Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By addition of entire unsaturated molecules – e.g.,...
Reexamination Certificate
2001-02-05
2002-12-31
Dang, Thuan D. (Department: 1764)
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By addition of entire unsaturated molecules, e.g.,...
C585S513000, C585S512000, C585S511000, C585S521000, C585S527000, C585S529000
Reexamination Certificate
active
06501001
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for selective dimerization of propylene principally into branched dimers. More particularly, it relates to a process in which propylene is brought into contact with a catalytic composition resulting from at least partly dissolving a nickel compound mixed or complexed with a tertiary phosphine carrying a functional group in a medium resulting from mixing at least one quaternary ammonium halide and/or at least one quaternary phosphonium halide, at least one aluminum halide and optionally at least one organometallic aluminum compound.
2. Description of the Prior Art
French Patent No. 2,611,700 describes the use of liquids of ionic nature formed from aluminum halides and quaternary ammonium halides as solvents for organometallic nickel complexes to catalyze olefin dimerization. The use of such media, which are not miscible with aliphatic hydrocarbons, in particular with the products from olefin dimerization, enables homogeneous catalysts to be used more effectively. French Patent No. 2,659,871 describes a liquid composition with an ionic nature resulting from bringing quaternary ammonium halides and/or quaternary phosphonium halides into contact with alkylaluminum dihalides and optionally also an aluminum trihalide. That same patent describes the use of such media as solvents for transition metal complexes, in particular nickel complexes containing no nickel-carbon bond, which are transformed into catalysts for olefin oligomerization. In the present text, such media will henceforth be termed “molten salts”, as they are liquid at moderate temperatures.
During those studies, it was shown that the most active and most stable nickel catalysts are obtained in “molten salts” constituted by one molar equivalent of an ammonium halide and/or a phosphonium halide with one equivalent and more of an aluminum trihalide, and optionally any quantity of an alkyl aluminum dihalide. That formulation has been shown to be particularly interesting as nickel complexes dissolved in it have high catalytic activity.
Further, it has been shown that under the conditions described in French Patent No. 2,611,700? the “phosphine effect”, as described by G. Wilke et al., in Ind. Eng. Chem., 1970, 62, No. 12, p. 34, and in U. K. Patent No. 1,058,680, which reports the influence of substituents carried by the phosphorus atom on the mode of enchainment of propylene molecules during catalytic dimerization by nickel, rapidly disappears over time. That unexplained phenomenon has deleterious consequences since it does not produce the desired selectivities.
French Patent No. 2,710,280 shows that adding an aromatic hydrocarbon to a “molten salt” can overcome this problem and result in catalysts with high activity which are more stable and which have a high selectivity for the most highly branched isomers. However, the aromatic hydrocarbon is continuously extracted in the organic phase constituted by the products, which implies that it must be separated and recycled to the reactor.
SUMMARY OF THE INVENTION
It has now been discovered that the use of a tertiary phosphine carrying a functional group or a nickel complex formed with a tertiary phosphine that is soluble in the “molten salt” results in catalysts for which the selectivity for the most highly branched isomers is high and stable over time and for which the activity is high.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides a process for selective dimerization of propylene into branched dimers in which a catalytic composition comprising at least one nickel compound mixed or complexed with at least one tertiary phosphine carrying a functional group is used, at least partly dissolved in a non aqueous medium with an ionic nature (“molten salt” type medium), resulting from bringing at least one aluminum halide (product B) into contact with at least one quaternary ammonium halide and/or at least one quaternary phosphonium halide (product A), the “molten salt” type medium possibly further comprising at least one organometallic aluminum compound (product C).
Thus the “molten salt” type medium, in which the nickel compound mixed or complexed with at least one tertiary phosphine carrying a functional group or at least one phosphite carrying a function croup is dissolved, is constituted by mixing:
a) at least one quaternary ammonium and/or quaternary phosphonium halide, more particularly a chloride and/or bromide (product A);
b) at least one aluminum halide (product B); and
c) optionally, at least one organometallic aluminum compound (product C).
Preferred quaternary ammonium and/or phosphonium halides that can be used within the context of the invention (product A), are:
those with general formula NR
1
R
2
R
3
R
4
X (with the exception of NH
4
X), PR
1
R
2
R
3
R
4
X, R
1
R
2
N═CR
3
R
4
X or R
1
R
2
P═CR
3
R
4
X, where X represents Cl or Br and R
1
, R
2
, R
3
and R
4
, which may be identical or different, each represent hydrogen or a hydrocarbyl residue containing 1 to 12 carbon atoms, for example saturated or unsaturated alkyl, cycloalkyl or aromatic groups, aryl groups or aralkyl groups, containing 1 to 12 carbon atoms, it being understood that preferably, only one of substituents R
1
, R
2
, R
3
and R
4
represents hydrogen;
or one of the following general formulae:
where the nitrogen-containing or phosphorus-containing heterocycles containing 1, 2 or 3 nitrogen and/or phosphorus atoms are constituted by 4 to 10 atoms and X, R
1
and R
2
are defined as above.
Examples which can be cited are tetrabutylphosphonium chloride, N-butyl pyridinium chloride, ethylpyridinium bromide, 3-butyl- l-methyl imidazolium chloride, diethylpyrazolium chloride, pyridinium hydrochloride, trimethylphenyl ammonium chloride and 3-ethyl-1-methyl imidazolium chloride. These salts can be used alone or as a mixture.
The aluminum halides used as products B of the invention are essentially aluminum chloride and bromide.
The organometallic aluminum compounds used as optional products C of the invention have general formula AlR
x
X
3-x
in which R is a linear or branched alkyl residue containing 2 to 8 carbon atoms, X is chlorine or bromine and the value of x is 1, 2 or 3. Examples of organometallic aluminum compounds that can be used are isobutylaluminum sesquichloride, ethylaluminum sesquichloride, dichloroisobutyl aluminum, dichloroethyl aluminum and chlorodiethyl aluminum.
The components of the “molten salts” as defined above are generally used in A:B mole ratios of 1:0.5 to 1:3, preferably 1:1 to 1:2; product C is used in a mole ratio of at most 100:1 with product B, preferably 0.005:1 to 10:1. However, the components and their proportions must be such that the mixture is liquid at the temperature at which the nickel compound and the functionalized tertiary phosphine are introduced, although the catalytic dimerization reaction can be carried out at a temperature which is lower than or higher than the fusion temperature of the catalytic composition.
Examples of nickel compounds used in the catalytic compositions of the invention are the chloride, bromide, sulfate, carboxylates (for example the 2-ethylhexanoate), phenates and acetyl acetonate. It is also possible to use organometallic nickel complexes which may or may not contain phosphines. These nickel complexes are used as a mixture with a functionalized tertiary phosphine. It is also possible to use nickel complexes that are already complexed with a tertiary phosphine carrying a function.
The functional phosphines used as a mixture with (or to complex) the nickel compounds of the invention have general formulae PR′
1
R′
2
R′
3
and R′
1
R′
2
P—R′—PR′
1
R′
2
, where R′
1
, R′
2
and R′
3
, which may be identical or different, are alkyl, cycloalkyl, aryl or aralkyl radicals containing 1 to 10 carbon atoms at least one of which carries a functional group such as an amine, a cyclic amine, a nitrogen-containing heterocycle, an ester, an acid, an alcohol
Commereuc Dominique
Le Pennec Dominique
Olivier-Bourbigou Helene
Dang Thuan D.
Institut Francais du Pe'trole
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