Tetrahydrofuran solution

Another method of aldehyde bromination, apart from Riehl s established method (432) from bromine at 20°C, is to use trimethylphenyl-ammonium bromide in tetrahydrofuran solution, prepared by Vorlander and Siebert s method (50). However, the yield of 5-phenylthiazole using this method with thioformamide dissolved in dioxane is only 8% (513). 

The potassium hydroxide may be added to the water in one pop. tion, but the resulting base solution should be allowed to cool to nearijr room temperature before adding to the reaction mixture. If the potaa sium hydroxide solution is cooled much below ambient temperature, the potassium hydroxide begins to separate hot potassium hydroxide solution could cause the tetrahydrofuran solution to boil. 

High molecular weight polymers are produced by an adiabatic bulk polymerisation process ° using di-tert-butyl peroxide (0.02%) and 2,2 -azo-bisdi-isobutyronitrile (0.01%) as initiators and pressurised with N2. Heating to 80-90°C causes an onset of polymerisation and a rapid increase in temperature. After the maximum temperature has been reached the mass is allowed to cool under pressure. A typical current commercial material (Luvican M.170) has a A -value of about 70 (as assessed in a 1% tetrahydrofuran solution). 

In Cram s first synthesis of a chiral bis-binaphthyl system, optically pure binaph-thol and diethylene glycol ditosylate were heated at reflux in tetrahydrofuran solution for 15 h with potassium f-butoxide, two products were obtained. The 1 + 1 product (mp 230—231°) was isolated in 5% and the 2 + 2 product (mp 123—126°) was obtained in 31% yield. The reaction is shown in Eq. (3.51). 

A suspension of lithium aluminum deuteride (80 mg) in dry tetrahydrofuran (6 ml) is stirred and cooled in an ice bath while f-butanol (0.4 ml) is added dropwise, followed by a tetrahydrofuran solution of crude cholest-5-en-3-one (200 mg, mixed with cholest-4-en-3-one). The stirring and cooling is continued for 0.5 hr at 0° and then at room temperature for 2 hr. The... 

A-Fluoro-2,4,6-tnmethylpyndmium inflate (1 mmol) is added m several portions at room temperature to a tetrahydrofuran solution of sodium diethyl phenyl-malonate, obtained from 1 mmol of diethyl phenyl malonate and sodium hydnde at 0 C in tetrahydrofuran The reaction imxture is poured mto dilute hydrochlonc acid and extracted with ether The ether extract is washed with sodium bicarbonate and water and dned over magnesium sulfate The oily residue obtamed after removal of tihe ether is chromatographed on sihca gel (dichloromethane-hexane, 1 1) to give diethyl fluorophenylmalonate in 83% yield... 

The procedure given above is applied to norbornene. However, the formation of the alcohol is accompanied by formation of moderate amounts of the acetate. Therefore, the dried tetrahydrofuran solution of the alcohol-acetate mixture is treated with 0.4 g (O.OI mole) of lithium aluminum hydride dissolved in 10 ml ofTHF. The excess hydride is decomposed by careful addition of water, followed by filtration, drying of the organic solution, and evaporation of the solvent. The residue is almost pure (>99.8%) exo-1-norborneol. It may be purified by direct distillation, bp 178-17971 atm, crystallizing slowly on cooling, mp 127-128°. 

Borane is very reactive because the boron atom has only six electrons in its valence shell. In tetrahydrofuran solution, BH3 accepts an electron pair from a solvent molecule in a Lewis acid-base reaction to complete its octet and form a stable BH3-THF complex. 

Cyanophenyl azide is of interest in that on photolysis in methanol/tetrahydrofuran solution, an unseparated 1 1 mixture (by HNMR spectroscopy) of 2-methoxy-3//-azepine-3-carbonitrile and -7-carbonitrile (44%) is formed.197-282 Likewise, irradiation of 2-azidophenyl methyl ketone in methanol furnishes a mixture of 3-acetyl-2-methoxy- (11 %) and 7-acetyl-2-methoxy-3//-azcpine (3%) along with 3-methyl-2,l-benzisoxazole (18%).78... 

Attempts to effect ring expansion of methyl 2-azidobenzoate in the presence of other nucleophiles have failed. Thus, photolysis in tetrahydrofuran solution saturated with hydrogen sulfide, or with ammonia, produced methyl 2-aminobenzoate in 54 and 37 % yield, respectively, as the sole identifiable product.197 Photolysis of phenyl azide in ethanolic phenol gave 2-phenoxy-3//-azepine in poor yield (8 %).203,204 2-Mesityl-3//-azepine (10 %) is the surprising, and only tentatively explained, product from the photolysis of phenyl azide in mcsitylene in the presence of trifluoroacetic acid.179... 

Interesting is a comparison of the volumes occupied by individual complexes in solution and in the solid state. The partial molal volumes can be obtained from precise measurements of the solution densities of the complexes as a function of concentration [177]. These values may be subsequently compared with the unit cell volumes per complex molecule derived from the crystal structure. For Fe[HB(pz)3]2, the apparent molal volume in tetrahydrofuran solution was determined as 340.9 em mol Taking into account that the complex in solution forms an equilibrium between 86% LS and 14% HS isomers and employing the volume difference between the two spin states AF° = 23.6 cm mol S the volume of the LS isomer was calculated as 337.6 cm mol This value agrees closely with the volume of 337.3 cm mol for the completely LS complex in solid Fe[HB(pz)3]2 [105]. 

A thio-substituted, quaternary ammonium salt can be synthesized by the Michael addition of an alkyl thiol to acrylamide in the presence of benzyl trimethyl ammonium hydroxide as a catalyst [793-795]. The reaction leads to the crystallization of the adducts in essentially quantitative yield. Reduction of the amides by lithium aluminum hydride in tetrahydrofuran solution produces the desired amines, which are converted to desired halide by reaction of the methyl iodide with the amines. The inhibitor is useful in controlling corrosion such as that caused by CO2 and H2S. 

A selective, mild, and facile reduction of aromatic and aliphatic carboxylic acid imida-zolides to primary alcohols is described in reference [33]. The reaction proceeds in water, water/dioxane or water/tetrahydrofuran solution at room temperature with 2-5 molar equivalents of NaBH4 in about 1 h. 

Brittle colorless films of PBPP may be cast from tetrahydrofuran solution. The insoluble portion of PBPP is swelled by the tetrahydrofuran and gives rise to free-standing films on solvent evaporation. Differential scanning calorimetry experiments on PBPP show a glass transition temperature at 40 °C, and some indication of a melting transition at 170° C. 

Rittmeyer, P. et al., Z. Naturforsch., B Chem. Sci., 1993, 48(9), 1223 An incident during concentration of a tetrahydrofuran solution on pilot plant led to a study of the concentration dependent exothermic decomposition of the reagent and generation of safety rules. 

The general procedure used for the synthesis of [l,2,3]triazolo[l,2-tf][l,2,4]benzotriazin-l-5(6//)-dione derivatives 506 is shown in Scheme 86. Ionic 1,3-dipolar cycloaddition of the appropriate azide 503 to ethyl phenylacetates gives l-(2-nitrophenyl)-4-aryl-5-oxo[l,2,3]triazoles 504. Catalytic reduction of these compounds affords the corresponding amines 505. Cyclocondenzation of these amines to the final tricyclic compounds 506 is performed using triphosgene in anhydrous tetrahydrofuran solution at room temperature (Scheme 86) <2005JME2936>. 

An improved procedure for preparing urea derivatives involves reaction of isocyanates or isothiocyanates with 4(5)-aminoimidazole (25 R = H) in tetrahydrofuran solution [92JCS(P1)2779]. A THF solution of 4(5)-aminoimidazole (25 R=H) generated in situ and then treated with the appropriate reagent gave either lV-imidazole-4-yl-AT-phenylurea (56 X = 0) (32%) or AT-imidazoM-yl-A/ -phenylthiourea (56 X = S) (21%). 

Bentley et al.m recently improved upon Julia s epoxidation reaction. By using urea-hydrogen peroxide complex as the oxidant, l,8-diazabicyclo[5,4,0]undec-7-ene (DBU) as the base and the Itsuno s immobilized poly-D-leucine (Figure 4.2) as the catalyst, the epoxidation of a, (3-unsaturated ketones was carried out in tetrahydrofuran solution. This process greatly reduces the time required when compared to the original reaction using the triphasic conditions. 

Resist solutions of o-cresol novolac-siloxane copolymers were prepared as 15 w/v % solutions of the polymer in 2-methoxyethyl acetate using 20 wt % (based on polymer) of the positive sensitizer. Poly(hydroxystyrene) and 2-methyl resorcinol copolymers were spun into films from 2-methyl tetrahydrofuran. Solutions were filtered through successive 1.0, 0.5 and 0.2 pm filters and stored in... 

Materials. PVCz (Takasago International Co. Ltd.) was purified by several reprecipitations froa benzene-methanol solution. 1-Ethylpyrene (EPy) was recrystallized and sublined in vacuo before use. PMMA was reprecipitated twice froa tetrahydrofuran solution with nethanol. PVCz films were prepared by spin-coating a 10 wtX anisole solution of the polyner on a quartz plate. PMMA and EPy were dissolved in chlorobenzene and cast on quartz or sapphire plates. 

Highly reactive calcium can be readily prepared by the reduction of calcium halides in tetrahydrofuran solution with preformed lithium biphenylide under an argon atmosphere at room temperature.5 This colored calcium species seems to be reasonably soluble in THF. However, the reactive calcium complex prepared from preformed lithium naphthalenide was insoluble in THF solution and precipitated out of solution to give a highly reactive black solid. The exact nature of this black calcium complex has not been determined. Acid hydrolysis of the black material releases naphthalene as well as THF. Accordingly, the most likely structure of the black material is a Ca-naphthalene-THF complex similar in nature to the soluble magnesium-anthracene complex recently reported.6... 

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