Chemistry: analytical and immunological testing – Tracers or tags
Reexamination Certificate
1999-06-30
2002-11-19
Warden, Jill (Department: 1743)
Chemistry: analytical and immunological testing
Tracers or tags
C436S060000, C436S166000
Reexamination Certificate
active
06482651
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to colorless or essentially colorless compounds useful for marking or tagging various products such as petroleum fuels or solvents and to compositions and methods associated therewith.
2. Description of the Related Arts
A marker is a substance which can be used to tag products, typically petroleum products, for subsequent detection. The marker is normally dissolved in a liquid to be identified, then subsequently detected by performing a simple physical or chemical test on the tagged liquid. Markers are sometimes used by the government to ensure that the appropriate tax has been paid on particular grades of fuel. Oil companies also mark their products to help identify those who have diluted or altered their products. These companies often go to great expense to make sure their branded petroleum products meet certain specifications regarding volatility and octane number, for example, as well as to provide their petroleum products with effective additive packages containing detergents and other components. Consumers rely upon the product names and quality designations to assure that the product being purchased is the quality desired.
It is possible for unscrupulous gasoline dealers to increase profits by selling an inferior product at the price consumers are willing to pay for a high quality branded or designated product. Higher profits can also be made simply by diluting the branded product with an inferior product. Policing dealers who substitute one product for another or blend branded products with inferior products is difficult in the case of gasoline because the blended products will qualitatively display the presence of each component in the branded products. The key ingredients of the branded products are generally present in such low levels that quantitative analysis to detect dilution with an inferior product is very difficult, time consuming and expensive.
Marker systems for fuels and other petroleum products have been suggested but various drawbacks have existed which have hindered their effectiveness. Many, for instance, lose their color over time, making them too difficult to detect after storage. In addition, reagents used to develop the color of markers often are difficult to handle or present disposal problems. Furthermore, some marking agents partition into water. This causes the markers to lose effectiveness when storage occurs in tanks that contain some water, especially alkaline water with a pH up to 10. Some pre-existing markers add color to the petroleum products they mark, which undesirably indicates their presence in the petroleum product, and in some cases violates government regulation by obscuring the colors of other additives.
In view of the above, it would be desirable to provide a compound useful as a marker and that exhibits high solubility in or compatibility with organic-based products, especially petroleum products. Additionally, the marker should have an increased resistance to undesired extraction or removal such as by unscrupulous distributors/retailers. The markers should also appear significantly less intensely colored when undeveloped than many pre-existing marker substances, and thus impart no visual color to the fuels they mark.
SUMMARY OF THE INVENTION
The present invention relates to compounds represented by formula I:
wherein Ar
1
and Ar
2
each independently represent a substituted or unsubstituted phenylene group or a substituted or unsubstituted naphthylene group; R
1
represents a straight or branched chain alkyl group having 1 to 22 carbon atoms; R
2
represents a hydrogen atom or a group of the formula C(O)R
4
where R
4
is a hydrogen atom or a straight or branched chain alkyl group having 1 to 22 carbon atoms; R
3
represents a hydrogen atom, a straight or branched chain alkyl group having 1 to 12 carbon atoms, a straight or branched chain alkoxy group having 1 to 12 carbon atoms, a hydroxyl group, a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group; and Z represents a hydrogen atom or a group of atoms that combine with Ar
2
or R
3
to form a lactone ring. It further relates to a solution containing one or more of these compounds dissolved in a solvent.
Another aspect of the present invention relates to the use of the compounds of formula I in forming a marked composition. The marked composition comprises an organic product such as a petroleum product or a an organic solvent and a detectable amount of a marker comprised of at least one of the compounds of formula I. These marked compositions can be identified by adding a developing reagent to a sample thereof which forms color in or changes the color of the sample. In one embodiment, a petroleum product can be identified by adding a developing agent and subsequently extracting the developed marker in an extraction medium.
The present invention is based on the discovery that the ester-containing compounds of formula (I) can serve as markers that are colorless or essentially colorless in organic products including liquid petroleum products, provide a distinctive color when reacted with a developing reagent, have good solubility and compatibility with organic products including liquid petroleum products, and are difficult to extract from the marked product in the undeveloped state. The reagents used to develop the color are themselves typically easy to handle and dispose. The colors produced may be chosen to be easily visible against the background color of the fuel and to be easily quantifiable by absorption spectrophotometry.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to the compounds of formula I.
Ar
1
and Ar
2
each independently represent a substituted or unsubstituted phenylene group or a substituted or unsubstituted naphthylene group. As used herein, a substitutent means any group that is attachable to the phenyl or naphthyl ring that does not ionize or otherwise undergo chemical reaction in the presence of a basic aqueous solution having a pH of 7-13. Typically the substituents include alkyl, halogen, hydroxyl, alkoxy, cyano, carboxylic acid and esters thereof. The OC(O)R
1
moiety on Ar
1
is preferably in the 4-position in view of the ease in making the compounds and the color and intensity produced. R
1
represents a straight or branched chain alkyl group containing 1 to 22 carbon atoms, typically 1-12 carbon atoms, and preferably 1 to 8 carbon atoms. Examples of alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, n-pentyl and isomers thereof, but it is not limited thereto.
The OR
2
moiety is preferably in the 4-position or 2-position, and more preferably in the 4-position. R
2
represents a hydrogen atom or, preferably, a group of the formula C(O)R
4
where R
4
is a hydrogen atom or a straight or branched chain alkyl group having 1 to 22 carbon atoms, typically 1-12 carbon atoms, and preferably having 1-8 carbon atoms. Such di-ester compounds exhibit superior solubility and stability in organic media such as petroleum products compared with their unesterified counterparts. They also show good color forming properties as will be discussed in more detail below. The alkyl groups R
1
and R
4
may be the same or different but typically are the same based on the ease and simplicity of the corresponding synthesis. The esters are also much more resistant to inadvertent removal from the petroleum product than their unesterified counterparts.
R
3
represents a hydrogen atom, a straight or branched chain alkyl group containing 1 to 12 carbon atoms, more typically 1 to 8 carbon atoms, a straight or branched chain alkoxy group having 1 to 12 carbon atoms, a hydroxyl group, or a substituted or unsubstituted phenyl or naphthyl group. Examples of the alkyl group include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, n-pentyl and isomers thereof, but it is not limited thereto. The substituents for the substituted phenyl and naphthyl groups are as defined above and include alkyl,
Desai Bharat
Smith Michael J.
Collier Shannon Scott PLLC
Coulby John N.
Gakh Yelena
Larmann Jamie M.
United Color Manufacturing Inc.
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