Lake Como 2|4 October 2011 - CHIMICA Oggi/Chemistry Today

Novel process windows
Boosted organic chemistry under harsh reaction conditions in microreactor
Qi Wang, Volker Hessel
Eindhoven Univ. of Technology (TU/e), Dept. of Chemical Engineering and Chemistry, Micro Flow Chemistry & Process Technology
Den Dolech 2, 5600 MB Eindhoven, The Netherlands
Microreactors possess high mass/heat transfer capability which provides a transport intensifi cation fi eld (1). For many organic
reactions, however, this on its own is not enough to ensure productivity (and sometimes selectivity) high enough to be competitive,
especially for an industrial application. A second chemical intensifi cation fi eld rather has to be added. Novel Process Windows
(NPW) stand for the use of highly intensifi ed, unusual and typically harsh process conditions to boost micro process technology and
fl ow chemistry for the fi ne chemical production (2-3). In extension, NPW give emphasis to a third process-design-intensifi cation
fi eld through process simplifi cation and integration. Five projects under the umbrella of the ERC Advanced Grant on Novel Process
Windows (NPW) are in the process of making fundamental investigations here (started April 2011). The ERC research aims to
be comprehensive and holistic: starting from a molecular-mechanistic (New Chemical Transformations) and kinetic scale (High-
Temperature/pressure Processing) (4-5) via the scale of reaction environment (Solvent-free
Operation and Tuneable/ eactive Solvents) (6-7) up to a process scale (Process Integration
and Simplifi cation).
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The 1,3-Huisgen cycloaddition-based triazole Click Chemistry is explored in a micro-capillary
fl ow reactor with two objectives:
1) high-p, T processing using two-step fl ow synthesis starting from inorganic azide; aim -
process simplifi cation to catalyst-free route
2) copper-catalyzed processing using one-step fl ow synthesis starting from hazardous
organic azide; aim - process simplifi cation to one elemental path by using smart catalyst.
Simplifi cation is also the motif for process design analysis of the oxidation of cyclohexane/
cylcohexene:
1) multiple chemically advanced routes with the classical air oxidant of cyclohexane (or by
photo and even ozone) to cyclohexanone (even further to ε-caprolactam) or formation
of oxime from cyclohexane by using nitrosyl chloride;
2) one-step direct oxidation of cyclohexene to adipic acid with hydrogen peroxide (or even
ozone) as oxidant;
3) double-direct route starting from H 2 and O 2 .
The known chemical rate acceleration of the Claisen rearrangement through high-p, T
processing will be used for subtle mechanistic analysis on:
1) selectivity and stereoselectivity issues at ring intermediate;
2) increasing space-time yield under the correspondingly short residence times, all
accompanied by theoretical considerations.
Selectivity and conversion effects through tunable solvents and process integration (reactionseparation)
are studied for the n-octene hydroformylation:
1) supercritical CO2 to decrease phase number;
2) nanoporous membranes for homogeneous catalyst separation;
3) possibly fl uorous solvents for catalyst separation;
4) possibly heterogeneous catalyst. Such new process chemistry will provide new conceptions
for system (multi-scaled multi-integrated microreactors) and process design at a pilot and
production level.
Through cost- and life-cycle analysis in a generic way it shall be ensured that the fi ndings are
mutually exploited and then can be transferred to a large number of reactions.
(1) Wirth T., Microreactors in organic synthesis and catalysis, Wiley-VCH, 2008.
(2) Hessel V., Renken A., et al., Handbook of micro-reactor engineering and micro-reactor
chemistry, three-volume edition, Wiley-VCH, Weinheim, 2009.
(3) Hessel V., Chem. Eng. Technol. 32 (2009) 1655-1681.
(4) Razzaq T., Glasnov T. N., et al., European J. Org. Chem. (2010) 1321-1325.
(5) Murphy E. R., Martinelli J. R., et al., Angew. Chem. Int. Ed. 119 (2007) 1764.
(6) Bourne R. A., Han X., et al., Angew. Chem. 121 (2009) 5426 –5429.
(7) Mehnert C. P., Cook R. A., et al., J. Am. Chem. Soc., 124 (2002) 12932-12933
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Lake Como
2|4 October 2011