omation mbers - Society for Laboratory Automation and Screening

TP070
Kate Ross
University of Leeds
Chemistry
Woodhouse Lane
Leeds LS2 9JT United Kingdom
kater@chem.leeds.ac.uk
The Enhancement of Selectivity of a Pd-catalysed Three-component Cascade Reaction
Using Automated Parallel Synthesis and Multivariate Data Analysis
181
Co-Author(s)
Ronald Grigg
Automated parallel synthesis with multivariate analysis is described for the optimization of a Pd-catalysed threecomponent
cascade reaction of 7-buta-2,3-dienyl-1,3-dimethyl-3,7-dihydropurine-2,6-dione with iodobenzene
and morpholine. Certain reactions of this type can yield a single isomer, although this is not the case with every
reaction, the chemistry presented here being one where the selectivity of the reaction has not responded to routine
one-factor-at-a-time optimization. Statistical experimental design is employed in the investigation of the effect of
seven reaction factors on selectivity, yield and impurity levels. Reagent and phosphine stoichiometry, palladium
source, time, temperature and concentration are included in the design, which is completed in 20 reactions on
the Anachem SK233 Workstation with online HPLC monitoring. A solvent and base screen is then carried out
using the predicted optimal conditions; these factors were previously controlled, as the substantial number of
discrete variables involved is unsuited to the fractional factorial design. Instead, principal component analysis is
used in selection of solvents, so gaining maximum variation in solvent properties and insight into which of these
affect selectivity. Heterocyclic tertiary amines are chosen by pKa for screening as bases alongside alkali metal
carbonates and acetates. This investigation will yield two-fold results, not only in enhancement of the reaction
selectivity, but also information gained from a repeat design using optimized base and solvent conditions will reveal
the importance of the sequence of experimentation if significantly different results are obtained.
TP071
Stephan Rudlof
Fachhochschule Wiesbaden – University of Applied Sciences
Computer Science
Kurt-Schumacher-Ring 18
Wiesbaden D-65197 Germany
rudlof@informatik.fh-wiesbaden.de
Robustness and Flexibility for Scheduling
In a lab automation environment the real duration of an activity often cannot be predicted. This complicates
the construction of a good scheduling algorithm. Say there is a sequence of device activities performed on
different devices. If the successor of an activity has to be started immediately after its predecessor, the allocation
time for its device needs to be long. This leads to the concept of time buffers between subsequent activities
giving flexibility to the scheduler. As a consequence the resulting working plan will be robust against variability
in execution times and will have short allocation times. This paper describes an approach needing very few
parameters: minimal and maximal execution and delay times are sufficient. Just two delay parameters are sufficient
to model all kind of delays from a fixed time delay (if time is zero, there is no delay) to a very flexible spring-like
one. Together with the two activity execution time limits it is possible to keep the reservation times for devices low.
Finally an outlook to a generalization to higher order activities follows: if there is a recursive definition of activities,
higher order activities are composed of sub-activities, which may be composed, too; at the leafs there are atomic
(device) activities. The time buffer approach above can be used at different levels in such an activity tree. This
approach may be useful to develop powerful scheduling algorithms.
POSTER ABSTRACTS