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.