Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Monoene compounds, isomerization

The bis-triphenylphosphine nickel halides are not activated by tin (II) halides. However, the iodide, (03P)2Nil2, is an effective catalyst for the hydrogenation of methyl linoleate to the monoene stage. The bromide is less effective, and the chloride has very little catalytic power. None of these nickel compounds has much ability to bring about isomerization. The nickel compounds are unstable in alcoholic solutions, and the experiments reported in Table III were carried out in either benzene, tetrahydro-furan, or toluene. [Pg.108]

The ready hydrogenation and isomerization of methyl oleate and palmitoleate with Fe(CO)s confirm the results of Ogata and Misono (18) with monounsaturated aliphatic compounds. In the isomerization of monoolefins Manuel (15) suggested the occurrence of equilibria involving either 7r-olefin HFe(CO)3 and a-alkyl Fe(CO)3 complexes, or TT-olefin Fe(CO)3 and 7r-allyl HFe(CO)3 complexes. The formation of olefin-iron tetracarbonyl complexes has been reported (19). The reaction of butadiene and Fe2(CO)9 has been observed to lead to the formation of butadiene-Fe(CO)4 and butadiene-[Fe(CO)4]2 complexes in which one or both double bonds are pi-bonded to the iron (16). A mechanism involving both monoene-Fe(CO)4 (I) and allyl-HFe(CO)3 complexes (II) is postulated for the isomerization of methyl oleate (Scheme II) and for its homogeneous hydrogenation. [Pg.188]

Complexes of the type (RsQ)2MX2 (R alkyl or aryl Q=P, As, Sb M=Ni, Pd, Pt and X=halogen or pseudohalogen) have been found to catalyze hydrogenation of all but one double bond (68-70) in polyolefins. In the palladium and platinum complexes, catalytic behavior is enhanced by the addition of a compound of the type M Xa or M X4 (M = Si, Ge, Sn, or Pb). The hydrogenation process occurs with very rapid isomerization to the conjugated isomer followed by a rapid reduction to the monoene product. The mechanism shown in Fig. 29 has been proposed for this system. [Pg.265]

Reaction of linoleate with toluene-4-sulfonic acid could conceivably be a method of hydrating one or both of the double bonds. In fact, the major products were the 9,12-and lOjlS-tetrahydrofiuans (44%) accompanied by the 9,13-tetrahydropyran (4%) and smaller amounts of isomeric tetrahydrofiuans (8,11-, 10,13-, and 11,14-) and tetrahydropyrans (8,12- and 10,14-) (Scheme 7). These compounds were readily identified by a combination of chromatographic and spectroscopic techniques (10). Similar products were obtained with the trans isomers of linoleate (but not with the conjugated 9,11- and 10,12-dienoates) and from several oxygenated monoene esters... [Pg.5]

Ironcarbonyl compounds are liable to form 7r-complexes with unsaturated compounds such as monoenes, butadiene, cyclobutadienes, and cyclopentadiene. In the case of diene, the two double bonds of 1,5-cyclooctadiene are able to coordinate to the metal, without a sterical strain as shown in Table 15.2. The two double bonds of 1,4-cyclohexadiene are difficult to bond to iron without strain, so 1,4-cyclohex-adiene isomerized to 1,3-cyclohexadiene. The iron atoms have such a high reactivity with diene compounds that the isomerization of the diene occurs [13,19,20,25]. [Pg.320]


See other pages where Monoene compounds, isomerization is mentioned: [Pg.171]    [Pg.76]    [Pg.103]    [Pg.287]    [Pg.130]    [Pg.32]    [Pg.334]    [Pg.500]    [Pg.3]    [Pg.361]    [Pg.221]    [Pg.191]    [Pg.738]   


SEARCH



Isomeric compounds

Isomerization monoenes

Monoenes

© 2024 chempedia.info