(a) A medium oil wherein a main component is a hydrocarbon, and the number of
paraffinic carbon atoms is 70% or more with respect to a total number of carbon
atoms, (b) a medium oil wherein a main component is a polybutene, (c) a medium
oil wherein a main component is a mixture of hydrocarbons of the formula (1):
CH3—C(CH3)2—[—CH2—C(CH3)2—]n—CH2—R (1)
wherein R is —CH(CH3)2 or —C(CH3)CH2,
and n is 1 to 10, (d) a medium oil wherein a main component is a hydrocarbon prepared
by a Fischer-Tropsch synthesis, or (e) a medium oil wherein a main component is
a branched paraffinic hydrocarbon prepared by hydrogenolysis of a hydrocarbon prepared
by a Fischer-Tropsch synthesis, and a process of producing dimethyl ether using
the medium oil, are disclosed.
