Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By addition of entire unsaturated molecules – e.g.,...
Patent
1991-08-16
1993-10-19
McFarlane, Anthony
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By addition of entire unsaturated molecules, e.g.,...
568675, 568690, C07C 218
Patent
active
052547825
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a continuous process for the telomerization of conjugated dienes comprising reacting a conjugated diene with a compound containing an active hydrogen atom in the liquid phase in the presence of a Group VIII transition metal catalyst and a tertiary phosphorous, arsenic or antimony ligand compound.
The telomerization reaction, which has been known per se for many years, involves the oligomerization and especially the dimerization of a conjugated diene under the concomitant addition of a nucleophilic agent, for example a compound containing an active hydrogen atom. The nucleophile is introduced mainly at the terminal position of the oligomer and especially of the dimer of the conjugated diene.
Telomerization reactions catalyzed by Group VIII transition metal catalysts are described extensively in the prior art. In the late sixties and early seventies attention was primarily focussed on the optimization of conversion and selectivity of the telomerization reaction under batch conditions. Representative publications are U.S. Pat. No. 3,499,042, U.S. Pat. No. 3,518,315, U.S. Pat. No. 3,530,187, GB-A 1178812, FR-A 1583249, NL-A 6816008, GB-A 1248593, NL-A 7003702, GB-A 1354507, DE-A 2154370.
As from the middle of the 1970's, research was directed to obtain a more catalyst-efficient telomerization process. In view of this desire, which was in part due to the relatively high costs of the catalyst used in the telomerization process, it was considered essential that after the telomerization reaction the catalyst is obtained (directly or indirectly) in an active form and then reused in the process. In most of the cases, however, the catalyst and the desired reaction products could not be easily recovered from the reaction mixture by means of separation techniques, such as e.g. distillation, precipitation or extraction. Extraction had the disadvantage that both the catalyst and reaction products were soluble in the organic solvents used for extraction. Distillation in general resulted in the catalyst remaining in the reaction by-products which were too heavy to be removed by distillation. Moreover, when distilling off the desired reaction products and/or the heavy by-products, special care should be exercised in view of the low heat stability of the catalyst, leading to catalyst decomposition or metallization at too high distillation temperatures, which would require regeneration of the catalyst.
As the catalyst generally is dissolved in the reaction solution, the residual reaction solution obtained after distillation has been reused or, alternatively, the catalyst was recovered in metallic form by precipitating it from the reaction solution, optionally after removing reaction products and reactants. The former methods however, leads to an increasing amount of residual solution due to by-production of high-boiling matter in repeated use of the solution and also to the problem of treatment of that portion of the catalyst which has lost its activity during the reaction. On the other hand, the latter method has the disadvantage of a complicated operation for reactivating the recovered material.
The following prior art attempted to solve the above discussed problems. U.S. Pat. Nos. 4,142,060 and 4,219,677 describe a telomerization process to prepare 2,7-octadiene derivatives in the presence of a transition metal catalyst, preferably palladium, and a water soluble phosphine, wherein during or after the reaction water is introduced. The water phase obtained at the end of the process contains the water soluble phosphine and the transition metal catalyst. In this way the active transition metal catalyst may be recovered and reused in the process, thus obtaining a continuous process.
U.S. Pat. No. 4,146,738 describes a process for telomerizing a conjugated diene and an alkanol wherein prior to the telomerization tetrakis(triphenyl phosphine) palladium is oxidized with oxygen to partially remove the triphenyl phosphine ligands. The telomerization is then carried out in the presence of this partial
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Jacobsen Grant B.
Pelt Hendrik L.
Schaart Barend J.
McFarlane Anthony
The Dow Chemical Company
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