The nitromethane initiator of the Friedel-Crafts naphthalene reaction using microwaves

Article abstract of DOI:10.1081/SCC-100106041

The alkylation of naphthalene using halogen derivatives may be achieved under very simple conditions by the Friedel-Crafts reaction. The products are obtained by irradiation of the paste containing the reaction mixture and a small quantity of nitromethane to initiate the reaction.

Full text of DOI:10.1081/SCC-100106041

This article was downloaded by: [Pennsylvania State University]
On: 03 June 2013, At: 18:07
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer
House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsyc20
THE NITROMETHANE INITIATOR OF THE FRIEDEL-
CRAFTS NAPHTHALENE REACTION USING
MICROWAVES
a
b
a
G. Brãtulescu , Y. Le Bigot & M. Delmas
a
Institut National Polytechnique de Toulouse, Ecole Nationale Supérieure de Chimie,
Laboratoire de Catalyse, Chimie Fine et Polymères, 118 route de Narbonne, Toulouse,
Cedex 4, 31077, France
b
Institut National Polytechnique de Toulouse, Ecole Nationale Supérieure de Chimie,
Laboratoire de Catalyse, Chimie Fine et Polymères, 118 route de Narbonne, Toulouse,
Cedex 4, 31077, France
Published online: 20 Aug 2006.
To cite this article: G. Brãtulescu , Y. Le Bigot & M. Delmas (2001): THE NITROMETHANE INITIATOR OF THE FRIEDEL-
CRAFTS NAPHTHALENE REACTION USING MICROWAVES, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 31:21, 3309-3313
To link to this article: http://dx.doi.org/10.1081/SCC-100106041
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to
anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation that the contents
will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses
should be independently verified with primary sources. The publisher shall not be liable for any loss, actions,
claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or
indirectly in connection with or arising out of the use of this material.

SYNTHETIC COMMUNICATIONS, 31(21), 3309–3313 (2001)
THE NITROMETHANE INITIATOR
OF THE FRIEDEL–CRAFTS
NAPHTHALENE REACTION
USING MICROWAVES
G. Bratulescu,Y. Le Bigot, * and M. Delmas
˜
Institut National Polytechnique de Toulouse,
Ecole Nationale Superieure de Chimie,
Laboratoire de Catalyse, Chimie Fine et Polyme
18 route de Narbonne,
´
`
res,
1
31077 Toulouse Cedex 4, France
ABSTRACT
The alkylation of naphthalene using halogen derivatives may
be achieved under very simple conditions by the Friedel–
Crafts reaction. The products are obtained by irradiation of
the paste containing the reaction mixture and a small quantity
of nitromethane to initiate the reaction.
The alkylation of naphthalene by the Friedel–Crafts reaction is, in
general, difficult to achieve (1–3). It requires high temperatures, very long
reaction times and the yields are nonetheless mediocre. Another method
of obtaining alkyl derivatives of naphthalene relies on the reactivity of
*
Corresponding author.
3
309
Copyright & 2001by Marcel Dekker, Inc.
www.dekker.com

ORDER
REPRINTS
˜
BRATULESCU,LE BIGOT,AND DELMAS
3
310
organometallic compounds (4), however, the operating conditions for this
procedure can be very delicate. Furthermore, these reactions are not selec-
tive and the yields are again limited (less than 50%).
Use of microwaves can sometimes favour certain reaction rates but
this technique often necessitates the use of absorbent supports. The separa-
tion of products from the absorbents, however, can at times reveal itself to
be difficult. With this in mind we have previously described methods for the
synthesis of ethers (5) and azoethers (6) with microwaves in the absence of a
support.
During previous work (7), we presented a process in which the absor-
bent support is replaced by a small quantity of ethanol. This addition of
ethanol initiates the chemical reaction by creating catalytic centres and has
the advantage of being easily extracted from the reaction mixture. However,
the alkylation of naphthalene reaction using microwaves was not initiated
by ethanol due to its reactivity with the constituents of the reaction mixture
in particular aluminium chloride and further cationic species.
The search for a ethanol substitute led us to choose nitromethane
because:
–
–
It is inert with regard to the other reactants.
It has sufficient polar characteristics to enable it to absorb micro-
waves (Table 1).
ꢀ
–
It has a relatively a low boiling point (101.2 C).
The alkylation of naphthalene is achieved with good yields (Table 2).
At the experimental level the reaction is carried out in two steps:
–
–
Preparation of the cation by the reaction of an halogen derivative
with aluminium chloride.
Addition of naphthalene with a few drops of nitromethane.
The obtained paste is irradiated in an open beaker for a very short
time (see Table 2). The strong polarity of nitromethane permits it to absorb
this radiation and to initiate the electrophilic substitution reaction.
Table 1. Comparison of the Polarity of Ethanol to That of
Nitromethane (8)
N
T
e
m
E ꢀ
EtOH
CH NO
24.55
35.94
5.8
11.9
51.9
46.3
3
2
*
-empirical parameters of solvent polarity.

ORDER
REPRINTS
FRIEDEL–CRAFTS NAPHTHALENE REACTION
3311
Table 2. Synthesis of 1-Alkylnaphthalene

ORDER
REPRINTS
˜
BRATULESCU,LE BIGOT,AND DELMAS
3
312
The separation of the absorbing support from the reaction medium is easily
achieved.
EXPERIMENTAL
All reagents were purchased from Aldrich.
Fusion points were measured using a Mettler Toledo apparatus.
Elemental analyses were performed with a Carlo Erba model 1106
apparatus.
IR/FT spectra were recorded on KBr pellets using a Perkin-Elmer
600 spectrometer.
1
A Optiquick Y71microwave oven was used: emission power ¼ 620 W,
ꢀ
¼ 12.2 cm.
Temperatures after irradiation were measured used a Hanna model HI
757 thermocouple thermometer.
8
EXPERIMENTAL PROCEDURE
Five mmol of the halogen derivative is added with vigorous mixing to
mmol of anhydrous aluminium chloride. The mixture obtained is then
5
added to an open beaker containing 5 mmol of finely grounded naphthalene.
After mixing and addition of 2 drops of nitromethane the resulting paste is
irradiated in a microwave oven for the required time (Table 2). Twenty mL
of water is then added and the paste vigorously mixed after which 20 mL of
chloroform is added, again with mixing. After phase separation and the
drying of the organic phase the chloroform is evaporated under vacuum
and the residue purified by recrystallisation in a mixture of ethanol : chloro-
form (1/1 vol.) or by distillation.
REFERENCES
1
. March, J. Advanced Organic Chemistry, John Wiley and Sons, 5th,
992, 536.
1
2. Beyer, H.; Walter, W. Handbook of organic chemistry, Prentice Hall,
Europe, London–Munich, 1996, p. 475.
3
4
5
. Banthorpe, D.V. Chem. Rew. 1970, 70, 295.
. Dixon, J.A.; Fishman, D.H. J. Am. Chem. Soc. 1963, 85, 1356.
. Bratulescu, G.; Le Bigot, Y.; Delmas, M.; Pogany, I. Revue. Roum.
Chim. 1998, 43, 321.

ORDER
REPRINTS
FRIEDEL–CRAFTS NAPHTHALENE REACTION
3313
6
7
8
9
. Bratulescu, G.; Le Bigot, Y.; Delmas, M. Synth. Commun. 1997,
7, 1037.
. Bratulescu, G.; Le Bigot, Y.; Delmas, M. Synth. Commun. 2000,
0, 171.
. Reichardt, C., Solvents and Solvent Effects in Organic Chemistry, VCH,
988, p. 365, 369, 408.
. Price, C.C.; Ciskowski, J.M. J. Am. Chem. Soc. 1938, 60, 2499.
2
3
1
1
1
1
1
0. Bradsher, C.K. J. Am. Chem. Soc. 1940, 62, 1077.
1. Mayer, F.; Schiffner, R. Ber. 1932, 65, 1337.
2. Bergman, F.; Weizmann, A. J. Org. Chem. 1944, 9, 352.
3. Bergman, F.; Szmuszkowicz, J.; Fawaz, G. J. Am. Chem. Soc. 1947,
69, 1773.
Received in the USA December 26, 2000

Request Permission or Order Reprints Instantly!
Interested in copying and sharing this article? In most cases, U.S. Copyright
Law requires that you get permission from the article’s rightsholder before
using copyrighted content.
All information and materials found in this article, including but not limited
to text, trademarks, patents, logos, graphics and images (the "Materials"), are
the copyrighted works and other forms of intellectual property of Marcel
Dekker, Inc., or its licensors. All rights not expressly granted are reserved.
Get permission to lawfully reproduce and distribute the Materials or order
reprints quickly and painlessly. Simply click on the "Request
Permission/Reprints Here" link below and follow the instructions. Visit the
U.S. Copyright Office for information on Fair Use limitations of U.S.
copyright law. Please refer to The Association of American Publishers’
(AAP) website for guidelines on Fair Use in the Classroom.
The Materials are for your personal use only and cannot be reformatted,
reposted, resold or distributed by electronic means or otherwise without
permission from Marcel Dekker, Inc. Marcel Dekker, Inc. grants you the
limited right to display the Materials only on your personal computer or
personal wireless device, and to copy and download single copies of such
Materials provided that any copyright, trademark or other notice appearing
on such Materials is also retained by, displayed, copied or downloaded as
part of the Materials and is not removed or obscured, and provided you do
not edit, modify, alter or enhance the Materials. Please refer to our Website
User Agreement for more details.
Order now!
Reprints of this article can also be ordered at
http://www.dekker.com/servlet/product/DOI/101081SCC100106041