Hydrogenation, catalytic furan

Catalytic hydrogenation of furan to tetrahydrofuran is accompHshed in either Hquid or vapor phase. Hydrogenation of the double bonds is essentially quantitative over nickel catalysts but is generally accompanied by hydrogenolysis over the noble metals. 

Similar procedures to those used for the catalytic hydrogenation of furan and thiophene can usually be applied to the functional derivatives of these heterocycles. 

Catalytic hydrogenation of furan Catalytic hydrogenation of furan with a palladium catalyst gives tetrahydrofuran, which is a clear, low-viscosity liquid with a diethyl-ether-like smell. 

The catalytic hydrogenation of furan and its derivatives is strongly dependent on reaction conditions and catalysts employed. A review is available.188 It is possible to classify the results of these reactions into three main groups ... 

The experiments were run with a view to determining how four experimental variables influence the yield in the catalytic hydrogenation of furan over a palladium catalyst. The variables were x2, the amount of palladium catalyst x2, the hydrogen pressure x3, the reaction temperature and x4, the stirring rate. The factorial design, 24, shown in Table 2 was used to fit a second-order intraction model to the yields obtained ... 

Table 2. Experimental design and yields obtained in the catalytic hydrogenation of furan...

Fig. 4. Response surface showing the variation in yield when hydrogen pressure and stirring rate was varied in the catalytic hydrogenation of furan. The twist due to an interaction effect is clearly seen. The remaining variables were set to their upper levels...

Derivation (1) Catalytic hydrogenation of furan with nickel catalyst. (2) Acid-catalyzed dehydration of 1,4-butanediol. 

The experiments were run to determine how four experimental variables influence the yield of tetrahydrofuran in catalytic hydrogenation of furan over a palladium catalyst. The variables and the experimental domain are shown in Table 5.10. 

Hydrogenation of Substituted Furan Derivatives Although one of the earliest approaches to the synthesis of nonactic acid involved catalytic hydrogenation of an appropriately 2,5-disubstituted furan, the hydrogenation of furan derivatives is limited by the formidable problem of controlling the well separated acyclic stereocentres at C-2 and C-8. 

Catalytic hydrogenation of furan can be effected by Sabatier s method with nickel at 170°. Cloke and Ayers236 effected it at 50° with Raney nickel. Starr and Hixon237 hydrogenated 120 g of furan in absence of solvent in about 20 h at 7 atm, obtaining a 96% yield by using palladium oxide as catalyst. 

The diacetylene 15 readily underwent Diels-Alder cycloaddition with furan to furnish the endoxide 16, which was hydrogenated catalytically to the tetrahydro compound 17. Dehydration of 77 with polyphosphoric acid gave 1 in 16% yield (Eq. 7) Alternatively, deoxy nation of 16 with low valent titanium generated by reducing titanium tetrachloride with lithium aluminium hydride also afforded 7 in 50% yield... 

Tetrahydrofuran te-tr9- hI-(i)dro- fyur- an (THF, tetramethylene oxide) n. A colorless liquid obtained by the catalytic hydrogenation of furan, with the empirical formula C4H8O. 

Catalytic hydrogenation of furfural in the presence of copper chromite leads to furfuryl alcohol, the major intermediate of the furan resins Figure 28.1). 

DeDiox A process for destroying polychlorinated dioxins and furans in flue-gases by catalytic oxidation with hydrogen peroxide. The catalyst is based on silica and the process is operated at 80 to 100°C. Developed by Degussa from 1994. The business was offered for sale in 1998. 

Previous studies on various aliphatic and aromatic alkynes have evidenced that this type of furan-2-ones could also be produced in the presence of the rhodium carbonyl cluster [Rh4(CO)i2] [39-41]. Labeling experiments using D2O allowed the authors to assign the origin of the hydrogen atoms (Scheme 6). Noteworthy, dicobalt octacarbonyl follows a different catalytic... 

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