TRIETHYLALUMINUM 15% solution

TRIETHYLALUMINUM 15% SOLUTION IN HYDROCARBONS (97-93-8) Forms explosive mixture in air [flash point (based on hexane) - 14°F/—26°C]. Once solvent has evaporated, this substance is pyrophoric this is dangerous on organic materials (wood, cloth, grease, fuels, etc.). Flow or agitation of substance may generate electrostatic charges due to low conductivity. See also above entry. 

The exact volume of the triethylaluminum added at this point is not critical, since the exact weight is determined later. I he use of a 25% solution of triethylaluminum in benzene, available from the Stauffer Chemical Company, 299 Park Avenue, New York, eliminates the tedious preparation of the triethylaluminum solution described in this procedure. 

Out of batch box 2 triethylaluminum (in the form of 10-12% isooctane or petrol solution) is pumped with batching pump 4 into the top part of absorber 3. The middle of the absorber is filled under the pressure of 3-4 MPa with ethylene, which has been dried and purified in the system of subsequent towers with active aluminum oxide and active coal. In the absorber the triethylaluminum solution is presaturated with ethylene to ensure exact operation of the batching equipment. The triethylalumi-num ethylene mole ratio can be from 1 9 to 1 25 depending on the desired distribution of alkyl groups in aluminumtrialkyls. 

The triethylaluminum solution, saturated with ethylene, is pumped with pump 5 out of the absorber and sent into polymeriser 6. The optimal conditions for polymerisation are 105-110 °C, 10-12 MPa, the reaction time is 6-8 hours. It should be kept in mind that when the temperature rises to 125 °C and pressure to 12.5 MPa, the considerable acceleration and release of much heat (—92.2 KJ/mole) can cause an explosion. The mixture from the polymeriser is sent into separator 7, where liquid products are separated from the unreacted ethylene. The ethylene is withdrawn through backflow condenser 8, where the solvent vapours condense the solution of higher aluminumtrialkyls enters collector 9. In this case the conversion degree of ethylene is 83-85 % the yield of higher aluminumtrialkyls is 75-77 %. 

Chiral 4,4, 6, 6 -tetraperfluorooctyl-BINOL 21 was applied to the titanium-catalyzed addition of EtyZn to aromatic aldehydes. The reaction was carried out in a hexane/perfluoromethyldecalin biphasic system at 45°C for 1 h. At this temperature, the reaction mixture became homogeneous and, after the reaction, the two phases were separated by cooling the homogeneous solution to 0°C. The fluorous phase was used nine times to give constant chemical yields (70-80%) and enantioselectivities (54-58% ee). When a triethylaluminum solution in hexane was used instead of EtyZn solution, the reaction mixture became homogeneous at... 

Precipitation of the catalyst can be effected by treating the polymer solution with acid/base and/or oxidants. Poloso and Murray [95] proposed a method to recycle the nickel octanoate ((CH3(CH2)6C02)2Ni)/triethylaluminum((C2H5)3Al) catalyst from a styrene-butadiene polymer solution. The polymer solution containing the catalysts was refluxed with 4 wt.% glacial acetic acid (relative to polymer) for 4 h, followed by treatment with 1.4 wt.% anhydrous ammonia. The solution was then filtered through a diatomaceous earth. The nickel content in the polymer was decreased from 310 ppm to 5.6 ppm. 

Tellurium-Al exchange (typical procedure)d Into a CHCI3 (3 mL) solution of the telluride ((ii) Ar = Ph R=n-Bu = f-Bu 344 mg, 1.0 mmol) was added triethylaluminum (3.0 equiv) at 20°C. After 5 h stirring, the reaction mixture was quenched with 3 N HCl at 0°C. Extraction followed by purification of the resulting mixture with HPLC afforded 3,3-dimethyl-l-phenyl-l-butene (Ar = Ph Ri = f-Bu) in 94% yield ( /Z=>99 l). As by-product BuTeEt was formed almost quantitatively. 

Neat triethylaluminum may be replaced by a 10-25% stock solution of it in anhydrous tetrahydrofuran with decreasing the amount of solvent in the reaction flask. The stock solution is prepared by using a graduated flask to measure the volume of the triethylaluminum and solvent added appropriately. The stock solution is very stable and not pyrophoric. 

Direct determination of C-labeled ethyl groups bound on the surface of titanium trichloride samples, treated either with triethylaluminum or di-ethylaluminum monochloride solutions, at different temperatures. 

Magnesium powder (6.12 g) and 250 ml of heptane were charged into a reaction flask and then refluxed and treated with iodine (0.05 g) and 1.0 ml of -butyl chloride. After refluxing for 1 hour -butyl chloride (19.5 g) was added dropwise over 3 hours and the mixture further heated for 2 hours. This mixture was then treated with 2.1 ml triethylaluminum and maintained at this temperature for 2 hours and then cooled to 50°C and filtered. The filter cake was washed with fresh heptane several times and the filtrate concentrated to give a heptane solution of (C4H9)2Mgo 2iEt3Al and the catalyst isolated. 

Fig. 7. Conversion curve (arbitrary unit) for polymerization of methyl methacrylate in toluene solution on the presence of triethylaluminum at 256° K in darkness and illuminated with 100 W tungsten light (Aixen and Casey [43))...

The complex RhCl(ttp), where ttp = PhP(CH2CH2CH2-PPh2)2, in the presence of either triethylaluminum or diethylaluminum chloride, is an effective homogeneous catalyst for hydrogenation of 1-olefins and 1-octyne. The rates of hydrogenation of substituted olefins are considerably slower than for terminal olefins. H-l and P-31 NMR spectra were used to identify several different chemical species [including RhH(ttp)] in these catalyti-cally active solutions. The observed rate of hydrogenation of 1-octene to n-octane at 20 0.3°C and under a constant H2 pressure of 750 torr is 6.4 x min 9... 

Activation of aluminum in a cavity, ball or vibration mill. This activation technique should be used in nitrogen and in 5% solution of triethylaluminum in n-heptane, because aluminum suspension is easily transported through pipes and activated aluminum is protected from oxidation (with oxygen in air) during transportation and storage. Besides, wet grinding is less explosive than dry. Aluminum powder should be activated in the mill for 20-30 hours. The aluminum ground in a vibration mill is the most active. 

This molecule is stable even in the gaseous stage and dissociates only above 100 °C. In dilute solutions aluminumtrialkyls dissociate with time e.g.,triethylaluminum dissolved in benzene dissociates into monomer within 6-8 hours. 

Reactor 3 with a shielded electric drive agitator, which has been dried with nitrogen, is loaded with a necessary amount of aluminum powder, petrol and 50-60% petrol solution of triethylaluminum sesquichloride. The agitator is switched on, the mixture is heated to 50-60 °C aluminum is activated by adding ethyl bromide gradually and at constant temperature. The heated reactor is filled with ethylchloride at such speed that the given temperature is maintained. After ethylchloride has been supplied, the mixture is held at reaction temperature for 1-2 hours to complete the synthesis. The obtained product is cooled and loaded off into collector 7. 

The "symmetrisation" of triethylaluminum sesquichloride takes place in reactor 8. The suspension of sodium in petrol is prepared there sesquichloride enters the reactor from collector 7 through batch box 9 at 125-135 °C and agitation. Then the mixture is agitated at the synthesis temperature for 2-3 hours to complete the reaction then it is cooled to ambient temperature. The obtained diethylaluminumchloride solution is settled for 2-3 hours to separate dirt the purified product enters container 12. 

These reactions require anhydrous aluminum chloride and a 50-80% petrol solution of triethylaluminum. The process is carried in a cylindrical steel apparatus, which has a propeller agitator with a shielded electric drive. The synthesis takes place at a temperature not exceeding 60 °C for 2-3 hours. Then the reaction products are subjected to filtering or distillation. 

Pure organoaluminum compounds are pyrophoric (capable of selfignition) at these temperatures from -68 °C for triethylaluminum to -40 °C for triisobutylaluminum and for -64 °C for diethylaluminumchloride. When organoaluminum compounds are diluted, the self-inflammation point of the solutions increases to +20 °C at 50-70% concentration (diluted even more, organoaluminum compounds are not pyrophoric). 

Triethylaluminum reacts violently with water and inflames in air. Care must also be taken in preparing the diethyl ether solution since an exothermic reaction occurs the ether solution is conveniently transferred to the addition funnel via a hypodermic syringe. 

EthoxydiethyIaluminum(in) can be prepared from commercial triethylaluminum by the addition of 1 mole of ethanol in benzene solution b.p. 50-54 at lO" torr. 

Triisobutylaluminum (racemic) is commercially available in toluene solution. Triethylaluminum and related compounds are used, of course, commercially in Ziegler-Natta polymerization. These solutions can be handled safely in contrast to the pure materials, which are violently reactive. The applications of triisobutylaluminum have been reviewed." Its use is difficult to divorce from its chemical relative, diisobutylaluminum hydride, which is probably more often used for reductions of carbonyl groups. This latter reagent reduces, of course, via the reactive aluminum-hydride bond. The thought that the dialkylaluminum is less bulky than the trimer is misleading there is a greater tendency of the former towards aggregation." ... 

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