Methyltetrahydrofurans reaction

Uses. Furfural is primarily a chemical feedstock for a number of monomeric compounds and resins. One route produces furan by decarbonylation. Tetrahydrofuran is derived from furan by hydrogenation. Polytetramethylene ether glycol [25190-06-1] is manufactured from tetrahydrofuran by a ring opening polymeri2ation reaction. Another route (hydrogenation) produces furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-methylfuran, and 2-methyltetrahydrofuran. A variety of proprietary synthetic resins are manufactured from furfural and/or furfuryl alcohol. Other... 

Finally the aminoquinoline bearing a primary amine at the terminal carbon atom of the side chain is itself an effective antimalarial drug. Ring opening of 2-methyltetrahydrofuran by bromine gives the dibromide, 99. The primary halide is sufficiently less hindered so that reaction with potassium phthalimide affords exclusively the product of displacement of that halogen (100). Alkylation of the aminoquinoline with lOO affords the secondary amine, 101. Removal of the phthalimide group by means of hydrazine yields primaquine (102). ... 

Little work has been done on bare lithium metal that is well defined and free of surface film [15-24], Odziemkowski and Irish [15] showed that for carefully purified LiAsF6 tetrahydrofuran (THF) and 2-methyltetrahydrofuran 2Me-THF electrolytes the exchange-current density and corrosion potential on the lithium surface immediately after cutting in situ, are primarily determined by two reactions anodic dissolution of lithium, and cathodic reduc-... 

The reactions can also be effected by phenyliodonium diacetate.377 A mechanistic prototype can be found in the conversion of pentanol to 2-methyltetrahydrofuran. The secondary radical is most likely captured by iodine or oxidized to the carbocation prior to cyclization.378... 

We have studied the anodic oxidation of unsaturated alcohols using the controlled potential electrolysis (E = 1.9V vs SCE) in CH3CN-O.I mol/1 Et4NC104 solution in a divided cell [110]. The oxidation of 4-pentenol after consumption of 0.8 F/mol gave 2-methyltetrahydrofuran and tetrahydropyran as the major products. The oxidation of 5-pentenol gave 2-methyltetrahydro-pyran and oxepam, while the oxidation of 3-butenol under the same reaction conditions did not give the cyclic products. We rationalized this reaction as the electrongenerated acid (EGA) catalyzed intramolecular cyclization (Scheme 44). 

Depending on the reaction conditions, the copolymer product can be isolated in the form of either polyketone as poly(l-oxo-2-raethyltrimethylene) (Chart 7.5a) or polyspiroketal as poly[spiro-2,5-(3-methyltetrahydrofuran)j (Chart 7.5b). This latter can be transformed into the thermodynamically more stable polyketone form, either thermally or by dissolution in HFIP [1, 41, 42]. 

The decay of the trapped electron spectrum was very slow at 77° K in the dark. This fact suggests that cationic intermediates are trapped through the reactions 1 and 2, and the electrons are also trapped rather deeply by the electric dipole of 2-methyltetrahydrofuran molecules, so that the charge recombination reaction is suppressed. 

Consider a small amount of monomer added to the glasses the reaction of monomer with the electrons and that with the cation radicals are thought to prevail in the glasses of 2-methyltetrahydrofuran and n-butylchloride, respectively. In the 3-methylpentane glass, whether the anionic reaction and/or the cationic one occurs depends on the nature of the monomer. 

From the viewpoint of the glass matrix, 2-methyltetrahydrofuran is useful to study the anionic reactions of solute monomers, while in n-butylchloride the cationic reactions are studied selectively. Such a selection of glass matrices was made in the study of radiation-formed ionic species by optical absorption measurements (24, 25). 

A large number of reactions of etr with acceptors was investigated at 77 K in vitrified 2-methyltetrahydrofuran (MTHF) [96]. The principal peculiarity of the kinetic curves for reactions of etr with electron acceptor additives in vitrified MTHF, as compared with water-alkaline or water-ethylene glycol matrices is that, in many instances, the kinetics of etr decay for long times is somewhat slower, and for short times somewhat faster, than is predicated by eqn. (7) of Chap. 5. 

Table 2 shows that in addition to THF (1), ethers and an acetal such as diethyl ether (7), oxetane (9), 2-methyltetrahydrofuran (12) and 1,3-dioxolane (11) undergo a-C-H hydroxyalkylation to provide adducts in good yields. Dibutyl ether (8) (64% yield dr 71 29) and oxepane (10) (63% yield dr 88 12) have also been found to afford a-hydroxyalkylated ethers under the same conditions in moderate yields [20], It is interesting to note that the reaction selectively provides threo alcohols (entries 1-5). Occasionally, ethyl adducts and/or 4-methoxybenzylalcohol are produced, but the amounts of the byproducts are usually negligible. 

Ring opening of tetrahydrofuran derivatives has been studied using chlorotrimethylsilane and sodium iodide 2-methyltetrahydrofuran is opened predominantly to give 5-iodopentan-2-ol but the reaction involving 3-methyltetrahy-drofuran is less selective. Lithium 4,4-di-/-butylbiphenylide has also been used to cause the ring opening of tetrahydrofuran at 80 C in the presence of boron trifluoride etherate. 

The following observation emphasizes the influence of the temperature on ion-solvation equilibrium. The reduction product of 1 with lithium metal in methyltetrahydrofuran is temperature-dependent11. At —120 °C only the radical anion (1 ) could be observed by ESR, while at higher temperatures the paramagnetism disappears and the dianion (12 ) is detected. This reaction must be endothermic it therefore seems that disproportionation is driven by entropy and not by energy, due to ion-pair-solvation equilibrium. It is noteworthy that 12 cannot be observed by NMR spectroscopy due to its special electronic structure12. 

The reaction of terpy with zinc amalgam in 2-methyltetrahydrofuran results in the formation of the ligand radical complex [Zn(terpy)2], which has been characterized by ESR spectroscopy (79). 

In contrast to the preceding atom-transfer reaction, the solvent-induced rate change for the reaction between l-ethyl-4-(methoxycarbonyl)pyridinyl and 4-(halomethyl)-nitrobenzenes is so large that a change in mechanism must be involved [215, 570]. In changing the solvent from 2-methyltetrahydrofuran to acetonitrile, the relative rate constant for 4-(bromomethyl)-nitrobenzene increases by a factor of up to 14800. This is of the order expected for a reaction in which an ion pair is created from a pair of neutral molecules [cf. for example, reaction (5-16)]. It has been confirmed therefore that, according to scheme (5-67), an electron-transfer process is involved [215, 570]. 

The rate constants for the reaction of a series of benzyl halides with 4 (Table 4) revealed that the rate for the 4-nitrobenzyl chloride was extraordinarily high, being millions of times faster than expected . A change of mechanism was suspected solvent polarity changes affected the rate constants very much, viHith the rate changing by a factor of 10 from 2-methyltetrahydrofuran (Z 55.4) to acetonitrile (Z 71.3)... 

Fig. 21. The variation with surface of the initial percentage yield of major products from the oxidation of n-pentane. Initial temperature = 290 °C initial pressure of n-pentane = 25 torr initial pressure of oxygen = 12.5 torr total pressure = 82 torr volume of reaction vessel = 500 cm. , pent-2-ene o, 2-methyltetrahydrofuran e, acetone , pent-l-ene e, butanone. (From ref. 106.)...

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