1.3- Butadiene selective reduction

Many of these cobalt complexes will catalyze the reduction of organic compounds by borohydride, hydrazine, thiols, etc. Cobalt cyanide complexes will catalyze the reduction of a,j8-unsaturated acids by borohydride (105) DMG complexes the reduction of butadiene and isoprene by borohydride, but not by H2 (124) Co(II) salen, the reduction of CHCI3 and CH3CCI3 to the dichloro compounds by borohydride (116) and cyanocobalamin, the selective reduction of -CCI2- by borohydride to -CHCl- in compounds such as aldrin, isodrin, dieldrin, and endrin without... 

The procedure described is based on the selective reduction with diimide described by Ohno and Okamoto and by Nozaki and Noyori. It illustrates the generation of diimide from the air oxidation of hydrazine and the use of diimide for the selective reduction of the trans double bond in cis,trans,trans-, S,9-cyc o-dodecatriene, the product of trimerization of butadiene. ... 

Selective reduction. Use of reagent, generated by cupric ion-catalyzed air oxidation of hydrazine, for the preparation of m-cyclododecene by the selective reduction of cis.trans.trans-1,5,9-cyclododccatriene, the product of trimerization of butadiene,7-8 is described by Ohno and Okamoto9 (see also 1,258, ref. 10). 

The cyclodimerization of 1,3-butadiene was carried out in [BMIM][BF4] and [BMIM][PF(3] with an in situ iron catalyst system. The catalyst was prepared by reduction of [Fe2(NO)4Cl2] with metallic zinc in the ionic liquid. At 50 °C, the reaction proceeded in [BMIM][BF4] to give full conversion of 1,3-butadiene, and 4-vinyl-cyclohexene was formed with 100 % selectivity. The observed catalytic activity corresponded to a turnover frequency of at least 1440 h (Scheme 5.2-24). 

Fig. 9. Selected geometric parameters (A) of the optimized structures of the key species for reductive elimination via the most feasible stereochemical pathway for the competing paths affording c,c,I-CDT, c,t,t-CDT and all-t-CDT, respectively, along 7b 8b. Free energies (AG, AG in kcalmol-1) are given relative to the favorable bis(r 3-anti),A-trans stereoisomer of the precursor 7b41 and 7b + C4H6 for the butadiene assisted all-t-CDT path.

Tellurium sources, 22-24 Thermodynamics in cyclo-oligomerization, 185-186 butadiene insertion, 187-188 reductive elimination, 193, 194 selectivity control, 212 polysilane isomerisation, 158-160 see also Stability Thermolysis, 135, 136, 158 THF (tetrahydrofuran), 97, 150, 153 Thio-Wittig reaction, 37 Tin, 121... 

Recently, the heterogenization technique has allowed more-selective reactions to be observed. For example, butadiene gives 95% of 1,3,6-octatriene (example 28 in Table 1) on a catalyst obtained by reduction of NiBr2(supported phenylphosphines)2 with NaBH4 (44). Nickel-carbonyl complexes have also been supported on phosphinated silica (55). 

The trianionic cobalt catalyst has been successfully employed in the hydrogenation of 1,3-butadiene in [bmim][BF4] [10], The product from this reaction is 1-butene which is formed with 100% selectivity. Unfortunately the catalyst undergoes a transformation to an inactive species during the course of the reaction and reuse is not possible. The cationic rhodium catalyst together with related derivatives have been used for numerous reductions, including the hydrogenation of 1,3-cyclohexadiene to cyclohexane in [bmim][SbF6] [11],... 

Pregnant mice exposed to 40, 200, or 1000 ppm 1,3 butadiene 6 hours/day on gestational days 6-15 had maternal toxicity at the two highest dose groups significant exposure-related reductions in the mean body weights of male fetuses occurred at 40 ppm and higher. There was no evidence of selective developmental toxicity in rats similarly exposed, and no increased incidence of malformations was observed in either study. " ... 

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