Solubility tetrahydrofuran

To remove water, the benzene was azeotroped and distilled over CaH2. The n-pentane was stored over LiAlH and distilled over CaH2. Toluene was distilled over CaH2. Toluene from Burdick Jackson, Muskegon, MI could also be used for dilute solution characterization without any adverse effects on polymer solubility. Tetrahydrofuran (THF) was dried over molecular sieves and doubly distilled over CaH2. The solvents were blanketed with nitrogen to maintain dryness. 

Aqueous mineral acids react with BF to yield the hydrates of BF or the hydroxyfluoroboric acids, fluoroboric acid, or boric acid. Solution in aqueous alkali gives the soluble salts of the hydroxyfluoroboric acids, fluoroboric acids, or boric acid. Boron trifluoride, slightly soluble in many organic solvents including saturated hydrocarbons (qv), halogenated hydrocarbons, and aromatic compounds, easily polymerizes unsaturated compounds such as butylenes (qv), styrene (qv), or vinyl esters, as well as easily cleaved cycHc molecules such as tetrahydrofuran (see Furan derivatives). Other molecules containing electron-donating atoms such as O, S, N, P, etc, eg, alcohols, acids, amines, phosphines, and ethers, may dissolve BF to produce soluble adducts. 

The products are Hquids, soluble in various solvents and stable over prolonged periods. Monochloroborane is an equiUbtium mixture containing small amounts of borane and dichloroborane complexes with dimethyl sulfide (81). Monobromoborane—dimethyl sulfide complex shows high purity (82,83). Solutions of monochloroborane in tetrahydrofuran and diethyl ether can also be prepared. Strong complexation renders hydroboration with monochloroborane in tetrahydrofuran sluggish and inconvenient. Monochloroborane solutions in less complexing diethyl ether, an equiUbtium with small amounts of borane and dichloroborane, show excellent reactivity (88,89). Monochloroborane—diethyl etherate [36594-41-9] (10) may be represented as H2BCI O... 

Dicyclohexylborane [1568-65-6], Chx2BH (12) is prepared in quantitative yield by the same method. It is a white soHd, sparingly soluble in ether or tetrahydrofuran. For most purposes isolation is not necessary and it can be used as a slurry in these solvents. Its stetic requirements are slightiy lower as compared to Sia2BH (57,106—109). Much better thermal stabiUty allows its use at higher temperatures. 

Other procedures have also been reported (38,110,111). The properties and chemistry of 9-BBN have been reviewed (112). The reagent is a white crystalline soHd, stable indefinitely at room temperature, soluble in hexane, carbon tetrachloride, benzene, tetrahydrofuran, and diethyl ether. It exists as a... 

The most hindered of all presently known hydroborating agents is possibly dimesitylborane, an air-stable white soHd, slightly soluble in tetrahydrofuran, the best etheral solvent. It is commercially available or can be prepared according to the following reaction (117) ... 

Iron(III) iodide [15600-49-4], Fefy, is prepared by the oxidative photodecarbonylation of diiodotetracarbonylkon(II) ki the presence of dkodine (7). The black soHd obtained is extremely hygroscopic, spariagly soluble only ki dichloromethane, and decomposes to kon(II) iodide and dkodine when exposed to donor solvents such as tetrahydrofuran, acetonitrile, water, or pyridine. It also decomposes when exposed to light. 

Many organic syntheses requHe the use of stericaHy hindered and less nucleophilic bases than //-butyUithium. Lithium diisopropylamide (LDA) and lithium hexamethyldisilazide (LHS) are often used (140—142). Both compounds are soluble in a wide variety of aprotic solvents. Presence of a Lewis base, most commonly tetrahydrofuran, is requHed for LDA solubdity in hydrocarbons. A 30% solution of LHS can be prepared in hexane. Although these compounds may be prepared by reaction of the amine with //-butyUithium in the approprite medium just prior to use, they are also available commercially in hydrocarbon or mixed hydrocarbon—THF solvents as 1.0—2.0 M solutions. 

Other, even milder bases than LDA and LHS, such as lithium methoxide and lithium /-butoxide, may be used in organic syntheses (143,144). Lithium methoxide is available commercially as a 10% solution in methanol and lithium /-butoxide as an 18% solution in tetrahydrofuran (145). Lithium /-butoxide is also soluble in hydrocarbon solvents (146). Both lithium alkoxides are also available as soHds (147) (see Alkoxides, metal). 

The dihydrate is very soluble ia polar solvents, such as methanol, ethanol, acetone, dioxane, and tetrahydrofuran, but insoluble ia benzene, chloroform, and petroleum ether. SolubiUty of the dihydrate ia diethyl ether (1.47 g/100 g solvent) is different from that of the anhydrous form (23.6 g/100 g solvent). 

Solubility and Solvent Resistance. The majority of polycarbonates are prepared in methylene chloride solution. Chloroform, i7j -l,2-dichloroethylene, yy -tetrachloroethane, and methylene chloride are the preferred solvents for polycarbonates. The polymer is soluble in chlorobenzene or o-dichlorobenzene when warm, but crystallization may occur at lower temperatures. Methylene chloride is most commonly used because of the high solubiUty of the polymer (350 g/L at 25°C), and because this solvent has low flammabiUty and toxicity. Nonhalogenated solvents include tetrahydrofuran, dioxane, pyridine, and cresols. Hydrocarbons (qv) and aUphatic alcohols, esters (see Esters, organic), or ketones (qv) do not dissolve polycarbonates. Acetone (qv) promotes rapid crystallization of the normally amorphous polymer, and causes catastrophic failure of stressed polycarbonate parts. 

Pyrrohdine [123-75-1] (tetrahydropyrrole) (19) is a water-soluble strong base with the usual properties of a secondary amine. An important synthesis of pyrrohdines is the reaction of reduced furans with excess amine or ammonia over an alumina catalyst in the vapor phase at 400°C. However, if labde substituents are present on the tetrahydrofurans, pyrroles may form (30). 

The gum is soluble in lower ketones and esters, amide solvents, methanol, and tetrahydrofuran. 

Dilongifolyl borane [77882-24-7] M 422.6, m 169-172 . Wash with dry Et20 and dry in a vacuum under N2. It has m 160-161 in a sealed evacuated capillary. It is sparingly soluble in pentane, tetrahydrofuran, carbon tetrachloride, dichloromethane, and chloroform but the suspended material is capable of causing asymmetric hydroboration. Disappearance of solid indicates that the reaction has proceeded. [J Org Chem 46 2988 1981.]... 

Titanium trichloride [7705-07-9] M 154.3, m >500 , pKj 2.55 (for hydrolysis of Ti to TiOH ). Brown purple powder that is very reactive with H2O and pyrophoric when dry. It should be manipulated in a dry box. It is soluble in CH2CI2 and tetrahydrofuran and is used as a M solution in these solvents in the ratio of 2 1, and stored under N2. It is a powerful reducing agent. [Inorg Synth 6 52 I960, Synthesis 833 7989.]... 

A more interesting example is given with PVC and the polycarbonate of bis-phenol A, both slightly crystalline polymers. It is noticed here that whilst methylene dichloride is a good solvent and tetrahydrofuran a poor solvent for the polycarbonate the reverse is true for PVC yet all four materials have similar solubility parameters. It would seem that the explanation is that a form of hydrogen bonding occurs between the polycarbonate and methylene dichloride and between PVC and tetrahydrofuran (Figure 5.7). In other words there is a specific interaction between each solvent pair. 

The solubility parameter is about 19.2MPa and being amorphous they dissolve in such solvents as tetrahydrofuran, mesityl oxide, diacetone alcohol and dioxane. Since the main chain is composed of stable C—C and C—O—C linkages the polymer is relatively stable to chemical attack, particularly from acids and alkalis. As already mentioned, the pendant hydroxyl groups are reactive and provide a site for cross-linking. 

Under the best conditions, sodium cyclopentadienide gives pale yellow or orange solutions. Traces of air lead to red or purple solutions, as does insufficiently purified solvent, without, however, lowering the reaction yield appreciably. If 1,2-di-methoxyethane is used, in which sodium cyclopentadienide is less soluble than in tetrahydrofuran, white crystals may be obtained at this point. 

Aromatic steroids are virtually insoluble in liquid ammonia and a cosolvent must be added to solubilize them or reduction will not occur. Ether, ethylene glycol dimethyl ether, dioxane and tetrahydrofuran have been used and, of these, tetrahydrofuran is the preferred solvent. Although dioxane is often a better solvent for steroids at room temperature, it freezes at 12° and its solvent effectiveness in ammonia is diminished. Tetrahydrofuran is infinitely miscible with liquid ammonia, but the addition of lithium to a 1 1 mixture causes the separation of two liquid phases, one blue and one colorless, together with the separation of a lithium-ammonia bronze phase. Thus tetrahydrofuran and lithium depress the solubilities of each other in ammonia. A tetrahydrofuran-ammonia mixture containing much over 50 % of tetrahydrofuran does not become blue when lithium is added. In general, a 1 1 ratio of ammonia to organic solvents represents a reasonable compromise between maximum solubility of steroid and dissolution of the metal with ionization. 

The solubility of many steroids in ammonia-tetrahydrofuran-/-butyl alcohol is about 0.06 A/, a higher concentration than has been reported in other solvent systems. Still higher concentrations may be possible in particular cases by suitable variation in the solvent ratios Procedure 3 (section V) describes such a reduction of estradiol 3-methyl ether at a 0.12 M concentration. A few steriods such as the dimethyl and diethyl ketals of estrone methyl ether are poorly soluble in ammonia-tetrahydrofuran-/-buty] alcohol and cannot be reduced successfully at a concentration of 0.06 even with a 6 hour reduction period. The diethyl ketal of estrone methyl ether is reduced successfully at 0.12 M concentration using a two-phase solvent system of ammonia-/-amyl alcohol-methylcyclohexane (Procedure 4, section V). This mixture probably would be useful for any nonpolar steroid that is poorly soluble in polar solvents but is readily soluble in hydrocarbons. 

The general reaction procedure and apparatus used are exactly as described in Procedure 2. Ammonia (465 ml) is distilled into a 2-liter reaction flask and to this is added 165mlofisopropylalcoholandasolutionof30g(0.195 mole) of 17/ -estradiol 3-methyl ether (mp 118.5-120°) in 180 ml of tetrahydrofuran. The steroid is only partially soluble in the mixture. A 5 g portion of sodium (26 g, 1.13 g-atoms total) is added to the stirred mixture and the solid dissolves in the light blue solution within several min. As additional metal is added, the mixture becomes dark blue and a solid (matted needles) separates. Stirring is inefficient for a few minutes until the mass of crystals breaks down. All of the sodium is consumed after 1 hr and 120 ml of methanol is then added to the mixture with care. The product is isolated as in Procedure 4h 2. After being air-dried, the solid weighs 32.5 g (ca. 100% for a monohydrate). A sample of the material is dried for analysis and analyzed as described in Procedure 2 enol ether, 91% unreduced aromatics, 0.3%. The crude product may be crystallized from acetone-water or preferably from hexane. 

NaBH4 is soluble in water, alcohols, pyridine, dioxane, dimethoxyethane, diglyme and triglyme. All these solvents, as well as aqueous tetrahydrofuran and aqueous dimethylformamide, have been used for reductions. The reductions go very slowly in di- and triglyme so these solvents are not suitable for preparative work. In some reductions in dry pyridine and dry dimethyl sulfoxide, reaction only takes place on aqueous work-up. This... 

The reaction is usually carried out in the presence of an anhydrous cosolvent such as ether, dioxane or tetrahydrofuran, depending on the solubility of the substrate. Since the primary aim of this reaction is generally... 

The reactivities of compounds of type 6 with aniline in acetone correlate quite well with substituent effects, and autocatalysis is unimportant here. In the less polar tetrahydrofuran, where the hydrochloride is only partly soluble, the reaction shows autocatalysis when aniline and -chloro aniline are reactants but not when the more basic -toluidine is involved. In these cases the solubility of the acidic product may also influence the differential behavior observed. 

Finally, with compounds of type 7, which have one chlorine atom and two ZR substituents, the reactions are, as expected, more frequently acid catalyzed than with compounds of type 6 e.g., the reaction with aniline in acetone is distinctly acid catalyzed. Again, reactions stiU occur, e.g., with benzylamine in tetrahydrofuran, in which autocatalysis is absent, possibly because of a combination of the marked basicity of the reagent and the low solubility of the acidic product. 

Another important issue that must be considered in the development of CSPs for preparative separations is the solubility of enantiomers in the mobile phase. For example, the mixtures of hexane and polar solvents such as tetrahydrofuran, ethyl acetate, and 2-propanol typically used for normal-phase HPLC may not dissolve enough compound to overload the column. Since the selectivity of chiral recognition is strongly mobile phase-dependent, the development and optimization of the selector must be carried out in such a solvent that is well suited for the analytes. In contrast to analytical separations, separations on process scale do not require selectivity for a broad variety of racemates, since the unit often separates only a unique mixture of enantiomers. Therefore, a very high key-and-lock type selectivity, well known in the recognition of biosystems, would be most advantageous for the separation of a specific pair of enantiomers in large-scale production. 

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