Diethylaluminum ethoxide

Addition of (R,S)-9 to the aromatic benzaldehyde proceeded with higher enantiosclcctivity than the addition of the diastereomeric reagent (S,S)-9. The reverse is true for additions to aliphatic aldehydes. Thus, the highest enantioselectivity of 92% ee was observed in the addition of (R,R)- 9 to cyclohexanccarboxaldehyde. The low chemical yields of most addition reactions can be improved by addition of the Lewis acid diethylaluminum ethoxide. The presence of the Lewis acid solely enhanced the chemical yield without changing the enantioselectivity of the addition reactions. 

Diethylaluminum ethoxide, (C2H5)2A10C2H5 (1), available from Aldrich. 

Here we discuss dispersion polymerizations that are not related to vinyl monomers and radical polymerization. The first one is the ring-opening polymerization of e-caprolactone in dioxane-heptane (30). A graft copolymer, poly(dodecyl acrylate)-g-poly(e-caprolactone), is used as a stabilizer. The polymerization proceeds via anionic or pseudoanionic mechanism initiated by diethylaluminum ethoxide or other catalysts. The size of poly(caprolactone) particles depends on the composition of stabilizer, ranging from 0.5 to 5 i,m. Lactide was also polymerized in a similar way. Poly(caprolactone) and poly(lactide) particles with a narrow size distribution are expected to be applied as degradable carriers of drugs and bioactive compounds. 

In the co-oligomerization of methylenecyclopropane (26) with allene (63 equation 25) on a palla-dium(O) catalyst, prepared in situ from [Pd(acac)2], triisopropylphosphine and diethylaluminum ethoxide, or from [Pd(DBA)2] and triisopropylphosphine, cyclic hydrocarbons such as 2-methylenespiro[2.4]hep-tane (27), 1,3-dimethylenecyclopentane (64) and 1,3,5-trimethylenecycloheptane (65) are formed. ... 

If, however, one of the ethyl groups in triethylaluminum is replaced by an ethoxide ligand, the resultant molecule is dramatically more stable thermally. For example, diethylaluminum ethoxide is stable up to at least 192 °C (37). A comparison of the percent decomposition of selected aluminum alkyls over 3 hours at °C is shown... 

Figure 5.5 Compounds used to produce supported chromium catalysts developed by Union Carbide for use in gas phase processes for LLDPE and HOPE. Catalysts must be supported, usually on silica, for optimal performance. Chromocene catalyst is used without a cocatalyst BTSC uses diethylaluminum ethoxide as cocatalyst.

Methylenecyclopropane (1 12 g, 222 mmol) was added at — 78 °C to a suspension of Pdfdba) (575 mg, 1 mmol) and an equimolar amount of the appropriate trialkylphosphane in anhyd toluene (6 mL) and placed in a 200-mL stainless steel autoclave cooled to — 78 C under an inert atmosphere of argon. The closed autoclave was heated to 100°C for 18 h with stirring after cooling, all volatile components were condensed off the mixture at 25°C/0.01 Torr and analyzed by GC. Toluene may serve as internal standard. The Pd(acac)2"based catalyst for a reaction on a similar scale was prepared from Pd(acac>2 (183 mg, 0.6 mmol), i-PrjP (96.1 mg, 0.6 mmol) and diethylaluminum ethoxide (156 mg, 1.2 mmol) in anhyd toluene (6 mL). >... 

The above reaction may be carried out using diethylaluminum ethoxide in place of triethylaluminum. The title compound can also be prepared by the reaction of Ni(cod)2 with triphenylphosphine [9] or by the reduction of NiCf with Zn powder in the presence of triphenylphosphine [61]. 

In another method of contacting catalyst and cocatalyst, the catalyst is treated with concentrated cocatalyst in a batch process. The catalyst is then dried and fed to the reactor as a single powder. This approach is most often used in the fluidized-bed process, in which a solvent is not available and in which the cocatalyst does not have high volatility. Both Cr(VI) oxide and bis(triphenylsilyl) chromate catalysts can be used as the catalyst component (see Section 3.8). Typically the latter is used, and treated with diethylaluminum ethoxide. 

Four examples illustrating this point are shown in Figure 219, where data represent experiments in which various cocatalysts were used at a concentration of 8 ppm with a Cr(II) /silica-titania catalyst. Each cocatalyst produced a different a-olefin profile. Triethylboron produced a prominent 1-hexene spike with a much smaller Schulz-Flory background. The addition of a small amount of 02 with the triethylboron cocatalyst increased the relative amount of 1-hexene while decreasing the overall yield of a-olefins. At the other extreme, diethylsilane produced a sharp Schulz-Flory distribution with little additional 1-hexene. The behavior of diethylaluminum ethoxide was intermediate, as a large amount of 1-hexene was produced, superimposed onto a significant Schulz-Flory... 

Aluminum, ethoxydiethyl-. See Diethylaluminum ethoxide Aluminum 2-ethyl hexanoate CAS 30745-55-2 EINECS/ELINCS 250-322-2 Empirical C16H31AIO5 Formula (CH3(CH2)3CH(CH2Hs)COO)2AIOH Properties M.w. 330.40... 

DEAL-E. See Diethylaluminum ethoxide DEA-lauraminopropionate CAS 65104-36-1 EINECS/ELINCS 265-417-4 Synonyms p-Alanine, N-dodecyl-, compd. with 2,2 -iminobis [ethanol] N-Dodecyl-p-alanine, compd. with 2,2 -iminodiethanol (1 1)... 

Manuf/Disthb. ABCR http //www.abcr.de] Acros Org. http //www.acros.be] Akzo Nobel http //www.akzonobel.com] Albemarle http //www.albemarle.com] Aldrich http //www.sigma-aldrich. com Fluka http //www.sigma-aidrich.com Diethylaluminum ethoxide CAS 1586-92-1 EINECS/ELINCS 216-447-1 UN 2003 (DOT)... 

Ethoxy-p-cymene. See Carvacryl ethyl ether Ethoxydiethylaluminum. See Diethylaluminum ethoxide Ethoxydiglycol... 

Di-t-butyl peroxide Di-n-butylzinc 1,1-Dichloroethane cis-1,2-Dichloroethylene cis-trans-1,2-Dichloroethylene (mixed isomers) trans-1,2-Dichloroethylene 2,4-Dichlorophenol 3,4-Dichlorophenyl isocyanate Dichloropropene cis-1,3-Dichloro-1-propene Dicyandiamide Diethanolamine Diethylaluminum bromide Diethylaluminum ethoxide Diethyl aniline Diethylboron methoxide Diethylene glycol diethyl ether Diethyl ketone Diethyl maleate Diethyl zinc... 

Diethylaluminum ethoxide 216-452-9 Cobalt octoate 216-472-8 ADK STAB CA-ST Afco-Chem CS Afco-Chem CS-1 Afco-Chem CS-S Akrochem F-4000 Akrochem P 4000 Akrochem P 4100(w)... 

This proposal was tentatively supported by the findings of Natta et al. (1960a). Using diethylaluminum ethoxide, labeled in the ethoxide group, they detected radioactivity in the polymer. However, no radioactivity was found when labeled triethylaluminum was used. 

A key attribute of the Bis(triphenylsilyl)chromate catalyst deposited into silica is that this catalyst does not require a high temperatme activation (oxidation) step in the catalyst preparation. Consequently, this catalyst is activated in the polymerization reactor by the ethylene, which results in an induction time similar to the Phillips catalyst before the onset of polymerization. However, because the Bis(triphenylsilyl)chromate catalyst on silica utilizes an aluminum alkyl such as diethylaluminum ethoxide (DEAEO), it is believed that the finished catalyst does not contain Cr(VI), but contains chromium in lower oxidation states probably Cr(II), Cr(III) and/or Cr(IV). Tables 3.4 and 3.5 summarize some polymerization data for... 

Consequently, the commercially important Bis(triphenylsilyl)chro-mate catalyst is prepared on silica in a two-step process. First, a solution of Bis(triphenylsilyl)chromate in isopentane is added to the dried silica to produce a slurry in which the Bis(triphenylsilyl)chromate is completely fixed to the silica surface. After the deposition process, an aluminum alkyl such as diethylaluminum ethoxide is added to the first intermediate and the catalyst is dried to produce a free-flowing powder. Unlike the Phillips catalyst. 

Figure 3.13 Effect of diethylaluminum ethoxide to triethylaluminum ratio on polymer Melt Index (12.16) for the Bis(triphenylsUyl) chromate catalyst supported on silica. The aluminum alkyl mixture is added after the deposition of the chromate compound onto the silica. Reprinted from [17] with permission from John WUey and Sons.

Figure 3.14 Effect of hydrogen/ethylene gas phase ratio on Melt Index (MI) for the Bis(triphenylsilyl) chromate supported on silica with diethylaluminum ethoxide as cocatalyst. Reprinted from [17] with permission from John Wiley and Sons.

Table 2 Propagation rate constants (kp) and equilibrium constants of aggregation (Ka) for polymerization of 8-caprolactone initiated by diethylaluminum ethoxide ...

The dispersion polymerizations of s-caprolactone and lactides were initiated with initiators used for initiation of polymerizations of the above-mentioned monomers in solution. Diethylaluminum ethoxide, stannous 2-ethylhexano-ate, ° stannous 2-ethylhexanoate/polyalcohols, and 2,2-dibutyl-2-stanna-l,3-dioxepane were used for the dispersion polymerizations of lactides. The dispersion polymerizations of 8-caprolactone were initiated with diethylaluminum ethoxide and sodium trimethylsilano-late. Of the above-mentioned initiators, only the latter one initiated the anionic polymerization. 

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