Organic compounds -- part of the class 532-570 series – Organic compounds – Four or more ring nitrogens in the bicyclo ring system
Reexamination Certificate
2001-06-22
2003-10-14
Shah, Mukund J. (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Four or more ring nitrogens in the bicyclo ring system
C544S219000
Reexamination Certificate
active
06632944
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a novel, efficient, economic and general-purpose process for isolating monophenolic-bisaryl triazine compounds from polyphenolic-triazines compounds and other impurities. More specifically, this invention relates to a process for isolating the monophenolic-bisaryl triazine compounds by contacting it with a base, an alcohol and/or a hydrocarbon solvent.
BACKGROUND OF THE INVENTION
Exposure to sunlight and other sources of ultraviolet (UV) radiation is known to cause degradation of a wide variety of materials, especially polymeric materials. For example, polymeric materials such as plastics often discolor and/or become brittle as a result of prolonged exposure to UV light. Accordingly, a large body of art has been developed directed towards materials such as UV light absorbers and stabilizers which are capable of inhibiting such degradation. Other areas of applications for the UV light absorbers include cosmetics (as sunscreen agents), fibers, spandex, inks, photographic materials, and dyes.
A class of materials known to be UV light absorbers are compounds which have aromatic substituents at the 2-, 4-, and 6-positions of the 1,3,5-triazine ring, and in which at least one of the aromatic rings has a hydroxyl substituent at the ortho position to the point of attachment to the triazine ring. In general, this class of compounds is well known in the art. Disclosures of a number of such triazine UV light absorbers (UVA's) as well as processes for preparing can be found in the following references and references cited therein, all of which are incorporated by reference as fully set forth herein: U.S. Pat. No. 6,239,275; U.S. Pat. No. 6,239,276; U.S. Pat. No. 6,242,597; U.S. Pat. No. 6,225,468 and WO 00/29392.
A preferred class of triazine UVA's are asymmetrical monophenolic-bisaryl triazines UVA's based on the 2-(2,4-dihydroxyaryl)-4,6-bisaryl-1,3,5-triazines, e.g., compounds where there are two non-phenolic aromatic groups, and one phenolic aromatic group that is derived from resorcinol, or substituted resorcinol. The 4-hydroxyl group of the parent compound, 2-(2,4-dihydroxyaryl)-4,6-bisaryl-1,3,5-triazine, is generally functionalized to make 2-(2-hydroxy-4-oxyaryl)-4,6-bisaryl-1,3,5-triazine derivatives for end use.
There are several approaches reported in the literature to make the preferred 2-(2,4-dihydroxyaryl)-4,6-bisaryl-1,3,5-triazine UVA's. (For a review of the previously known methods for making triazine UVA's, please see the following articles: 1. H. Brunetti and C. E. Luethi,
Helvetica Chimica Acta,
vol 55, 1972, pages 1566-1595; 2. S. Tanimoto and M. Yamagata,
Senryo to Yakahin,
vol. 40(12), 1995, pages 325-339.)
A majority of the approaches consists of three stages. The first stage, which can involve single or multi-steps from the commercial raw materials, deals with the preparation of the key intermediate, 2-chloro-4,6-bisaryl-1,3,5-triazine, which is subsequently arylated in the second stage with 1,3-dihydroxybenzene (resorcinol) or a substituted 1,3-dihydroxybenzene in the presence of Lewis acid to form the parent compound 2-(2,4-dihydroxyaryl)-4,6-bisaryl-1,3,5-triazine. The parent compound 2-(2,4-dihydroxyaryl)-4,6-bisaryl-1,3,5-triazine, as mentioned above, is generally functionalized further, e.g., alkylated, to make the final product 2-(2-hydroxy-4-oxyaryl)-4,6-bisaryl-1,3,5-triazine.
General Scheme for Making 2-(2-hydroxy-4-oxyaryl)-4,6-bisaryl-triazines
It has been recognized that the most versatile and economical method to prepare asymmetrical monophenolic-bisaryl triazine UVA's is to use a Friedel-Crafts reaction on cyanuric chloride with non-phenolic aromatics to first form 2-chloro-4,6-bisaryl-1,3,5-triazine, followed by another Friedel-Crafts reaction with the phenolic aromatic, in this case resorcinol, to make the desired monophenolic-bisaryl-triazine. However, it has been realized in the prior art (see, U.S. Pat. No. 3,394,134) that this known process as disclosed in U.S. Pat. No. 3,268,474 gives, only in exceptional cases, rise to the desired disubstituted derivatives of cyanuric chloride with some selectivity. Even when the aromatic compound and cyanuric chloride are reacted in molar proportions (1:1), the result is in general a mixture which contains mono-, di-, and tri-aryl substituted products, and, in addition, unreacted cyanuric chloride (U.S. Pat. No. 3,394,134) (Scheme 1).
Using the above mentioned process, a useful yield of the desired intermediate 2-chloro-4,6-bisaryl-1,3,5-triazine is obtained only with m-xylene as the aromatic reactant (GB 884802). 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, free of polyresorcinol-triazine impurities, was prepared from the isolated 2-chloro-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine that was purified by recrystallization, before reacting with resorcinol in a second step (see U.S. Pat. No. 3,244,708). The isolation and recrystallization of the 2-chloro-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine results in yield loss. With other aromatics, a difficult to separate mixture of all possible products are formed with no selectivity for the desired 2-chloro-4,6-bisaryl-1,3,5-triazine (For example, see H. Brunetti and C. E. Luethi,
Helvetica Chimica Acta,
vol 55, 1972, page 1575 and S. Tanimoto and M. Yamagata,
Senryo to Yakahin,
vol. 40(12),1995, pages 325-339).
When the reaction mixture from the first Friedel-Crafts reaction (Scheme 1) without any purification is treated in a subsequent Friedel-Crafts reaction with resorcinol, the bisaryl-derivative leads to the formation of desired monoresorcinol-bisaryl-triazine, and the monoaryl-substituted product leads to the formation of monoaryl-bisresorcinol derivative. Whereas, the unreacted cyanuric chloride leads to the formation of bis-and tris-resorcinol-triazine derivatives, i.e. polyresorcinol-triazines (see Scheme 2).
These polyresorcinol-triazine impurities (triazine ring with more than one resorcinol attached) lead to yellowing in the use of the UV absorbers prepared from the monoresorcinol-bisaryl-triazine in various polymer substrates, e.g., in polycarbonates, in lacquers, in automotive top-coatings, etc. Thus it is highly desirable for many such applications that the monoresorcinol-bisaryl-triazine derivative is free of these impurities. Unfortunately, there has been no process known in the literature to isolate monoresorcinol-bisaryl-triazine derivative from the mixture containing polyresorcinol impurities. The lack of selectivity for the bisaryl substitution in the Friedel-Crafts reaction of cyanuric chloride, coupled with the problems associated with the isolation of the bisaryl intermediate and the monoresorcinol-bisaryl-triazine derivative, had severely limited the usefulness of the most versatile and economic approach to the preferred class of triazine UVA's.
To overcome this obstacle, and to exclude the formation of polyresorcinol-triazines, other economically less attractive routes have been developed in which either cyanuric chloride was not used as starting material, and the triazine ring was synthesized by different methods, or the formation of polyresorcinol impurities was excluded by means of the circuitous routes (For example, see: A. Ostrogovich, Chemiker-Zeitung No. 78, page 738, 1912; von R. Hirt, H. Nidecker and R. Berchtold, Helvitica Chimica Acta, vol. 33, page 1365, 1950; H. Brunetti and C. E. Luethi,
Helvetica Chimica Acta,
vol 55, 1972, page 1575; U.S. Pat. No. 4,092,466; U.S. Pat. No. 5,084,570; U.S. Pat. No. 5,106,972; U.S. Pat. No. 5,438,138; U.S. Pat. No. 5,726,310; U.S. Pat. No. 6,020,490; EP 0941989 and Japanese Patent 09059263)
An alternate direct approach for the preparation of monoresorcinol-bisaryl-triazine as described in U.S. Pat. No. 6,225,468 B1 from cyanuric chloride also results in the formation of polyresorcinol products, and no method was disclosed to isolate the monoresorcinol-bisaryl-triazine product from the mixture.
More recently, a major breakthrough discovery in the field has led to the developme
Cappadona Russell C.
Gupta Ram Baboo
Singh Hargurpreet
Balasubramanian Venkataraman
Cytec Technology Corp.
Didamo Valerie T.
Jubinsky James A.
Schultz Claire M.
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