Diethylzinc- 3,3 dimethyl

We were able to isolate species of both types in the case of diethylzinc-(+) 3,3 dimethyl 2 butanol initiator system. The antisteric species has a composition close to Etf.Zn(0R)j, or Zn(0R) . (EtZnOR)g (-OR being the 3,3 dimethyl 2 butoxy group), while an homosteric initiator had a Zn(0R)j>. EtZnOR composition. Both species were soluble in benzene and were studied by H-NMR (18). It was possible to transform one specie into the other by ailing ZnEtp or by drying or heating (loss of ZnEt, and disproportionation . ... 

We have polymerized propylene sulfide and propylene oxide of different enantiomeric composition with the same initiator system, diethylzinc-/ (-)-3,3-dimethyl-1,2-butanediol (1 1). Starting from a non racemic mixture we have to use Equation (1) for the determination of stereoelectivity ratio r. 

SODIUM ACID FLUORIDE (1333-83-1) NaHFj Dry material reacts, possibly violently, withchromyl chloride, diethylzinc, dimethyl sulfoxide, lead dioxide, nitric acid, redphosphoras, potassium, sodium peroxide. Incompatible with hexafluoroisopropylidene-aminolithium. Reacts with water releasing heat and, forming a highly acidic solution. Incompatible with sulfuric acid, bases, caustics, ammonia, amines, amides, organic... 

BROMURO de AZUFRE (Spanish) (13172-31-1) Combustible liquid. Reacts with moisture in air, steam, or oxidizers, emitting fumes of hydrogen bromide and sulfur dioxide. Reacts with water, forming hydrobromic acid and fumes of hydrogen bromide and sulfur dioxide. Violent reaction with strong oxidizers, chromyl chloride, diethylzinc, dimethyl sulfoxide, lead dioxide, nitric acid, potassium. Incompatible with hexafluoroisopropylide-neaminolithium, iron sulfide, nickel, red phosphorus. Attacks most metals in the presence of moisture. 

SODIUM DIFLUORIDE (1333-83-1) Dry material reacts, possibly violently, with chromyl chloride, diethylzinc, dimethyl sulfoxide, lead dioxide, nitric acid, red phosphorus. 

The use of cyclic a,p-unsaturated ketones as starting materials in the enantioselective addition of dimethyl- and diethylzinc reagents catalysed by the HOCSAC ligand was introduced by Walsh and Jeon, in 2003. As shown in Scheme 4.16, the corresponding cyclic tertiary alcohols were formed in high enantioselectivities of up to 99% ee. 

Further optimization of this reaction was carried out with TFE as an achiral adduct, since reaction with TFE is much faster than that with neopentyl alcohol. We found that dimethyl- and diethylzinc were equally effective, and the chiral zinc reagent could be prepared by mixing the chiral modifier, the achiral alcohol and dialkylzinc reagent in any order without affecting the conversion and selectivity of the reaction. However, the ratio of chiral to achiral modifier does affect the efficiency of the reaction. Less than 1 equiv of the chiral modifier lowered the ee %. For example with 0.8 equiv of 46 the enantiomeric excess of 53 was only 58.8% but with 1 equiv of 46 it was increased to 95.6%. Reaction temperature has a little effect on the enantiomeric excess. Reactions with zinc alkoxide derived for 46 and TFE gave 53 with 99.2% ee at 0°C and 94.0% ee at 40°C. 

Dimethyl- and diethylzinc reacted with dimethylpyrrole- and mesityl-substituted cyclopentadiene ligands to give monocyclopentadienyl(methyl)zinc and -ethyl(zinc) compounds. These products then formed, Scheme 20, crystalline adducts with tetramethylethylenediamine (TMEDA) such as 24, whose solid-state structure is shown in Figure 11. 

Organophosphonates are isoelectronic with organotrisiloxides. Like zinc siloxides and zinc siloxanes, zinc phosphonates are actively investigated as porous materials, for applications in catalysis, as molecular sieves, and for electronic devices. Dimethyl- and diethylzinc reacted with / //-butylphosphonic acid in THF solution to furnish,... 

The interactions of dimethyl- and diethylzinc with bulky tris(hydroxyphenyl)methanes, Scheme 86, yielded, depending on the reaction conditions, a variety of alkylzinc alkoxides, featuring two-, three-, and four-coordinate zinc centers. These polynuclear compounds (Figure 63 shows the trinuclear ethylzinc derivative 136) are relatively poor catalysts for the co-polymerization of cyclohexene oxide and carbon dioxide.197... 

Tellurium-Zn exchange (typicalprocedure) Into aTHF (5 mL) solution of f-l-Cbutyl-telluro)-l-phenyl-3,3-dimethyl-l-butene was added diethylzinc (1.0 equiv) at 20°C. After stirring for 5 h the reaction mixture was quenched with 1 N HCl at 0°C. Purification of the resulting mixture by HPLC afforded l-phenyl-3,3-dimethyl-l-butenine in 85% yield (ElZ ratio, 6 94) along with butylethyl telluride in 89% yield. 

Merck scientists made changes to this process, resulting in fewer equivalents of acet-ylide and chiral ligand without the use of Ai-protection (Chen et al., 1998). In a general procedure, a solution of the chiral ligand (1.5 equivalents) is treated with either dimethyl or diethylzinc at 0°C to room temperature (Scheme 6.4). This mixture is stirred for 1 h followed by the addition of an additive. Most of the additives studied are either carboxylic acids or alcohols. The range of ee values from the different additives is 71.6% (2,2-dimethylpropanoic acid) to 96% (2,2,2-trichloroethanol). This solution is mixed... 

In a recent synthesis of a mixed zinc/cadmium telluride alloy, a mixture of dimethyl-cadmium and diethylzinc was employed. The original authors interpreted the results by assuming that the redistribution reaction 3 is essentially thermoneutral since the difference between the enthalpies of formation for the symmetrical dialkylzincs is small. 

The alcoholysis reaction starting from dimethyl- or diethylzinc remains the major approach to Zn(OR)2. The latter can contain admixtures R Zn(OR )2.0, which can be separated by destination in vacuum [255]. The alkyl-alkoxode-rivatives are usually very stable. Thus EtZnOR, R = Pr Bu and C6H3Bu 2-2,6... 

Diethyllead dinitrate, 1686 Diethylmagnesium, 1681 Diethylzinc, 1712 Diisobutylzinc, 3075 Diisopentylmercury, 3362 Diisopentylzinc, 3365 DiisopropylberyIlium, 2530 Dimethyl-1 -propynylthallium, 1932 Dimethylberyllium, 0886... 

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