Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
2000-09-29
2002-09-17
Siegel, Alan (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
C570S164000, C570S165000, C570S166000, C570S162000, C570S168000, C570S169000
Reexamination Certificate
active
06452057
ABSTRACT:
The present invention relates to a process for preparing halohydrocarbons comprising at least 3 carbon atoms, by catalytic reaction between a haloalkane and an olefin.
The addition of a haloalkane to an olefin is a well-known reaction. However, it is occasionally difficult to control the reaction such that only one olefin molecule adds to one haloalkane molecule (formation of a 1:1 addition product or adduct).
Patent application WO 97/07083 discloses a process for preparing halohydrocarbons under the catalytic action of cuprous chloride in the presence of t-butylamine as co-catalyst. Patent application EP-A-787 707 discloses a process for preparing 1,1,1,3,3-pentachlorobutane under the catalytic action of cuprous chloride in the presence of co-catalysts of amine type. In such processes, the various constituents of the reaction medium are first introduced into a reactor which is then brought to the reaction temperature. However, the yield of and selectivity towards telomerization product are unsatisfactory. Furthermore, considerable, or even total, losses of co-catalyst are observed therein due to spurious degradation reactions in the reaction medium.
The invention is consequently directed towards providing a process which gives access, in excellent yields and selectivities, to halohydrocarbons comprising at least 3 carbon atoms, in a single step starting with readily accessible reagents and in which the losses of co-catalyst are minimized, thus allowing maximum re-use.
Consequently, the present invention relates to batchwise process for preparing halohydrocarbons comprising at least 3 carbon atoms, according to which haloalkane and an olefin are reacted, in a reaction medium, in the presence of a catalyst and a co-catalyst, in which process
a) in a first step, at least some of the co-catalyst is gradually added to the reaction medium during the reaction;
b) in a subsequent step, at least some of the co-catalyst is recovered with a view to its re-use.
It has been found, surprisingly, that when a gradual addition to the reaction medium of at least some of the co-catalyst is carried out during the reaction, very little degradation of the co-catalyst is observed, while at the same time an excellent yield of halohydrocarbon is achieved. The process according to the invention also makes it possible to control the exothermicity of the reaction, which is a considerable advantage in an industrial-scale synthesis of halohydrocarbons.
In the process according to the invention, the initial reaction medium generally comprises the catalyst, the haloalkane, the olefin and optionally a solvent. The initial reaction medium also advantageously comprises a fraction of the co-catalyst. In this case, the fraction of the co-catalyst included in the initial reaction medium is generally at least 1% of the total amount of co-catalyst used. This fraction is often at least 5%. It is usually at least 10%. It is preferably at least 15%. It is generally not more than 80% of the total amount of co-catalyst. It is often not more than 70%. It is preferably not more than 60%.
The gradual addition can be carried out in the liquid phase or in the gas phase. The liquid-phase addition can be carried out, for example, by means of a tube dipping into the reaction medium. The gas-phase addition can be carried out, for example, by introducing the co-catalyst in vapour form into the reactor atmosphere.
The gradual addition of the co-catalyst can be, for example, an addition carried out in several portions, which may or may not be identical. This method of adding the co-catalyst corresponds to what is called, for bioreactors, a reaction of “fed-batch” type (Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed. Vol. B4 pp. 387-388). Generally, a portion of co-catalyst is introduced into the initial reaction medium, and at least one other portion is then added subsequently, during the reaction. The number of portions to be used is theoretically not limited, thus approaching another mode of addition of the co-catalyst according to which the gradual addition is carried out continuously. However, a number of portions of not more than 100 is generally used. The number is often not more than 50. The number is usually not more than 20. A number of not more than 10 gives good results. A number of not more than 5 is advantageous. A number of not more than 4 is preferred. Excellent results are obtained with a number of 2 or 3.
The time intervals between the additions of the portions are generally at least 1 min. The intervals are often at least 5 min. The intervals are usually at least 30 min. The intervals are preferably at least 1 h. Intervals of about 2, 3, 4, 5 or 6 h give good results.
In another mode of addition of the co-catalyst in the process according to the invention, the gradual addition of at least some of the co-catalyst is carried out continuously. This mode of addition corresponds to what is called, for bioreactors, a reaction of “extended fed-batch” type (Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed. Vol. B4 pp. 387-388). It is possible, for example, to introduce a portion of co-catalyst into the initial reaction medium, and then subsequently to add a desired amount of co-catalyst continuously during the reaction.
In this embodiment of the process according to the invention, the ratio between the molar flow rate of co-catalyst added continuously and the molar amount of catalyst used is called R and is defined by the following equation:
R
=[amount of co-catalyst/time] (mol/h)/amount of catalyst per batch (mol).
The ratio R is generally at least 0.1 h
−1
. The ratio is usually at least 0.5 h
−1
. The ratio is preferably at least 1 h
−1
. In a particularly preferred manner, the ratio is at least 2. In a most particularly preferred manner, the ratio is at least 3. The ratio is generally not more than 1000 h
−1
. The ratio is often not more than 500 h
−1
. The ratio is usually not more than 100 h
−1
. The ratio is preferably not more than 50 h
−1
. In a particularly preferred manner, the ratio is not more than 10. In a most particularly preferred manner, the ratio is not more than 9. The time over which the continuous addition is carried out is generally at least 10 min. The time is usually at least 30 min. The time is preferably at least 1 h. Times of about 2, 3, 4, 5 or 6 h give good results.
One particularly advantageous embodiment of the process consists in regulating the addition of the co-catalyst as a function of the temperature of the reaction medium.
In one variant of the process according to the invention, in addition to the gradual addition of the co-catalyst, at least some of the olefin is gradually added. In this variant, the initial reaction medium generally comprises the catalyst, the haloalkane and, optionally, solvent. The initial reaction medium also advantageously comprises co-catalyst and/or olefin. It has been found, surprisingly, that when at least some of the co-catalyst and at least some of the olefin are added gradually, in addition to the advantages mentioned above, an increase is observed in the selectivity towards halohydrocarbons derived from the addition of one molecule of haloalkane to one molecule of olefin.
The gradual addition of the olefin can be carried out separately from the gradual addition of the co-catalyst. A gradual addition of a mixture of olefin and co-catalyst can also be carried out.
In another variant of the process according to the invention, in addition to the gradual addition of at least some of the co-catalyst or of at least some of the co-catalyst and of at least some of the olefin, a gradual addition of at least some of the haloalkane is carried out. In this variant, the initial reaction medium generally comprises the catalyst and, optionally, solvent. The initial reaction medium also advantageously comprises co-catalyst and/or haloalkane. The initial reaction medium can also comprise olefin. The gradual addition of the haloalkane can be carried out separately from the gradual a
Anciaux Charles-Marie
Lambert Alain
Mathieu Véronique
Connolly Bove & Lodge & Hutz LLP
Siegel Alan
Solvay ( Societe Anonyme)
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