Method of making perfluorocyclobutane-containing monomer

A method for manufacturing a compound of general formula [formula (I)]:

• wherein each of G and G′, equal to or different from each other, is independently selected from the group consisting of
• halogens selected from F, Cl, Br, I;
• —NRH1RH2, with RH1 and RH2 being independently H or a C1-C6, hydrocarbon group;
• —OH;
• nitrile group of formula —CN and nitro group of formula —NO2;
• —COY, with Y being —X, with X being a halogen selected from F, Cl, Br, I;
• —OH;
• —ORH3, —NRH1RH2, with RH3 being a C1-C12 hydrocarbon group;
• and RH1 and RH2 having the meaning detailed above;
• —SO2Y′, with Y′ being —OH, or being —X′, with X′ being a halogen selected from F, Cl, Br, I;
• -E-Ar—X″, with X″ being hydrogen, —OH, —Xoo, —C(O)X# with X# being —OH, or being —Xoo;
• with Xoo being a halogen selected from F, Cl, Br, I;
• -E- being a divalent bridging group selected from the group consisting of a bond, a C1-C6 carbon-containing bridging group;
• a sulphur-containing bridging group,
• a group of formula
• with Xz being —NH2;
• —NO2;
• —OH, —Xoo, —C(O)X# with X# being —OH, or being —Xoo;
• with Xoo being a halogen selected from F, Cl, Br, I;
• each of n, equal to or different from each other, is an integer of 1 to 3, said method comprising:
• Step (a):
• a step of reacting an anion of formula [formula (II)]:
• wherein G″ is a group G or G′, as described above, or is a precursor thereof, with tetrafluoroethylene at a temperature of at most 115° C. and at a pressure of at least 4 bar, so as to obtain a compound of formula [formula (III)]:
• Step (b):
• a step of dimerizing at least one compound of formula (III) obtained from step (a) by thermal treatment at a temperature exceeding 150° C., so as to obtain a compound of formula [formula (IV)]:
• wherein each of G″ and G′″ is a group G or G′, as described above, or is a precursor thereof, being understood that when G″ and G′″ are a group G or G′ as detailed above, compound of formula (IV) qualifies as a compound of formula (I);
• and
• Step (c):
• optionally, a step of reacting compound of formula (IV) in appropriate conditions to transform precursor groups G″ and G′″ of formula (IV) into groups G and G′ so as to obtain compound of formula (I) above.