Tracers and method of marking liquids

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.

1 - 14 . (canceled) 
     
     
         15 . 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, 
         wherein at least one of R1, R2, R3, and R4 is not hydrogen, and 
         wherein the hydrocarbon fuel is a gasoline fuel, a diesel fuel, a kerosene-based fuel, a liquified petroleum gas fuel, a bio-diesel fuel, or a bio-ethanol fuel. 
       
     
     
         16 . The method according to  claim 15  wherein R3 and R4 are not hydrogen. 
     
     
         17 . The method according to  claim 15  wherein R1 and R2 are not hydrogen. 
     
     
         18 . The method according to  claim 15  wherein R1, R2, R3, and R4 are selected such that the substituted fluorene tracer compound consists only of atoms selected from the group carbon, hydrogen, and oxygen. 
     
     
         19 . The method according to  claim 15  wherein R1 and R2 and/or R3 and R4 are selected from the same or different C 3  to C 20  group. 
     
     
         20 . The method according to  claim 15  wherein R1 and R2 and/or R3 and R4 are selected from the same or different, straight chain, branched or cyclic alkyl groups. 
     
     
         21 . The method according to  claim 20  wherein R1 and R2 and/or R3 and R4 are selected from the same or different branched or cyclic alkyl groups. 
     
     
         22 . The method according to  claim 21  wherein R1 and R2 and/or R3 and R4 are selected from the same or different branched alkyl groups. 
     
     
         23 . A method according to  claim 22  wherein R3 and R4 are tert-butyl groups. 
     
     
         24 . A method according to  claim 15  wherein R3 and R4 are at the C-2 and C-7 positions of the aromatic rings of the substituted fluorene tracer compound such that the substituted fluorene tracer compound has a structure of Formula II: 
       
         
           
           
               
               
           
         
       
     
     
         25 . A hydrocarbon fuel comprising the tracer compound as defined in  claim 15 , wherein the hydrocarbon fuel is a diesel fuel, a gasoline fuel, a kerosene-based fuel, a liquified petroleum gas fuel, a bio-diesel fuel, or a bio-ethanol fuel in which the tracer compound is disposed. 
     
     
         26 . Use of a compound as a tracer compound for marking a hydrocarbon fuel, the 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, 
         wherein at least one of R1, R2, R3, and R4 is not hydrogen, and 
         wherein the hydrocarbon fuel is a diesel fuel, a gasoline fuel, a kerosene-based fuel, a liquified petroleum gas fuel, a bio-diesel fuel, or a bio-ethanol fuel.