Fluorescent dyes

Details Fluorescent dyes Fluorescent dyes

1999-12-03

2001-04-10

Qazi, Sabiha N. (Department: 1616)

Organic compounds -- part of the class 532-570 series

Organic compounds

Polycyclo ring system containing anthracene configured ring...

C552S276000, C552S277000, C552S279000, C552S280000, C552S281000, C564S426000, C568S632000, C568S634000, C570S183000

Reexamination Certificate

active

06215008

ABSTRACT:

The present invention is directed to fluorescent dyes useful for leak detection, pipeline interface detection, and crude oil detection in depleted wells. The invention provides fluorescent dyes which fluoresce at a variety of wavelengths.
BACKGROUND OF THE INVENTION
Fluorescent dyes have been produced from violanthrone (C.I. Vat Blue 20) and isoviolanthrone (C.I. Vat Violet 10), nine-ring aromatic diketone structures, by reductive alkylation with alkyl halides and zinc powder at elevated temperatures. These dyes fluoresce a green-yellow color. Complex apparatus may have a number of fluid lines; thus, it would be desirable to be able to differentiate by fluorescent dye color the source of a leak.
Also, the dyes may be used for tagging and identifying liquids, such as petroleum fuels. The availability of fluorescent dyes of a variety of hues increases the utility of such dyes for this purpose. Fluorescent dyes may be detected by apparatus described in U.S. Pat. No. 5,958,780, the teachings of which are incorporated herein by reference. Two fluorescent dyes which fluoresce at significantly different wavelength may be used in a binary tagging system which provides for an essentially unlimited number of identifying combinations.
Accordingly, it is a general object of the present invention to provide fluorescent dyes which fluoresce at wavelengths different from currently available fluorescent dyes.
SUMMARY OF THE INVENTION
In accordance with the present invention, fluorescent dyes which fluoresce at a variety of wavelengths are produced by reductive alkylation of substituted violanthrone and substituted isoviolanthrone. The substituted violanthrone and substituted isoviolanthrone structures are reacted with alkyl halides and zinc, the reductive alkylation removing the dione functionality from the structure and adding between 2 and 6 alkyl groups, on average, to the ring structures. Depending upon the number of substituent groups on the ring structure, and the number and structure of the alkyl groups added, fluorescent dyes which fluoresce at a variety of wavelength are produced. Example of fluorescent colors which are produced include green, green-yellow, yellow and orange.
DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS
Substituted voilanthrones used as starting materials in accordance with the invention have the general formula:
where the Xs are the same or different and are selected from Cl, H, F, I, O—(C1-C8)alkyl, and NY
2
where the Ys are the same or different and are selected from H or (C1-C8)alkyl; provided that at least one X is other than H.
Substituted isoviolanthrones used as starting materials have the general formula, where the Xs as defined above:
where the Xs are as defined above; again providing that at least one X is not H. Because it is known that substituent groups tend to de-stabilize multi-ring structures of this type, it is surprising that the substituted violanthrone and substituted isoviolanthrone structures may be alkylated by the relatively harsh conditions of reductive alkylation without break-down of the ring structure.
In the above formulae (I) and (II), the slash lines into the ring structures indicate that the Xs may be on any available location on the nine-ring structures.
Examples of suitable starting dyes include for example:
C.I. Vat Blue 18
C.I. Vat Violet 1
C.I. Vat Violet 9
C.I. Vat Black 16
C.I. Vat Green 1.
The starting dyes are reacted with an excess alkyl halide, generally an alkyl chloride, in the presence of zinc so as to provide a high degree of alkylation of the ring structure. Reductive alkylation occurs at the ketone group sites and additional alkylation occurs around the ring structures when an excess of alkyl halide is used. Typically, on each molecule, the ring structure is alkylated with 2-6 alkyl groups, most typically 6 alkyl groups, when a substantial excess of alkyl halide is used as the reactant. By “excess” is meant herein an amount above 6 moles of alkyl halide per mole of dye of formula (I) or (II).
The alkyl groups of the alkyl halides have between 1 and 12 carbon atoms, preferably between 6 and 12. Preferably the alkyl groups of the alkyl halides are linear. As the zinc is provided in powdered, zero valence, form, it is generally used at a considerable stoichiometric excess. In the reaction, both reductive and non-reductive alkylation occur. In substituted ring structures, some loss of substituent (X) groups may occur, though it is difficult to determine the extent, if any, this may occur.
Accordingly, the Dyes in accordance with the invention have the general formulae:
where the Xs are as defined above; at least one X is other than H; and m═0-4.
The dyes produced in accordance with the invention are liquids, making them easy to mix with other fluids, such as petroleum fuels and air conditioning refrigerants. The dyes are fully miscible with both petroleum fuels and refrigerants.


REFERENCES:
patent: 4486587 (1984-12-01), Seybold
patent: 5958780 (1999-09-01), Asher et al.
Nair et al. (DN 76:73710 CAPLUS; abstract of Indian J. Chem. (1971), 9(9), 925-7.

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