Previously we performed successfully a reaction of 150 deg C by using solid acid catalyst under CEM Microwave reactor for half an hour but now I am unable to do the same reaction by using butyl imidazole based catalyst instead of solid acid catalyst. The solvent evaporated out after 140 deg C within a minute.
Butyl imidazole decreases the boiling point of the solvent (MIBK). You may vary the percentage of butyl imidazole to the lower side so that MIBK can survive upto 150 degree C.
Thank you Mr. Mahato for sparing your precious time and giving response. I have varied the percentage of imidazolium based IL but the condition remain same.Can you suggest me some references where butyl imidazole is effective in decreasing the b.p. of solvent.
Chemical components present in the system interact differently with microwaves, depending on their polarity. Polar solvents or reagents couple
well with microwaves and reach high temperatures in a short time.
Non-polar solvents are transparent to microwaves.
Temperature-Time:
If the reaction has already been performed with conventional heating, take in consideration the standard reaction temperature and time. Based on these two parameters, consider the Arrhenius equation, e.g. how the time decreases when the temperature increases. This law defines that every ten degrees that the temperature
increases, the time of the reaction is halved.
For example, if a reaction is run in EtOH at 80°C for 8 hours and the
Arrhenius law is applied, the time is reduced in accordance to the table
below:
Temperature (°C) Time
80 8 h
90 4 h
100 2 h
110 60 min
120 30 min
130 15 min
140 8 min
150 4 min
By increasing the temperature of 70°C, the time is reduced from 8
hours (480 minutes) to 4 minutes.
This simple procedure can be applied to all the reactions.
Reference: Basic Guidelines for Microwave Organic Chemistry Applications
By Laura Favretto
Microwave Organic Chemistry.
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