Oxyhalogenation of 1,3-Butadiene

Hydrolysis of l,4-dichloro-2-butene to produce 1,4-butanediol was previously 

Exploration of Basic Catalyst Components The study of direct oxidative acetoxyla-tion of 1,3-butadiene began with the use of Wacker-type homogeneous catalyst Pd(OAc)2-CuCl2 [10]. This catalyst system gave low l,4-diacetoxy-2-butene selectivity, and there was a problem in separating the catalyst. After that, liquid-and vapor-phase methods using a Pd-based catalyst were studied in parallel. Catalyst activity was greatly improved by the addition of Bi or Sb to the Pd catalyst in the gas-phase reaction [11]. However, catalyst activity was reduced by the adhesion of resin by-product derived from unsaturated aldehydes on the catalyst surface. Various improvements have been tried in the gas phase, but catalyst robustness has never met industrial requirements. 

Mitsubishi Chemical started solid-state Pd catalyst development in the liquid phase reaction to avoid the polymerization of 1,3-butadiene and by-products. There were some challenges to be overcome, including polymerization, low catalytic activity, and leaching of palladium into the reaction media. At first, the addition of Sb or Bi to Pd alkali metal catalyst on charcoal was found to be beneficial for the catalyst activity because of an inhibition of the polymerization (Table 10.1) [12]. 

Catalyst Amount of metal (mg-atom/g-cat) Production rate (mol/g-atom Pd h) 1,4-Diacetoxy-2-butene selectivity (%) 

Reaction conditions catal) t (10 g), acetic acid (210 ml), 1,3-butadiene (55 mmol/h), and oxygen (55 mmol/h). 

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