Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
1995-06-06
2002-11-19
Lambkin, Deborah C. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S013000, C549S023000, C549S407000, C549S427000, C562S899000
Reexamination Certificate
active
06482950
ABSTRACT:
REFERENCES TO RELATED APPLICATIONS
U.S. patent application Ser. No. 07/795,034, filed Nov. 20, 1991 (now U.S. Pat. No. 5,227,498), U.S. patent application Ser. No. 07/979,250, filed Nov. 20, 1992 and International Application PCT/US92/09992 (Publication No. WO 93/09956, all describe amino-substituted squarylium infra-red dyes, including (in the last two applications) dyes containing 6-alkoxybenzpyrylium nuclei.
U.S. patent application Ser. No. 07/795,038, filed Nov. 20, 1991, describes and claims bis(benzpyrylium) squarylium dyes, including certain asymmetric dyes produced by processes of the present invention.
U.S. patent application Ser. No. 07/965,161, filed Oct 23, 1992 now U.S. Pat. No. 5,286,612, describes a process for generation of acid, which process comprises:
providing a medium containing a mixture of a superacid precursor and a dye capable of absorbing actinic radiation of a first wavelength which does not, in the absence of the dye, cause decomposition of the superacid precursor to form the corresponding superacid, the superacid precursor being capable of being decomposed by actinic radiation of a second wavelength shorter than the first wavelength;
irradiating the medium with actinic radiation of the first wavelength, thereby causing absorption of the actinic radiation, and decomposition of part of the superacid precursor, without formation of free superacid but with formation of a protonated product derived from the dye; and
thereafter irradiating the medium with actinic radiation of the second wavelength, thereby causing decomposition of part of the remaining superacid precursor, with formation of free superacid.
At least some of the dyes produced by the process of the present invention may be used in the process of this copending application.
The disclosures of the aforementioned U.S. applications and patents are herein incorporated by reference.
BACKGROUND OF THE INVENTION
This invention relates to squarylium compounds, and processes and intermediates for the synthesis of these compounds. More specifically, this invention relates to processes and intermediates useful for the synthesis of squarate dyes (and to such dyes themselves) in which two heterocyclic nuclei are linked to the 1- and 3-positions of a squarate ring via a single sp
2
hybridized carbon atom (hereinafter called the “meso” carbon atom); these dyes will hereinafter be called “pentamethine squarate dyes”. The processes of the present invention are especially useful for the synthesis of asymmetric pentamethine squarate dyes, i.e., those in which the two heterocyclic nuclei are dissimilar. The present invention is also useful for the synthesis of related dyes in which one meso carbon atom and its associated heterocyclic nucleus are replaced by an aromatic nucleus directly bonded to the squarylium ring.
It is known that compounds in which two heterocyclic nuclei are linked by a pentamethine chain, the three central carbon atoms of which form part of a squarate ring, are useful as dyes, especially near infra-red dyes. (The term “near infra-red” is used herein to mean electromagnetic radiation having a wavelength of about 700 to about 1200 nm.) For example, Japanese Patent Application No. 103,604/82 (Publication No. 220,143/83, published Dec. 21, 1983), discloses a broad class of bis-heterocyclic pentamethine dyes in which the central three carbon atoms of the pentamethine chain form part of a squarylium or croconylium ring. The heterocyclic nuclei can be pyrylium, thiopyrylium, selenopyrylium, benzpyrylium, benzthiopyrylium, benzselenopyrylium, naphthopyrylium, naphthothiopyrylium or naphthoselenopyrylium nuclei, which can be substituted with alkyl, alkoxy, aryl or styryl groups.
Japanese Patent Application No. 60-8730 (Publication No. 167,681/86, published Jul. 29, 1986), discloses bis(4-benz[b]thiopyrylium) pentamethine dyes in which the central three carbon atoms of the pentamethine chain form part of a squarylium ring. The dyes are intended for use as infra-red absorbers.
U.S. Pat. No. 4,508,811, issued Apr. 2, 1985, describes an optical recording element in which the recording layer comprises a bis(2,6-dialkyl)-pyrylium or -thiopyrylium squarylium salt.
Application Ser. No. 07/616,639, filed Nov. 21, 1990 (now abandoned) by Stephen J. Telfer et al. and assigned to the same assignee as the present application, and the aforementioned U.S. patent application Ser. No. 07/795,038, describe 4-[[3-[(benz[b]-4H-pyran-4-ylidene)methyl]-2-hydroxy-4-oxo-2-cyclobuten-1-ylidene]methyl]benz[b]pyrylium hydroxide inner salt dyes, in which at least one benzpyrylium nucleus carries at its 2-position a substituent in which a non-aromatic carbon atom is bonded directly to the benzpyrylium nucleus, subject to the proviso that if this 2-substituent contains an aromatic nucleus, this aromatic nucleus is not conjugated with the benzpyrylium nucleus. These dyes have high absorptions in the near infra-red, and improved solubility in semi-polar solvents and plastics.
Most of these aforementioned pentamethine squarate dyes are symmetrical, that is to say the two heterocyclic nuclei are the same. Such symmetrical dyes are typically prepared by condensing two moles of the appropriate alkyl-substituted heterocyclic compound (usually, a salt) with squaric acid in the presence of a-base.
In certain applications of pentamethine squarate dyes, it may be advantageous to use a dye which is asymmetric, i.e., which contains two different heterocyclic groupings. For example, some symmetrical near infra-red pentamethine squarate dyes have significant absorption in the visible region, and this visible absorption restricts the utility of the dyes in certain applications, for example thermal imaging media. In particular, if the symmetrical dye absorbs strongly in one part of the visible spectrum but not in another, it will tend to introduce color distortion into any image created using the symmetrical dye. Although asymmetrical analogues of these infra-red pentamethine squarate dyes may have some visible absorption, this visible absorption tends to take the form of several separate small peaks, and is thus more spread out over a wide range of wavelengths than in the symmetrical dyes. Such absorption over a range of wavelengths tends to produce lower peak absorption and less color distortion (because the dye tends to produce a grey tint) than that produced by the symmetrical dyes, and thus the asymmetric dyes may advantageously be used in applications where the visible absorption of the symmetric dyes causes problems.
Moreover, there are a number of applications where infra-red dyes are needed which absorb at specific wavelengths. For example U.S. Pat. Nos. 4,602,263 and 4,826,976 both describe thermal imaging systems for optical recording and particularly for forming color images. These patents describe a preferred form of thermal imaging medium for forming multicolor images; in this preferred imaging medium, three separate color-forming layers, capable of forming yellow, cyan and magenta dyes respectively, are superposed on top of one another. Each of the three color-forming layers has an associated infra-red absorber, these absorbers absorbing at differing wavelengths, for example 760, 820 and 880 nm. This medium is imagewise exposed simultaneously to three lasers having wavelengths of 760, 820 and 880 nm. The resultant imagewise heating of the color-forming layers causes the leuco dyes to undergo color changes in the exposed areas, thus producing a multicolored image, which needs no development. If the choice of infra-red dyes is restricted to symmetrical compounds, it may be difficult to find a dye which absorbs at the precise wavelength required, and which meets the other requirements, such as storage stability and miscibility in polymers, for use in such media. Asymmetric dyes, which allow the two groups linked to the squarylium nucleus to be varied independently, provide an extra degree of freedom, which renders it easier to find a dye which absorbs at the desired wavel
Garcia Paulina P.
Lee John W.
Marshall John L.
McGowan Donald A.
Puttick Anthony J.
Lambkin Deborah C.
Polaroid Corporation
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