Styrene diethyl ether

Anionic polymerization of vinyl monomers can be effected with a variety of organometaUic compounds alkyllithium compounds are the most useful class (1,33—35). A variety of simple alkyllithium compounds are available commercially. Most simple alkyllithium compounds are soluble in hydrocarbon solvents such as hexane and cyclohexane and they can be prepared by reaction of the corresponding alkyl chlorides with lithium metal. Methyllithium [917-54-4] and phenyllithium [591-51-5] are available in diethyl ether and cyclohexane—ether solutions, respectively, because they are not soluble in hydrocarbon solvents vinyllithium [917-57-7] and allyllithium [3052-45-7] are also insoluble in hydrocarbon solutions and can only be prepared in ether solutions (38,39). Hydrocarbon-soluble alkyllithium initiators are used directiy to initiate polymerization of styrene and diene monomers quantitatively one unique aspect of hthium-based initiators in hydrocarbon solution is that elastomeric polydienes with high 1,4-microstmcture are obtained (1,24,33—37). Certain alkyllithium compounds can be purified by recrystallization (ethyllithium), sublimation (ethyllithium, /-butyUithium [594-19-4] isopropyllithium [2417-93-8] or distillation (j -butyUithium) (40,41). Unfortunately, / -butyUithium is noncrystaUine and too high boiling to be purified by distiUation (38). Since methyllithium and phenyllithium are crystalline soUds which are insoluble in hydrocarbon solution, they can be precipitated into these solutions and then redissolved in appropriate polar solvents (42,43). OrganometaUic compounds of other alkaU metals are insoluble in hydrocarbon solution and possess negligible vapor pressures as expected for salt-like compounds. 

Some chemicals are susceptible to peroxide formation in the presence of air [10, 56]. Table 2.15 shows a list of structures that can form peroxides. The peroxide formation is normally a slow process. However, highly unstable peroxide products can be formed which can cause an explosion. Some of the chemicals whose structures are shown form explosive peroxides even without a significant concentration (e.g., isopropyl ether, divinyl acetylene, vinylidene chloride, potassium metal, sodium amide). Other substances form a hazardous peroxide on concentration, such as diethyl ether, tetrahydrofuran, and vinyl ethers, or on initiation of a polymerization (e.g., methyl acrylate and styrene) [66]. 

After 5 minutes the cooling bath was removed and the two-phase reaction mixture was stirred at room temperature. The reaction was monitored by TLC (eluent petroleum ether-diethyl ether, 8 2). (Z)-Methyl styrene was UV active, R 0.85. The epoxide visualized withp-anisaldehyde dip stained yellow, R 0.63. 

The results of Plesch s analysis (1993)indicate that for the VE the mc is ca. 2 mold 1 in benzene, diethyl ether, and diglyme, possibly as high as 9 mold 1 in CH2C12 for styrene... 

As shown in Tab. 11.5, multi-component catalyst (27) matches the activity of its corresponding monomer (4), promoting efficient RCM of (19) in just 15 minutes at 40 °C. The reaction mixture was passed through a short column in methylene chloride to isolate the desired product. Subsequent washing of the silica with diethyl ether led to quantitative recovery of the dendritic catalyst. 400 MHz NMR analysis revealed that 13% of the styrene ligands on the dendrimer were va-... 

Typical procedure. Into a two-necked, 20 mL, round-bottomed flask containing PdClj (8.8 mg, 0.05 mmol), AgOAc (388 mg, 2.00 mmol) and di(/7-methoxyphenyl) teUuride (0.171 g, 0.50 mmol) were added dry methanol (10 mL), EtjN (0.202 g, 2.00 mmol) and styrene (0.104 g, 1.00 mmol). After the heterogeneous reaction mixture had been stirred at 25°C for 20 h, the sohd part was filtered. The filtrate was poured into brine (200 mL) and extracted with diethyl ether (3x50 mL). GLC determination of the ether extract with diphenyhnethane as an internal standard showed the presence of 0.99 mmol (99%) of (E)-p-methoxystilbene. 

To 5.3 g of 4-vinylpyridine is added to THE up to a volume of 50 ml 5 ml of this solution (containing 5 mmol 4-vinyl pyridine) are added in the same way to the above solution containing the "living" polystyrene, with vigorous agitation. After 15 min another 40 mmol of styrene are added, followed 15 min later by another 5 mmol of 4-vinylpyridine this operation is repeated once more. 15 min after the last addition of monomer the block copolymer is precipitated by dropping the solution into a mixture of 300 ml of diethyl ether and 300 ml of petroleum ether.The polymer is filtered, washed with ether,filtered again, and dried in vacuum at room temperature. 

It was also discovered at Phillips. that the four rate constants discussed above can be altered by the addition of small amounts of an ether or a tertiary amine resulting in reduction or elimination of the block formation. Figures 13 and 14 illustrate the effect of diethyl ether on the rate of copolymerization and on the incorporation of styrene in the copolymer. Indeed, random copolymers of butadiene and styrene or isoprene and styrene can be prepared by using alkyllithium as initiator in the presence of small amounts of an ether or a tertiary amine. 

Figure 14. Effect of amount of diethyl ether styrene incorporation at 50°C (16).

The first results of anionic polymerization (the polymerization of 1,3-butadiene and isoprene induced by sodium and potassium) appeared in the literature in the early twentieth century.168,169 It was not until the pioneering work of Ziegler170 and Szwarc,171 however, that the real nature of the reaction was understood. Styrene derivatives and conjugated dienes are the most suitable unsaturated hydrocarbons for anionic polymerization. They are sufficiently electrophilic toward carbanionic centers and able to form stable carbanions on initiation. Simple alkenes (ethylene, propylene) do not undergo anionic polymerization and form only oligomers. Initiation is achieved by nucleophilic addition of organometallic compounds or via electron transfer reactions. Hydrocarbons (cylohexane, benzene) and ethers (diethyl ether, THF) are usually applied as the solvent in anionic polymerizations. 

This group covers polymeric peroxides of indeterminate structure rather than polyfunctional macromolecules of known structure. These usually arise from autoxidation of susceptible monomers and are of very limited stability or explosive. Polymeric peroxide species described as hazardous include those derived from butadiene (highly explosive) isoprene, dimethylbutadiene (both strongly explosive) 1,5-p-menthadiene, 1,3-cyclohexadiene (both explode at 110°C) methyl methacrylate, vinyl acetate, styrene (all explode above 40°C) diethyl ether (extremely explosive even below 100°C ) and 1,1-diphenylethylene, cyclo-pentadiene (both explode on heating). 

Diaminobutyl dendrimers (DAB-POPAM) were functionalised with terminal diphenylphosphanyl groups and employed as catalysts in the Heck coupling of bromobenzene and styrene to give stilbene. Owing to their greater thermal stability, these dendritic palladium catalysts afforded higher yields than conventional palladium catalysts. In addition, the dendritic catalyst could be completely recovered by precipitation after addition of diethyl ether [7]. 

For instance, in cases where the mechanism of the propagation of the polymer chain is by means of cationic polymerization, the rate increases with the polarity of the solvent. Thus, when the boron trifluoride-diethyl ether complex is used as the catalyst for styrene polymerization, then at 0°C the rate equation for a series of solvents takes the simple form of dependence on the solvent polarity (Heublein 1985) ... 

Suzuki et al. [Ill] screened three solvents—methylene chloride, diethyl ether, and benzene—to determine their ability to produce optimum elution of phthalic acid monoesters sorbed on a styrene divinylbenzene polymer (Figure 2.40). The effect of elution solvent strength on the recovery of the free acid form of the monomethyl (MMP), ethyl (MEP), -propyl (MPRP), K-butyl (MBP), K-pentyl (MPEP), and -octyl (MOP) phthalates is compared. The phthalic acid monoesters are arranged in Figure 2.40 in the order of increasing number of carbons in the alkyl chain, which in turn is roughly correlated with an increase in hydrophobicity. 

A mixture of 0.2 mmol Pd(OAc)2 (2 mol%), 10 mmol benzoquinone, and 1 mL perchloric acid (72%) in 50 mL acetonitrile-H20 (7 1) is stirred under Ar at r.t. until complete dissolution. The olefin (10 mmol) is added and the reaction mixture stirred at r.t. (aliphatic olefins, cyclohexene) or 60 °C (styrene, cycloheptene, internal olefins) until completion of the reaction (from 10 min to 90 min), as judged by TLC. The mixture is poured into diethyl ether and washed with aqueous NaOH (30 %). The aqueous layer is extracted with ether. The combined organic layers are dried over MgS04, filtered, and the solvent is evaporated. The crude product is purified by chromatography. 

Kessler and coworkers44 investigated the indole synthesis using DMF as the electrophile, which in the reaction sequence provides the unsubstituted C2 carbon of the indole ring. In a typical procedure, the organolithium reagent was added dropwise over 30 min to a solution of styrene in dry diethyl ether at — 78 °C under an inert nitrogen... 

Racemic cyclopropanation reactions have been performed with rhodium1 241 and palladium11251 catalysts. The reaction between an olefin and ethyl diazoacetate in the presence of 1 mol% Rh2(OAc)4 in [C4Ciim][PF6] proceeded with higher rates, improved yields and better trans-selectivity relative to conventional solvents for both electron-rich and electron-deficient styrene derivatives. The product was obtained by extraction with diethyl ether and in this manner only trace amounts of the catalyst were leached from the ionic liquid. Nevertheless, yields drop from 88% in the first run to 72% in the fifth run. 

A reaction corresponding to Eq. (5-30) is the addition of nitrosyl chloride to alkenes such as cyclohexene or styrene [84, 85]. The reaction seems to be faster in polar solvents e.g. nitrobenzene and trichloromethane) than in less polar solvents e.g. toluene and tetrachloromethane). This is consistent with the view that the reaction involves an electrophilic attack of NO —Cl . The reaction was, however, also found to be very slow in diethyl ether. Presumably, this is due to strong bonding of the NO+ cation to the ether oxygen atom [84]. 

EtjN (4.89 g, 48.4 mmol) diluted with toluene (20 mL) was added to asolution of trifluoroacetohydroximoyl bromide diethyl ether complex (6.45 g. 24.2 mmol) and styrene (7.55 g, 72.6 mmol) in toluene (50 mL) over a 1-h period, and the mixture was stirred at rt for an additional 10 h. After excess hexane was added to the mixture, the resulting salt (4.51 g) was collected on a filter. The filtrate was washed with H,0 and brine, dried (MgSOi). and evaporated to leave crude isoxazoline which was purified under reduced pressure to give pure material yield 4.35 g (84%) bp 85-87 C/3.S Ton. ... 

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