OA19999A - Compounds for chemically marking a petroleum hydrocarbon. - Google Patents

Abstract

The present invention relates to a use of a compound of general formula (I) wherein the residues R1 -R12 are independently of each other selected from the group consisting of hydrogen, C1-C4-alkyl, and the residues Ra -Re , Ra'-Re',Ra''-Re'' and Ra'''-Re''' are independently of each other selected from the group consisting of hydrogren and C1 -C4alkyl; with the proviso that at least two of the substituents R1 R12 are selected from: (formula) for chemically marking a petroleum hydrocarbon selected from the group consisting of gasoline, diesel fuel, kerosene, and jet fuel, to prevent counterfeiting of said petroleum hydrocarbon. The presence and concentration of the chemical marker of general formula (I) in the composition of the petrolem hydrocarbon can be advantageously determined by laser ionization coupled with mass spectrometry or laser ionization coupled with ion mobility spectrometry.

Description

The présent invention relates to the technical field of compounds for chemically marking a petroleum hydrocarbon to prevent counterfeiting of said petroleum hydrocarbon.

BACKGROUND OF THE INVENTION

Marking of petroleum hydrocarbons with the scope of auditing the custody transfer of such products, to prevent and/or prove theft and/or counterfeiting is of great importance for the petroleum industry. In addition, marking of petroleum hydrocarbons may be also used to control whether a distributor has sold a low-priced petroleum hydrocarbon as a more 15 expensive petroleum hydrocarbon or has used a low-priced petroleum hydrocarbon to dilute a more expensive petroleum hydrocarbon.

Additionally, national governments are interested in technical solutions that allow to détermine whether applicable taxes hâve been paid on petroleum hydrocarbons, whether 20 tax exempt petroleum hydrocarbons are being sold as tax paid petroleum hydrocarbons or if they are being used to dilute tax paid petroleum hydrocarbons, and whether a petroleum hydrocarbon, which meets environmentally mandated spécifications has been diluted with a product that does not meet such spécifications.

A limited number of Chemical markers for tagging petroleum hydrocarbons and methods for detecting said markers in the tagged products hâve been described.

The use of halogenated compounds, such as halogenated alkanes, halogenated olefins and halogenated aromatic compounds (WO02098199A2), perfluorinated C9-C18 30 polycyclic hydrocarbons (EP0120641A2), chlorinated hydrocarbons and chlorocarbons (US4141692), and brominated or fluorinated benzene and naphthalene dérivatives (WO2012153132A1), as tracers for marking a hydrocarbon liquid, as well as their détection by gas chromatography - mass spectrometry (WO2012153132A1), gas chromatography - électron capture détection (EP0120641A2, US4141692) or X-ray 35 fluorescence (WO02098199A2) hâve been previously described.

Aryl ethers, including bis(alkyloxy)-1,1’-biphenyl dérivatives (WO2013003573A1), bis(phenoxymethyl)-1 ,T-biphenyl dérivatives (US20120090225A1), alkyl aryl ethers and alkenyl aryl ethers (WO2014081556A1), ortho-pher\y\ phénol ethers (WO2012154646A1), tritylated alkyl aryl ethers (WO2014008164A1), bisphenol A substituted benzyl ethers (US20140179955A1), deuterated bis(4(alkyloxy)phenyl)sulfane dérivatives (US9366661B1) and deuterated 4,4’oxybis((alkyloxy)benzene dérivatives (US9366661B1) are also known as Chemical markers for petroleum hydrocarbons. The détection of such type of Chemical markers include gas-chromatography - flame ionization détection (WO2013003573A1), gas chromatography - mass spectrometry (US20120090225A1, WO2012154646A1, WO2014008164A1, US20140179955A1, US9366661B1) and two-dimensional gas chromatography coupled with mass spectrometry (WO2014081556A1).

Further, US patent application publication number US2014008164A1 describes the use of 4,4’-bis(benzyl)-1,1 ’-biphenyl dérivatives as Chemical markers for liquid hydrocarbons and gas chromatography as détection technique of such Chemical markers.

US patent application publication number US2011290997A1 discloses the use of 1,3diphenyl-2-buten-1-one dérivatives for marking a petroleum hydrocarbon and gas chromatography - mass spectrometry for détection of such Chemical markers.

International patent application publication number WO2004068113A2 describes a method of marking a fuel with a Chemical marker of general formula RCAR', wherein R is a compound selected from the group consisting of alkyl, olefin, aryl, heterocycle and hydrogen; R' is a compound selected from the group consisting of alkyl, olefin, aryl, heterocycle and hydrogen; and wherein A is a compound selected from the group consisting of ketones, alcohol, amines, cyano, sulfate, nitrile, nitrate, halogen, organic acid, mercaptan, aldéhyde, formyl, thiocyano, and isothiocyano, and the use of ion mobility spectrometry for détection of said Chemical marker. The ion mobility spectrometry détection method described by WO2004068113A2 uses nickel 63 (⁶³Ni) as ionization source, which results in unselective ionization of the sample leading to difficult identification ofthe marker ion peak among the fuel matrix ion peaks.

The main disadvantage associated with the methods of marking with Chemical markers whose détection and eventual quantification relies upon the use of the gas chromatography (GC) is that the GC column used in the séparation of the marked petroleum hydrocarbon components has to be frequently replaced as a resuit of the contaminations caused by the high amount of petroleum hydrocarbon components injected on the column. For the Chemical markers whose détection and quantification techniques rely upon the use of gas chromatography - mass spectrometry (GC-MS), the frequent cleaning and/or replacement of the ionization source of the mass spectrometer is additionally required.

Because of the limited number of currently available Chemical markers for tagging petroleum hydrocarbon products and the different disadvantages associated with some of them, such as light and heat instability in the marked petroleum hydrocarbon, insolubility in the marked petroleum hydrocarbon, toxicity, unsatisfactory counterfeit-resilience and unsatisfactory laundering résistance, there is a constant need for the development of additional Chemical markers to satisfy the high demand from government bodies and the petroleum industry.

In selecting a suitable Chemical marker, several factors must be taken into considération. Among the major ones are: cost, ease of détection, stability, solubility and compatibility with the petroleum hydrocarbon, inertness to air, water and normal soil components, corrosivity, volatility and toxicity. Additionally, the Chemical markers for low tax petroleum hydrocarbons, should not be laundered by an economically viable process using common available Chemicals.

The problem addressed by the présent invention is to provide additional Chemical compounds for marking petroleum hydrocarbons to prevent counterfeiting of said petroleum hydrocarbons.

SUMMARY OF THE INVENTION

Accordingly, it is the object of the présent invention to provide a use of a compound of general formula (I)

wherein the residues R¹ - R¹² are independently of each other selected from the group consisting of hydrogen, Ci-C4-alkyl,

and the residues R^a - R^e, R^a’ - R^e’, R^a” - R^e” and R^a”’ - R^e”’ are independently of each other selected from the group consisting of hydrogen and Ci-C4-alkyl; with the proviso that at least two of the substituents R¹ - R¹² are selected from:

and for chemically marking a petroleum hydrocarbon selected from the group consisting of gasoline, diesel fuel, kerosene, and jet fuel, to prevent counterfeiting of said petroleum hydrocarbon.

Minute quantities of the naphthacene dérivatives of general formula (I) in a petroleum hydrocarbon as defined herein are easily détectable, identifiable and quantifiable after sample vaporization by laser ionization at a wavelength of between about 300 nm and about 370 nm coupled with mass spectrometry, or by laser ionization at a wavelength of between about 300 nm and about 370 nm coupled with ion mobility spectrometry. Sample vaporization followed by laser ionization at a wavelength of between about 300 nm and about 370 nm coupled with mass spectrometry, or by laser ionization at a wavelength of between about 300 nm and about 370 nm coupled with ion mobility spectrometry enables identification and quantification of a naphthacene dérivative of general formula (I) in a petroleum hydrocarbon, and thereby determining the authenticity of said petroleum hydrocarbon and/or detecting the adultération of said petroleum hydrocarbon. Détection of the peak corresponding to the ion (M⁺) of the naphthacene dérivative of general formula (I) in the mass spectrum or the ion mobility spectrum (i.e. identification of the naphthacene dérivative of general formula (I)) is indicative of the authenticity of said petroleum hydrocarbon. For certain applications, such as Chemical marking of low tax petroleum hydrocarbon, détection of the presence of the naphthacene dérivative of general formula (l) in the petroleum hydrocarbon is typically considered a sufficient condition for acknowledging the authenticity of said petroleum hydrocarbon. In an équivalent manner, détection of the presence of a compound of general formula (I) used for chemically marking low tax petroleum hydrocarbon in an alleged high tax petroleum hydrocarbon (i.e. a petroleum hydrocarbon that is not supposed to contain said Chemical marker) is a sufficient condition for acknowledging that the high tax petroleum hydrocarbon is not authentic. As well known to the skilled person adultération of a petroleum hydrocarbon refers to altering, mixing, diluting, laundering, etc., of the petroleum hydrocarbon. In some cases, a petroleum hydrocarbon (e.g. a petroleum hydrocarbon taxed at a higher rate) can be combined (e.g. illegally) with another petroleum hydrocarbon (e.g. an untaxed petroleum hydrocarbon or petroleum hydrocarbon taxed at a lower rate) or solvent to form an adulterated (e.g., altered, mixed, diluted, laundered, etc.) petroleum hydrocarbon. For example, a petroleum hydrocarbon can be mixed with one or more other petroleum hydrocarbons, solvents, and the like, or combinations thereof. If undetected, the adulterated petroleum hydrocarbon can be sold, sometimes illegally, at the price ofthe petroleum hydrocarbon taxed at the higher rate to yield a profit. In some instances, the adulterated petroleum hydrocarbon can be potentially hazardous for the user, such as for example when a hazardous solvent is used for adulterating the petroleum hydrocarbon. In other instances, the petroleum hydrocarbon can be treated or laundered in an attempt to remove identifying features, such as Chemical markers from the petroleum hydrocarbon (e.g. to disguise the origin of the petroleum hydrocarbon the amount of tax paid on the petroleum hydrocarbon, etc.) before the petroleum hydrocarbon is mixed with another petroleum hydrocarbon to form an adulterated petroleum hydrocarbon. Chemical marking of a petroleum hydrocarbon with a compound of general formula (I) renders the above-described adultération activities difficult and constitutes an extremely useful tool for proving and/or preventing counterfeiting of said petroleum hydrocarbon.

The Chemical markers of general formula (I) are inert to air, water and soil components, as well as conventional petroleum hydrocarbon components, and they are non-corrosive. Further, they are commercially available at low cost or can be obtained by well-established organic chemistry methods, and their détection and quantification methods do not suffer from the drawbacks encountered for the GC-MS based détection and quantification methods. Moreover, the naphthacene dérivatives of general formula (I) are relatively nontoxic, do not produce harmful products upon combustion and exhibit excellent laundering résistance.

Further claimed and described herein is a method for preventing counterfeiting of a petroleum hydrocarbon selected from the group consisting of gasoline, diesel fuel, kerosene, and jet fuel, wherein said method comprises adding to and uniformly mixing with said petroleum hydrocarbon a compound of general formula (I)

wherein the residues R¹ - R¹² are independently of each other selected from the group consisting of hydrogen, Ci-C4-alkyl,

and the residues R^a - R®, R^a’ - R®’, R^a” - R®” and R^a”’ - R®’” are independently of each other selected from the group consisting of hydrogen and Ci-C4-alkyl; with the proviso that at least two of the substituents R¹ - R¹² are selected from:

Fig. 1 illustrâtes the mass spectrum of a composition of diesel containing the Chemical marker 5,6,11,12-tetraphenylnaphthacene obtained by laser ionization at 355 nm coupled with mass spectrometry. The peak corresponding to the ion (M⁺) of the Chemical marker 5,6,11,12-tetraphenylnaphthacene (m/z of 532) is indicated by a

Fig. 2 illustrâtes the variation of the intensity of the peak corresponding to the ion (M⁺) of the Chemical marker 5,6,11,12-tetraphenylnaphthacene with the concentration of the Chemical marker in a composition of diesel and a composition of gasoline. The compositions containing the Chemical marker 5,6,11,12-tetraphenylnaphthacene were analyzed by laser ionization at 355 nm coupled with mass spectrometry.

DETAILED DESCRIPTION

Définitions

The following définitions are to be used to interpret the meaning of the terms discussed in the description and recited in the daims.

As used herein, the article a/an” indicates one as well as more than one and does not necessarily limit its referent noun to the singular.

As used herein, the term “about” means that the amount or value in question may be the spécifie value designated or some other value in its neighbourhood. Generally, the term “about” denoting a certain value is intended to dénoté a range within ± 5% of the value. As one example, the phrase “about 100” dénotés a range of 100 ± 5, i.e. the range from 95 to 105. Preferably, the range denoted by the term “about” dénotés a range within ± 3% of the value, more preferably ± 1 %. Generally, when the term “about” is used, it can be expected that similar results or effects according to the invention can be obtained within a range of ±5% of the indicated value.

As used herein, the term “and/or” means that either ail or only one of the éléments of said group may be présent. For example, “A and/or B” means “only A, or only B, or both A and B”. In the case of “only A”, the term also covers the possibility that B is absent, i.e. “only A, but not B”.

The term “comprising” as used herein is intended to be non-exclusive and open-ended. Thus, for instance a solution comprising a compound A may include other compounds besides A. However, the term “comprising” also covers, as a particular embodiment thereof, the more restrictive meanings of “consisting essentially of’ and “consisting of’, so that for instance “a solution comprising A, B and optionally C” may also (essentially) consist of A and B, or (essentially) consist of A, B and C.

Where the présent description refers to “preferred” embodiments/features, combinations of these “preferred” embodiments/features are also deemed to be disclosed as long as the spécifie combination of “preferred” embodiments/features is technically meaningful.

The présent invention provides a use of a compound of general formula (I)

wherein the residues R¹ - R¹² are independently of each other selected from the group consisting of hydrogen, Ci-C4-alkyl,

and and the residues R^a - R®, R^a’ - R^e’, R^a” - R^e” and R^a”’ - R^e”’ are independently of each other selected from the group consisting of hydrogen and C1-C4 alkyl; with the proviso that at least two of the residues R¹ - R¹² are selected from:

for chemically marking a petroleum hydrocarbon selected from the group consisting of gasoline, diesel fuel, kerosene, and jet fuel, to prevent counterfeiting of said petroleum hydrocarbon.

The présent invention further provides a method for preventing counterfeiting of a 15 petroleum hydrocarbon selected from the group consisting of gasoline, diesel fuel, kerosene, and jet fuel, wherein said method comprises adding to and uniformly mixing with said petroleum hydrocarbon compound of general formula (I)

wherein the residues R¹ - R¹² are independently of each other selected from the group consisting of hydrogen, Ci-C₄-alkyl,

other selected from the group consisting of hydrogen and C1-C4 alkyl; with the proviso that at least two of the residues R¹ - R¹² are selected from:

Preferably, the petroleum hydrocarbon is selected from gasoline and diesel fuel.

The term “Ci-C₄-alkyl” as used herein refers to a saturated linear or branched-chain monovalent hydrocarbon radical of one to four carbon atoms (Ci-C₄). Examples of Ci-C₄alkyl groups include methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, CH2CH2CH3), 2-propyl (/-Pr, /so-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, CH2CH2CH2CH3), 2-methyl-1-propyl (/-Bu, /-butyl, -CH₂CH(CH₃)2), 2-butyl (s-Bu, s-butyl, -CH(CH3)CH₂CH3) and 2-methyl-2-propyl (t-Bu, f-butyl, -C(CH3)3).

Preferably, the at least one Chemical marker of general formula (I) is characterized by a boiling point lower than about 650 °C at 760 mm Hg. Such a Chemical marker is particularly useful for marking subsidized petroleum hydrocarbons, such as subsidized kerosene and subsidized diesel, because it renders economically not viable the removal ofthe Chemical marker from the subsidized petroleum via distillation that is known as one the most used techniques for eliminating the Chemical markers from the subsidized petroleum hydrocarbons.

As attested for example by Fig. 1 and Fig. 2, the naphthacene dérivatives of general formula (I) are easily détectable, identifiable and quantifiable in minute quantities in a petroleum hydrocarbon as defined herein after sample vaporization by laser ionization at a wavelength of between about 300 nm and about 370 nm coupled with mass spectrometry. As shown by Fig. 1 and Fig. 2, the naphthacene dérivatives of general formula (I) contained by a composition of a petroleum hydrocarbon can be selectively ionized by illumination with pulsed laser light having a wavelength of 355 nm. The inventors hâve found that sélective ionization of the naphthacene dérivatives of general formula (I) in a composition of petroleum hydrocarbon can be achieved by illumination with pulsed laser light having any wavelength of between about 300 nm and about 370 nm, for example 308 nm, 337 nm and 355 nm.

In addition, the naphthacene dérivatives of general formula (I) are inert to air, water and soil components, as well as conventional petroleum hydrocarbon components, and they are non-corrosive. Further, they are commercially available at low cost or can be obtained by well-established organic chemistry methods, and their détection and quantification methods do not suffer from the drawbacks encountered for the GC-MS based détection and quantification methods. Moreover, the naphthacene dérivatives of general formula (!) are relatively non-toxic, do not produce harmful products upon combustion and exhibit excellent laundering résistance.

Preferably, the concentration of the at least one Chemical marker of general formula (I) in the petroleum hydrocarbon described herein is of at least about 1 μΜ (micromolar). Depending on the petroleum hydrocarbon to be marked and the method used for the détection and quantification of the Chemical marker, namely laser ionization at a wavelength of between about 300 nm and about 370 nm coupled with mass spectrometry, or laser ionization at a wavelength of between about 300 nm and about 370 nm coupled with ion mobility spectrometry, higher concentration of the compound of general formula (I) in the petroleum hydrocarbon may be required. Owing to the high solubility of the Chemical marker of general formula (!) in a variety of petroleum hydrocarbons, even high marking concentrations of about 0.2 mM (millimolar) may be considered. It remains within the skills of the person skilled in the art of petroleum hydrocarbon marking to détermine via routine work an adéquate marking concentration for a spécifie Chemical marker of general formula (I), taking into account the type of petroleum hydrocarbon to be marked, the method used for the détection and quantification of said spécifie Chemical marker, namely laser ionization at a wavelength of between about 300 nm and about 370 nm coupled with mass spectrometry, or laser ionization at a wavelength of between about 300 nm and about 370 nm coupled with ion mobility spectrometry, as well as the cost of the Chemical marker.

Preferably, in the general formula (I), at the most four of the residues R¹ - R¹² are selected from the group consisting of:

Thus, a naphthacene of general formula (I), wherein at the least two, but at the most four 5 of the residues R¹ - R¹² are selected from the group consisting of:

is especially preferred.

A preferred embodiment according to the présent is directed to a use as claimed and described herein and a method for preventing counterfeiting as claimed and described herein, wherein the residue R¹ in general formula (I) represents

: , and the residues R^a- R® hâve the meanings defined herein. Thus, a preferred embodiment according to the présent invention is directed to a use as claimed and described herein, as well as to a method for preventing counterfeiting as claimed and described herein, wherein the compound used for Chemical marking is of general formula

R\ Ra R12 R9 R8 wherein the residues R2 - R12, Ra - Re, Ra’ meanings defined herein. 5 Preferably, in general formula (II), the residue R7 represents rc' Ra,X^T^ the residue R8 represents rc' Ra'^^r the residue R2 represents rc' R£/Xy 10 the residue R7 represents rc RF^A^ R®^^^

Rd ^Re R2 R3 R7 R6 (il) - R®’, Ra” - R®” and Ra”’ - R®’” hâve the or ^Rd' ^Re > or ,Rd' ^Re' 5 ,Rd' ^Re 1 /Rd ^Re

and residue R⁸ représente

Thus, a use as claimed herein, as well as a method for preventing counterfeiting as claimed herein, wherein the compound used is of general formula (ll-a), (ll-b), or (ll-c)

with the residues R² - R⁶, R⁸ - R¹², herein,

R^a- R^e and R^a’ - R^e’ having the meanings defined

with the residues R² - R⁷, R⁹ - R¹², R^a - R® and R^a’ - R®’ having the meanings defined herein,

with the residues R³ - R⁶, R⁹ - R¹², R^a- R^e, R^a’ - R®’, R^a” - R^e” and R^a”’ - R®’” having the meanings defined herein, is also preferred.

A further preferred embodiment according to the présent invention pertains to a use as claimed and described herein, as well as to a method for preventing counterfeiting as claimed and described herein, wherein in general formula (I), the substituents R⁴, R⁵, R¹⁰ and R¹¹ hâve the following meanings:

and the residues R¹ - R³, R⁶ - R⁹, R¹², R^a- R^e, R^a’ - R^e’, R^a” - R^e” and R^a”’ - R^e”’ hâve the meanings defined herein.

Thus, a preferred embodiment according to the présent invention pertains to a use as claimed and described herein, as well as to a method for preventing counterfeiting as claimed and described herein, wherein the compound used for Chemical marking is of general formula (III)

wherein the residues R¹ - R³, R⁶ - R⁹, R¹², R^a- R®, R^a’ - R^e’, R^a” - R^e” and R^a”’ - R®’” hâve the meanings defined herein.

An additional embodiment according to the présent invention is directed to a use as claimed and described herein, as well as to a method for preventing counterfeiting as claimed and described herein, wherein in general formula (I), the residues R³, R⁶, R⁹ and R¹² hâve the following meanings:

and R¹² =

R⁹ =

and the residues R¹, R², R⁴, R⁵, R⁷, R⁸, R¹⁰, R¹¹, R^a - R®, R^a’ - R®’, R^a” - R^e” and

R^a”’ - R®’” hâve the meanings defined herein.

Hence, an additional preferred embodiment according to the présent invention is directed to a use as claimed and described herein, as well as to a method for preventing counterfeiting as claimed and described herein, wherein the Chemical marker is of general formula (IV)

wherein the residues R¹, R², R⁴, R⁵, R⁷, R⁸, R¹⁰, R¹¹, R^a- R^e, R^a’ - R^e’, R^a” - R^e” and R^a”’

- R®’” hâve the meanings defined herein.

Preferably, in the general formulae described herein, the residues R^a - R®, R^a’ - R®’, R^a” - R®” and R^a”’ - R®’” represent hydrogen and/or the residues R¹ - R¹² other than

represent hydrogen.

and

More preferably, in the general formulae described herein, the residues R^a - R^e, R^a’ - R^e’, R^a” - R^e” and R^a”’ - R^e”’ represent hydrogen and the residues R¹ - R¹² other than

represent hydrogen.

Hence, examples of compounds to be used for chemically marking a petroleum hydrocarbon as described herein, include but are not restricted to the following compounds:

(IV).

The naphthacene dérivatives of general formula (I) can be prepared by well-known 5 methods described in the literature. For example, a naphthacene dérivative of general formula (ll-b) can be obtained from commercially available 5,12-naphthacenequine (Sigma Aldrich) as starting material using the following synthetic pathway:

In a similar manner, a naphthacene dérivative of general formula (ll-a) can be obtained using 5,11-naphthacenequinone as starting material. Introduction of Ci-Û4-alkyl substituents on the naphthacene core can be achieved by weil-known organic chemistry reactions, such as bromination of the naphthacene followed by treatment of the brominated naphthacene with a commercially available Grignard reagent, such as C1-C4alkylMgBr.

Examples of commercially available naphthacene dérivative of general formula (I), include, but are not limited to: 1,11-diphenyl-naphthacene (CAS no.: 927669-50-9; provider: Advanced Organic Synthesis); 5,12-diphenyl-naphthacene (CAS no.: 27130-321; provider: Chemieliva Pharmaceutical Co); 5,6,11,12-tetraphenyl-naphthacene (CAS no.: 517-51-1; provider: Chemieliva Pharmaceutical Co); and 5,12-bis[4-(1,1dimethylethyl)phenyl]-naphthacene (CAS no.: 478799-46-1; provider: Chemieliva Pharmaceutical Co).

The naphthacene dérivative of general formula (1) may be used in combination with a further Chemical marker for chemically marking a petroleum hydrocarbon selected from the group consisting of gasoline, diesel fuel, kerosene, and jet fuel, to prevent counterfeiting of said petroleum hydrocarbon. Use of multiple Chemical markers facilitâtes incorporation into the petroleum hydrocarbon of coded information that may be used to identify the origin and other characteristics of the petroleum hydrocarbon. The code comprises the identities and relative amounts, for example fixed integer ratios, of the Chemical markers. One, two, three or more Chemical marker compounds that are preferably détectable and quantifiable by laser ionization at a wavelength of between about 300 nm and about 370 nm (for e.g.: 308 nm, 337 nm, 355 nm) - mass spectrometry or laser ionization at a wavelength of between about 300 nm and about 370 nm (for e.g.: 308 nm, 337 nm, 355 nm) - ion mobility spectrometry may be used to form the code. The naphthacene dérivative of general formula (1) may be combined with further Chemical markers, such as:

i) a diphenyl-polyene of general formula (V)

R²³ R²⁴ R¹⁵ R¹⁶

wherein the residue -L- represents -CR¹³=CR¹⁴-, wherein R¹³ and R¹⁴ are independently of each other selected from the group consisting of hydrogen and methyl;

the residues R¹⁵ - R²⁴ are independently of each other selected from the group consisting of hydrogen and C1-C4 alkyl; and n is an integer comprised between 2 and 6, preferably between 2 and 4;

ii) an aromatic compound substituted by one or more A/./V-disubstituted amino groupe, wherein the substituents of the one or more /\/,A/-disubstituted amino groups are independently of each other selected from Ci-C4-alkyl; or iii) an aromatic compound substituted by at least one group selected from C1C4-alkyloxy.

The aromatic compound substituted by one or more /\/,/V-disubstituted amino groups and the aromatic compound substituted by at least one group selected from Ci-C4-alkyloxy may be further substituted by one or more substituents selected from Ci-C4-alkyl and are preferably characterized by a boiling point lower than about 600 °C at 760 mm Hg, more preferably lower than 500 °C at 760 mm Hg, and even more preferably lower than 450 °C at 760 mm Hg.

Examples of aromatic compounds substituted by one or more A/,A/-disubstituted amino groups include, but are not limited to: A/,/\/-dimethylbenzenamine (CAS no.: 121-69-7; provider: ASW MedChem); A/^A/^A/^A/Metramethyl-1,4-benzenediamine (CAS no.: 10022-1; provider: ASW MedChem); /V⁷,A/⁷-diethyl-A/⁴,A/⁴-dimethyl-1,4-benzenediamine (CAS no.: 5775-53-1; provider: Chemieliva Pharmaceutical); /V^A/^A/^/VMetraethyl-l ,4benzenediamine (CAS no.: 18996-77-5; provider: Chemieliva Pharmaceutical); Λ/¹,Ν\Ν⁴,Ν⁴,2,5-hexamethyl-1,4-benzenediamine (CAS no.: 858341-35-2; provider: Chemieliva Pharmaceutical); N¹, N¹, N⁴, /V⁴-tetrakis(1 -methylethyl)-1,4-benzenediamine (CAS no.: 6864-03-5; provider: Chemieliva Pharmaceutical); N¹,N¹,N⁴,N⁴,2,3,5,6octamethyl-1,4-benzenediamine (CAS no.: 66907-63-9; provider: Chemieliva

Pharmaceutical); A/,/V,3,5-tetramethylbenzenamine (CAS no.: 4913-13-7; provider: ASW MedChem); 3,5-diethyl-A/,/\/-dimethylbenzenamine (CAS no.: 99052-31-0; provider: Milestone Pharmtech); 3,5-bis(1,1-dimethylethyl)-A/,/\/-diethylbenzenamine (CAS no.: 94042-96-3; provider: Chemieliva Pharmaceutical); A/^/V^/V^/V'Metramethyl-l ,3benzenediamine (CAS no.: 22440-93-3; provider: ABCIabtory Scientific Co.); N¹,N¹,N³,N³tetraethyl-1,3-benzenediamine (CAS no.: 64287-26-9; provider: Chemieliva Pharmaceutical); A/⁷,A/⁷W³,A/³,4-pentamethylbenzene-1,3-diamine (CAS no.: 65198-15-4; provider: Chemieliva Pharmaceutical); ArWWTAP-tetramethyl-S-propyl-l ,3benzenediamine (CAS no.: 1586869-62-6; provider: Chemieliva Pharmaceutical); N,Ndimethylnaphthalen-1-amine (CAS no.: 86-56-6; provider: Alchem Pharmtech); /V-ethyl-/Vmethyl-naphthalen-1-amine (CAS no.: 83777-94-0; provider: Chemieliva Pharmaceutical); A/,/\/,4-trimethylnaphthalen-1-amine (CAS no.: 4523-52-8; provider: ASW MedChem); A/,/\/,5-trimethylnaphthalen-1-amine (CAS no.: 847449-78-9; provider: Chemieliva Pharmaceutical); /VW,2-trimethylnaphthalen-1 -amine (CAS no.: 57585-25-8; provider: Chemieliva Pharmaceutical); A/,A/-diethylnaphthalen-1 -amine (CAS no.: 84-95-7; provider: ASW MedChem); A/-isopropyl-/V-methylnaphthalen-1-amine (CAS no.: 110014-41-0; provider: Chemieliva Pharmaceutical); A/,A/,4,5-tetramethylnaphthalen-1-amine (CAS no.: 4619-41-4; provider: Chemieliva Pharmaceutical); /\/-ethyl-/V-isopropylnaphthalen-1amine (CAS no.: 114326-20-4; provider: Chemieliva Pharmaceutical); A/-ethyl-/\/,2dimethylnaphthalen-1-amine (CAS no.: 130523-07-8; provider: Chemieliva Pharmaceutical); /V,A/-bis(1-methylethyl)-naphthalen-1 -amine (CAS no.: 4960-24-1; provider: Chemieliva Pharmaceutical); Λ/-(1,1-dimethylethyl)-A/-methyl-naphthalen-1amine (CAS no.: 110014-43-2; provider: Chemieliva Pharmaceutical); N^N^N^N⁵tetramethyl-naphthalene-1,5-diamine (CAS no.: 10075-69-1; provider: Chemieliva Pharmaceutical); WW.Ari.A/Metramethyl-naphthalene-l,4-diamine (CAS no.: 13764-142; provider: Chemieliva Pharmaceutical); /V-(1-ethylpropyl)-/\/-methyl-naphthalen-1 -amine (CAS no.: 110014-42-1; provider: Chemieliva Pharmaceutical); A/,2-dimethyl-/\/-(1 methylethyl)-naphthalen-1-amine (CAS no.: 130523-08-9; provider: Chemieliva Pharmaceutical); A/¹,A/¹W⁸W⁸-tetramethyl-naphthalene-1,4-diamine (CAS no.: 20734-581 ; provider: ASW MedChem); /VW-diethyl-2-methyl-naphthalen-1 -amine (CAS no.: 2161405-1; provider: Chemieliva Pharmaceutical); /V,/V-diethyl-8-methyl-naphthalen-1-amine (CAS no.: 130523-22-7; provider: Chemieliva Pharmaceutical); /\/-(2,2-dimethylpropyl)-/\/methyl-naphthalene-1-amine (CAS no.: 110014-40-9; provider: Chemieliva Pharmaceutical); A/-(2,2-dimethylpropyl)-A/-ethyl-naphthalene-1-amine (CAS no.: 11432622-6; provider: Chemieliva Pharmaceutical); /V,2-diethyl-A/-methyl-naphthalene-1 -amine (CAS no.: 130523-10-3; provider: Chemieliva Pharmaceutical); A/,A/-dibutyl-naphthalene1-amine (CAS no.: 204126-63-6; provider: Chemieliva Pharmaceutical); A/-ethyl-2-methylA/-(1-methylethyl)-naphthalene-1 -amine (CAS no.: 130523-09-0; provider: Chemieliva Pharmaceutical); 2-ethyl-A/-methyl-A/-(1-methylethyl)-naphthalene-1-amine (CAS no.: 130523-12-5; provider: Chemieliva Pharmaceutical); A/¹-ethyl-A/¹ , A/⁸, A/⁸-trimethylnaphthalene-1,8-diamine (CAS no.: 79687-92-6; provider: Chemieliva Pharmaceutical); A/-ethyl-/\/-(1-ethylpropyl)-naphtahalene-1 -amine (CAS no.: 114326-21-5; provider: Chemieliva Pharmaceutical); A/-ethyl-A/-methyl-2-(1-methylethyl)-naphtahalene-1-amine (CAS no.: 130523-14-7; provider; Chemieliva Pharmaceutical); 8-butyl-A/,A/-dimethylnaphtahalene-1-amine (CAS no.: 1469538-06-4; provider: Chemieliva Pharmaceutical); A/,A/-bis(2-methylpropyl)-naphtahalene-1-amine (CAS no.; 109556-56-1; provider: Chemieliva Pharmaceutical); A/,A/,2-triethyl-naphthalene-1-amine (CAS no.: 130523-11-4; provider: Chemieliva Pharmaceutical); A/,2-diethyl-A/-(1-methylethyl)-naphthalene-1amine (CAS no.: 130523-13-6; provider: Chemieliva Pharmaceutical); A/-methyl-A/,2bis(1-methylethyl)-naphthalene-1-amine (CAS no.: 130523-16-9; provider; Chemieliva Pharmaceutical); A/,A/-diethyl-2-(1-methylethyl)-naphthalene-1 -amine (CAS no.: 13052315-8; provider: Chemieliva Pharmaceutical); 2-(1,1-dimethylethyl)-A/-ethyl-A/-methylnaphthalene-1-amine (CAS no.; 130523-18-1; provider: Chemieliva Pharmaceutical); A/AA/éAA.A/Metraethyl-naphthalene-l,8-diamine (CAS no.: 53463-80-2; provider: Chemieliva Pharmaceutical); A/¹ ,/\/¹ ,/\/⁵,A/⁵-tetraethyl-naphthalene-1,5-diamine (CAS no.: 861347-34-4); A/¹,A/⁵-dimethyl-A/¹,A/⁵-bis(1-methylethyl)-naphthalene-1,5-diamine (CAS no.: 110971-36-3; provider: Chemieliva Pharmaceutical); A/-ethyl-A/,2-bis(1 -methylethyl)naphthalene-1-amine (CAS no.: 130523-17-0; provider: Chemieliva Pharmaceutical); 2(1,1-dimethylethyl)-A/-methyl-A/-(1-methylethyl)-naphthalene-1 -amine (CAS no.: 13052320-5, provider: Chemieliva Pharmaceutical); 2-(1,1-dimethylethyl)-A/,A/-diethylnaphthalene-1-amine (CAS no.: 130523-19-2, provider: Chemieliva Pharmaceutical); 3butyl-A/,A/-diethyl-naphthalene-1-amine (CAS no.: 398458-74-7, provider: Chemieliva Pharmaceutical); 2-(1,1-dimethylethyl)-A/-ethyl-A/-(1-methylethyl)-naphthalene-1 -amine (CAS no.: 130523-21-6, provider: Chemieliva Pharmaceutical); /V¹-butyl-A/¹ ,A/⁸,A/⁸trimethyl-naphthalene-1,8-diamine (CAS no.: 852630-17-2, provider: Chemieliva Pharmaceutical); A/¹, A/⁸-dibutyl-A/¹,A/⁸-dimethyl-naphthalene-1,8-diamine (CAS no.: 852630-27-4, provider: Chemieliva Pharmaceutical); A/,A/-dimethyl-naphthalene-2-amine (CAS no.: 2436-85-3, provider: ASW MedChem); A/-ethyl-A/-methyl-naphtahalene-1amine (CAS no.: 68172-51-0, provider: Chemieliva Pharmaceutical); A/,A/,4-trimethylnaphtahalene-2-amine (CAS no.: 4523-53-9, provider: Chemieliva Pharmaceutical);

A/,A/,1-trimethyl-naphtahalene-2-amine (CAS no.: 5672-92-4, provider: Chemieliva Pharmaceutical); A/,A/-diethyl-naphtahalene-2-amine (CAS no.: 13672-17-8, provider: Chemieliva Pharmaceutical); /V-methyl-/\/-(1-methylethyl)-naphtahalene-2-amine (CAS no.: 110014-44-3, provider: Chemieliva Pharmaceutical); A/,A/,4,5-tetramethylnaphtahalene-2-amine (CAS no.: 4536-94-1, provider: Chemieliva Pharmaceutical); Nbutyl-A/-methyl-naphtahalene-2-amine (CAS no.: 872801-93-9, provider: Chemieliva Pharmaceutical); /V,/\/-bis(1-methylethyl)-naphtahalene-2-amine (CAS no.: 92596-72-0, provider: Chemieliva Pharmaceutical); /V,A/-dibutyl-naphtahalene-2-amine (CAS no.: 97943-52-7, provider: Chemieliva Pharmaceutical); A/,A/-bis(2-methylpropyl)naphthalene-2-amine (CAS no.: 109554-95-2, provider: Chemieliva Pharmaceutical); 1(naphthalen-l-yl)piperidine (CAS no.: 62062-39-9, provider: Chemieliva Pharmaceutical); and A/,A/-dibutyl-1 -methyl- naphthalene-2-amine (CAS no.: 92834-61-2, provider: Chemieliva Pharmaceutical).

Examples of aromatic compounds substituted by at least one group selected from Ci-C4-alkyloxy include, but are not limited to: methoxybenzene (CAS no.:100-66-3; provider: abcrGmbH); 1,4-dimethoxybenzene (CAS no.: 150-78-7; provider: abcrGmbH); 1,4-diethoxybenzene (CAS no.: 122-95-2; provider: abcr GmbH); 1,4-bis(1methylethoxy)benzene (CAS no.: 7495-78-5; provider: Chemieliva Pharmaceutical); 1,4dimethoxy-2-methylbenzene (CAS no.: 24599-58-4; provider: Alchem Pharmtech); 1,4dimethoxy-2,5-dimethyl-benzene (CAS no.: 2674-32-0; provider: Chemieliva Pharmaceutical Co.); 1,4-dimethoxy-2,3-dimethylbenzene (CAS no.: 39021-83-5; provider: Chemieliva Pharmaceutical Co.); 1,4-diethoxy-2-methylbenzene (CAS no.: 41901-72-8; provider: Chemieliva Pharmaceutical Co.); 1,4-dibutoxy-benzene (CAS no.: 104-36-9; provider: Chemieliva Pharmaceutical Co.); 1,3-dimethoxybenzene (CAS no.: 151-10-0; provider: Alchem Pharmtech); 1,3-diethoxybenzene (CAS no.: 2049-73-2; provider: Chemieliva Pharmaceutical Co.); 1,3-dimethoxy-5-methyl-benzene (CAS no.: 4179-19-5; provider: ASW MedChem); 1,3,5-trimethoxybenzene (CAS no.: 621-23-8; provider: AK Scientific); 1,3,5-triethoxybenzene (CAS no.: 2437-88-9; provider: Chemieliva Pharmaceutical); 1,3-dimethoxy-5-(1-methylethoxy)benzene (CAS no.: 86635-94-1; provider: Chemieliva Pharmaceutical); 2-ethoxy-1,3,5-trimethoxybenzene (CAS no.: 69832-53-7; provider: Chemieliva Pharmaceutical); 1,3,5-trimethoxy-2,4,6trimethylbenzene (CAS no.: 1521-62-6; provider: Chemieliva Pharmaceutical); 1,3dimethoxy-2-methyl-5-(1-methylethoxy)-benzene (CAS no.: 93680-97-8; provider: Chemieliva Pharmaceutical); 1,3-dibutoxy-5-methoxy-benzene (CAS no.: 869740-90-9;

provider: Chemieliva Pharmaceutical); 1,2,3,4,5,6-hexamethoxybenzene (CAS no.: 22015-34-5; provider: Chemieliva Pharmaceutical); 4-methoxy-1 ,T-biphenyl (CAS no.: 613-37-6; provider: ASW MedChem); 4-methoxy-4'-methyl-1 ,T-biphenyl (CAS no.: 53040-92-9; provider: ASW MedChem); 4-ethoxy-biphenyl (CAS no.: 613-40-1; provider: Chemieliva Pharmaceutical); 2-methyl-9,10-dimethoxyanthracene (CAS no.: 26708-05-4; provider: Chemieliva Pharmaceutical Co.); 2-ethyl-9,10-dimethoxyanthracene (CAS no.: 26708-04-3; provider: Aldrich); 2-(1,1-dimethyl-ethyl)-9,10-dimethoxyanthracene (CAS no.: 62770-63-2; provider: Chemieliva Pharmaceutical Co.); 2-ethyl-9,10diethoxyanthracene (CAS no.: 205515-07-7; provider: Chemieliva Pharmaceutical Co.); 9,10-dimethoxyanthracene (CAS no.: 2395-97-3; provider: Chemieliva Pharmaceutical Co.); 9,10-diethoxyanthracene (CAS no.: 68818-86-0; provider: ASW MedChem); 9,10bis(1-methylethoxy)-anthracene (CAS no.: 134767-44-5; provider: Chemieliva Pharmaceutical Co.); 9,10-bis(1,1-dimethylethoxy)-anthracene (CAS no.: 873914-42-2; provider: Shanghai Chemhere Co.); 9,10-dibutoxy-anthracene (CAS no.: 76275-14-4; provider: Chemieliva Pharmaceutical Co.); 9-ethoxy-10-methoxy-anthracene (CAS no.: 106500-38-3; provider: Chemieliva Pharmaceutical Co.); 9,10-dimethoxy-1,4,5,8tetramethyl-anthracene (CAS no.: 76466-58-5; provider: Chemieliva Pharmaceutical Co.); 9,10-dimethoxy-1,2,3,4,5,6,7,8-octamethyl-anthracene (CAS no.: 75670-41-6; provider: Chemieliva Pharmaceutical Co.); 9,10-dimethoxy-1,2,3,4-tetramethyl-anthracene (CAS no.: 72049-50-4; provider: Chemieliva Pharmaceutical Co.); 2,6-dimethyl-9,10dimethoxyanthacene (CAS no.: 1221786-94-2; provider: Rare Chemicals GmbH); 1,2dimethoxy-anthracene (CAS no.: 132814-35-8; provider: Shanghai Chemhere Co.); 1,3dimethoxyanthracene (CAS no.: 144493-74-3; provider: Chemieliva Pharmaceutical Co.); 1,4-dimethoxy-9-ethyl-anthracene (CAS no.: 107328-77-8; provider: Chemieliva Pharmaceutical Co.); 1,4-diethoxy-anthracene (CAS no.: 75830-00-1; provider: Chemieliva Pharmaceutical Co.); 1,5-dimethoxy-anthracene (CAS no.: 16294-32-9; provider: Chemieliva Pharmaceutical Co.); 1,5-diethoxy-anthracene (CAS no.: 75829-957; provider: Chemieliva Pharmaceutical Co.); 1,8-dimethoxy-anthracene (CAS no.: 1629434-1; provider: Chemieliva Pharmaceutical Co.); 1,8-diethoxy-anthracene (CAS no.: 75829-96-8; provider: Chemieliva Pharmaceutical Co.); 1,8-dimethoxy-3-methylanthracene (CAS no.: 144493-77-6; provider: Chemieliva Pharmaceutical Co.); 1,8dimethoxy-2,7-dimethyl-anthracene (CAS no.: 1202400-23-4; provider: Chemieliva Pharmaceutical Co.); 2,3-dimethoxy-anthracene (CAS no.: 51790-19-3; provider: Chemieliva Pharmaceutical Co.); 2,3-diethoxy-anthracene (CAS no.: 863889-35-4; provider: Chemieliva Pharmaceutical Co.); 2,6-dimethoxy-anthracene (CAS no.: 3631919999

03-6; provider: Chemieliva Pharmaceutical Co.); 2,6-diethoxy-anthracene (CAS no.: 75830-05-6; provider: Chemieliva Pharmaceutical Co.); 2,6-dimethoxy-9-methylanthracene (CAS no.: 110038-59-0; provider: Chemieliva Pharmaceutical Co.); 2,6dimethoxy-9,10-dimethyl-anthracene (CAS no.: 105858-59-1; provider: Chemieliva Pharmaceutical Co.); 2,6-dipropoxy-anthracene (CAS no.: 1395499-89-4; provider: Chemieliva Pharmaceutical Co.); 2,6-dibutoxy-anthracene (CAS no.: 134277-70-6; provider: Chemieliva Pharmaceutical Co.); and 2,7-dimethoxy-anthracene (CAS no.: 55360-36-6; provider: Chemieliva Pharmaceutical Co.).

Preferably, the diphenyl-polyene of general formula (V) is characterized by a boiling point lower than about 600 °C at 760 mm Hg, more preferably lower than about 500 °C at 760 mm Hg, and even more preferably lower than 450 °C at 760 mm Hg. Examples of diphenyl-polyene of general formula (V) include, but are not limited to: 6-diphenyl-1,3,5hexatriene (CAS. no.: 1720-32-7; provider: Sigma Aldrich); (7E,3E)-1,4-diphenylbuta-1,3diene (CAS no.: 538-81-8; provider: ASW MedChem); ((7E,3E)-penta-1,3-diene-1,4diyl)dibenzene (CAS no.: 23637-42-5; provider: Chemileva Pharmaceutical); 1-methyl-4((7E,3E)-4-phenylbuta-1,3-dien-1-yl)benzene (CAS no.: 37985-11-8; provider: Chemileva Pharmaceutical); ((1E,3E)-2-methylbuta-1,3-diene-1,4-diyl)dibenzene (CAS no.: 2363743-6; provider: Chemileva Pharmaceutical); ((2E,4E)-hexa-2,4-diene-2,5-diyl)dibenzene (CAS no.: 16914-12-8; provider: Chemileva Pharmaceutical); 1-methyl-2-((7E,3E)-4phenylbuta-1,3-dien-1-yl)benzene (CAS no.: 93333-38-1; provider: Chemileva Pharmaceutical); 1-methyl-3-((7E,3E)-4-phenylbuta-1,3-dien-1-yl)benzene (CAS no.: 82102-26-9; provider: Chemileva Pharmaceutical); (7E,3E)-1,4-di-o-tolylbuta-1,3-diene (CAS no.: 848354-92-7; provider: Shanghai Chemhere Co.); (7E,3E)-1,4-di-m-tolylbuta1,3-diene (CAS no.: 1261146-08-0; provider: Chemileva Pharmaceutical); (7E,3E)-1,4-dip-tolylbuta-1,3-diene (CAS no.: 72033-82-0; provider: Chemileva Pharmaceutical); ((7E,3E)-2-methylpenta-1,3-diene-1,4-diyl)dibenzene (CAS no.: 117847-11-7; provider: Chemileva Pharmaceutical); ((7E,3E)-2,3-dimethylbuta-1,3-diene-1,4-diyl)dibenzene (CAS no.: 54631-95-7; provider: Shanghai Chemhere Co.); 1-methyl-4-((7E,3E)-3-methyl4-phenylbuta-1,3-dien-1-yl)benzene (CAS no.: 916764-21-1; provider: Chemileva Pharmaceutical); (7E,3E)-1,4-di-m-tolylbuta-1,3-diene (CAS no.:12611146-10-4; provider: Chemileva Pharmaceutical); 4,4'-((7E,3E)-2-methylbuta-1,3-diene-1,4diyl)bis(methylbenzene) (CAS no.:102080-29-5; provider: Chemileva Pharmaceutical); (7E,3E)-1,4-dimesitylbuta-1,3-diene (CAS no.:1261146-09-1 ; provider: Chemileva Pharmaceutical); 4,4'-((2E,4E)-hexa-2,4-diene-2,5-diyl)bis(methylbenzene) (CAS no.:

110746-28-6; provider: Chemileva Pharmaceutical); 1,2,4,5-tetramethyl-3-((7E,3E)-4phenylbuta-1,3-dien-1-yl)benzene (CAS no.: 39117-47-0; provider: Chemileva Pharmaceutical); (7E,3E)-1,4-bis(2,4,5-trimethylphenyl)buta-1,3-diene (CAS no.: 9621475-4; provider: Chemileva Pharmaceutical); (7Z,3Z)-1,4-diphenylbuta-1,3-diene (CAS no.: 5807-76-1; provider: Chemileva Pharmaceutical); (7Z,3Z)-1,4-di-o-tolylbuta-1,3-diene (CAS no.: 1006055-80-6; provider: Chemileva Pharmaceutical); (7Z,3E)-1,4diphenylbuta-1,3-diene (CAS no.: 5808-05-9; provider: Chemileva Pharmaceutical); ((7E,3Z)-penta-1,3-diene-1,4-diyl)dibenzene (CAS no.: 40391-41-1; provider: Chemileva Pharmaceutical); ((7Z,3E)-2-methylbuta-1,3-diene-1,4-diyl)dibenzene (CAS no.: 8389770-5; provider: Chemileva Pharmaceutical); 1-methyl-4-((7Z,3E)-4-phenylbuta-1,3-dien-1yl)benzene (CAS no.: 57668-27-6; provider: Chemileva Pharmaceutical); ((2Z,4E)-hexa2,4-diene-2,5-diyl)dibenzene (CAS no.: 84174-09-4; provider: Chemileva Pharmaceutical); ((7E,3E)-2,3-dimethylbuta-1,3-diene-1,4-diyl)dibenzene (CAS no.: 38023-36-8; provider: Chemileva Pharmaceutical); (7E,3E,5E,7E)-1,8-diphenylocta1,3,5,7-tetraene (CAS no.: 22828-29-1; provider: Chemileva Pharmaceutical); (7E,3E,5E)-1,6-diphenylhexa-1,3,5-triene (CAS no.: 17329-15-6; provider: ASW MedChem); ((7E,3E,5E)-3-methylhexa-1,3,5-triene-1,6-diyl)dibenzene (CAS no.: 15533776-1; provider: Aurora Fine Chemicals LLC); ((7E,3E,5E)-hepta-1,3,5-triene-1,6diyl)dibenzene (CAS no.: 140654-06-4; provider: Chemileva Pharmaceutical); 1-methyl4-((7E,3E,5E)-6-phenylhexa-1,3,5-trien-1-yl)benzene (CAS no.: 36288-10-5; provider: Chemileva Pharmaceutical); 1-methyl-3-(6-phenylhexa-1,3,5-trien-1-yl)benzene (CAS no.: 95278-12-9; provider: Chemileva Pharmaceutical); 1-methyl-2-(6-phenylhexa-1,3,5trien-1-yl)benzene (CAS no.: 95278-13-0; provider: Chemileva Pharmaceutical); 1,6-di-ptolylhexa-1,3,5-triene (CAS no.: 31382-31-7; provider: Chemileva Pharmaceutical); 3,4dimethylhexa-1,3,5-triene-1,6-diyl)dibenzene (CAS no.: 1295646-09-1; provider: Chemileva Pharmaceutical); 1,3-dimethyl-5-(6-phenylhexa-1,3,5-trien-1-yl)benzene (CAS no.: 63296-77-5; provider: Chemileva Pharmaceutical); 1-isopropyl-4-(6-(p-tolyl)hexa1,3,5-trien-1-yl)benzene (CAS no.: 558453-19-3; provider: Shanghai Chemhere Co.); 2,4dimethyl-1-(6-phenylhexa-1,3,5-trien-1-yl)benzene (CAS no.: 63296-78-6; provider: Chemileva Pharmaceutical); (7Z,3E,5Z)-1,6-diphenylhexa-1,3,5-triene (CAS no.: 17008016-7; provider: Chemileva Pharmaceutical); (7Z,3Z,5E)-1,6-diphenylhexa-1,3,5-triene (CAS no.: 205808-71-5; provider: Chemileva Pharmaceutical); (7Z,3Z,5Z)-1,6diphenylhexa-1,3,5-triene (CAS no.: 170080-17-8; provider: Chemileva Pharmaceutical); ((7E,3E,5E)-2,3-dimethylhexa-1,3,5-triene-1,6-diyl)dibenzene (CAS no.: 57833-31-5; provider: Chemileva Pharmaceutical); (7E,3E,5E,7E)-1,8-di-p-tolylocta-1,3,5,7-tetraene (CAS no.: 82720-17-0; provider: Chemileva Pharmaceutical); 1-methyl-4-((7E,3E,5E,7E)8-phenylocta-1,3,5,7-tetraen-1-yl)benzene (CAS no.: 94871-35-9; provider: Chemileva Pharmaceutical); ((1E,3Z,5E, 7E)-2,7-dimethylocta-1,3,5,7-tetraene-1,8-diyl)dibenzene (CAS no.: 82720-21-6; provider: Chemileva Pharmaceutical); (7E,3E,5E, 7E,9E)-1,105 diphenyldeca-1,3,5,7,9-pentaene (CAS no.: 20576-64-1; provider: Chemileva Pharmaceutical); (3,8-dimethyldeca-1,3,5,7,9-pentaene-1,10-diyl)dibenzene (CAS no.: 1884-48-6; provider: Chemileva Pharmaceutical); and (7E,3E,5E,7E,9E,HE)-1,12diphenyldodeca-1,3,5,7,9,11-hexaene (CAS no.:20576-65-2; provider: Shanghai Chemhere Co.).

EXAMPLES

The présent invention is now described in greater detail with respect to non-limiting examples.

General

The Chemical marker 5,6,11,12-tetraphenylnaphthacene (rubrene) (CAS no.: 517-51-1;

>98%) was purchased from Sigma Aldrich and was used without further purification.

I. Description instrument and method for analysis by laser ionization - mass 20 spectrometry.

The set-up used for conducting the laser ionization - mass spectrometry analysis contains a thermal desorption unit (Thermo desorberTC-13.006 from PAS Technology), an optical parametric oscillator (OPO) pumped by a Nd:YAG laser (NT342A-SH, Ekspla), and a 25 commercial mass spectrometer (LTQ XL™, Thermo Fisher Scientific) equipped with a self-made ion source (J. Mass Spectrom. (2016), 51,566-577) having two quartz Windows transparent to a laser beam. The thermal desorption unit is connected via a métal capillary (stainless steel tubing 1/8 OD x 2.0 mm ID, about 60 mm long from Ziemer Chromatographie) to the ion source of the mass spectrometer.

The compositions of chemically marked petroleum hydrocarbon were analyzed by the following method:

pL of the liquid sample were introduced using a syringe (Hamilton, 10 pL) into the thermal desorption unit heated to 250 °C. Following vaporization, the gaseous sample 35 was transferred via the métal capillary heated to 200 °C (about 60 mm long) using a N2 flow (600 ml/min) in the ionization chamber heated to 120 °C (about 18 mm long, inner diameter of 20 mm) of the ion source, where the gaseous sample was subjected to laser ionization. The ionized sample was then transferred into the MS spectrometer (N₂ flow: 1000 ml/min; V: 50 Volts) and the MS spectrum was measured in relative intensities as a function of mass to charge ratio (m/z).

II. Marking of petroleum hydrocarbons

For petroleum hydrocarbon marking, a concentrate of 5,6,11,12-tetraphenylnaphthacene (rubrene) in toluene was prepared to a concentration of 1 mmol/L and added to diesel to yield a marked diesel sample (Chemical marker concentration: 1 μΜ, 2 μΜ, 5 pM, 10 pM, 20 pM, 50 pM, 100 pM, 200 pM) and to gasoline to yield a marked gasoline sample (Chemical marker concentration: 5 pM, 10 pM, 20 pM, 50 pM, 100 pM, 200 pM). To minimize contamination ofthe mass spectrometer, the marked diesel sample was diluted in hexane (1 : 100, v / v) prior to the analysis.

III. Results

The marked diesel prepared as described at item II above was analyzed by laser ionization at 355 nm (puise energy density of 0.63 mJ/mm²) coupled to mass spectrometry (see Fig. 1) using the set-up and following the procedure described at item I above.

Fig. 1 illustrâtes the mass spectrum of the diesel marked with the Chemical marker 5,6,11,12-tetraphenylnaphthacene obtained by laser ionization at 355 nm (puise energy density of 0.63 mJ/mm²) coupled with mass spectrometry. Prior to the analysis, the diesel marked with the Chemical marker 5,6,11,12-tetraphenylnaphthacene was diluted in hexane (1 : 100, v/v) to minimize the contamination ofthe mass spectrometer. Following dilution, the concentration of the Chemical marker in the sample was of 50 nM. The peak corresponding to the ion (M⁺) of the Chemical marker 5,6,11,12-tetraphenylnaphthacene (m/z of 532) is indicated by a “*”. As attested by the mass spectrum, the Chemical marker 5,6,11,12-tetraphenylnaphthacene can be easily detected and identified even at low concentration in a diesel matrix because it exhibits the highest intensity in the mass spectrum, thereby enabling the easy authentication of a diesel marked with the Chemical marker 5,6,11,12-tetraphenylnaphthacene. These surprising results are due to the sélective ionization ofthe Chemical marker 5,6,11,12-tetraphenylnaphthacene in a diesel matrix upon illumination with pulsed laser light of a wavelength of 355 nm. The poor ionization of the diesel matrix upon illumination with pulsed laser light of a wavelength of 355 nm (puise energy density: 0.63 mJ/mm²) leads to a negligible noise in the mass spectrum that does not interfère with the détection and identification of the Chemical 5 marker 5,6,11,12-tetraphenylnaphthacene.

Fig. 2 illustrâtes the variation ofthe intensity ofthe peak corresponding to the ion (M⁺) of the Chemical marker 5,6,11,12-tetraphenylnaphthacene with the concentration of the Chemical marker in the marked diesel and the marked gasoline. The compositions containing the Chemical marker 5,6,11,12-tetraphenylnaphthacene were analyzed by laser ionization at 355 nm (puise energy density of 0.63 mJ/mm²) coupled with mass spectrometry. To minimize the contamination ofthe mass spectrometer, the compositions of diesel and gasoline containing the Chemical marker were diluted in hexane (1 : 100; v/v) prior to the analysis. Following dilution, the marker concentration in the analyzed sample was: 10 nM, 20 nM, 50 nM, 100 nM, 200 nM, 500 nM, 1000 nM, 2000 nM for the marked diesel and 50 nM, 100 nM, 200 nM, 500 nM, 1000 nM, 2000 nM for the marked gasoline. As attested by Fig. 2, the Chemical marker 5,6,11,12-tetraphenylnaphthacene is easily détectable, identifiable and quantifiable in a diesel composition and a gasoline composition even at low concentration.

Claims (7)

1. A use of a compound of general formula (I)

5 wherein the residues R¹ - R¹² are independently of each other selected from the group consisting of hydrogen, C1-C4 alkyl,

10 other selected from the group consisting of hydrogen and C1-C4 alkyl; with the proviso that at least two of the residues R¹ - R¹² are selected from:

for chemically marking a petroleum hydrocarbon selected from the group consisting of gasoline, diesel fuel, kerosene, and jet fuel, to prevent counterfeiting of said petroleum

15 hydrocarbon.

2. The use according to claim 1, wherein the compound is of general formula (II),

R^{v R}\ /^Rd Y Y R¹² R² R³ η^ιο'Υ/ΥΥγΥ^χΥ^κ R⁹ R⁸ R⁷ R⁶ wherein the residues R² - R¹², R^a - R®, R^a’ - R®’, R^a” meanings as defined in claim 1. 3. The use according to claim 2, wherein 5 R⁷ = rc' r’/^^.r^0, 1 i 1 R⁸ = rc' r/^/kx _Ra' \Y\_Re' R² = R^c Ra^^Y^Re' R⁷ = R^{c R}Y^Y^^Rd Ra^\Y\_Re /R^{4 X}R⁵ (II) - R®” and R^a”’ - R®’” hâve the or or and R⁸ =

4.

R⁴ =

The use according to claim 1, wherein

R⁵ =

R¹⁰ =

and R¹¹ =

5. The use according to claim 1, wherein

R⁶ = and R¹² =

6. The use according to any one of the claims 1 - 5, wherein the residues R^a - R^e,

R^a’ - R^e’, R^a” - R^e” and R^a”’ - R®’” represent hydrogen and/or the residues R¹ - R¹² other than

represent hydrogen.

7. The use according to any one of the daims 1 - 6, wherein the petroleum hydrocarbon is selected from the group consisting of gasoline and diesel fuel.

5

8. The use according to any one ofthe daims 1 - 7, wherein the compound ofgeneral formula (I) is présent in the petroleum hydrocarbon in a concentration of at least 1μΜ (micromolar).

9. The use according to claim 8, wherein the concentration is lower than or equal to 0.2 mM (millimolar).

10 10. A method for preventing counterfeiting of a petroleum hydrocarbon selected from the group consisting of gasoline, diesel fuel, kerosene, and jet fuel, wherein said method comprises adding to and uniformly mixing with said petroleum hydrocarbon a compound of general formula (I) as recited by any one ofthe daims 1 - 7.