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Publication Date: 2014-Mar-14
Document File: 7 page(s) / 36K

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The Prior Art Database


The addition of an oxidant to the telomerization pre-catalyst used in the production of 1-methoxy-2,7-octadiene reduces the rate of formation of [Pd(TCMPP)2{CH3C(=O)}2C=CH2)], allowing a longer time before precipitation of this material is possible. Addition of solvents that are less polar than, but still miscible with, methanol increase the solubility limit of [Pd(TCMPP)2{CH3C(=O)}2C=CH2)], allowing a longer time before precipitation of this material is possible.

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This invention relates generally to the preparation of a butadiene telomerization catalyst precursor.

United States Patent (US) 8,558,030 B2 discloses a process for telomerizing butadiene that includes contacting butadiene and an organic hydroxyl compound represented by the formula ROH, where R is a substituted or unsubstituted C1-C20 hydrocarbyl and the organic hydroxyl compound is not glycerol in a reaction fluid in the presence of a palladium catalyst and a phosphine ligand represented by formula PAr3, wherein each Ar is independently a substituted or unsubstituted aryl having a hydrogen atom on at least one ortho position, at least two Ar groups are ortho-hydrocarbyloxyl substituted aryls.  The phosphine ligand has a total of 2, 3, 4, 5 or 6 substituted or unsubstituted C1-C20 hydrocarbyloxyls and, optionally, two adjacent substituents on an Ar group can be bonded to form a 5- to 7-membered ring.  This process can be used to produce alkoxyoctadienes, such as 1-methoxyocta-2,7-diene, useful for conversion to 1-octene, a valuable olefin comonomer.

A typical process for preparing a catalyst precursor or pre-catalyst used in telomerization of butadiene to produce 1-methoxyocta-2,7-diene involves batchwise dissolution of one equivalent of palladium acetyl acetonate ([Pd(acac)2]) and two equivalents of a phosphine ligand, preferably a triarylphosphine ligand (PAr3) (e.g. triphenyl phosphine (TPP) or tris(5-chloro-2-methoxyphenyl)phosphine (TCMPP)) in methanol.  In some instances, the pre-catalyst complex has been shown to be bis(triarylphosphine)palladium(II) (acetyl acetonato) cation, described formulaically as [Pd(acac)(PAr3)2]+, containing palladium in the +2 oxidation state.  This precursor is stabilized by acetic acid that is also added during pre-catalyst solution make-up, resulting in the formation of an acetate salt that is soluble in methanol.  Under telomerization reaction conditions, the palladium(II)-containing catalyst precursor appears to be reduced by an added sodium methoxide promoter in methanol in the presence of 1,3-butadiene to a palladium(0) bis(phosphine) complex designated as [Pd(PAr3)2].  Subsequent addition of 1,3-butadiene results in formation of a (PAr3)1 or 2-Pd-(octadienyl) complex.  Further reaction with methanol leads to formation of either 1-methoxyocta-2, 7-diene (MOD-1) or 3-methoxy-1, 7-octadiene (MOD-3).  Under pre-catalyst storage conditions, the pre-catalyst can also be reduced by methanol to form a palladium(0) complex, which can precipitate from the pre-catalyst solution as a solid when its concentration in the solution exceeds its solubility limit.  The precipitation of solids can result in process equipment fouling and operating difficulties. It has been found that the palladium (II) pre-catalyst is reduced to palladium(0) complexes, such as tris-(TPP) palladium, [Pd(PPh3)3], or bis-(TCMPP)palladium{CH3C(=O)}2C=CH2),  [Pd{P(C6H3-2-OMe...