Abstract: A method of marking a hydrocarbon fuel, the method comprising adding to said hydrocarbon fuel a tracer compound for marking the hydrocarbon fuel, the tracer compound being a substituted fluorene having a structure of Formula (I): wherein R1 and R2 are the same or different and selected from hydrogen, straight chain, branched or cyclic alkyl groups, phenyl or substituted phenyl groups, benzyl or substituted benzyl groups, or R1 and R2 form a single substituent linked intramolecularly to each other, or R1 and R2 are ether groups excluding acetal groups, wherein R3 and R4 are the same or different and selected from hydrogen, straight chain, branched or cyclic alkyl groups, phenyl or substituted phenyl groups, benzyl or substituted benzyl groups, and wherein at least one of R1, R2, R3, and R4 is not hydrogen.

Abstract: A method of marking a hydrocarbon liquid comprising adding to said hydrocarbon liquid a tracer compound, the tracer compound being a substituted biphenol ether having a core structure of Formula I, wherein the two R groups are the same or different and selected from straight chain, branched or cyclic alkyl groups, phenyl or substituted phenyl groups, benzyl or substituted benzyl groups, or the two R groups form a single substituent linked intramolecularly to both oxygen atoms, and wherein one or both of the aromatic rings of the core structure is further substituted with at least one non-planar group.

Abstract: A method of marking a hydrocarbon liquid includes the step of adding to the liquid, as a tracer compound, a compound of Formula I: wherein at least one of R1-R4 is selected from: i. a bromine or fluorine atom; ii. a partially or fully halogenated alkyl group; iii. a branched or cyclic C4-C20 alkyl group; iv. an aliphatic substituent linking two positions selected from R1-R4 in Formula I to one another; or v. a phenyl group substituted with a halogen atom, an aliphatic group or halogenated aliphatic group. The tracer compounds are resistant to removal from the fuel by chemical laundering or by contact with absorbents such as charcoal.

Abstract: A method of marking a hydrocarbon liquid includes the step of adding to the liquid, as a tracer compound, a compound of Formula I: wherein at least one of R1-R4 is selected from: i. a bromine or fluorine atom; ii. a partially or fully halogenated alkyl group; iii. a branched or cyclic C4-C20 alkyl group; iv. an aliphatic substituent linking two positions selected from R1-R4 in Formula I to one another; or v. a phenyl group substituted with a halogen atom, an aliphatic group or halogenated aliphatic group. The tracer compounds are resistant to removal from the fuel by chemical laundering or by contact with absorbents such as charcoal.

Abstract: Method of marking a hydrocarbon liquid includes: adding thereto, a tracer compound of Formula I: wherein, each A is independently selected from the group consisting of (i) a phenyl group, (ii) a phenyl group substituted with one or more halogen atoms, an aliphatic group or a halogenated aliphatic group, (iii) a partially or fully halogenated alkyl group or (iv) a linear branched or cyclic C1-C20 alkyl group, and each B is independently selected from the group consisting of a (i) phenyl, (ii) phenylmethyl group, (iii) a cyclohexyl group, (iv) a cyclohexylmethyl group, (v) a substituted phenyl or phenylmethyl group in which the benzene ring is substituted by at least one substituent selected from the group consisting of a fluorine atom, a partially or fully halogenated alkyl group and a linear, branched or cyclic C1-C20 alkyl group or (vi) a linear, branched or cyclic C1-C20 alkyl group.

Abstract: Method of marking a hydrocarbon liquid includes: adding thereto, a tracer compound of Formula I: wherein, each A is independently selected from the group consisting of (i) a phenyl group, (ii) a phenyl group substituted with one or more halogen atoms, an aliphatic group or a halogenated aliphatic group, (iii) a partially or fully halogenated alkyl group or (iv) a linear branched or cyclic C1-C20 alkyl group, and each B is independently selected from the group consisting of a (i) phenyl, (ii) phenylmethyl group, (iii) a cyclohexyl group, (iv) a cyclohexylmethyl group, (v) a substituted phenyl or phenylmethyl group in which the benzene ring is substituted by at least one substituent selected from the group consisting of a fluorine atom, a partially or fully halogenated alkyl group and a linear, branched or cyclic C1-C20 alkyl group or (vi) a linear, branched or cyclic C1-C20 alkyl group.

Abstract: A method of marking a hydrocarbon liquid includes the step of adding to the liquid, as a tracer compound, a compound of Formula I: wherein at least one of R1-R4 is selected from: i. a bromine or fluorine atom; ii. a partially or fully halogenated alkyl group; iii. a branched or cyclic C4-C20 alkyl group; iv. an aliphatic substituent linking two positions selected from R1-R4 in Formula I to one another; or v. a phenyl group substituted with a halogen atom, an aliphatic group or halogenated aliphatic group. The tracer compounds are resistant to removal from the fuel by chemical laundering or by contact with absorbents such as charcoal.