Method of marking hydrocarbon liquids

Abstract

A method of marking a hydrocarbon liquid includes the step of ##STR00001##
adding to the liquid, as a tracer compound, a compound of Formula I:
wherein at least one of R.sup.1-R.sup.4 is selected from: i. a bromine or fluorine atom; ii. a partially or fully halogenated alkyl group; iii. a branched or cyclic C.sub.4-C.sub.20 alkyl group; iv. an aliphatic substituent linking two positions selected from R.sup.1-R.sup.4 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.

Claims

1. A method of marking a hydrocarbon fuel or octane comprising the step of adding to said hydrocarbon fuel or octane, as a tracer compound in an amount of 1 ppbv to 1 ppmv of said hydrocarbon fuel or octane, a compound of Formula I: ##STR00004## wherein at least one of R.sup.1-R.sup.4 is selected from a group consisting of: i. a bromine or fluorine atom; ii. a partially or fully halogenated alkyl group; iii. a branched or cyclic C.sub.4-C.sub.20 alkyl group; iv. an aliphatic substituent linking two positions selected from R.sup.1-R.sup.4 in Formula I to one another; and v. a phenyl group substituted with a halogen atom, an aliphatic group or halogenated aliphatic group; and further wherein none of R.sup.1-R.sup.4 consists of a hydroxyl group or an amino group.

2. The method according to claim 1, wherein, when any of R.sup.1-R.sup.4 is a halogen or halogenated alkyl group, the halogen atom is selected from bromine or fluorine and the halogenated alkyl group is a bromoalkyl or fluoroalkyl group.

3. The A method according to claim 1, wherein at least two of R.sup.1-R.sup.4 in Formula I consist of substituents selected from the group consisting of fluorine, bromine and a halogenated alkyl group.

4. The method according to claim 1, wherein none of R.sup.1-R.sup.4 in Formula I contains fused aromatic rings, saturated heterocycles where the heteroatom is anything other than oxygen, unsaturated heterocycles, amino, imino, N-oxide, nitro, hydroxyl, carboxyl, ester, amide, acetal, thiol, thiol ethers, disulfides, sulfoxide, sulfone, sulfonate, phosphite ester, phosphate ester, cationic, anionic or zwitterionic groups; or metal containing substituents.

5. The method according to claim 1, wherein, in Formula I, each R.sup.1-R.sup.4 is selected from the group consisting of a bromine or fluorine atom; a partially or fully halogenated alkyl group; a branched or cyclic C.sub.4-C.sub.20 alkyl group; an aliphatic substituent linking two positions selected from R.sup.1-R.sup.4 in Formula I to one another; and a phenyl group substituted with a halogen atom, an aliphatic group or halogenated aliphatic group.

6. The method according to claim 1, wherein the tracer compound is selected from the group consisting of bis(3,5-bis trifluoromethyl-phenyl)-diazene, bis(3,5-bis t-butyl-phenyl)-diazene, bis(3-t-butyl, 5-trifluoromethyl-phenyl)-diazene, and (3,5-trifluoromethyl-phenyl)-(3,5-di-t-butylphenyl)-diazene.

7. A method of identifying a hydrocarbon fuel or octane comprising the steps of marking said hydrocarbon fuel or octane by the method of claim 1, and subsequently analysing a sample of a hydrocarbon fuel or octane for the presence of said tracer compound to determine whether said sample is a sample of said marked hydrocarbon fuel or octane.

Description

COMPARATIVE EXAMPLE

(1) The compound shown below, corresponding to Dye 7 of EP 1580254, was made according to the following procedure.

(2) ##STR00003##

(3) Aniline (1.517 ml) was added to a beaker containing hydrochloric acid (2 ml) and de-ionised water (10 ml). The mix was then placed into an ice bath and cooled to <5 C. Once the mix was cold enough, a solution of sodium nitrite (1.808 g) in water (20 ml) was prepared and added to the aniline mix slowly over 10 minutes, keeping the temperature below 5 C. The mixture was then left to stir in an ice bath for 30 minutes. After 30 minutes, sulfamic acid (1.62 g) was added to the mixture. A solution of nonylphenol (3.68 g) in toluene (20 ml) was added to the reaction mix and stirred vigorously. A solution of sodium acetate (20 g) in water (100 ml) was added to the reaction mix as a buffer over 30 minutes ensuring that it was kept cold. The mixture was then left to stir for another 5 hours and allowed to warm in the process.

(4) The reaction mix was then added to a separating funnel and diluted with toluene (20 ml). The mixture was shaken and then left to settle. The organic phase was then washed with de-ionised water (100 ml) three times. It was then dried over anhydrous magnesium sulphate and the solvent removed on a rotary evaporator yielding a dark yellow oil.

(5) A 10 mg/L solution of the prepared comparative dye was prepared in a synthetic test fuel, made by mixing together 76% iso-octane, 16% toluene, 5% t-butyl methylether and 3% ethanol (all quantities vol/vol). 10 ml of synthetic test fuel marked with the test tracer compound was shaken vigorously for 1 minute with 0.5 g of activated charcoal (decolourising) obtained from Sigma Aldrich (product number 161551). The mixture was allowed to stand for 1 minute and then shaken for a further minute before being filtered to remove the adsorbent. A sample of the fuel was analysed by UV/Vis spectrophotometry and the percentage of the tracer remaining was calculated.

(6) This test procedure was repeated for a sample of the synthetic fuel containing bis(3,5-bis trifluoromethyl-phenyl)-diazene (T1), with the analysis of the sample being made by GC-MS because T1 is not susceptible to detection by UV/vis. Both results are shown in Table 4. The test shows that T1 is more resistant to removal by shaking with activated charcoal than the comparative example containing a phenolic moiety described in EP1580254.

(7) TABLE-US-00004 TABLE 4 % of original concentration remaining after treatment Tracer compound with activated charcoal Dye 7 of EP1580254 16% T1 87%