A process for producing a perfluoropolyether acyl fluoride which includes reducing a peroxyperfluoropolyether by using a formyl group-containing compound in the presence of a transition metal catalyst.

One embodiment of the present invention is a fullerene derivative represented by general formula (1)

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(wherein FLN is a fullerene backbone; each A is independently a monovalent group including a divalent perfluoropolyether group; each R is each independently a hydrogen atom, a hydrocarbon group, or an alkoxycarbonyl group including a divalent perfluoropolyether group; at least one of the 2m R is a hydrocarbon group or an alkoxycarbonyl group including a divalent perfluoropolyether group; m is an integer from 1 to 5; and n is an integer from 1 to 6).

A process for producing a perfluoropolyether acyl fluoride which includes reducing a peroxyperfluoropolyether by using a formyl group-containing compound in the presence of a transition metal catalyst.