Rapid determination of reaction order and rate constants of an imine synthesis reaction using a mesoscale oscillatory baffled reactor Fatimah R. Mohd Rasdi, Anh N. Phan ⇑ , Adam P. Harvey School of Chemical Engineering & Advanced Materials (CEAM), Newcastle University, Newcastle upon Tyne NE1 7RU, UK highlights " Reduce 75% the amount of reagent required when using a mesoOBR. " Highly reproducible kinetic data compared to typical beakers. " Produce more data per volume of reactants at steady state than batch screening. " Reduce 50% process development time compared to beaker batch screening. article info Article history: Received 6 November 2012 Received in revised form 1 February 2013 Accepted 18 February 2013 Available online 28 February 2013 Keywords: Reaction kinetics Imine synthesis Rate constant Mesoscale-OBR Steady-state Dynamic screening abstract The reaction of benzaldehyde with n-butylamine to form the imine (1-butanamine, N-(phenylmethyl- ene)) was chosen to demonstrate the ability of the mesoscale OBRs to rapidly screen process conditions and obtain kinetic data in both continuous ‘‘multi-steady state’’ and ‘‘dynamic screening’’ manner. The two methods give 98% degree of agreement, with clear step-changes between different residence times. In situ FTIR spectroscopy was used to determine concentrations in real time. The results showed that the average rate constant was 2.0  10 1 ± 0.006 mol 0.9 L 0.9 s 1 with about 1.0% different between the methods. In determining such kinetic information, the meso-OBR was able to reduce the process devel- opment time by about 50% of, and required 75% less reagent, compared to batch screening using standard beaker. Furthermore, the data was more reproducible with the average deviation three times lower across all the data points. Crown Copyright Ó 2013 Published by Elsevier B.V. All rights reserved. 1. Introduction Organic synthesis and reaction kinetics investigation are com- monly conducted at laboratory scale in batch standardized glass- ware [1,2]. This normally involves general mixing apparatus such as the magnetic stirrer or upright impeller mixer without baffles to break up the mixing flow. This leads to inconsistencies with regard to mass transfer, energy transfer and agitation during scale-up to pilot and industrial scale, necessitating time-consum- ing re-optimisation [3]. Laboratory- and pilot plant scale data can be very different. Furthermore, screening in typical laboratory ves- sels (50–500 mm diameter) leads to substantial reagent usage and waste generation [4]. One screening/process development laboratory-scale reactor that may address some of these problems is the ‘‘Mesoscale Oscil- latory Baffled Reactor’’ (meso-OBR). Typically Mesoscale-OBRs consist of 5 mm inner diameter tubes containing equally spaced baffles [5,6]. The mixing inside the reactor is achieved by superim- posing an oscillatory flow upon a net flow. The oscillatory flow can be created by the movement of piston and diaphragm placed at the bottom of the reactor, or various other designs. The fluid acceler- ates and decelerates, usually following a sinusoidal velocity time function, as shown in Fig. 1, in which as the flow accelerates up- wards or downwards, the vortices are formed downstream of the baffles. When the flow decelerates, these vortices are swept into the bulk fluid and subsequently unravel as flow accelerates in the opposite direction. Several baffle designs have been developed, including the ‘‘smooth periodic baffle’’ (SPC), integral baffle, centrally (axially) baffle and helical baffle. The SPC and integral baffle designs are suitable for shear-sensitive applications, such as in bioprocessing applications [7,8] whereas the sharp-edged centrally baffled design provides high shear, and which aids mixing in 2-phase liquid–li- quid systems. This design has been demonstrated for biodiesel screening, where it demonstrates more uniform mixing than smooth round helical wire baffles [9]. The helically baffled design has advantages for solid–liquid reactions as the main flow is less 1385-8947/$ - see front matter Crown Copyright Ó 2013 Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cej.2013.02.080 ⇑ Corresponding author. Tel.: +44 191 222 5747; fax: +44 191 222 5292. E-mail address: anh.phan@ncl.ac.uk (A.N. Phan). Chemical Engineering Journal 222 (2013) 282–291 Contents lists available at SciVerse ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej