Benzene and tetrahydrofuran

The effect of crown ethers on the alkylation of sodium diethyl n-butylmalonate by 1-bromobutane has been studied by Zaug et al. (1972). The absence of a common-ion rate depression in dimethylformamide (DMF) pointed to an ion pair being the kinetically active species. The addition of dicyclohexyl-18-crown-6 (a mixture of [20] and [21]) accelerates the alkylation in both benzene and tetrahydrofuran (THF) (Table 24). The rates reach a plateau, indicating that at a crown-ether concentration of 0.5 M the ion pair is fully converted to the crown ether-separated ion pair which is slightly less reactive than the uncomplexed ion pair in DMF. The rate constant in pure dimethoxyethane (DME) is equal to that observed in THF or benzene... 

Styrene, benzene, and tetrahydrofuran were purified as described previously (8,11). Solutions of ec-butyllithium (Lithium Corporation of America, 12.0 wt % in cyclohexane) and methyllithium (Alfa, 1.45 M in ether) and lithium naphthalene were analyzed using the double titration procedure with 1,2-dibromoethane (12). Lithium naphthalene was prepared in tetrahydrofuran from lithium metal and a 25 mole % excess of sublimed naphthalene at -25°C using standard high vacuum procedures. Sealed ampoules of lithium naphthalene were stored in liquid nitrogen. 

Since Lewis base additives and basic solvents such as tetrahydrofuran are known to deaggregate polymeric organolithium compounds, (21,23,26) it was postulated that ketone formation would be minimized in the presence of sufficient tetrahydrofuran to effect dissociation of the aggregates. In complete accord with these predictions, it was found that the carbonation of poly(styryl)lithium (eq. 9), poly(isoprenyl)-lithium, and poly(styrene-b-isoprenyl)lithium in a 75/25 mixture (by volume) of benzene and tetrahydrofuran occurs quantitatively to produce the carboxylic acid chain ends (8 ). 

The sodium naphthalene polymerization of methyl methacrylate is carried out in benzene and tetrahydrofuran solutions. Which solution will yield the highest polymerization rate Discuss the effect of solvent on the relative concentrations of the different types of propagating centers. 

As was stated above, the interpretation that the field affects the dis-sodation state of the growing chain ends was not uniquely substantiated by the experimental data, except those on copolymerizations. Thus it is interesting to investigate the field influence on much simpler systems than cationic homopolymerizations. For this purpose we have chosen living anionic systems in which only propagation steps are involved. The system first studied was a living anionic polymerization of styrene with n-butyllithium in the binary mixtures of benzene and tetrahydrofuran (17,24) and in the binary mixtures of benzene and dimethoxyethane (15). 

As was mentioned above, tetrahydrofuran and dimethoxyethane have about the same dielectric constant. Nonetheless no triple ions were formed in the binary mixtures of benzene and tetrahydrofuran. Thus, the triple ion formation is not due to coulombic forces alone. It is reasonable to ascribe it to the solvating power of dimethoxyethane molecules toward both anions and cations. We believe that Li+ ion can be included in the negative cavity surrounded by four oxygen atoms of two dimethoxyethane molecules (26), and two negatively charged growing chain ends are coordinated to two positive cavities. Thus, a solvent-separated type of triple ions can be formed. The large value of the distance parameter, 21 A, may reflect this situation. 

Ise, N., H. Hirohara, T. Makino, and I. Sakurada Ionic polymerization under an electric field. XII. Living anionic polymerization of styrene in the binary mixtures of benzene and tetrahydrofuran. J. Pliys. Chem. 72, 4543 (1968). 

Figure 6. Variation of intrinsic viscosity with conversion in stepwise polymerization of propylene oxide in benzene and tetrahydrofuran with Zn3[Co(CN)6]2 glyme ZnCk at 50°C...

Marsh et al, (60, 64) examined optical textures of cokes from carbonizations of soluble and insoluble fractions of coal-extract solutions as well as conditions of extraction. Generally, the low-molecular-weight fractions of the coal-extract solution produced cokes with larger sized optical textures than the coke from the parent coal-extract solution. The higher-molecular-weight fractions produced cokes with smaller sized optical texture. Isotropic coke was produced from material which was insoluble in benzene and tetrahydrofuran. 

Chlorohydridobis(triisopropylphosphine)nickel is a yellow-brown solid. It is thermally stable at ambient temperatures but reacts with air. It is very soluble in benzene and tetrahydrofuran and is soluble in diethyl ether and petroleum ether. Carbon tetrachloride, carbon disulfide, and chloroform decompose the complex. The infrared spectrum shows a sharp v(Ni—H) band at 1937 cm-1 (Nujol mull). The high-held nmr spectrum in benzene solution shows a triplet (1 2 1) at t34.3 (TMS) with JPH 77.8 Hz. The splitting is caused by the coupling of the hydride proton with the two equivalent 31P nuclei. The trans square-planar configuration has been confirmed by x-ray crystallography.9... 

This, however, is interpreted by the authors as a consequence of differential solvatation (31). When the lithium salt of 2,3,4,6-tetra-0-benzyl-D-glucose is prepared in benzene and tetrahydrofuran, there are equal proportions of both anomers, but we do not know whether equilibrium has been reached in this experiment (32). 

With acetic acid as solvent, the reaction came to a standstill after about 2 months, but examination of the greyish solid which had separated showed that crystals of adduct had occluded the purple diene component. Similar results invalidated trials in benzene and tetrahydrofurane. It was evident that for comparisons to be signifi-ctmt the suspensions would have to be agitated. 

The solid complex is decomposed after several minutes in air solutions are more rapidly decomposed. It is moderately soluble in benzene and tetrahydrofuran, but heating these solutions above ca. 60° causes decomposition. It is nearly insoluble in diethyl ether and saturated hydrocarbons. The complex may be purified by extraction with benzene at 45-50°, addition of w-heptane to the yellow filtrate, and concentration of the mixture on a rotary evaporator. 

Biscyclooctadiene nickel Ti-complexes ((COD)2Ni) shown in eq. (19.10) is an 18-electron compound, and thus it is stable and soluble in organic solvents such as benzene and tetrahydrofuran, and furthermore its reactivity is high. It is available as a starting material for synthesis of organonickel compounds as shown in Scheme 19.1 [20]. 

Polymer synthesis. The synthesis of linear terpolymers of NIPAAm, BMA and AA, with feed ratio of NIPAAm/BMA/AA = 85/5/10 or 80/10/10, was carried out in varying volume percent of benzene and tetrahydrofuran (THF) as solvent. AIBN was used as free radical initiator (7.41 mmol AIBN per mol monomer). Dried N2 gas was bubbled through the solution for 20 min to remove dissolved oxygen. The solution was polymerized for 24 hours at 60 C under N2 atmosphere. The synthesized terpolymers were recovered by precipitation in diethylether. The polymers were filtered and dried under vacuum overnight. 

The orange Pd3(OAc)6 is readily soluble in dichloromethane, toluene, benzene, and tetrahydrofuran, and is stable in air. Crystals can be easily obtained by slow... 

According to Nampoothiri et al. (2010), PLA can be dissolved in chloroform, methylene chloride, dioxane, acetonitrile, 1,1,2-trichloroethane and dichloroacetic acid. PLA can also be soluble in toluene, acetone, ethyl benzene and tetrahydrofuran (THF) when heated to boiling temperatures, but its solubility is limited at low temperatures. Generally, no PLA can be dissolved in water, selective alcohols and alkanes. Highly crystalline PLLA resists solvent attack of acetone, ethyl acetate and tetrahydrofuran, whereas amorphous PLA, such as the copolymer of poly (L,D-lactide), can be easily dissolved in various organic solvents, such as THF, chlorinated solvents, benzene, acetonitrile and dioxane. 

Other attempts made by Rempp et al. [48, 49] and VoUmert et al. [50] used a similar method but changed the solvent conditions using, for example, a mixture of benzene and tetrahydrofuran (THF). This allowed good coupling for the synthesis of cyclic polymers with different building blocks such as poly(2-vinyl pyridine), polybutadiene, poly(dimethylsiloxane), poly(propylene oxide), poly(ethylene oxide), and a variety of other polymers (Scheme 4). 

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