Cyclic ethers 2.5- dimethyl tetrahydrofuran

Five- and six-membered cyclic ethers are readily formed by loss of water from appropriate diols.li,k As examples of reactions in the liquid phase, cyclization of, <5-alkanediols to tetrahydrofurans and of a,e-alkanediols to tetrahydropyrans generally occurs when they are warmed in the presence of an inorganic or organic acid. These reactions can also be induced by warming the diols in dimethyl sulfoxide.674... 

Other cyclic ethers have been prepared, but yields are highly dependent on product ring size. The following transformations are representative 2,2-dimethyl-1,3-propanediol to 3,3-dimethyloxetane (86%), 1,4-butanediol to tetrahydrofuran (72%), 1,5-pentanediol to tetrahydropyran (39%), and diethylene glycol to dioxane (40%). Longer chain diols yield ethers [(CF3)2PhCO(CH2) OCPh(CF3)2]. ... 

Ionization potential of Continued) butenone, 123 cyclic diacetylenes, 305 cyclohexene, 48, 102 cis-cyclooctene, 102 Zraus -cyclooctene, 102 DABCO, 81 dimethyl ether, 123 ethylene, 80, 319 formaldehyde, 123, 319 hydrogen atom, 55, 75 methanol, 123 methyl acetate, 123 methyl acrylate, 123 nitrous oxide (N2O), 172 norbornadiene, 48 norbornene, 48 oxetane, 123 tetrahydrofuran, 123 trimethylamine, 81 water, 123... 

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