6
018
G. K. Surya Prakash et al. / Tetrahedron Letters 50 (2009) 6016–6018
Table 2
Effect of PVP and temperature on methanolysis of methylene bromide
a
Entry
Molar ratio (MeOH:CH
2
2
Br :PVP)
Temperature (°C)
Conversion of CH
2
Br
2
(%)
Selectivity of DMM (%)
1
2
3
4
4:1:1
4:1:1
4:1:1
4:1:0
75
None
25
58
None
100
100
100
125
125
None
None
a
Reaction time 2 h.
PVP (MW is indefinite because of cross-linking) 2% cross-linked
with divinyl benzene having a surface area of 17 m /g and a parti-
Acknowledgments
2
cle size of ꢂ60 mesh was used for the reactions. The basicity of
Authors thank Department of Energy, USA for financial support.
Support by the Loker Hydrocarbon Research Institute is gratefully
acknowledged. Dr. Colmenares thanks Professor George A. Olah
and Professor G. K. Surya Prakash for their invaluable help.
PVP, pK
a
ꢃ 4.08, has been estimated from Refs. 14 and 15.
The methanolysis of methyl and methylene bromide was car-
ried out in a closed pressure tube (internal volume, 20 mL). In a
typical experiment, PVP (0.17 g) was added to a pressure tube fol-
lowed by the addition of methanol (0.14 g, 4.38 mmol) and then
sealed. Then, at room temperature, the tube was pressurized to
References and notes
1
2
.
.
Müller, M.; Hübsch, U. Dimethyl Ether. In Ullmann’s Encyclopedia of Industrial
Chemistry, 6th ed.; Wiley-VCH: Weinheim, 2003.
Fleisch, T. H.; Basu, A.; Gradassi, M. J.; Masin, J. G. Stud. Surf. Sci. Catal. 1997, 107,
117.
5
.5 bar with methyl bromide and heated to 125 °C for 2 h under
stirring (600 rpm). The mixture was then cooled to room tempera-
ture. The gas phase (unreacted methyl bromide and dimethyl
3
4
.
.
Dybkjaer, B. H. Stud. Surf. Sci. Catal. 1997, 107, 99.
Olah, G. A.; Goeppert, A.; Prakash, G. K. S. In Beyond Oil and Gas: The Methanol
Economy; Wiley-VCH, 2006.
ether) was collected by absorption in CDCl
3
solution kept at
ꢀ
50 °C (dry ice-acetone bath). The reaction mixture was washed
several times with CDCl
3
and the solution was collected each time
Br methanolysis, methanol
0.21 g, 6.56 mmol) was added to methylene bromide (0.28 g,
after filtration. In the case of CH
(
2
2
6
.
.
Zhu, R.; Wang, X.; Miao, H.; Huang, Z.; Gao, J.; Jiang, D. Energy Fuels 2009, 23.
doi:10.1021/ef8005228.
Takashi, O.; Norio, I.; Tutomu, S.; Yotaro, O. J. Nat. Gas Chem. 2003, 12, 219.
1
.61 mmol) along with PVP (0.17 g) and the reaction was con-
7
ducted under the conditions mentioned in Table 2. After each
run, the reaction mixture was cooled to room temperature
and PVP was separated from the mixture by filtration. All the
products were characterized and analyzed by 1H and C NMR
spectroscopy.
8. Lee, S.; Sardesai, A. Top. Catal. 2005, 32, 197.
9.
Royer, S.; Secordel, X.; Branhorst, M.; Dumeignil, F.; Cristol, S.; Dujardin, C.;
Capron, M.; Payen, E.; Dubois, J.-L. Chem. Commun. 2008, 865. and references
cited therein.
13
10. Wang, K. X.; Xu, H. F.; Li, W. S.; Au, C. T.; Zhou, X. P. Appl. Catal., A 2006, 304,
68.
1
11. Lorkovic, I. M.; Sun, S.; Gadewar, S.; Breed, A.; Macala, G. S.; Sardar, A.; Cross, S.
After each cycle, PVP was filtered and washed with CH
2 2
Cl (3
E.; Sherman, J. H.; Stucky, G. D.; Ford, P. C. J. Phys. Chem. A 2006, 110, 8695.
times) and H O (3 times) and then dried overnight at 100 °C under
2
12. Prakash, G. K. S.; Colmenares, J. C.; Batamack, P. T.; Mathew, T.; Olah, G. A. J.
Mol. Catal. A: Chem. 2009, 310, 180.
vacuum. The surface morphology of fresh and recycled PVP (after
five consecutive reactions) was investigated by means of a
scanning electron microscopy (SEM Cambridge 360, 3.0 nm
resolution).
1
1
3. Hine, J.; Duke, R. B.; Glod, E. F. J. Am. Chem. Soc. 1969, 91, 2316.
4. Borowiak-Resterna, A.; Szymanowski, J.; Voelkel, A. J. Radioanal. Nucl. Chem.
1996, 208, 75.
15. Ripoll, C.; Muller, G.; Selegny, E. Eur. Polym. J. 1971, 7, 1393.