Chemistry: analytical and immunological testing – Tracers or tags
Reexamination Certificate
1999-11-08
2002-03-19
Warden, Jill (Department: 1743)
Chemistry: analytical and immunological testing
Tracers or tags
C436S055000, C422S003000, C422S016000, C422S062000, C546S100000, C544S126000, C544S331000, C544S332000, C544S333000, C544S361000
Reexamination Certificate
active
06358746
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to fluorescent compounds. In one aspect it relates to fluorescent compounds that have been synthesized and undergone stability testing for use as inert tracers in industrial water systems. In another aspect of this invention there are provided alternative processes for the production of fluorescent compounds.
BACKGROUND OF THE INVENTION
Using an inert fluorescent compound to track the hydraulic losses and gains from an industrial water system has been known since the late 1980's.
Industrial water systems are very numerous. One typical industrial water system is a cooling tower where water is used in a heat exchange role. To optimize use of treating agents in such systems and to assure overall appropriate hydraulic conditions are maintained in the system, it is advantageous to determine the amount of treating agent added to the system in accordance with recommended use levels specific to the environment. If there is an under treatment of treating agent, deposition of scaling salts and corrosion may rapidly occur. If there is an over treatment of treating agent, treating agent will be wasted with a commensurate loss of money.
The continuous on-stream monitoring of the amount of a treating agent added to a moving body of water through the use of a tracer comprising an inert fluorescent compound is an established practice as described in U.S. Pat. Nos. 4,783,314 and 4,992,380. These patents contain background information which need not be repeated here but the contents of which are incorporated herein by reference.
To be useful in such systems, the fluorescent compound employed must be non-consumable or system-inert. There are certain known compounds that are capable of functioning as inert fluorescent tracers, however, there are not an abundance of such compounds. Therefore, there is a continuous need for the development of additional inert fluorescent tracer compounds that are capable of functioning in aqueous systems, particularly where such systems contain oxidizing biocides.
SUMMARY OF THE INVENTION
The first aspect of the instant claimed invention is a fluorescent compound of the formula:
wherein R
1
and R
2
are either both SO
3
M, or one of R
1
and R
2
is SO
3
M and the other is COOM, where M is selected from the group consisting of H, Na, K, Rb, Cs, Li or ammonium.
The second aspect of the instant claimed invention is a process for the preparation of a fluorescent compound having the formula:
wherein R
1
and R
2
are as defined previously, which comprises condensing a 1,8-naphthalic anhydride of the formula:
with an o-phenylene diamine of the formula:
where R
1
and R
2
are as defined previously.
The third aspect of the instant claimed invention is a process to make fluorescent compounds of formula I:
by condensing o-amino-nitro aromatics of the formula
where R
1
is as defined previously, with the appropriate 1,8-naphthalic anhydride:
where R
2
is as defined previously,
wherein such condensation is carried out in such a manner that in situ reduction of the nitro group is accomplished with a suitable reducing agent.
The fourth aspect of the instant claimed invention is the use of a compound of formula:
where R
1
and R
2
are as defined previously, as an inert fluorescent tracer in an industrial water system.
DETAILED DESCRIPTION OF THE INVENTION
This invention is based upon the discovery of certain naphthalimide-based compounds. These naphthalimide-based compounds are not only fluorescent, but are also stable in the presence of oxidizing biocides such as bleach, bromine, stabilized chlorine and stabilized bromine. Therefore, these certain naphthalimide-based compounds are particularly useful as inert fluorescent tracers in industrial water systems containing bleach and/or stabilized bromine.
These certain naphthalimide-based compounds can be readily prepared through the condensation between a 1,8-naphthalic anhydride possessing the appropriate functionalities with the appropriately substituted o-phenylene diamine. They can also be prepared by the condensation of a 1,8-naphthalic anhydride possessing the appropriate functionalities with an o-amino-nitro aromatic in the presence of a suitable reducing agent.
The fluorescent compounds of the present invention are naphthalimide-based compounds of the following structure:
wherein R
1
and R
2
are either both SO
3
M, or one of R
1
and R
2
is SO
3
M and the other is COOM, where M is selected from the group consisting of H, Na, K, Rb, Cs, Li or ammonium.
The fluorescent compounds of the present invention can be conveniently prepared by a one-step condensation between a 1,8-naphthalic anhydride possessing the desired functionalities and the appropriately substituted o-phenylene diamine. Suitable 1,8-naphthalic anhydrides for preparing the fluorescent compounds in accordance with the present invention are ones selected from the group of the formula:
wherein R
2
is as defined previously. When R
2
is SO
3
K, then Compound II is 4-sulfo-1,8-naphthalic anhydride, potassium salt and Compound II is available from Aldrich Chemical Company, P.O. Box 2060, Milwaukee, Wis. 53201 USA; Telephone Numbers (414) 273-3850 and (800) 558-9160.
Similarly suitable o-phenylene diamine compounds which are useful in the preparation of the fluorescent compounds of the present invention are ones of the formula:
wherein R
1
is as defined previously. When R
1
is COOH, then Compound III is 3,4-diaminobenzoic acid and Compound III is available from Aldrich. When R
1
is SO
3
H, then Compound III is 3,4-diaminobenzene sulfonic acid and Compound III is available from Bayer AG, Organic Chemicals Business Group, Marketing, Leverkusen, D-51368, Germany, Telephone Number +49 214 30-8514.
In a presently preferred embodiment of this invention, the fluorescent compounds can be prepared in a one-step condensation between an appropriately substituted naphthalic anhydride and an appropriately substituted o-phenylene diamine.
Alternatively, o-amino-nitro aromatics of the formula
where R
1
is as defined previously, can be condensed with the appropriate 1,8-naphthalic anhydride when such condensation is carried out in such a manner that in situ reduction of the nitro group is accomplished with a suitable reducing agent such as, but not limited to, iron powder. When R
1
is SO
3
M then compound IV is o-nitroaniline-p-sulfonic acid (and salts thereof) and Compound IV is available from Bayer AG. When R
1
is CO OH, then Compound IV is 4-amino-3-nitro benzoic acid, and Compound IV is available from ACROS Organics, which is part of Fisher Scientific, 600 Business Center Drive, Pittsburgh Pa. 15205, telephone number 1-800-227-6701. When R
1
is SO
3
M then Compound IV is 2-nitroaniline-4-sulfonic acid and its salts, and Compound IV is available from TCI America, 9211 North Harborgate Street, Portland Oreg. 97203, telephone number 800-423-8616.
Fluorescence is defined as the reemission of longer wavelength (lower frequency) photons (energy) by a molecule that has absorbed photons (light) of shorter wavelengths (higher frequency). Both absorption and radiation (emission) of energy are unique characteristics of a particular molecule (structure) during the fluorescence process. Light is absorbed by molecules causing electrons to become excited to a higher electronic state. The electrons remain in the excited state for about 10
−8
second then, assuming all of the excess energy is not lost by collisions with other molecules, the electron returns to the ground state. Energy is emitted during the electrons' return to their ground state. The Stokes' shift is the difference in wavelength between absorbed and emitted light. The emitted wavelength is always longer or equal to the incident wavelength, due to energy conservation; the difference is absorbed as heat in the atomic lattice of the material.
When their fluorescent properties were tested, it was found that the instant claimed compounds have a fluorescent signal excitation value above 380 nm. Thus, these compounds have a different fluor
Moriarty Barbara E.
Reddinger Jerry L.
Breininger Thomas M.
Brumm Margaret M.
Cole Monique T.
Nalco Chemical Company
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