Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-08-07
2001-11-06
Powers, Fiona T. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
active
06313314
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a method for the preparation of azide photo-initiators. More specifically, the present invention relates to a novel method for the preparation of N-azidosulfonyl-arylimides, which are known as photo-initiators.
2. Description of the Related Art
In the photochemical related industry, photoresist agent is the most important application. The photo image forming process makes possible the selective formation of via holes, the formation of heat and corrosion resistant protective films, dielectric films or alignment layers, in addition to the disposition of specific patterns onto substrates. Hence, photoresist agents are widely used in the manufacturing and sealing processes of ICs, and the manufacturing of LCDs and printed circuit boards.
The formula of the photoresist agent includes photo-initiators, photo-resistant agent, solvents and other additives. Among these, photo-initiators are the most expensive, the most difficult to synthesize, and have the greatest influence on the overall photosensitivity, quality and function of the agent. Generally, by exposure, the photo-initiators generate free radicals, carbene, nitrene, protons and other cations or anions to initiate the polymerization reaction and allow a subsequent series of follow-up applications.
Azide photo-initiator is one of the most important photo-initiators. By exposure to light, the Azide photo-initiator is in an excited state, in which N
2
is removed to form nitrene. The high reactivity of nitrene causes difficulties in polymerization, purification, usage and storage.
Various methods for the preparation of azide photo-initiators are disclosed in U.S. Pat. No. 4,329,556 (Siemens) and D.E. Pat. No. 4,328,838 (BASF). The formulation of the photoresist agent with the azide photo-initiators is disclosed in E. Pat. No. 188,205 (Merck).
In general, the method disclosed by Siemens is by reacting 4-acetamidobenzenesulfonyl chloride and CH
2
Cl
2
solvent under the presence of the dehydrating agent N,N′-dicyclohexylcarbodiimide (DCC) to carry out the polymerization. The DCC is high-priced and moisture absorbing, hence it is hard to manage. Similarly, CH
2
Cl
2
, being regulated, is not easy to use and manufacture in Taiwan. Since the purification of product is done by chromatography, which lowers product yield to 30%, it is hard to achieve mass production.
The BASF method discloses a process in which N-phenylmaleimide, which is 10 times the price of the 4-acetamidobenzenesulfonyl chloride (310 U.S.$/kg vs. 30 U.S.$/kg), is utilized as a reactant. Moreover, as the polymerization reaction is carried out by sulfonyl chloride, problems such as waste acids and wastewater arise, making this method dirty and non-environmentally friendly.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a novel method of preparation of azide photo-initiators.
The present invention achieves the above-indicated objects by providing a novel polymerization process using N-azidosulfonyl-arylimides. According to the invention, substitution reaction of 4-acetamidobenzenesulfonyl halide with MN
3
(M denotes hydrogen or alkaline metal) provides the corresponding azide. After de-protection to remove the actyl group, aminoarylsulfonyl azide is extracted with an organic solvent, and the extract is directly used for addition reaction with maleic anhydride without being concentrated. Finally, end products are obtained by dehydration of the addition products using acetic anhydride/metal acetate, followed by re-crystallization in alcohol solvent. The product yield is greater than 69% with an assay greater than 99%. Moreover, it is easy to ramp up the manufacturing to mass production, making the method useful to industry. With the addition of phenolic aldehyde resins with double-bonded and photosensitive groups, epoxy resin, polyamic resin and acrylate, etc, this method is suitable for application in the microelectronics industry.
DETAILED DESCRIPTION OF THE INVENTION
The method of the invention is now described in detail.
The azide photo-initiator used in the invention is shown as formula I:
wherein R
1
, is hydrogen, halogen or alkyl of 1-4 carbon atoms; R
2
and R
3
are independently the same or different and each represent hydrogen, alkyl of 1-6 carbon atoms or cycloalkyl, or R
2
and R
3
combined together represent cycloalkenyl, aryl or heteroaryl; and n is 1 or 2.
The term ‘aryl’ or ‘heteroaryl’ represents groups of aromatic nature having 5 or 6 membered rings which may be selected from phenyl, biphenyl, naphthyl, pyridyl, quinoline, indole, pyrol, furan, benzofuran, thiophene, pyramidine, piperizine and imidazol etc. The rings could also include substituents, such as halogen, nitro, cyano, alkyl, alkoxyl, haloalkyl, hydroxyl, carboxyl, amido, and amino.
The method of the invention comprises the following steps:
(a) Substitution reacting compound II and MN
3
in a ketone solvent to obtain compound III, wherein M denotes hydrogen or alkaline metal;
wherein R
1
is hydrogen, halogen or alkyl of 1-4 carbon atoms, X is halogen, and n is 1 or 2.
(b) de-protecting the acetyl-amino of compound III under acidic conditions, adding alkaline solution to the resulting solution to adjust the pH to be larger than 7, and extracting by organic solvent to obtain compound IV;
wherein R
1
and n are defined as above;
(c) addition reacting the resulting organic solvent extract with compound V to obtain compound VI;
wherein R
2
and R
3
are independently the same or different and each represent hydrogen, alkyl of 1-6 carbon atoms, or cycloalkyl, or R
2
and R
3
combined together represent cycloalkenyl, aryl or heteroaryl; and
(d) dehydrating compound IV with acetic anhydride and metal acetate to obtain azide photo-initiator compound I;
wherein R
1
, R
2
, R
3
and n are defined as above.
According to the method of the invention, step (a) is the substitution reaction of 4-Acetamidobenzenesulfonyl halide or alkanes thereof and aromatic derivatives II with MN3 in ketone solvent at temperature of 25° C. This reaction is very rapid and finishes in 5 min. TLC chromatography is then performed to ensure the reactants are completely consumed in the reaction. Next, compound III is obtained by filtration of white solid precipitate by dripping the substitution product in ice water. In this case, the ketone solvent used is ketone of 3 to 12 carbon atoms, preferably acetone. MN
3
is preferably NaN
3
.
Step (b) is the de-protection of the actyl group of azide compound III under acidic conditions. This reaction is usually completed by reflux-stirring at 95° C. for 15 minutes in hydrogen halide (such as hydrogen chloride) solution, adding alkaline solution to the resultant solution to adjust the pH to be greater than 7, followed by extraction with organic solvents to obtain amino compound IV. The alkaline solution used is alkaline metal or ammonium hydroxide solution, preferably ammonium hydroxide solution. The organic solvents suitable for use in the extraction include esters, ketones, ethers, alcohols, aliphatics, aromatic solvents etc, preferably ethyl acetate. The obtained organic solvent extract is then used in the next addition reaction. However, the extract may be concentrated, dried and weighed in order to calculate the accurate product yield of this step.
Step (c) is the addition reaction of the obtained organic solvent extract with maleic anhydride or alkanes thereof and aromatic derivative V to obtain amide compound VI. This addition reaction normally takes place at a temperature of 35-40° C. for 6.5-7 hours. A slightly yellowish and green product is obtained after filtration and drying.
The same organic solvent is used in the above two reaction steps (b and c), thereby decreasing the number of steps for concentration work-up. This reaction is simple and easy to conduct, which is one of the features of the invention.
Dehydration of amide compound VI with acetic anhydride and metal acetate in step (d) is carried out for about 7 hours at roo
Cheng Kung-Lung
Hong Se-Tsun
Lin Shu-Chen
Tzeng Woan-Shiow
Industrial Technology Research Institute
Powers Fiona T.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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