Decomposition of THF

An unexpected result was obtained when DTBB-catalyzed lithiation was applied to the vinyl-oxetane 313 . After work-up, lactone 314 was isolated, the process being explained by an elimination reaction via a radical pathway more than by reduction of the benzyl radical into the anion. Thus, this hypothetical intennediate reacted with the lithium enolate of acetaldehyde, generated in situ by reductive decomposition of THF (Scheme 92). 

Tetrahydrofuran (THF, 52) is a very stable five-membered ring ether. The thermal decomposition of THF was studied in a heated bulb over the temperature range 530-670°C (46JA506 51JA175) and behind reflected shocks in a single-pulse shock tube over the temperature range 1070-1530 K... 

The half-life of n-BuLi in THF (in the presence of TM ED A) is 40 min at20°C, 5.5 h atO°C, and 2 days at-20°C. Diethyl ether is much less readily deprotonated at 20 °C in ether o-BuLi has a half-life of 10 h. With more basic organolithiums, the rate of decomposition of THF is even faster, and t-BuLi can be used in THF only at-78 °C. At-20°C t-BuLi has a half-life in THF of only 45 min in ether its half-life at this temperature is 7.5 h. 

Pathway A 186 is further reduced to the dianion 186 which is immediately protonated by THF to give the benzylic anion 187 . The ethylene formed on decomposition of THF reacts with some 187 to give 188 which is also protonated by... 

A simple one-pot synthesis of anthracenes uses the reaction of the enolate of acetaldehyde with bromozene. The enolate, generated by the decomposition of THF with a strong base, reacts with benzyne to give a benzocyclobutene (593) which reacts with a second benzyne, via its valence isomer (594), to give the dihydroanthracenol. 

The decomposition of THF with n-butyllithium is a very efficient method for producing the lithium enolate of acetaldehyde. The reaction is easily rationalized by assuming deprotonation in the a-oxygen position, followed by a [2-1-3] cycloreversion of the anion 186. The enolate 187 resulting under concomitant liberation of ethylene has been trapped by different electrophiles among them the silylation proves the existence of the enolate [176]. 

Remarkably, the enolates of lanthanides also form in a thermolysis of Cp2MMe, LiCl, and THF under metallation and decomposition of THF cf. Section 2.7 Ref. [51]. 

Unsaturated cychc ethers have been proposed as intermediates in the decomposition of THF and derivatives,but studies on their chemistry are limited. Alwe et examined the reactions of THF, THP, 2,5-... 

PTMEG is a polymeric ether susceptible to both thermal and oxidative degradation. It usually contains 300—1000 ppm of an antioxidant such as 2,6-di-/ f2 -butyl-4-hydroxytoluene (BHT) to prevent oxidation under normal storage and handling conditions. Thermal decomposition in an inert atmosphere starts at 210—220°C (410—430°E) with the formation of highly flammable THE. In the presence of acidic impurities, the decomposition temperature can be significantly reduced contact with acids should therefore be avoided, and storage temperatures have to be controlled to prevent decomposition to THF (261). 

The indol-3-yl-substituted indolo[2,3-()]carbazole 143 has been isolated as a product from the complex mixture generated by the decomposition of urorosein (144) (99CHE561). Interestingly, when subjected to alkylation conditions involving sodium hydride and dimethyl sulfate in THF, 143 was transformed into the N. -dimethyl derivative 145 in 36% yield (00MI2). 

Thermal decomposition of Fe[0Si(0 Bu)3]3(THF) occurs at ca. 140 °C (by TGA) to provide a material with a lower ceramic yield (25.9%) than that calculated for FeOi.5 3Si02 (30.7%), suggesting potential loss of HOSi(0 Bu)3... 

The white crystals change to yellow powder upon grinding, presumably with loss of THF and possibly some AuCN formation. Thermal gravimetric analysis of [Au2(2,6-Me2Ph-form)2] 2Hg(CN)2 2THF showed the release of THF gradually at >120 °C followed by decomposition at >200 °C. The powder diffraction pattern of the yellow residue after heating above 265 °C showed a pattern typical of AuCN (IR 2236 cm ) as confirmed by comparison with the powder diffraction pattern of a sample of AuCN obtained from the Aldrich Chemical Co. 

Cobalt(II) alkoxides are known and monomeric forms are part of a wider review.413 The interest in these compounds pertains to a potential role in catalysis. For example, a discrete cobalt(II) alkoxide is believed to form in situ from a chloro precursor during reaction and performs the catalytic role in the decomposition of dialkyl pyrocarbonates to dialkyl carbonates and carbon dioxide.414 A number of mononuclear alkoxide complexes of cobalt(II) have been characterized by crystal structures, as exemplified by [CoCl(OC(t-Bu)3)2 Li(THF)].415 The Co ion in this structure and close relatives has a rare distorted trigonal-planar coordination geometry due to the extreme steric crowding around the metal. 

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