DD150748A1 - PROCESS FOR PREPARING N-ALKYLALUMINIO-N-SILYLAMINES - Google Patents

Abstract

The invention relates to a process for the preparation of N-alkylaluminum-N-silylamines by the reaction of aluminum alkyls of the general. Formula R & indm! AlX & ind3-m! with silylamines of the general Formula (formula) wherein N-alkylaluminino-N-silylamines according to the present invention are general. Formula arise where X is halogen, R & exp1! an aliphatic, cycloaliphatic or araliphatic radical having 2 to 12 C atoms or a silylalkyl radical, R & exp2! an alkyl, cycloalkyl, aralkyl, aryl or silylalkyl radical and R & exp3 !, R & exp4! and R & exp5! Represent hydrogen and identical or different alkyl, cycloalkyl, aryl or alkenyl radicals, and m and Z can assume the values 1, 2 and 3 and n the values 0, 1 and 2. The process is a very simple method for the preparation of the compounds mentioned and is characterized by an unusual range of variation in terms of the usable starting materials. The compounds may optionally be used without expensive purification operations as active constituents of catalyst systems for olefin polymerization.

Description

Title of the invention

Process for the preparation of N-alkylaluminum N-silylamines

Field of application of the invention

The invention relates to a process for the preparation of N-alkylaluminum N-silylamines which are suitable components of catalyst systems for olefin polymerization.

Compounds of this type are often referred to as Ziegler-Natter catalysts. They are used industrially as cocatalysts in admixture with titanium compounds for the production of polyethylene and polypropylene.

Characteristic of the known technical solutions

From DD-AP 96 711, DE-OS 1 936 201, 2 414 875 and 2 519 956, DE-AS 2 700 454 and GB-PS 1 504 930 are compounds with the structural units

C - N - Al I I R R R

H - O - Al I I Si R I R

or

These are oligomeric compounds which are usually not exactly defined in addition to the other constituents of the catalyst system. This makes it very difficult to achieve a reproducible quality of the catalyst To guarantee links that are a prerequisite for equal

represents permanent process results * / Also with regard to further possible uses, use of these oligomeric compounds is associated with problems.

Also known is the preparation of the compound He ₃ Si - NH - AlCl ₂ from hexamethyldisiiazane and aluminum tri-chloride (M. Becke-Goehring and H _# Krill, Chem. Ber. 94, 1059/1961 /) and their further reaction with methyllithium for Dimethylaluminum-trimethylsilylamine (H. Schmid-Baur and M, Schmidt _/ Angew. Chem. 74, 327/1962 /) »This two-stage process is complicated and not arbitrarily applicable to other species with the basic structure = Si-N-Al.

Moreover, due to its difficult production, methyllithium is not readily available technically «

The method used by Zinkin and Mitarb for the reaction of disilazanes or silylamines with aluminum trialkyls (Z · obsc '. Chim. 36., 350/1966 /) involves a reaction without a solvent, which leads to a reaction sequence that is difficult to control and because of the strong exothermicity the complex formation precedes the reaction hinders the use of thermally unstable silylamines. In this procedure, side reactions are also promoted.

The reaction of trimethylsilylmethylamine and trimethylsilylaniline with aluminum alkyls is also known from Sakakibara and Mitarb, (3 × Organometal.Chem. 36, 267/1972 /). In this case, exclusively short-chain trialkylaluminums are used. The yields obtained are sometimes very low. "The process can not be transferred to any starting materials of the listed classes of compounds.

Object of the invention

It is the object of the invention to prepare N-alkylaluminio-N-silylamines having a wide variety of substituents by a uniform method and with favorable possibilities for following the course of the reaction, including the use of long-chain alutninium alkyls and hydrosilylamines.

Explanation of the essence of the invention

This object is achieved according to the invention by a process for the preparation of N-alkylaluminio-N-silylamines of the general formula I

R ⁵ R ⁴ R ³ Si - N - AlR ¹ X ₀ 1

I ₂ ^I

^R J

in the R, an optionally branched aliphatic, cycloaliphatic or araliphatic radical having 2 to 12 carbon atoms

R 2 represents 2 atoms or a silylalkyl radical, R represents an optionally substituted alkyl, cycloalkyl, aralkyl, aryl or silylalkyl radical and R, R and R represent hydrogen, identical or different alkyl, cycloalkyl, alkenyl or aryl radicals, X represents halogen, preferably chlorine or bromine, and η can be the values 0, 1 or 2 and Z can have the values 1, 2 or 3, irrespective of the trialkyuminum compounds or alkylaluminum halides of the general formula II,

± n where R and X have the abovementioned meaning and b> can assume the values 1, 2 or 3, with N-silylamines of the general formula III,

R ⁵ R ⁴ R ³ Si - NH III

'2 R ^

in which R and R, R and R have the abovementioned meaning, are reacted in inert solvents under a protective gas atmosphere.

The reaction preferably takes place in a molar ratio of 1: 1, but deviations of up to a molar ratio of organoaluminum compound to N-silylamine of from 2: 1 to 1: 2 are possible.

The inert solvents are halogenated hydrocarbons, aliphatic, cycloaliphatic and aromatic

4 2 2C

Hydrocarbons such as dichloroethane, n-heptane, benzines, cyclohexane, benzene or xylene suitable * serve as a protective gas, for example, pure nitrogen or argon.

It is advantageous to run the reaction in two phases. First, the N-silylamine III, which may also be diluted with a solvent, is added to the organoaluminum compound II which has been introduced in the solvent while cooling at not more than 20. This results in a donor-acceptor complex. which reacts in a second reaction phase at temperatures between 20 and 180 ^° C., preferably between 50 and 90 ° C., with virtually quantitative evolution of the by-product HR, where R has the abovementioned meaning, to the N-alkylaluminum-N-silylamine.

Otherwise, the reaction takes place in a stage in which the dissolved components II and III are combined at 20 to 180 ° C., preferably 50 to 90 ° C.

The course of the reaction can be followed not only by determining the possibly gaseous by-product, but also by recording the H-NMR spectra of the reaction solution. "

The isolation of the products according to the invention is often already the removal of the solvent and the reaction product still possibly adhering starting or by-products in Wasserstrahlpumpenvakuum under possibly mild heating sufficient «The purification itself is carried out by fractional distillation in vacuo« Solid N-AlkylaluiTiinio-N-silylatnine can also be obtained by crystallization from the reaction solution and purified by recrystallization «

According to the process of the invention, the various N- ^ alkylaluminio-N-silylamines can also be produced industrially with a hitherto unknown composition, for example by using long-chain aluminum alkyls and hydrosilines! "The products obtained according to the invention can, optionally without expensive purification operations, be used as active constituents of catalyst systems used for olefin polymerization «

220597

Exemplary embodiments Example 1

N-Diisobutylaluminio-N-trimethylsilyl-methylamine

To 5.95 g (30 mmol) of triisobutylaluminum in 2.5 ml of benzene, 3.10 g (30 mmol) of trisethylsilylmethylamine, dissolved in 5 ml of benzene, are added dropwise within 10 min with stirring and gentle cooling (5-10 ° C.) After heating, the reaction mixture starts from ca, 55 ⁰ C slowly split off isobutane. After reaching a temperature of 70 ⁰ C, the reaction solution is stirred for four hours until the evolution of gas has completely ceased. The amount of gas evolved corresponds to 87 % of theory,

After removal of the solvent, a white crystalline product remains. Yield: 5.6 g (77 % of theory);

¹ H-NMR: 0 _{S ± CH} = 0.22 ppm; O _NCH = 2.58 ppm,

Example 2: N-Diethylaluminio-N-dimethylsilyl-isopropylamine

3.0 g (26 mmol) of triethylaluminum are reacted with 3.1 g (27 mmol) of dimethylsilylisopropylamine as in Example 1.

After the evolution of ethane (91 % of theory) has subsided, about 60 % of the solvent (benzene) is taken off and 1.5 ml of pentane are added to the reaction mixture. After prolonged standing at 5 ⁰ C, white crystals separate, yield: 3.1 g (62 % of theory);

¹ H-NMR: _ΟSiCH = 0.34 ppm (d); O _{N (CH} j-1.18 ppm (d).

Example 3s N-Diethylaluminio ~ N-dimethylsilyl-tert-butylamine

To 1.37 g (12 mmol) of triethylaluminum in 5.5 ml of toluene are added dropwise at room temperature 1.71 g (13 mmol) of dimethylsilyl-tert-butylamine. After 3.5 hours of stirring at a temperature of 85 C, the evolution of ethane comes to a standstill (93 % of theory). After stripping off all volatile constituents, a viscous, almost colorless liquid remains

Yield: 2.0 g (78 % of theory); ¹ H-NMR: Og ₁ QH = '0.32 ppm (d); C% / _CH ν 1.24 and 1.31 ppm;

Analysis: ΔΙ gef . 12.78 % over, 12.53 %.

Example 4:

N-Dihexylaluminio-N-methylamine trimethyIsilyl

To 5.7 g (20 mmol) of trihexylaluminum in 6 ml of xylene are added dropwise at room temperature 2.1 g (20 mmol) of N-trimethylsilyl-methylamine in 5 ml of xylene with vigorous stirring within 30 min. The solution is slowly heated in the course of about two hours at 75 to 80 ⁰ C. During this process, 80 % of the hexane which forms is distilled over. After four hours the reaction is over «

After the solvent has been removed, a pale yellow, viscous liquid remains behind

Yield: 4.5 g (75 % of theory);

H-NMR: c / _SiCH = 0.21 ppm; C ^ _NCH = 2.51 ppm;

Analysis: Al "8.75 %. About _e 9.00%.

Claims (2)

220597 claim for invention: 1. A process for the preparation of N-alkylaluminio-N-silylamines of general formula I, R ⁵ R ⁴ R ³ Si N ^A l n ^R 2 _n ^X
R ² in the R is an optionally branched aliphatic cycloaliphatic or araliphatic radical with 2 to 2 12 carbon atoms or a silylalkyl radical, R is an optionally substituted alkyl, cycloalkyl, aralkyl. Aryl or silylalkyl radical and R, R and R are hydrogen, identical or different alkyl, cycloalkyl, alkenyl or aryl radicals, X is halogen, preferably chlorine or bromine, and η is the values 0, 1 or 2 and Z is the values 1, 2 or 3, characterized in that trialkylaluminum compounds or alkylaluminum halides of the general formula II, ^R m ^A1X 3-m « in which R and X have the meaning given in the general formula I and m can assume the values 1, 2 or 3, with N-silylamines of the general formula III, R ⁵ R ⁴ R ³ Si - NH III 2 3 4 5
in which R and R, R and R have the meaning given in general formula I, are reacted in inert solvents under a protective gas atmosphere. « 2 # Method according to item 1, characterized in that organoaluminum compounds of the general formula II in inert solvents below a temperature of 20 ⁰ C with N-SiIylaminen of the general formula III be converted to a donor-acceptor complex, which is then by raising the temperature to 20 to 180 ⁰ C, preferably between 50 and 90 ⁰ C, transferred to the N-alkylaluminum-N-silylamine compound « A process according to Puntk I _1, characterized in that the reaction of the Organoalurniniumverbindungen of the general formula II with the N-SiIylaminen of the general formula III at temperatures of 20 to 180 ⁰ C, preferably from 50 to 90 ⁰ C, takes place. Process according to items 1 to 3, characterized in that the inert solvents used are, for example, aliphatic, cycloaliphatic, aromatic hydrocarbons and halogenated hydrocarbons. Process according to items 1 to 3, characterized in that, for example, pure nitrogen or argon are used as protective gas. Process according to items 1 to 5, characterized in that the reaction takes place up to a molar ratio of organoaluminium compound of general formula II to N-silylamine of general formula III of 2: 1 up to 1: 2, preferably in molar ratio 1: 1. Process according to items 1 to 6, characterized in that the isolation of the reaction products by removal of the solvent and the adhering starting and by-products by vacuum, optionally with heating.