Pg.20]    [Pg.136]   
See also in sourсe #XX -- [ Pg.963 ]




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1.3- Butadiene addition

Addition, hydrogenation

Additives, hydrogenated

Cyanides hydrogen cyanide

Cyanides, addition

Hydrogen cyanid

Hydrogen cyanide

Hydrogen cyanide addition

Hydrogenated butadiene

Hydrogenative addition

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