Organic derivatives of rhenium oxides and their preparation and use for the metathesis of olefins

A process for the metathesis or olefins which comprises reacting an olefin of the formula

• YCZ.dbd.CZ--(CX.sub.2).sub.n R.sup.2 (II)
• wherein n is an integer from 1 to 28,
• X represents H or F,
• Y represents H or alkyl having from 1 to 10 carbon atoms and
• Z represents H or a non-aromatic hydrocarbon group having from 1 to 6 carbon atoms and
• R.sup.2 represents H, alkyl, halogen, COOR.sup.3 or OR.sup.4, wherein R.sup.3 and R.sup.4 represent alkyl having from 1 to 15 carbon atoms or phenyl which is unsubstituted or contains from 1 to 3 substituents or wherein R.sup.4 is trialkylsilyl R.sup.5.sub.3 Si, wherein R.sup.5 represents alkyl having from 1 to 5 carbon atoms, at a catalyst comprising an oxidic carrier charged with a rhenium compound of the general formula R.sup.1.sub.a Re.sub.b O.sub.c, wherein a is an integer from 1 to 6, b is an integer from 1 to 4 and c is an integer from 1 to 14 and the sum of a, b and c conforms to the 5- to 7-valency of rhenium with the proviso that c does not exceed 3.b, and wherein R.sup.1 represents alkyl having from 1 to 9 carbon atoms, cycloalkyl having from 5 to 10 carbon atoms or aralkyl having from 7 to 9 carbon atoms and wherein R.sup.1 is unsubstituted or at least partially fluorinated, said compounds containing not more than three compounds of more than 6 carbon atoms per rhenium atom and containing a hydrogen atom bound to the carbon atom in a .alpha.-position to the rhenium atom, wherein the reaction is carried out in the absence of an activating compound.