Diethylaluminum chloride, chemical

Materials. 5-Methyl-1,4-hexadiene was obtained by the codimerization of isoprene and ethylene with a catalyst (18) consisting of iron octanoate, triethylaluminum and 2,2 -bi-pyridyl. The product mixture which contained principally 5-methyl-1,4-hexadiene and 4-methy1-1,4-hexadiene was fractionated through a Podbielniack column to yield high purity (>99%) 5-methylxhexadiene, b.p. 92.80C,njj 1.4250 (Lit. (19) b.p. 88-89°C, np 1.4249). 1-Hexene (99.9% purity), 1-decene (99.6% purity), 4-methyl-1-hexene (99.5% purity) and 5-methyl-l-hexene (99.7% purity) were obtained from Chemical Samples Co. 6-TiCl3 AA (Stauffer Chemical Co.j contains 0.33 mole AICI3 per mole of TiClj). Diethylaluminum Chloride was obtained from Texas Alkyls (1.5 M in hexane). 

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... 

Reaction of norbomadiene with a Co-(S,5)-NORPHOS catalyst (0.2-0.3 mol %, norbomadiene phenylacetylene (5,5)-NORPHOS cobalt = 500 500 1.5 1), when performed in the presence of diethylaluminum chloride, produces the corresponding subtituted deltacyclene ([2+2+2] cycloadduct) in quantitative chemical yield and excellent optical yield (98.4% ee) (eq 15). Similar results were obtained when either 7 or (-)-BDDP (10) was used in place of (S,5)-NORPHOS.23 3 However, the use of other optically active diphosphines, e.g., 3, (-)-MENO (11), or 6, generally afforded 4-phenyldeltacyclene in lower optical yield. Interestingly, the use of [Rh(norbomadiene) (R,R)-NORPHOS]PF6 as catalyst did not result in deltacyclene formation instead, 3-phenylethynylnortricyclene was produced in 45% chemical yield and 60% optical yield (eq 15). ... 

Preparation of the in situ Catalyst and Catalytic Reaction. (This is a typical procedure for norbomadiene and phenylacetylene or 1-hexyne). Tris(acetylacetonato)cobalt (7.1 mg, 2.0x10 mmol) and (+)-NORPHOS (13.8 mg, 3.0 x 10 mmol) are dissolved in 1 ml of THF under dry nitrogen, using standard Schlenk techniques. Norbomadiene (1.0 mL, 10.0 mmol) and 10 mmol of phenylacetylene or 1-hexyne are added. The reaction is started by addition of 5 mL of a IM solution of diethylaluminum chloride in hexane. The reaction mixture is kept at 35 °C for 4 h. Then 5 mL of isopropanol are added and the volatile components are removed in vacuum. The oily residue is distilled at 80 °C in high vacuum in a Kugelrohr apparatus. Chemical yield >99% enantiomeric excess 98.4-99.6% for (+)-4-phenyldeltacyclene and 97.6-98.0% for (+)-4-n-butyldeltacyclene. 

All solvents and monomers were purified and stored under nitrogen atmosphere. The r-butyl chloride (r-BuCl, Eastman) was distilled from calcium hydride under nitrogen atmosphere prior to use. Diethylaluminum chloride (Et2 A1C1, Texas Alkyls Co.) was purified by vacuum distillation (bp °C/mm Hg 110/25). Ethyl chloride (EtCl, Linde Division, Union Carbide Co.) was purified by passing through a column packed with Molecular Sieves and barium oxide. The m-3-hexene (Chemical Samples Company) was distilled under nitrogen prior to use. The polybutadiene, Diene 35, from the Firestone Tire and Rubber Company and high 1,2-polybutadiene were purified by reprecipitations from benzene into excess acetone. 

Cr(N03)3-9H20, trimethylaluminum (TMA), tri-i-butylaluminum (TIBA), diethylaluminum chloride (DEAC) were all analytical grade chemicals fiom Aldrich. 

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