Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By double-bond-shift isomerization
Reexamination Certificate
2000-02-29
2002-03-12
Griffin, Walter D. (Department: 1764)
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By double-bond-shift isomerization
C585S665000
Reexamination Certificate
active
06355855
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for the oligomerization of 1-alkenes to internal alkenes, particularly 2-alkenes. The present invention also relates to a catalytic composition for the isomerization of 1-alkenes to internal alkenes.
2. Discussion of Background and Other Information
Several processes for the isomerization of alkenes (olefins) are known. For example, alkenes having more than four carbon atoms can be subjected to random isomerization using acids as catalysts, as described, e.g., by Barry et al. in J. Chem. Soc., Chem. Commun. 177 (1973). However, isomerization with acid catalysts is usually accompanied by oligomerization as a side reaction. Isomerization of alkenes can also be achieved by thermal means, i.e., by heating the alkenes. Disadvantages of corresponding processes are the relatively high temperatures necessary for effecting the isomerizations and the numerous side reactions caused thereby. HBr or I
2
in the presence of UV light can also induce isomerization of alkenes (see, e.g., Golden et al., J. Am. Chem. Soc., 86, 5416 (1964)). Such processes involve highly reactive free radicals. Moreover, upon termination of the isomerization process, the catalyst has to be removed by reduction and extraction. Metal hydrides such as Rh(I) hydride have also been used to catalyze the isomerization of alkenes (Cramer, J. Am. Chem. Soc., 88, 2272 (1966)). Additionally, metal carbonyls such as Fe
3
(CO)
12
have been reported to afford isomerization of alkenes via a &pgr;-allyl complex (Casey et al., J. Am. Chem. Soc., 95, 2284 (1973)).
Cox, U.S. Pat. Nos. 5,545,792 and 5,789,645, describes the isomerization of 1-alkenes to internal alkenes in the presence of a catalyst composition comprising (I) alkyl aluminum alkoxide of the formula R
3
n
Al(OR
4
)
p
where R
3
and R
4
are alkyl radicals, n is in the range of from 0.75 to 1.85, p is in the range of from 1.15 to 2.25 and the sum of n and p is 3, and (ii) a cobalt salt of an organic carboxylic acid or reduced form thereof. It is stated in these patents that while the alkyl aluminum alkoxide can be formed by controlled oxidation of aluminum trialkyl in any known manner, e.g., by oxidation with air, a preferred method comprises the in situ formation of the alkyl aluminum alkoxide. To this end, suitable proportions of aluminum trialkyl and cobalt carboxylate are added to the isomerization reactor, whereby the alkyl aluminum alkoxide is generated in situ, presumably by oxygen atoms released from the cobalt carboxylate as it is reduced by the aluminum trialkyl.
U.S. Pat. No. 3,439,054 to Kroll describes a catalyst composition for the hydrogenation of olefinically unsaturated compounds. This catalyst composition comprises the reaction product of an Fe or Co carbonyl compound and an aluminum trialkyl or alkylaluminum hydride.
Internal alkenes find a number of commercial uses. They are, for example, used for the preparation of alkyl succinyl anhydride (ASA), a paper size, by reacting them with maleic anhydride. Internal alkenes are usually made by isomerization from the corresponding primary or 1-alkenes (also known as &agr;-olefins), the latter compounds being available from refineries. The most common isomerization procedure for this purpose involves the use of acid catalysts. As already mentioned, the acid-catalyzed isomerization of alkenes also affords oligomers as side products. Oligomers, on the other hand, do not form adducts with maleic anhydride and, therefore, lower the effectiveness of the ASA paper size. Moreover, oligomers may also contribute to the formation of deposits in the paper mill. It would, thus be desirable to be able to isomerize 1-alkenes to internal alkenes without simultaneously producing substantial amounts of oligomers.
SUMMARY OF THE INVENTION
The present invention is directed to a process for the isomerization of 1-alkene to internal alkene wherein 1-alkene is combined, under isomerization conditions, with combinations of (I) salts of Group VIII transition metals such as nickel, cobalt, iron, palladium, platinum, rhodium and iridium and (ii) alkylaluminum compounds, particularly aluminum trialkyls and/or alkylaluminum halides, said combinations isomerizing the 1-alkene to internal alkene with only little formation of oligomers.
The present invention relates to a process for the isomerization of 1-alkene to internal alkene wherein 1-alkene is combined with a catalyst formed by contacting at least one Group VIII transition metal salt and at least one alkylaluminum compound. The process is conducted in liquid phase and at a temperature of from about 50 to about 200° C. If the at least one Group VIII transition metal salt includes cobalt and the at least one alkylaluminum compound includes trialkylaluminum compound the process is carried out in the substantial absence of alkoxyaluminum species.
With respect to the terms “combined” and “combinations” as used herein and in the appended claims in conjunction with the the components of the catalytic composition of the present invention it is to be understood that the exact structure of the catalytic species formed upon contact between the above components (i) and (ii) is not known. Without wishing to be bound to any theory, it is assumed that some kind of reaction (interaction) between these components takes place which eventually results in the formation of the catalytically active species.
While the 1-alkene subjected to the process of the present invention may have any number of carbon atoms (but of course not less than 4) it will usually have between about 5 and about 40 carbon atoms, preferably about 6 to about 30 carbon atoms and even more preferred about 10 to about 20 carbon atoms. The 1-alkene can either be an individual alkene or a mixture of two or more 1-alkenes.
The Group VIII transition metal will usually be selected from Ni, Co, Pd, Pt, Rh and Ir. Preferably it is at least one of Ni, Co and Pd, Co and Pd being the two most preferred Group VIII transition metals.
Preferred Group VIII transition metal salts contain halogen, especially chlorine, and/or chelate-forming ligand, such as acetylacetonate.
Alkylaluminum compounds for use in the present invention preferably are those of the general formula AlR
a
X
b
in which R represents an alkyl radical, X represents a halogen radical, particularly chlorine, a is an integer of from 1 to 3, b is 0, 1 or 2, and the sum (a+b) is 3. The alkyl radicals R in the general formula above will usually have from 1 to about 40, particularly from 1 to about 10, and even more preferred 1 to about 6 carbon atoms. Specific examples of said alkyl radicals include methyl, ethyl, isopropyl, n-butyl, 2-butyl, isobutyl, n-pentyl and n-hexyl.
The value of a in the above general formula will usually be 2 or 3. Trialkylaluminum compounds (a=3) are preferred.
Examples of particularly preferred trialkylaluminum compounds for use in the present invention are trimethylaluminum, triethylaluminum and diethylaluminumchloride.
The molar ratio of 1-alkene to be isomerized to Group VIII transition metal(s) employed in the present process usually ranges from about 1:1 to about 10,000:1, more frequently from about 10:1 to about 5,000:1. Preferred ratios range from about 500:1 to about 4,000:1, particularly from about 700:1 to about 2,000:1.
The atomic ratio of Group VIII transition metal(s) to aluminum in the alkylaluminum compound(s) is generally in the range of from about 2:1 to about 1:500, more frequently from about 1:1 to about 1:300, with a range from about 1:2 to about 1:100 being even more preferred.
A preferred temperature at which the present isomerization is to be conducted is from about 80 to about 150° C., particularly from about 80 to about 120° C.
The present process can be carried out in the presence or absence of solvent. If a solvent is used it is suitably selected from optionally halogenated aliphatic and aromatic hydrocarbons, aliphatic ethers and combinations thereof.
The present invention also relates to a catalytic composition for the
Lloyd Brenda A.
Nguyen Tuyen T.
Greenblum & Bernstein, P.L
Hercules Incorporated
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