Aqueous Kolbe-Schmitt Synthesis Using Resorcinol in a Microreactor Laboratory Rig under High-p,T Conditions
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- 作者：Volker Hessel ; C. Hofmann ; P. Lö ; b ; J. Lö ; hndorf ; H. Lö ; we ; and A. Ziogas
- 刊名：Organic Process Research & Development
- 出版年：2005
- 出版时间：July 2005
- 年：2005
- 卷：9
- 期：4
- 页码：479 - 489
- 全文大小：319K
- 年卷期：v.9,no.4(July 2005)
- ISSN：1520-586X
文摘
The aqueous Kolbe-Schmitt synthesis using resorcinol to yield2,4-dihydroxy benzoic acid was performed in a microreactorrig. This small-scale plant was equipped initially with onecapillary reactor and one microstructured cooler only. Later,two upgraded versions were constructed, having in addition amicrostructured cooler and a microstructured mixer, respectively. The chemical protocol was significantly varied ascompared to standard laboratory operation as described in theliterature. Higher temperatures (up to 220 
C) and pressures(up to 74 bar) were employed in a facile manner, termed high-p,T processing. In this way, the reaction time could be shortenedby orders of magnitude, from about 2 hours to less than oneminute, in some cases to some seconds. This resulted in aremarkable increase of the space-time yield by a factor of 440at best. Productivity was in the L/h range and yielded at best111 g/h product, corresponding to 4 t/a. Scale-out solutions areindicated. Drawbacks of the microreactor operation were alsoidentified such as high sensitivity to fouling and delicateregulation of the system pressure, leading to partly unstableplant operation. Possibly even a considerable part of the productwas rearranged to 2,6-dihydroxybenzoic acid and then thermally decomposed under the harsh reaction conditions. Solutions to overcome or at least diminish these restrictions areenvisaged, and in the hope that this may be achieved, a processinnovation and business perspective for the high-p,T microreactor processing is depicted.
C) and pressures(up to 74 bar) were employed in a facile manner, termed high-p,T processing. In this way, the reaction time could be shortenedby orders of magnitude, from about 2 hours to less than oneminute, in some cases to some seconds. This resulted in aremarkable increase of the space-time yield by a factor of 440at best. Productivity was in the L/h range and yielded at best111 g/h product, corresponding to 4 t/a. Scale-out solutions areindicated. Drawbacks of the microreactor operation were alsoidentified such as high sensitivity to fouling and delicateregulation of the system pressure, leading to partly unstableplant operation. Possibly even a considerable part of the productwas rearranged to 2,6-dihydroxybenzoic acid and then thermally decomposed under the harsh reaction conditions. Solutions to overcome or at least diminish these restrictions areenvisaged, and in the hope that this may be achieved, a processinnovation and business perspective for the high-p,T microreactor processing is depicted.