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  Process and catalyst for the preparation of acetylpyridinesUSPTO Application #: 20060240978Title: Process and catalyst for the preparation of acetylpyridines Abstract: wherein R1 is C1-6-alkyl, with acetic acid in the gas phase in the presence of a catalyst. The active material of the catalyst is titanium dioxide and at least one alkali or alkaline earth metal oxide, and it is supported on an alumina-silica support having an apparent porosity of at least 50 percent. The process has the advantage of producing only small amounts of by-products (e.g., pyidine). by reacting a pyridinecarboxylic ester of the formula (II): A process for the production of acetylpyridines of the formula (1): (end of abstract) Agent: Fisher, Christen & Sabol - Washington, DC, US Inventor: Roderick John Chuck USPTO Applicaton #: 20060240978 - Class: 502300000 (USPTO) Related Patent Categories: Catalyst, Solid Sorbent, Or Support Therefor: Product Or Process Of Making, Catalyst Or Precursor Therefor, Metal, Metal Oxide Or Metal Hydroxide The Patent Description & Claims data below is from USPTO Patent Application 20060240978. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The invention relates to a process for the production of acetylpyridines of formula in particular 3-acetylpyridine. It further relates to a catalyst suitable for the process of the invention. [0002] 3-Acetylpyridine is assuming increasing importance in the pharmaceutical and fine chemical industry as an intermediate and a building block. Up to the present, 3-acetylpyridine has been prepared using often multistage processes starting from nicotinic acid, or from other starting materials which are not readily available (for example 3-ethylpyridine). Instead of using a heteroaromatic acid, it is possible to use derivatives. This is particularly useful when the acid is non-volatile and/or has a tendency to decompose at higher temperatures. Thus ethyl nicotirate was condensed with acetic acid at 520.degree. C. to give 37% yield of 3-acetylpyridine (Houben-Weyl, Vol. VI/2a, pp. 632-633). [0003] Recently a process for the production of 3-acetylpyridine has been described in EP-A-0 352 674, which utilises a catalyst based on titanium dioxide and an alkali or alkaline earth metal oxide or hydroxide. Using the methyl ester of nicotinic acid and acetic acid and a catalyst composed of 98% titanium dioxide (as anatase) and 2% sodium oxide, selectivities between 54% and 60% were reported. Pyridine was produced as a side product through decarboxylation of the nicotinate in amounts between 29 and 41%. [0004] Various other methods have been described which do not lead to satisfactory results (cf. EP-A-0 352 674). [0005] The purpose of the present invention is to improve the selectivity of the state-of-the-art processes for 3-acetylpyridine, thus avoiding or reducing the losses caused by the formation of large quantities of unwanted side-products. [0006] According to the invention, this has been accomplished by the process of claim 1. [0007] It has been found that in the gas-phase reaction of pyridinecarboxylic esters of formula wherein R.sup.1 is C.sub.1-6alkyl, with acetic acid to give acetylpyridines (I) the selectivity of the titanium dioxide-based catalysts of EP-A-0 352 674 can be substantially improved by employing a high-porosity alumina-silica support having an apparent porosity of at least 50%, as determined by the Archimedes method. [0008] Preferably, the process according to the invention is carried out with a C.sub.1-6-alkyl nicotinate as starting material to give 3-acetylpyridine. [0009] It has further been found that by employing higher boiling pyridinecarboxylic esters (II) the ease of separation of the reaction products can be increased. Lower esters of e. g. nicotinic acid have boiling points similar to those of the desired product, which results in separation difficulties in distillation if the conversion is less than 100%. Use of higher boiling (and more stable) esters largely avoids this problem. Examples of this are the butyl, pentyl or hexyl (including the isomers such as isobutyl, sec-butyl, isopentyl etc.) esters of nicotinic acid instead of methyl, ethyl or propyl esters, whose boiling points at atmospheric pressure differ only by 3-4 K (ethyl) and 15-16 K (methyl and propyl), respectively, from that of 3-acetylpyridine. The difference in boiling point between butyl nicotinate and 3-acetylpyridine at atmospheric pressure is 32 K. [0010] Preferably, pyridine carboxylic esters (II) having a boiling point (at atmospheric pressure) exceeding that of the product acctylpyridine (I) by more than 20 K are used as starting materials. [0011] The preferred reaction temperature is 350 to 450.degree. C. [0012] Advantageously, the reaction is carried out in the presence of water and using an excess of acetic acid. [0013] The weight ratio of alumina to silica in the catalyst support is advantageously between 70:30 and 90:10, preferably between 75:25 and 85:15. [0014] Preferably, the apparent porosity of the catalyst support is between 60 and 70%. [0015] The packing density of the catalyst support is preferably lower than 1000 kg/m.sup.3, more preferably between 600 and 800 kg/m.sup.3. [0016] Preferably, the titanium dioxide content of the catalyst is 5 to 20 wt. percent, based on the weight of the support. [0017] The catalyst may be prepared by a process comprising the steps of (i) impregnating an alumina-silica support having an apparent porosity of at least 50% with a solution of titanium tetrachloride in aqueous hydrochloric acid to obtain a first catalyst precursor, (ii) drying, (iii) calcining, (iv) impregnating the calcined first catalyst precursor with a solution or suspension of a hydroxide and/or oxide of an alkali metal and/or alkaline earth metal to obtain a second catalyst precursor, (v) drying and (vi) calcining the dried second catalyst precursor to obtain the final catalyst. [0018] The impregnation of the support is not limited to the use of titanium tetrachloride. Thus either other soluble salts of titanium, or even a finely-divided slurry of titanium oxide can be used. It is also possible to replace the hydroxides or oxides of alkali or alkaline earth metals by suitable precursors, e. g. salts of said metals which decompose on heating. [0019] Advantageously, the ratio of alumina to silica in the support is between 70:30 and 90:10, preferably between 75:25 and 85:15. [0020] The apparent porosity of the catalyst support is preferably between 60 and 70%. [0021] Preferably, the titanium dioxide content of the catalyst is 5 to 20 wt. percent, based on the weight of the support. [0022] The following non-limiting examples will illustrate the process of the invention and the preparation of the catalyst of the invention. EXAMPLE 1 Preparation of Catalyst Continue reading... Full patent description for Process and catalyst for the preparation of acetylpyridines Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Process and catalyst for the preparation of acetylpyridines patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Process and catalyst for the preparation of acetylpyridines or other areas of interest. ### Previous Patent Application: A catalyst for purifying an exhaust gas and a preparation process of the catalyst Next Patent Application: Activated carbon for use in electric double layer capacitors Industry Class: Catalyst, solid sorbent, or support therefor: product or process of making ### FreshPatents.com Support Thank you for viewing the Process and catalyst for the preparation of acetylpyridines patent info. IP-related news and info Results in 1.601 seconds Other interesting Feshpatents.com categories: Accenture , Agouron Pharmaceuticals , Amgen , AT&T , Bausch & Lomb , Callaway Golf |
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