DRC, Differential Reaction Calorimeter,
is used in laboratories working on the optimization of industrial processes and
the safety of
chemical reactions. It is a
laboratory reactor capable of simulating experimental industrial conditions,
permitting fast access to important
thermodynamic properties linked
with liquid-liquid and liquid-gas mixtures of chemical products: reaction heat,
mixing heat, reaction time, maximum
elevations of temperature during
reaction, monitoring of reaction kinetics, heat capacities, etc. Used as a
screening tool to determine reaction heats, the
DRC offers numerous advantages.
? Saving of the
products studied Due to its measurement principle, the DRC allows working on
very low product quantities (from 10 g). This saving of material is a
considerable
advantage when the reagents are
only available in small quantities or are very costly.
? Saving of time Operating time
using the DRC has been reduced to the minimum. 15 minutes are needed to start
and prepare the calorimeter before testing, 1 hour
to measure a classical reaction and
also 15 minutes to process the data. This time-saving results in an equivalent
reduction of delays in industrial development.
? Ease of use Thanks to its simple
design, the DRC is extremely user-friendly and easy to use. Designed by chemists
for chemists, it requires no specific training and can be used by everyone.
? Principle of
differential measurement The differential construction permits the elimination
from any reaction heat measurement of parasite variations due to
agitation, heat
dissipation into the walls, thermostat temperature and ambient temperature
variations.
?
Simultaneous measurement of reaction heat and heat capacity (Cp) Calibration of
the calorimeter by Joule effect, vital for every reaction enthalpy measurement,
also
permits
measuring the heat capacity of the chemical reaction.
Calibration is
carried out by dissipating a constant thermal power (Joule effect) into the
mixture during a specified time. The temperature of the liquid therefore rises
to reach an equilibrium value
which will be determined by the
heat flux balance and thus the heat capacity of the reaction mixture.
The major
innovation provided by the DRC is the possibility of measuring the heat of a
reaction and the heat capacity of the reaction mixture simultaneously. It is
also possible to monitor the variation of heat
capacity during the chemical reaction. ? Given the reaction heat and heat
capacity, it is possible to determine the elevation of temperature ΔT in
adiabatic mode.
? The capacity of measuring Qdos
(heat due to the introduction of a reagent at a temperature differing from that
of the environment) makes it possible to forego thermostating the liquid
added. Furthermore,
this cannot always be carried out.
Accessories The reagent can be introduced in
the reaction flask by using a syringe. It is possible, for example, to add one
or more electrochemical analysis
devices (pH-meter, conductivity
meter, etc.) and a gas scanning for hydrogenation study for instance.
Applications
The DRC is used
daily in development laboratories to optimize industrial processes and make them
safe. It has been used successfully to study a great? variety of reactions. The
following is a
Nonexhaustive list of reactions:
Oxidation reactions - Reduction reactions Hydrogenation - Epoxydation ?
Ozonization Bromination - Chloration ? Cyanuration Diazotization - Grignard
reactions
(organomagnesium) - Dehydrogenation
- Wolff Kishner reaction - Reformatsky reaction - Barton reaction Micka?l
reaction - Wittig reaction - Friedel and Crafts reaction (acylation) -
Decarboxylation
Esterification, transesterification
? Oximation Methylation - Tosylation ? Beckmann rearrangement -
Chlorosulfonation, Sulfonation Knoevenagelc condensation - Fermentation
Polymerization ?
Dissolution.
Principle of differential
measurement The DRC is based on the simple
principle of differential thermal analysis which measures, continuously, the
difference of temperature ΔT between a measurement reactor and a reference
reactor. The
measurement reactor is the receptacle of the reaction to be measured while the
reference reactor contains a solvent having chemical and physical properties
close to those of reagents
introduced in the reactor studied.
The two calorimetric reactors are two double skinned flasks connected in
parallel. A thermostated fluid circulates between the two skins, allowing the
operator to
determine the temperature desired.
This experimental mode is known as isoperibolic mode (the environment is kept at
constant temperature). The difference of temperature, measured by
platinum probes,
between the mixture in reaction and the reference, is recorded as a function of
time in order to obtain a thermogram characterized by a peak whose shape varies
as a
function
of the reaction under study. The heat released in the reaction environment is
calculated from the area of the reaction peak on the thermogram. Simple
calibration by Joule effect
before and after the reaction
supplies the productof the transfer coefficient by the area of exchange, UA. As
with any laboratory reactor, the operator can monitor visually the progression
of the reaction in
the reactor at any moment. The
technique is associated with a new data processing procedure that permits
calculation of heat capacities of solvents before a chemical reaction, thus
supplying the heat
capacity of the mixture during and
after the reaction.
DRC operating temperature range: from -80?C to 150?C Atmospheric pressure Calibration by Joule effect Reactor ? Double skinned flasks ? Volume: 100, 250 or 500 ml ? Material: Pyrex Stirrer ? Anchor shape ? Material: Teflon ? Speed: 50 to 1,000 rpm ? Torque: 30 N.cm Dosing system ? Dosing funnel ? Volume: 50 ml Probes ? Tantalum sheathed platinum probe
100W ? Joule effect probe ? pH-meter Cryo-thermostat ? Temperature control: ? 0.01?C The DRC has been developed with AVENTIS,
Neuville location.