Chlorination cuprous chloride catalyst

At one time, the only commercial route to 2-chloro-1,3-butadiene (chloroprene), the monomer for neoprene, was from acetylene (see Elastomers, synthetic). In the United States, Du Pont operated two plants in which acetylene was dimeri2ed to vinylacetylene with a cuprous chloride catalyst and the vinyl-acetylene reacted with hydrogen chloride to give 2-chloro-1,3-butadiene. This process was replaced in 1970 with a butadiene-based process in which butadiene is chlorinated and dehydrochlorinated to yield the desired product (see Chlorocarbonsandchlorohydrocarbons). 

Derivation (1) Reaction of adipic acid and ammonia (catalytic vapor phase) to yield adiponitrile, followed by liquid-phase catalytic hydrogenation. (2) Chlorination of butadiene followed by reaction with sodium cyanide (cuprous chloride catalyst) to 1,4-dicyanobutylene and hydrogenation. 

The orientation of the addition of HC1 to a variety of halogen-substituted 1,3-butadienes has been extensively studied under preparative conditions39-43. The results are given in Table 3. No significant polymerization was observed and the products were in all cases those resulting from a 1 1 addition process. The regiochemistry control by the position of the chlorine atom was quite versatile. A Cl at C(l) favored formation of the 4,3-adduct whereas with Cl on C(2) the 1,4-adduct predominated. The competition between substitution by chlorine and methyl attenuated but did not markedly modify this orientation. However, all these reactions were quite slow and took from 5 to 10 h, even in the presence of a catalyst (mostly cuprous chloride). Therefore, product... 

Analysis of the white solid showed a high chlorine content, presumably derived from the catalyst, cuprous chloride, used to form the trimer. Preliminary analytical studies indicated the starting reactant was similar in structure to isoprene, the starting material for synthetic rubber. Because of the structural similarity, the starting material, now known to be 2-chloro-1,3-butadiene, was dubbed chloroprene. In fact, it was derived from the dimer and was found to be readily synthesized from the reaction of the dimer and hydrogen chloride. 

Typically, butadiene is chlorinated in the vapour phase at 330—420 C and atmospheric pressure. The major products are the isomeric 1,4-dichlorobut-2-ene and 3,4-dichlorobut-l-ene. The mixture is then treated with sodium cyanide in the presence of cuprous chloride at 80—95°C to give predominantly 1,4-dicyano-but-2-ene. This is hydrogenated in the vapour phase over a palladium catalyst at 300°C to give adiponitrile. 

In the first step, butadiene is chlorinated in the vapour phase at 330-420°C and atmospheric pressure. The main products are 3,4-dichloro-l-butene and l,4-dichloro-2-butene in approximately equal amounts. The latter material is then isomerized to the former by heating with a copper catalyst such as cuprous chloride. The 3,4-dichloro-l-butene is dehydrochlorinated by treatment with 10% aqueous sodium hydroxide at 85°C. Chloroprene is isolated by distillation under reduced pressure in the presence of polymerization inhibitors. 

Catalyst, alumina, 34, 79 35, 73 ammonium acetate, 31, 25, 27 copper chromite, 31, 32 36, 12 cuprous oxide-silver oxide, 36, 36, 37 ferric nitrate, hydrated, 31, 53 piperidine, 31, 35 piperidine acetate, 31, 57 Raney nickel, 36, 21 sulfuric acid, 34, 26 Catechol, 33, 74 Cetylmalonic acid, 34, 16 Cetylmalonic ester, 34,13 Chlorination, by sulfuryl chloride, 33, 45 ... 

In the late 1950s processes for producing ethylene dichloride from ethylene by oxychlorination rather than by direct chlorination were developed. In these processes ethylene is treated with a mixture of oxygen and hydrogen chloride in the presence of a catalyst consisting of a mixture of cuprous and cupric chlorides ... 

The formation of 1,2-dichloroethane from ethane and ethylene is described in patents issued to National Distillers (11) and I.C.I. (12), respectively. Englin et at. (13) report the formation of vinyl chloride from chloroalkanes using catalysts containing melts of cuprous and cupric chloride. The details of the mechanism and kinetics of many of these reactions are still unresolved. It appears, though, that copper chloride can function effectively as a catalyst for chlorination and dehydrochlorination as well as being able to participate in os chlorination reactions. 

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