- Mesostructured aluminosilicate alkylation catalysts for the production of aromatic amine antioxidants
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The conversion of diphenylamine (DPA) and α-methylstyrene (AMS) to the antioxidants mono- and dicumenyldiphenylamine was carried out over mesostructured aluminosilicate catalysts with hexagonal (2% Al-MCM-41), wormhole (2% Al-HMS), and lamellar/vesicular (2% Al-MSU-G) framework structures. A commercial acid-treated clay catalyst, Engelhard F-20, was included for comparison perposes. The yields of the desired antioxidant, namely dicumenyldiphenylamine (DCDPA), increased in the order F-20 (～57%)3PW12O40·xH2O (PW 12) supported on mesostructured wormhole HMS and lamellar/vesicular MSU-G silica, also was examined as a catalyst for DCDPA production. The supported catalyst systems, however, afforded lower maximum yields of DCDPA (～73-80%) in comparison to the mesostructured aluminosilicate catalysts. The exceptionally high yields of alkylated products obtained with the mesoporous aluminosilicate catalysts in comparison to the F-20 clay and the supported PW12 catalysts are attributable in part to intermediate acid strengths that minimize completing dimerization reactions of the AMS alkylating agent. Also, the pore structures of the mesostructured catalysts facilitate access to active sites on the framework walls and provide more efficient transport of reagents to framework reaction centers. Also, the regular mesoporosity of the aluminosilicate catalysts makes these structures less prone to pore plugging and to the masking of acidity through the adsorption of the high molecular weight reaction products.
- Liu, Yu,Kim, Seong Su,Pinnavaia, Thomas J.
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- Alkylation of diphenylamine with α-methylstyrene and diisobutylene using acid-treated clay catalysts
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Alkylation of diphenylamine was carried out with α-methylstyrene and diisobutylene using acid-treated clay catalyst Engelhard F-24 to produce mono- and dialkylated diphenylamines. Dialkylated diphenylamines are industrially useful as antioxidants and heat stabilizers. Mono and dialkylated diphenylamines were separated in pure form from the reaction mixture and characterized by FTIR and 1H NMR. Reaction conditions for obtaining high selectivity of each of the alkylated products were studied. A comparative study of the reaction rates, with various other grades of acid-treated clay catalysts, was done for the reaction between diphenylamine and α-methylstyrene. The reaction between diphenylamine and α-methylstyrene was also studied in a continuous mode of operation in a fixed bed reactor. Deactivation of the catalyst occurred during the course of these reactions and reuse of the catalyst posed problems; alternative schemes were considered to regenerate the deactivated catalyst. The basic reasons for the deactivation of the catalyst were investigated in the case of reaction between diphenylamine and α-methylstyrene. The fresh and used catalysts were characterized using various spectroscopic and other techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, UV-visible and nuclear magnetic resonance spectroscopy, surface area (BET) and surface acidity (TPD), pore size distribution, and pore volume. These studies indicated that the deactivation of the catalyst was due to irreversible adsorption on the surface, loss of microporous structure and loss of surface acidity. The adsorbed species appeared to be diphenylamine and/or alkylated product(s), coordinated to the surface oxygen of the catalyst through nitrogen, forming a nitro kind of species.
- Chitnis, Sandeep R.,Sharma, Man Mohan
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- Zinc-Catalyzed Alkylation of Aromatic Amines in Continuous Flow
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A practical approach to the synthesis of antioxidant 4,4′-dicumyldiphenylamine (DCDPA) and its derivatives by Friedel-Crafts alkylation of aromatic amines was developed under continuous flow conditions. Because of the enhanced mass and heat transfer features of the microreactor, the reaction time was significantly reduced in contrast to a batch mode. The reaction was carried out using a 1:6 v/v ethanol/Cl(CH2)2Cl cosolvent system with ZnCl2 as the catalyst to achieve satisfactory yields. This is an effective method for the synthesis of DCDPA and its derivatives with excellent para selectivity that has the merits of shorter reaction time, easy operation, and straightforward scale-up.
- Bo, Xiaofan,Mao, Mengmei,Wan, Li,Xin, Zhong,Yao, Hanlin,Zhang, Le
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- Anti-oxidant 4, 4' - double (α, α - dimethyl benzyl) diphenylamine preparation method (by machine translation)
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The invention discloses a method for antioxidant 4, 4' - double (α, α - dimethyl benzyl) diphenylamine preparation method. First of all the raw materials diphenylamine added to a reaction vessel, heating to melt; melting compound catalyst added after continued heating and stirring; after stir dropwise α - methyl styrene, after dropping the heating reaction; after the reaction, the temperature of the resulting reaction solution, then adding petroleum ether and methanol mixed solvent, cooling to room temperature to crystallize; filtering the final turn, petroleum ether washing, washing and drying, drying to obtain the anti-oxidant 4, 4' - double (α, α - dimethyl benzyl) diphenylamine. This invention adopts the disposable synthetic antioxidant, only need to filter after the reaction, washing can obtain high-quality antioxidant product, without the need of acidified, alkali neutralization, washing and other complex post-treatment process, not three wastes to produce, also saves the many complex steps. Therefore, the invention has obvious economic and social benefits. (by machine translation)
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Paragraph 0020; 0036-0070
(2018/04/01)
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- Preparation method of diphenylamine rubber aging inhibitor
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The invention relates to a preparation method of a diphenylamine rubber aging inhibitor. An immobilized catalyst is prepared from a Lewis acidic ionic liquid by supporting the Lewis acidic ionic liquid on the surface of a molecular sieve and is applied to an alkylation reaction of diphenylamine. The method can have remarkable progress in the aspects of yield, purity, service life of the catalyst and other aspects as compared with the prior art.
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Paragraph 0041; 0059-0060
(2018/01/14)
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- ALKYLATED PANA AND DPA COMPOSITIONS
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The invention relates to a composition comprising a mixture of alkylated N-α-naphthyl-N-phenylamine (PANA) and alkylated diphenylamine (DPA), the product obtainable by alkylat-ing PANA or a mixture of PANA and DPA with alkenes and the process for alkylating PANA or a mixture of PANA and DPA with alkenes. The compositions according to the present in-vention have an outstanding anti-oxidative action, which can be demonstrated by established test methods.
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Page/Page column 26-29
(2010/02/14)
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