Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
2000-06-23
2002-04-02
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S171000, C502S133000, C502S103000, C502S104000
Reexamination Certificate
active
06365540
ABSTRACT:
The invention relates to a complex product containing magnesium, halogen and alkoxy. The invention also relates to a process for the preparation and use of such a complex product. By a complex product is meant either a distinct complex or a mixture of complexes.
To be able to activate magnesium with TiCl
4
to produce amorphous MgCl
2
for a Ziegler-Natta catalyst, the magnesium has to be brought in a reactive state with respect to TiCl
4
. This is commonly done in two ways:
1. By forming a complex between MgCl
2
and an organic compound having an active hydrogen like an alcohol ROH. This MgCl
2
.mROH complex is allowed to react with TiCl
4
. Thereby amorphous MgCl
2
* is liberated. Equivalent amounts of titanous waste material: TiCl
3
OR and HCl are formed. This waste material has to be washed away with an excess of TiCl
4
, which is a disadvantage.
2. By forming a Mg-alcoholate, i.e. Mg(OR)
2
. This reacts with TiCl
4
to give amorphous MgCl
2
*. An equivalent of waste material, TiCl
3
OR, is formed also here.
MgR
2
is soluble in inert hydrocarbon and reacts with TiCl
4
to give amorphous MgCl
2
* but as MgR
2
is a strong reduction agent, an equivalent proportion of TiCl
3
is co-precipitated with the MgCl
2
*. The co-precipitation of TiCl
3
is a disadvantage when preparing a high yield polypropylene Ziegler-Natta catalyst.
With Grignard reagents like RMgCl and RMgBr, a strong solvent, i.e. an ether is needed to keep them in solution. If this kind of reagent is reacted with TiCl
4
, amorphous MgCl
2
* is formed but at the same time TiCl
4
complexates with all the R—O—R-oxygen atoms of the ether and a large amount of a catalytically inactive by-product complex R
2
O—TiCl
4
is formed.
The reagents, reacting with TiCl
4
to give amorphous MgCl
2
* are listed in Table 1. In Table 1, CH denotes hydrocarbon.
TABLE A
Reagents reacting with TiCl
4
giving amorphous MgCl
2
*
Reagent
MgCl
2
.ROH
Mg(OR)
2
MgR
2
ClMgR
Solvent
CH
CH
CH
R—O—R
Reaction by product
HClTiCl
3
OR
TiCl
3
OR
TiCl
3
R
2
O—TiCl
4
According to Coates, G. E., et al., Principles of Organometallic Chemistry, Methuen & Co Ltd, London, 1971, pages 60 and 61, this type of complexes are prepared in diethyl ether, whereby e.g. a dimeric etherate is formed as follows:
In the equation Me is methyl, Et is ethyl and tert-Bu is tertiary butyl. The etherate is dimeric in both benzene and ether media. The book also mentions that ether-free tert-BuOMgBr is insoluble in hydrocarbons and is likely to be polymeric. Tert-BuOMgCl can be assumed to behave in the same way, i.e. a strong polar solvent like an ether is needed to keep the reaction product in solution.
WO 92/16533 discloses a process for producing alkoxymagnesium halides in a single step by stoichoimetrically reacting magnesium alkyl activated magnesium with an equimolar mixture of an alkyl halogenide and an alcohol. However, in this process an additional equimolar amount of alcohol is added to the reaction media to bring the components into a liquid state in a inert hydrocarbon solution. The achieved solution is thus not RO.Mg.Cl but RO.Mg.Cl.ROH. This solution will in this way contain an equimolar amount of ROH that will react with TiCl
4
forming TiCl
3
OR and HCl in a typical catalyst synthesis where TiCl
4
is one of the reaction components.
The same situation can be seen in WO91/05608 where MgCl
2
is dissolved in 3ROH to produced MgCl
2
.3ROH that in turn is brought into contact with Mg(OEt)
2
to give an adduct of MgCl
2
.Mg(OEt)
2
.3ROH. 1.6ROH is then removed from this adduct by azeotropic evaporation with heptane to give a product of EtO.Mg.Cl.0.7ROH corresponding to the product described in WO92/16533.
WO 91/05608 added toluene and two different alcohols to magnesium chloride and refluxed for a short time. Then, dialkyl magnesium was added and the mixture was further refluxed. A complex of a magnesium haloalkoxide and two alcohols was obtained. Due to the alcohols in the complex, it was not suitable for the activation of TiCl
4
, see above.
U.S. Pat. No. 4,727,051 reacted MgCl
2
-ROH complexes and obtained stoichiometric compositions without giving their chemical structure.
When using dissolved magnesium compounds for the activation of the transition metal compound of a Ziegler-Natta procatalyst, such as magnesium chloride, MgCl
2
, dissolved in a polar solvent, or magnesium alkyl, MgR
2
or RMgCl, dissolved in diethyl ether or a hydrocarbon, other problems arise. In the case of MgCl
2
, problems are caused by the large amount of polar solvent needed for dissolving MgCl
2
. Evaporation operations of the polar solvent during the process of procatalyst preparation are laborous and, besides, traces of polar solvent on the formed procatalyst has to be removed by separate chemical treatment. In the case of MgR
2
, if not reacted with TiCl
4
, a separate chlorination agent and a separate chlorination step is need for activation. In addition to this MgR
2
and RMgCl have the drawback that they easily overreduce the transition metal and have to be modified to a less reductive form, e.g. to a magnesium alkoholate Mg(OR)
2
, before use.
When preparing the procatalyst from starting materials which will react into a final catalytically active complex, i.e. by means of a stoichiometric process, the product generally tends to have unsufficiently Mg and Cl (or other halogen) for satisfactory activity. Thus there is a need for starting materials having an enhanced amount of Mg and Cl (or other halogen) in their molecules.
One purpose of the invention is to provide a soluble magnesium compound, which gives good activity and is soluble in non-polar solvents. The magnesium compound must not overreduce the transition metal, because overreduction leads to low procatalyst activity. Another independent purpose of the invention is to provide a molecule, which contains sufficiently Mg and Cl (or other halogen) to produce high catalytic activity when reacted stoichiometrically with other compounds into a procatalyst or a complete Ziegler-Natta catalyst system.
The above problems have now been eliminated and the purposes fulfilled with a complex product containing magnesium, halogen and alkoxy, essentially characterised by having the following formula (1):
Mg
p
X
q
(OR)
2p-q
(1)
wherein X is a halogen, preferably a chlorine, R is an alkyl group having from 1 to 20 carbon atoms, p is from 2 to 20 and q is <p, preferably <0.66 p. If there are several halogens X and alkoxy groups OR in the complex product, they can be different or equal.
The complex product according to the invention can, depending on the quality and quantity of elements and groups, be soluble in non-polar organic solvents. Thus, complexes which are both soluble and insoluble in non-polar solvents can be selected among the claimed complexes. The soluble complexes can e.g. be used as starting material for catalytically active stoichiometrical procatalyst complexes and the insoluble complexes can e.g. be used as supporting activators of the transition metal compounds. Further, the complex product of the invention is always less reductive than the above mentioned magnesium alkyls MgR
2
and RMgX and is therefore more suitable for activation of the transition metal compound. The complex product has, even at its smallest Mg (p=2) and X (q=1) contents, more magnesium and halogen in its molecule unit than the above mentioned non-reductive Mg(OR)
2
. Whereas Mg(OR)
2
has Mg:X:OR=1:0:2, the claimed complex has at least the ratio M:X:OR=2:1:3.
The chemical structure of the claimed complex product is based on the bivalence and bridge-forming ability of magnesium. It is believed, without limiting the scope of the invention, that the chemical structure is (a):
wherein each G is the same or different and is selected from said X and said OR to form q units of X and 2p-q units of OR, and p is from 3 to 20. If p/3 is greater than 1 there is in formula (a) a . . . —bridge from the furthest Mg—G to the nearest M—G of the next unit.
The chemical structure can also be (b):
wherein each G i
Ala-Huikku Sirpa
Garoff Thomas
Leinonen Timo
Bell Mark L.
Borealis Technology OY
Pasterczyk J.
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