Methyltetrahydrofuran production

Depending on catalysts and conditions, products of hydrogenation can include furfuryl alcohol [98-00-0] tetrahdrofurfuryl alcohol [97-99-4] 2-meth5ifuran [534-22-5] and even 2-methyltetrahydrofuran [96-47-9]. Under strongly reducing conditions, the ring is opened. 

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). ... 

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]. 

Furfural. Furfural is readily obtainable from dehydration of pentoses. Reduction of furfural can lead to a variety of products that are more volatile, more stable and possibly also more useful than furfural itself. Selective reduction of the aldehyde moiety leads to furfuryl alcohol (Scheme 15), whereas further reduction of the furan core will lead to tetrahydrofurfuryl alcohol. Reductive deoxygenation can result in the formation of either 2-methylfuran or 2-methyltetrahydrofuran, which can be used as liquid fuels or solvents. 

The synthetic utility of this procedure was illustrated by the practical synthesis of the versatile intermediate y-lactone (i )-5-methyltetrahydrofuran-2-one (Fransson et al, 2005). Chiral y-lactones are important structural syn-thons for the synthesis of natural products and biologically active compounds (Benincori et al, 2004). 

Vapor-phase hydrogenation of 2-methylfuran over a nickel catalyst gave 2-methyltetrahydrofuran as the chief product (86% yield) at 100°C, but as the temperature was raised, the amount of the tetrahydro compound decreased with formation of increased amounts of 2-pentanone, which attained a maximum (75% yield) at about 185°C. Along with the ketone, a small amount of 2-pentanol was also formed.186... 

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. 

Tabata and coworkers studied extensively the radiation-induced polymerization of vinylcarbazole (VC) in various solvents27-32. In one paper27 they studied the initial species formed in the polymerization of VC in benzonitrile solutions. To identify the products, they used the optical spectrum obtained for glassy solutions of vinylcarbazole in butyl chloride and 2-methyltetrahydrofuran irradiated at 77 K with y-rays. Irradiation in butyl chloride matrix is known, similarly to that in other organic chlorides, to give... 

Fig. 8.36 Production of levulinic acid and transformation into 2-methyltetrahydrofuran. Compounds LA, levulinic acid MTHF, 2-methyltetrahydrofuran.

Bromo-2-chloro-3-hexylthiophene (0.0355 mol) was added over a period of 30 minutes to a mixture consisting of 75 ml of 2-methyltetrahydrofuran, magnesium (0.0355 mol), and 0.15 ml of IM t-butylmagnesium chloride solution in THF at 60°C to 70°C. The mixture was stirred for 90 minutes at 70°C. It was then cooled to 60°C and treated with a suspension of l,2-bis(diphenylphosphino)ethane nickel(II) chloride (0.177 mmol) in 12.5 ml of 2-methyltetrahydrofuran for over 30 minutes. The mixture was stirred an additional 3 hours at 80°C and further treated with triethylphosphite (3 mmol) and stirred for 30 minutes at 80°C. The mixture was then concentrated and the residue dissolved in 10 ml of toluene. This solution was poured into 100 ml of EtOAc, which created a suspension, and the suspension was stirred for 30 minutes at 80°C. The cooled suspension was filtered, the residue washed twice with 20 ml of EtOAc, and the product isolated in 81% yield having a Mn of 19,543 daltons with a of 224°C. 

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.)...

A number of other chiral catalysts have been reported, among them the proline (111), lithium amides (112) and the tetrahydrofiirylamine (113). Hie optical yields of the products isolated, however, are only moderate at best. Hie use of optically active 2-methyltetrahydrofuran in Grignard reactions has also been reported however, minimal induction is observed. ... 

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