Hydrofuran-diethyl ether

Early attempts to metalate 1,1-difluoroethylene with -butyllithium in tetra-hydrofuran or diethyl ether were unsuccessful. Another example whereby the course of the reaction may be altered by substitution of rec-butyllithium in place of n-butyllithium is the metalation of 1,1 -difluoroethylene [60] (equation 26)... 

Unreacted chloride remains at the end of the roaetion (with R2CuLi 15%, with RLi 40%) 1.5 equivalents of R2CuLi per equivalent of chloride givos 95% (. /)-2-undecene after 5 days at 25°. e A volumo of THF equal to that of the ether present was added after formation of the cuprate was complete. THF tetra-hydrofuran HMPA hexamethylphosphoric triamide EtaO diethyl ether DME 1,2-diinethoxyethane. 

The procedures described below require rigorous exclusion of water and oxygen. All solvents should be distilled and stored under an inert atmosphere. Tetra-hydrofuran (THF) and diethyl ether are initially dried with calcium hydride or 4A molecular sieves, bubbled with nitrogen, and then heated to reflux with sodium wire plus 0.1 g of benzophenone per 500 mL of ether. After a deep blue color develops the solvent is distilled from the sodium benzophenone ketyl. 

Ethers are also organic relatives of water, where alkyl groups replace both hydrogen atoms. Thus, ethers have two hydrocarbons bonded to an oxygen atom. The simplest and most common ethers are diethyl ether and tetra-hydrofuran (THF), which is a cyclic ether. 

The contents of the test-tube are mixed and warmed at 55 °C for 1-5 h. The mixture is cooled and an aliquot portion is spotted on to a TLC plate for separation. Two-dimensional chromatography is carried out on silica gel layers with cyclohexane-ethyl acetate (1 1) and light petroleum-chloroform-diethyl ether-acetic acid (33 33 33 1). Chromatography on polyamide layers is accomplished with heptane-ethyl acetate-butanol (8 1 1). The Rp values of six NBD-amines in these systems [99] are given in Table 4.15. Amounts of less than 15 ng of NBD-amine per spot can be detected. HPLC of some NBD-amines has been carried out using Zipax coated with 0.5% 0,/3 -oxydipropionitrile and 1% tetra-hydrofuran in hexane as the mobile phase (see Section 4.2.4.2.2). 

This starting material is prepared in three steps from commercially available (from Research Organic/Inorganic Chemical Corp., Belleville, NJ) 3,4-methylenedioxyphenylacetic acid according to well-established procedures that have been applied to similar compounds. First, 16.0 g (88.8 mmol) of the acid, recrystallized from chloroform, is dissolved in 50 mL of tetra-hydrofuran, and the solution is added to a suspension of 5.98 g (158 mmol) of lithium aluminum hydride powder in 225 ml of distilled diethyl ether (Note 3) at 0°C. [Caution Lithium aluminum hydride ie very sensitive to mechanical shock, and very reactive towards moisture and other protic substances its dust is very irritating to skin and mucous membranes. It should not be allowed to come into contact with metallic species or apparatus, including metal... 

The Grignard reaction of benzaldehyde with ethylmagnesium bromide in diethyl ether in the presence of molar amounts of (J , J )-TADDOL as a chiral additive leads predominantly to (S)-l-phenyl-l-propanol, while the same reaction carried out in tetra-hydrofuran gives mostly the corresponding (i )-alcohol according to Eq. (5-154a) [852]. TADDOL is the acronym for tetraaryl-l,3-fi ioxolane-4,5-fiSmethano/, which reacts with... 

Dibutyl ether is the only solvent suitable for this reaction. Dibutyl ether has relatively low volatility and complexes with trimethylaluminum without solvent decomposition. Dibutyl ether complexes with BBr, sulTiciently strongly to slow the rate of reaction ofBBrj with AIMe, to a safe rate. Boron tribromide reacts explosively with trimethylaluminum in diethyl ether or anisole solutions because of the weak complexation between these solvents and BBr,. Tetra-hydrofuran and p-dioxane undergo decom X)sition reactions with trimethylaluminum, and thus are unsuitable as solvents in this synthesis. 

Bis(triphenylphosphine)iminium tridecacarbonyltetraferrate(2-), [PPN] 2-[Fe4(CO)i3], is obtained as shiny, very dark, red-black crystals. The compound is moderately air sensitive in solid form and decomposes slowly in solution when exposed to air, complete decomposition requiring several hours. It is soluble in CH2C12, CH3CN, and pyridine and is insoluble in diethyl ether, benzene, tetra-hydrofuran, ethanol, and methanol. It can be stored for long periods of time in an inert atmosphere (e.g., N2) at room temperature. The IR spectrum in di-chloromethane solution contains the following CO stretching frequencies 2020 (w), 1943 (s), 1778 (w), 1682 (w), cm 1 (w = weak, s = strong). 

The phenylethynyl complex forms lemon-yellow crystals mp 205° (dec.) (checker, 200-205°), which are insoluble in light petroleum, diethyl ether, methanol, and ethanol but soluble in dichloromethane, chloroform, and tetra-hydrofuran. The infrared spectrum has a sharp v(C=C) band at 2068 cm"1, and the H nmr spectrum contains resonances at r 2.52m, 2.90m (35H, Ph) and 5.67s (5H, CSHS). The mass spectrum contains a parent ion centered on m/e 792 (calcd. for 102Ru, 792). 

To a stirred, red solution of 1.00 g (2.6 mmole) Rh2Cl2(C2H4)46 in 25 mL tetra-hydrofuran (THF), 2.95 g (10.3 mmole) o-phenylenebis(dimethylarsine) (diars) in 5 mL THF is added dropwise. Filtration after Vi hour affords a light-brown solid which is recrystallized from acetonitrile with diethyl ether. The resultant golden crystals are diethyl ether washed and then vacuum dried, yielding 2.32 g (63% yield). The IR spectrum shows 2240(vw) cm 1 ascribable to r c=N of lattice acetonitrile. 

Conditions for auxiliary removal have to be carefully chosen to avoid partial racemization of the newly formed stereogenic center. Such complications arise under reductive cleavage conditions (lithium aluminum hydride/diethyl ether) as well as basic hydrolysis employing potassium hydroxide in ethanol. However, treatment with lithium hydroxide in aqueous tetra-hydrofuran appears to effect clean cleavage whilst avoiding this complication713. 

The white crystalline sodium triethyl-1-propynylborate of m.p. 90° is completely stable at room temperature under an inert gas (N2 or Ar). The salt is sparingly soluble in pentane or in hexane, soluble in benzene, and easily soluble in diethyl ether or in tetra-hydrofuran. The compound can be recrystallized from benzene or from cyclohexane. The salt is oxidized by air and is quantitatively cleaved by water with formation of propyne. 

A volume of THE equal to that of the ether present was added after formation of the cuprate was complete. THF tetra-hydrofuran HMPA hexamethylphosphoric triamide EtjO diethyl ether DME 1,2-dimethoxyethane. 

Figure 3.28 Dependence of equilibrium swelling on the solubility parameter in a number of solvents (I) diethyl ether (II) diethylene glycol diethyl ether (III) butyl acetate (IV) ethyl acetate (V) tetra-hydrofuran (VI) dioxane. Polsnirethane networks based on ODA and PPG mixture without additives (6) and containing various KEP-2 mass fractions (1) 1.7 X 10 (3) 5.5 X 10 (2) 1.1 x 10 ...

Isomerization has been effected under a range of alkaline conditions including potassium hydroxide in ethanediol at 170-180 °C, potassium r-butoxide in r-butanol at 70 °C or in diethyl ether at 25 °C, the potassium salt of the methyl ether of triethylene glycol at 25 or 60 °C, dimsyl sodium or dimsyl potassium in dimethyl sulphoxide and/or tetra-hydrofuran at 25 °C, the potassium salt of 1,3-diaminopropane at 50 °C and tetramethylammonium hydroxide. 

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