Basic Guidelines for
Microwave Organic Chemistry
Applications
By Laura Favretto
Microwave Organic Chemistry
Application Specialist
MicroSYNTH
START
UNI EN ISO 9001:2000
Vision certified
Basic Guidelines for Microwave Organic Chemistry Applications
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
INDEX
1.
Introduction
Page 2
2.
How to convert a conventional reaction
into a microwave reaction
• Solvent
• Temperature-Time
• Vessel
• Microwave program
• Stirring
Page 3
Page 3
Page 4
Page 5
Page 6
3.
When and how to use Weflon
Page 6
4.
How to regulate microwave power
Page 7
5.
How to optimize the microwave program
Page 8
6.
How to optimize the reaction condition
Page 9
7.
How to use the rotor
Page 9
8.
When it is possible to open the reactor
Page 10
9.
What to do when an exothermic is present
Page 10
10. Is it possible to use microwave at constant
power
Page 11
11. How to perform solid state reaction
Page 11
12. How to work with metal powder
(heterogeneous solution)
Page 13
13. Maximum heating time
Page 13
14. Which chemistry is not suitable
for microwave
Page 14
15. Solvent Library
• Solvent List
• Solvent Graphics
Page 15
Page 28
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
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Basic Guidelines for
Microwave Organic Chemistry Application
1. INTRODUCTION
The main advantages of microwave assisted organic synthesis are:
a) Faster reaction: the microwave can use higher temperatures than
conventional heating system, and consequently the reactions are
completed in few minutes instead of hours.
b) Better yield and higher purity: less formation of side product are
observed using microwave irradiation, and the product is recovered in
higher yield. Consequently, also the purification step is faster and
easier.
c) Easy scale-up: MicroSYNTH, with its technology and large range
of reactor vessels, allows scale-up from few milliliters to one liter
without changing reaction parameters.
d) Reproducibility: the patented microwave diffuser for homogeneous
microwave irradiation inside the cavity and precise control of reaction
parameters, such as temperature, pressure and power, always reproduces the same reaction conditions. It is very simple to save and
use an optimized synthesis method.
e) Easy to use: all the reactors and software are very easy to use and
all reactions can be easily moved from conventional to microwave
heating.
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Basic Guidelines for
Microwave Organic Chemistry Application
2. HOW TO CONVERT A CONVENTIONAL REACTION INTO A
MICROWAVE REACTION
When the reaction is performed the first time under microwave
irradiation, run the reaction in small scale, slowly increasing the
temperature.
The parameters that are needed to be defined are:
- solvent
- temperature-time
- vessel
- microwave program
Solvent
The same solvent that is usually used with conventional heating
chemistry can also be used with microwave heating.
Solvents interact differently with microwaves, depending on their
polarity. Polar solvents (alcohols, DMF, water, ketone, acid) couple
well with microwaves and reach high temperatures in a short time.
Non-polar solvents (toluene, chloroform, hexane) are transparent to
microwaves. Therefore, two situations are possible:
1) non polar solvent, but polar reagents or at least one polar
reagent: the reaction mixture is heated by microwave.
2) non polar reaction mixture (both solvent and reagents).
(Weflon has to be added in order to heat the mixture. For
more information, see chapter 3 “When and how to use
Weflon”).
Temperature-Time
a) 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.
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Basic Guidelines for
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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 Time
(°C)
80
90
100
110
120
130
140
150
8h
4h
2h
60 min
30 min
15 min
8 min
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.
b) If the reaction has never been performed before with conventional or
microwave heating, fix the temperature at 30-40°C higher than the
boiling point of the solvent, and run the reaction for 10 minutes.
Then check the obtained reaction mixture.
Vessel
All reactors that work with the MicroSYNTH have different:
a) volume limit
b) temperature limit
c) pressure limit
When the target temperature is fixed, consult the solvent library in
chapter 15 (also present in the “EasyWAVE” software). Check which
vapor pressure is developed from the solvent at the chosen
temperature. Based on this value, and on the volume that is needed,
decide the appropriate reactor vessel.
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Basic Guidelines for
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Example:
The target temperature of the reaction is 150°C in EtOH. Based on the
solvent library and on the graphic temperature vs. pressure (see
graphic below), it is possible to predict that a pressure of 10 bar will be
developed during the reaction.
If the reaction is completely unknown, and there is possible exothermic
reaction or development of gas during the test, use the vessel with the
highest specification of temperature and pressure (for example the 100
ml High Pressure reactor (Tmax = 250°C, pmax = 55 bar)).
Microwave program
The microwave program usually consists of two steps:
The first step is the ramp to reach the target temperature.
The second step is to keep the temperature for the desired reaction
time. The second step is always the same for all sample amounts.
In any case, a maximum total program time of 1 hour is advised.
The first step must be regulated on the base of:
- sample amount
- characteristics of solvent
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Basic Guidelines for
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- Polar mixture:
- small amount (up to 30 mL): the increasing of the temperature
can be fixed in the rate 25°C/min.
For example a suitable ramp for 15 mL of DMF could be
Time Power Temperature (°C)
(min) (Watt)
6
500
room temp to190
Step1
- large amount (more than 30 mL): the first step needs to be
longer. In this case, it’s advised an increase of 10°C/min
- Non polar mixture:
see the below “When and how to use Weflon” .
Stirring
Always put a stir bar in every reactor/vessel when a reaction is run.
This enhances temperature, and therefore, reaction uniformity.
3) WHEN AND HOW TO USE WEFLON
When the reaction mixture (reagents and solvent) are not polar, the
Weflon is necessary in order to heat the solution. When Weflon is
used, it’s necessary to use low value of microwave power and long
heating ramp. This is necessary as there is a time lapse due to the
transfer of heat from the Weflon to the solution.
In this case, it’s advised to build the ramp with 4 steps: ramp up to the
boiling point of the solvent with a rate of 15°C/min and keep the
temperature for 1-2 minutes; ramp up to the fixed temperature with a
rate of 5°C/min and keep the temperature for the desired time.
The maximum power value to use is 500 Watt.
If Weflon is used in one vessel, then it should be used in every vessel
when processing multiple reactions simultaneously.
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Basic Guidelines for
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An example of Toluene heating ramp with Weflon is reported below:
MonoPREP P/N MOP0000, 20 mL of toluene in P/N QRS1550, stirring
bar P/N 86116 and Weflon button P/N WO1703:
Time Power Temperature
(min) (Watt)
(°C)
5
500
110
2
400
110
15
500
160
5
500
160
Step1
Step2
Step3
Step4
Below is the temperature profile of 20 mL of Toluene
Toluene,20 mL, 160C
200
1,000
[3] 160
900
[4] 160
800
700
[1] 110 [2] 110
600
100
500
400
P ow e r [W a tt]
Te m pe ra ture [°C]
150
300
50
200
20
100
0
00:05:00
00:10:00
00:15:00
00:20:00
00:25:00
00:30:00
0
00:35:00
Time [hh:mm:ss]
T1 Set Values
Pow er
Temp. 1
Temp. 2
If the temperature is not following the temperature profile, change the
time using longer ramp, but do not increase the power.
4) HOW TO REGULATE THE MICROWAVE POWER
The value of the maximum microwave power depends on the amount
of sample and of the number of reaction vessel. Up to 30 mL of
volume and/or up to three vessels, 400-500 Watt of microwave
power is enough to heat the reaction mixture.
If the temperature is not following the designed temperature profile, use
longer heating time (step n. 1), but do not increase the power.
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Basic Guidelines for
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For example:
MonoPREP with 15 mL of water:
Time Power Temperature
(min) (Watt)
(°C)
3
400
150
Step1
5
300
150
Step2
When large volume or more than three reactors are used with the
rotor, it’s better to use an higher value of power (about 700-800
watt) and longer heating ramp.
For example:
PRO-6 with 15 mL of water in each vessel, use the following heating
program:
Step1
Step2
Time Power Temperature
(min) (Watt)
(°C)
10
800
150
5
700
150
PRO-24 with 10 ml of isopropanol in each vessel, use the following
heating program:
Step1
Step2
Time Power Temperature
(min) (Watt)
(°C)
16
1000
150
10
800
150
5) HOW TO OPTIMIZE A MICROWAVE PROGRAM
1) if the temperature doesn’t follow the designed profile, make the
ramp longer and/or increase the power.
2) if during the heating ramp the temperature overshoots, reduce
the value of microwave power of about 100-150 Watt.
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Basic Guidelines for
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In any case, remember that at high temperatures the solvents
change their behavior. In general, their polarity decreases and
they require more power to reach the desired temperature.
For this reason, temperature spikes may be present at the
beginning, but decrease or disappear at higher temperatures.
6) HOW TO OPTIMIZE THE REACTION CONDITIONS
After the first run of the reactions, there could be four different cases:
1) the reaction is complete (the starting material is not present any
more): transfer the mixture in a proper glassware and proceed
with the usual work-up of the reaction
2) the reaction starts to work but is not complete (some starting
material is still present):
- extend the reaction time
- increase the temperature (not over the temperature and
pressure limit of the vessel)
3) the reaction doesn’t work at all:
- extend the time
- increase the temperature
- use more equivalent of one of the starting material or of
the catalyst
4) decomposition of the reagents:
- use lower temperature
- use short reaction time
Note: always remember to check the temperature and pressure limit of
the vessel before increasing the temperature.
7) HOW TO USE THE ROTOR
When a rotor is utilized (with multiple vessels), it is necessary to use
- the same solvent in all the vessels
- similar chemistry, i.e. same reaction, changing only one
substituent of one reagent at time
Temperature and pressure are measured in one vessel, called
reference vessel. This ensures the same conditions of temperature
and pressure in all the vessels of the rotor.
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Basic Guidelines for
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For example, if the Heck reaction is considered:
Br
Pd(OAc)2, PPh3
+
MeOOC
R
COOMe
DMF
R
Heck reaction
R = - OMe
- NO2
- Cl
-H
- CHO
The nature of the group R- in the aryl bromide compound could be
changed in each vessel in order to verify how the R- substituent
influences the coupling reaction.
If the catalyst varies from vessel to vessel, use the high concentration
of catalyst in the reference vessel. In fact, the higher concentration of
catalyst is usually the most reactive one, and needs to be controlled.
The rotor can be used also to perform the same reaction in all the
vessels.
8) WHEN IT IS POSSIBLE TO OPEN THE REACTOR
Before opening the vessel, it’s always better to wait at least until the
temperature is 10°C below the boiling point of the solvent to be sure
there isn’t any pressure inside the vessel. It is recommended to open
the reactor slowly under a fume hood.
9) WHAT TO DO WHEN AN EXOTHERMY IS PRESENT
If a very fast increase of temperature is noticed during the ramp-step of
the reaction (80-100°C/min),
immediately stop the microwave
program. Probably one reagent is highly reactive and the efficient
microwave heating creates a large exothermic effect in the reaction.
For example, a big exothermic effect (100°C in less than minute) has
been observed in the alkylation of a primary ammine. No problem is
observed with secondary or tertiary ammine.
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Basic Guidelines for
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Also, the presence of a salt in a solution (for example salt plus water)
has shown a large reactivity with microwave. In this case, it is better to
use:
- a small amount of salt (to have a small “ionic conduction” effect)
- a small quantity of power
- long heating ramp.
10) IS IT POSSIBLE TO USE MICROWAVE AT CONSTANT POWER
A microwave program at constant power can be used, but only with
an open system. In this case the maximum temperature that can be
reached is the boiling point of the solvent. The two parameters that
need to be fixed are: time and power.
Constant power is not recommended in closed vessels because the
temperature can rise without limit, and the vessels can be damaged.
11) HOW TO PERFORM SOLID STATE REACTION
In the case of solid state reaction, two situations can be considered:
a) reagent absorption on solid support (as silice or alumina)
b) reaction between neat reagent (liquid-liquid, liquid-solid)
a) reagents absorption on solid support: in this case a very efficient
stirring is needed. Magnetic stirring is not enough, and
mechanical stirring is required in order to have an homogeneous
heating of the solid and to be sure that no hot spots are present
in the mixture. In this case, a specific modification of the
labstation is required to have a more efficient stirring
b) reaction between neat reagents: here, three cases can be
distinguished:
-
the two reagents are liquid: proceed as standard reaction with
solvent
For example, the synthesis of the ionic liquid 1-Butyl-3methylimidazolium chloride is run between neat reagents under
microwave irradiation. Both reagents, the butyl chloride (bp =
77°C) and the 1- methylimidazole (bp = 198°C), are liquid at
room temperature.
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Me N
N
+ BuCl
Me N
N
Bu
+
Cl-
Synthesis of 1-butyl-3-methylimidazolium chloride
-
one reagent is liquid (in large quantity as a solvent), one is solid:
presence of heterogeneous mixture, use a good magnetic
stirring and proceed as a standard reaction in an open or closed
system
For example, in the hydrolysis of benzamide, one reagent
(benzamide) is solid, the other one, the 20% sulfuric acid, is a
liquid present in large quantity (ratio benzamide/sulfuric acid:
100 mg benzamide/ml sulfuric acid)
O
O
NH2
20% H2SO4
OH
Hydrolysis of benzamide
-
the two reagents are solid: two cases can be considered:
•
the two solid reagents are melted during the heating:
if the quantity is small (up to 5-10 grams), the reaction
can be run with standard magnetic stirring.
if quantity is large, a specific stirring system is required
(see chapter 11, point a).
For example, in the synthesis of 4,5-diphenyl-4imidazolin-2-one,
N
OH
NH2
N
+ O
O
NH2
Condensation of benzoine and urea
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O
Basic Guidelines for
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•
-
the two reagents (benzoin and urea) have a melting
point of 130°C. The reaction is usually performed at
150°C. At this temperature both the reagents are
liquid and the reaction can be run under standard
conditions.
the two solid reagents remain solid during the reaction:
specific stirring system is required (see chapter 11, point a)
12) HOW TO WORK WITH METAL POWDER (HETEROGENEOUS
SOLUTION)
Metal powders in the reaction mixture can create a spark and source of
ignition that it is possible to prevent in a solvent environment.
In order to reduce the risk of exothermic reaction, it is recommended:
- That the metal powders always be completely submerged in the
solvent and that the vessel be purged with inert gas (Nitrogen,
Argon) before closing.
- Good stirring of the mixture is needed to ensure a homogeneous
distribution of the powders.
- Use the minimum amount of catalyst.
- Make sure when using the 100 mL/ 270 mL/ or PRO 16/24 TFM
reactors, that all the reaction solids (catalyst, etc.) are rinsed
down into the solvent pool and do not adhere to the sides of the
vessel. Catalyst “sticking” to the side of the vessel wall can
absorb microwave energy excessively, resulting in vessel “melt
down”.
- Never use metal without solvent.
13) MAXIMUM HEATING TIME
To avoid overheating the reactor, the maximum heating time for a
reaction is one hour.
If a longer reaction time is needed, repeat the same program more
times for one hour.
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Basic Guidelines for
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14) WHICH CHEMISTRY IS NOT SUITABLE FOR MICROWAVE
Reactions that are extremely exothermic should not be performed in
the instrument. Hydrogen peroxide is, for example, not suitable to use
at high temperature, regardless of the technique, because it is
explosive. When working with reaction mixtures that contain large
amounts of ions or that can release gases, extra precaution is
advisable since the heating rate might be very high and the pressure
increase may be correspondingly quick due to the closed vessel
system. In this case, the experiment can be performed at low
concentration (very diluted solution).
Ionic liquids are often used as an alternative for organic solvent or as a
co-solvent for microwave transparent (non polar) reaction mixtures.
Ionic liquids are environmentally friendly, recyclable alternatives to
dipolar solvents. Their dielectric properties make then highly suitable
for use as solvents or additives as they absorb microwaves efficiently.
Consequently, their heating rate is very high and the temperature rises
very quickly. Therefore, to avoid an exothermic reaction, it is
recommended to use a small amount of the ionic liquid.
The recommended ratio is 0.2 mmol of ionic liquid/ 2 ml of solvent.
Example:
1-butyl-3-methylimidazolium hexafluorophosphate:
Me N
N
Bu
+
PF6-
PM = 284.2 and density 1.37 g/ml
0.2 mmol correspond to 56 mg of reagent and in term of volume is 41
µl, or 0.04 ml.
The ratio solvent: ionic liquid is: 2:0.04 = 50.
The amount of ionic liquid needed to heat up the solvent is very small
but sufficient and ensures safety when working with them.
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LIST OF THE COMMON SOLVENTS USED
Solvent Name
Boiling Point [°C]
(+)-Camphor
207,4
59,5
(Trifluoromethyl)benzene
102,1
32,6
1,1,2,2-Tetrabromoethane
243,5
48,7
1,1,2,2-Tetrachloro-1,2-d
92,8
dH evap [KJ/mol]
35
1,1,2-Trichloroethane
113,8
34,8
1,1,2-Trichlorofluoroetha
47,7
27
1,1-Dichloroethane
57,4
28,9
1,1-Dichloroethylene
31,6
26,1
1,1-Difluoroethane
-24,9
21,6
1,2,3,4-Tetrahydronaphtha
207,6
43,9
1,2,3-Trichloropropane
157
37,1
1,2-Dibromoethane
131,6
34,8
1,2-Dibromopropane
141,9
35,6
1,2-Dibromotetrafluoroeth
47,3
27
1,2-Dichloroethane
83,5
32
1,2-Dichlorotetrafluoroet
3,8
23,3
1,2-Epoxybutane
63,3
30,3
1,2-Propanediol
187,6
52,4
1,3-Butanediol
207,5
58,5
1,3-Propanediol
214,4
57,9
1,4-Dioxane
101,5
34,2
1,5-Pentanediol
239
60,7
1-Bromobutane
101,6
32,5
1-Bromonaphthalene
281
39,3
1-Bromopentane
129,8
35
1-Bromopropane
71,1
29,8
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Solvent Name
1-Butanethiol
Boiling Point [°C]
dH evap [KJ/mol]
98,5
32,2
117,7
43,3
1-Chloro-2-methylpropane
68,5
29,2
1-Chloro-3-methylbutane
98,9
32
1-Chlorobutane
78,6
30,4
1-Butanol
1-Chloronaphthalene
259
52,1
1-Chloropentane
107,8
33,2
1-Chloropropane
46,5
27,2
1-Decene
170,5
38,7
1-Dodecene
213,8
44
1-Hexanol
157,6
44,5
1-Hexene
63,4
28,3
1-Iodo-2-methylpropane
121,1
33,5
1-Iodobutane
130,6
34,7
1-Iodopropane
102,6
32,1
1-Methylcyclohexanol
155
79
1-Methylnaphthalene
244,7
45,5
1-Nitropropane
131,1
38,5
1-Octanol
195,1
46,9
1-Octene
121,2
34,1
1-Pentanol
137,9
44,4
1-Pentene
29,2
25,2
1-Propanol
97,2
41,4
2,2,3-Trimethylbutane
80,8
28,9
2,2,3-Trimethylpentane
110
31,9
2,2,4,4-Tetramethylpentan
122,2
32,5
99,2
30,8
2,2,4-Trimethylpentane
2,2,5-Trimethylhexane
124
33,7
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Solvent Name
Boiling Point [°C]
dH evap [KJ/mol]
2,2-Dimethylbutane
49,7
26,3
2,2-Dimethylhexane
106,8
32,1
2,2-Dimethylpentane
79,2
29,2
2,3,3-Trimethylpentane
114,8
32,1
2,3,5-Trimethylhexane
131,4
34,4
2,3-Dimethylbutane
57,9
27,4
2,3-Dimethylpentane
89,7
30,5
170,6
39,9
80,4
29,6
2,4-Lutidine
158,5
38,5
2,4-Xylenol
210,9
47,1
2,5-Xylenol
211,1
46,9
2,6-Lutidine
144,1
37,5
2,6-Xylenol
201
44,5
2,4,6-Trimethylpyridine
2,4-Dimethylpentane
2-Bromo-2-methylpropane
73,3
29,2
2-Bromobutane
91,2
30,8
2-Bromopropane
59,5
28,3
2-Butanol
99,5
40,8
2-Chloro-2-methylpropane
50,9
27,6
2-Chlorobutane
68,2
29,2
2-Chloropropane
35,7
26,3
2-Ethyl-1-butanol
147
43,2
2-Ethyl-1-hexanol
184,6
54,2
2-Ethylhexyl acetate
199
43,5
2-Ethylhexylamine
169,2
40
2-Hexanol
140
41
2-Iodobutane
120
33,3
2-Iodopropane
89,5
30,7
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Solvent Name
Boiling Point [°C]
dH evap [KJ/mol]
2-Methyl-1-butanol
128
45,2
2-Methyl-1-pentanol
149
50,2
2-Methyl-1-propanol
107,8
41,8
2-Methyl-2-butanol
102,4
39
2-Methyl-2-pentanol
121,1
39,6
2-Methyl-2-propanol
82,4
39,1
2-Methylheptane
117,6
33,3
2-Methylhexane
90
30,6
2-Methylpentane
60,2
27,8
103,9
32,4
12,6
33,9
2-Nitropropane
120,2
36,8
2-Octanol
180
44,4
2-Pentanol
119,3
41,4
2-Picoline
129,3
36,2
2-Propanol
82,3
39,9
3,3-Diethylpentane
146,3
34,6
3,3-Dimethylhexane
111,9
32,3
3,3-Dimethylpentane
86
29,6
3,4-Dimethylhexane
117,7
33,2
3,4-Xylenol
227
49,7
3,5-Xylenol
221,7
49,3
3-Ethyl-2-methylpentane
115,6
32,9
3-Ethyl-3-methylpentane
118,2
32,8
3-Ethylhexane
118,6
33,6
3-Ethylpentane
93,5
31,1
2-Methylpropanenitrile
2-Methylthiophene
3-Heptanol
157
42,5
3-Methyl-1-butanol
131,1
44,1
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Solvent Name
Boiling Point [°C]
dH evap [KJ/mol]
3-Methyl-2-butanol
112,9
41,8
3-Methylheptane
116,5
33,7
3-Methylhexane
92
30,9
3-Methylpentane
63,2
28,1
3-Methylthiophene
115,5
34,2
3-Pentanol
116,2
43,5
3-Picoline
144,1
37,4
4-Methyl-2-pentanol
131,6
44,2
4-Methylheptane
117,7
33,4
4-Picoline
145,3
37,5
Acetal
102,2
36,3
20,1
25,8
Acetic acid
117,9
23,7
Acetic anhydride
139,5
38,2
Acetone
56
29,1
Acetonitrile
81,6
29,8
Acetaldehyde
Acetonphenone
202
38,8
Acetylacetone
138
34,3
Acrolein
52,6
28,3
Acrylonitrile
77,3
32,6
Allyl acetate
103,5
36,3
Allyl alcohol
97
40
Aniline
184,1
42,4
Anisole
153,7
39
Benzaldehyde
179
42,5
80
30,7
Benzenethiol
169,1
39,9
Benzonitrile
191,1
45,9
Benzene
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 April 2004 Milestone Srl
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Basic Guidelines for
Microwave Organic Chemistry Application
Solvent Name
Boiling Point [°C]
dH evap [KJ/mol]
Benzyl acetate
213
49,4
Benzyl alcohol
205,3
50,5
Benzyl benzoate
323,5
53,6
Bis(2-chloroethyl) ether
178,5
45,2
Bromochloromethane
68
30
Bromoethane
38,5
27
Bromoethylene
15,8
23,4
Bromomethane
3,5
23,9
Butanal
74,8
31,5
Butane
-0,5
22,4
Butanenitrile
117,6
33,7
Butanoic anhydride
200
50
Butyl acetate
126,1
36,3
92,3
31,6
Butyl formate
106,1
36,6
Butyl methyl ketone
127,6
36,4
Butyl vinyl ether
94
31,6
Butylamine
77
31,8
Butylbenzene
183,3
38,9
Butyrolactone
204
52,2
Carbon disulfide
46
26,7
Chlorobenzene
131,7
35,2
Chlorodifluoromethane
-40,7
20,2
Chloroethane
12,3
24,7
Chloroethylene
-13,3
20,8
Chloromethane
-24
21,4
Chloropentafluoroethane
-37,9
19,4
Chlorotrifluoromethane
-81,4
15,8
Butyl ethyl ether
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 April 2004 Milestone Srl
Page 20
Basic Guidelines for
Microwave Organic Chemistry Application
Solvent Name
Boiling Point [°C]
cis-1,2-Dichloroethylene
cis-1,2-Dimethylcyclohexa
cis-2-Pentene
dH evap [KJ/mol]
60,1
30,2
129,8
33,5
36,9
26,1
cis-Decahydronaphthalene
195,8
41
Cumene
152,4
37,5
Cyclohexane
Cyclohexanone
Cyclohexene
Cyclohexylamine
Cyclopentane
80,7
30
155,4
40,3
82,9
30,5
134
36,1
49,3
27,3
Cyclopentanone
130,5
36,4
Decane
174,1
38,8
97
32,9
Dibutyl ether
140,2
36,5
Dibutyl phthalate
340
79,2
Dibutyl sulfide
185
41,3
Dibutylamine
159,6
38,4
Dichlorodifluoromethyane
-29,8
20,1
8,9
25,2
Dibromomethane
Dichlorofluoromethane
Dichloromethane
40
28,1
Diethanolamine
268,8
65,2
Diethyl carbonate
126
36,2
Diethyl ether
34,5
26,5
Diethyl ketone
101,9
33,5
Diethyl malonate
200
54,8
Diethyl oxalate
185,7
42
Diethyl sulfide
92,1
31,8
Diethylamine
55,5
29,1
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 April 2004 Milestone Srl
Page 21
Basic Guidelines for
Microwave Organic Chemistry Application
Solvent Name
Boiling Point [°C]
dH evap [KJ/mol]
Diethylene glycol
245,8
52,3
Diethylene glycol diethyl
188
49
Diiodomethane
182
42,5
Diisobutyl ketone
169,4
39,9
Diisopentyl ether
172,5
35,1
Diisopropyl ether
68,5
29,1
Diisopropyl ketone
125,4
34,6
Diisopropylamine
83,9
30,4
Dimethyl disulfide
109,8
33,8
Dimethyl ether
-24,8
21,5
Dimethyl sulfide
37,3
27
Dimethyl sulfoxide
Dimethylamine
189
6,8
43,1
26,4
Diphenyl ether
258
48,2
Dipropyl ether
90
31,3
Dipropylamine
109,3
33,5
Dodecane
216,3
44,5
78,2
38,6
Ethanol
Ethanolamine
171
49,8
Ethyl acetate
77,1
31,9
Ethyl acrylate
99,4
34,7
121,5
35,5
54,4
29,9
Ethyl butanoate
Ethyl formate
Ethyl isovalerate
135
37
Ethyl propanoate
99,1
33,9
Ethyl vinyl ether
35,5
26,2
Ethylbenzene
136,1
35,6
Ethylcyclohexane
131,9
34
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 April 2004 Milestone Srl
Page 22
Basic Guidelines for
Microwave Organic Chemistry Application
Solvent Name
Boiling Point [°C]
dH evap [KJ/mol]
Ethylene glycol
197,3
50,5
Ethylene glycol diacetate
190
45,5
Ethylene glycol diethyl e
119,4
36,3
Ethylene glycol dimethyl
85
32,4
143
43,9
Ethylene glycol monoethyl
Fluorobenzene
Formic acid
Furan
84,7
101
31,2
22,7
31,5
27,1
Furfural
161,7
43,2
Furfuryl alcohol
171
53,6
Glycerol
290
61
Heptane
98,5
31,8
Hexafluorobenzene
80,2
31,7
Hexane
68,7
28,9
Hexylene glycol
197,1
57,3
Iodobenzene
188,4
39,5
Iodoethane
72,5
29,4
Iodomethane
42,5
27,3
Isobutane
-11,7
21,3
Isobutyl acetate
116,5
35,9
Isobutyl formate
98,2
33,6
148,6
38,2
67,7
30,6
172,7
37,8
27,8
24,7
Isopentyl acetate
142,5
37,5
Isopentyl isopentanoate
190,4
45,9
88,6
32,9
Isobutyl isobutanoate
Isobutylamine
Isobutylbenzene
Isopentane
Isopropyl acetate
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 April 2004 Milestone Srl
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Basic Guidelines for
Microwave Organic Chemistry Application
Solvent Name
Isopropylamine
Boiling Point [°C]
31,7
dH evap [KJ/mol]
27,8
Isoquinoline
243,2
49
m-Cresol
202,2
47,4
m-Dichlorobenzene
173
38,6
m-Toluidine
203,3
44,9
m-Xylene
139,1
35,7
Mesityl oxide
130
36,1
Mesitylene
164,7
39
Methanol
64,6
35,2
Methyl acetate
56,8
30,3
Methyl acrylate
80,7
33,1
Methyl ethyl ketone
79,5
31,3
Methyl formate
31,7
27,9
Methyl isobutyl ketone
116,5
34,5
Methyl pentyl ketone
151
38,3
Methyl propyl ketone
102,2
33,4
Methyl salicylate
222,9
46,7
Methylacrylonitrile
90,3
31,8
Methylamine
-6,3
25,6
Methylcyanoacetate
200,5
48,2
Methylcyclohexane
100,9
31,3
Methylcyclopentane
71,8
29,1
Methylmethycrylate
100,5
36
Morpholine
128
37,1
N,N-Dimethylacetamide
165
43,4
N,N-Dimethylformamide
153
38,4
Naphtalene
217,9
43,2
9,4
22,7
Neopentane
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 April 2004 Milestone Srl
Page 24
Basic Guidelines for
Microwave Organic Chemistry Application
Solvent Name
Boiling Point [°C]
dH evap [KJ/mol]
Nitroethane
114
38
Nitromethane
101,1
34
Nonane
150,8
36,9
o-Chloraniline
208,8
44,4
o-Chlorotoluene
159
37,5
o-Cresol
191
45,2
o-Dichlorobenzene
180
39,7
o-Fluorotoluene
115
35,4
o-Toluidine
200,3
44,6
o-Xylene
144,5
36,2
Octane
125,6
34,4
Octanoic acid
239
58,5
Oleic acid
360
67,4
p-Chlorotoluene
162,4
38,7
p-Cresol
201,9
47,5
p-Cymene
177,1
38,2
p-Dichlorobenzene
174
38,8
p-Fluorotoluene
116,6
34,1
p-Toluidine
200,4
44,3
p-Xylene
138,3
35,7
Pentachloroethane
159,8
36,9
36
25,8
Pentanenitrile
141,3
36,1
Pentanoic acid
186,1
44,1
Pentyl acetate
149,2
41
Pentylamine
104,3
34
Pentane
Perfuorobutane
-1,9
22,9
Perfuorocyclobutane
-5,9
23,2
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 April 2004 Milestone Srl
Page 25
Basic Guidelines for
Microwave Organic Chemistry Application
Solvent Name
Boiling Point [°C]
dH evap [KJ/mol]
Phenetole
169,8
40,7
Phenol
181,8
45,7
Propanal
48
28,3
Propane
-42,1
19
Propanenitrile
97,1
31,8
Propanoic acid
141,1
32,3
Propanoic anhydride
170
41,7
Propyl acetate
101,5
33,9
Propyl formate
80,9
33,6
Propylamine
47,2
29,6
Pyridine
115,2
35,1
Pyrrole
129,7
38,8
Pyrrolidine
86,5
33
Quinoline
237,1
49,7
Salicylaldehyde
197
38,2
sec-Butylamine
63,5
29,9
Styrene
145
38,7
Succinonitrile
266
48,5
44
28,3
Tetrachloroethylene
121,3
34,7
Tetrachloromethane
76,8
29,8
Tetrahydrofuran
65
29,8
178
45,2
88
31,2
121
34,7
84
31,5
110,6
33,2
48,7
28,9
tert-Butylamine
Tetrahydrofurfuryl alcoho
Tetrahydropyran
Tetrahydrothiophene
Thiophene
Toluene
trans-1,2-Dichloroethylen
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 April 2004 Milestone Srl
Page 26
Basic Guidelines for
Microwave Organic Chemistry Application
Solvent Name
Boiling Point [°C]
dH evap [KJ/mol]
trans-1,2-Dimethylcyclohe
123,5
33
trans-2-Methylcyclohexano
167,5
53
trans-2-Pentene
36,3
26,1
trans-Decahydronaphthalen
187,3
40,2
Triacetin
259
57,8
Tribromomethane
149,1
39,7
Tributyl borate
234
56,1
Tributylamine
216,5
46,9
Trichloroethylene
87,2
31,4
Trichlorofluoromethane
23,7
25,1
Trichloromethane
61,1
29,2
235,4
45,7
Tridecane
Triethylamine
Triethylene glycol
Trifluoroacetic acid
Trimethylamine
89
31
285
71,4
73
33,3
2,8
22,9
Trinonafluorobutylamine
178
46,4
Vinyl acetate
72,5
34,6
Water
100
40,23
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 April 2004 Milestone Srl
Page 27
Basic Guidelines for
Microwave Organic Chemistry Application
GRAPHICS OF THE COMMON SOLVENTS USED
Page
Solvent
30
30
31
31
32
32
33
33
34
34
35
35
36
36
37
37
38
38
39
39
40
40
41
41
42
42
43
43
1-Butanol
1-Hexanol
1-Propanol
2-Butanol
2-Hexanol
2-Propanol
Acetone
Acetylacetone
Benzaldehyde
Butyl acetate
Chlorobenzene
Cyclohexane
Cyclohexene
Dibuthyl ether
Dibuthylamine
Dichloromethane
Diethyl ether
Ethanol
Ethyl acetate
Heptane
Hexane
Isobuthyl acetate
Methanol
Methyl ethyl ketone
Tetrahydrofuran
Toluene
Trichloromethane
Water
Page 28
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
1-Butanol
1-Hexanol
Page 29
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
1-Propanol
1-Butanol
Page 30
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
2-Hexanol
2-Propanol
Page 31
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Acetone
Acetylacetone
Page 32
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Benzaldehyde
Butyl acetate
Page 33
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Chlorobenzene
Cyclohexane
Page 34
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Cyclohexene
Dibuthyl ether
Page 35
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Dibuthylamine
Dichloromethane
Page 36
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Diethyl ether
Ethanol
Page 37
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Ethyl acetate
Heptane
Page 38
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Hexane
Isobuthyl acetate
Page 39
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Methanol
Methyl ethyl ketone
Page 40
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Tetrahydrofuran
Toluene
Page 41
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl
Basic Guidelines for
Microwave Organic Chemistry Application
Trichloromethane
Water
Page 42
Basic Guidelines for Microwave Organic Chemistry Application
Rev. 0/04 Milestone Srl