Novel method for the synthesis of (trifluoromethyl)oxirane

Article abstract of DOI:10.1023/A:1015541225993

The reaction of 3,3,3-trifluoropropene with N-bromosuccinimide in acetic acid at 65-70 deg C affords 3-acetoxy-2-bromo-1,1,1-trifluoropropane. When treated with an alkali, the latter is readily converted into (trifluoromethyl)oxirane.

Full text of DOI:10.1023/A:1015541225993

550
Russian Chemical Bulletin, International Edition, Vol. 51, No. 3, pp. 550—551, March, 2002
Novel method for the synthesis of (trifluoromethyl)oxirane
ꢀ
S. A. Lermontov, N. V. Kuryleva, and T. N. Velikokhat´ko
Institute of Physiologically Active Substances, Russian Academy of Sciences,
142432 Chernogolovka, Moscow Region, Russian Federation.
Fax: +7 (095) 785 7024. Eꢀmail: lermon@ipac.ac.ru
The reaction of 3,3,3ꢀtrifluoropropene with Nꢀbromosuccinimide in acetic acid at 65—70 °C
affords 3ꢀacetoxyꢀ2ꢀbromoꢀ1,1,1ꢀtrifluoropropane. When treated with an alkali, the latter is
readily converted into (trifluoromethyl)oxirane.
Key words: (trifluoromethyl)oxirane, trifluoropropylene carbonate, Nꢀbromosuccinimide,
carbon dioxide.
(Trifluoromethyl)oxirane 1 is a key compound for the
CF3CH(OAc)CH2Br 2´ (5—6%), which also undergoes
synthesis of trifluoropropylene carbonate, which is curꢀ
rently believed to be one of the most promising solvents
for the production of lithium cells.1—4
cyclization into oxirane 1 under the action with hot alkali.
Isomers 2 and 2´ are spectrally discernible; bands were
assigned using general rules for electrophilic addition, on
the assumption that an electrophilic species is the Br+ ion
or its equivalent (e.g., protonated Nꢀbromosuccinimide).
Experimental
i. Catalyst.
1
H and 19F NMR spectra were recorded on a Bruker
DPXꢀ200 spectrometer (200 and 188 MHz, respectively) with
TMS and CF3COOH as external standards.
Oxirane 1 is generally prepared either from hexaꢀ
fluoropropylene oxide by laborious synthesis in many
steps,5 or by the reduction of difficultly accessible bromoꢀ
trifluoroacetone followed by cyclization,6,7 or by the reꢀ
action of 3,3,3ꢀtrifluoropropene with bromine in acetic
acid in the presence of mercury salts with subsequent
alkaline treatment of bromoacetates.8,9 The latter method
involves the dangerous and toxic starting reagents and
hence is inconvenient. The reaction of trifluoroacetꢀ
aldehyde with diazomethane, which affords oxirane 1 in
low yield, has also been described.10
We found that 3,3,3ꢀtrifluoropropene easily reacts with
Nꢀbromosuccinimide in acetic acid at 65—70 °C in the
presence of a catalytic amount of sulfuric acid to give
3ꢀacetoxyꢀ2ꢀbromoꢀ1,1,1ꢀtrifluoropropane 2 in good
yield, and the latter is converted into oxirane 1.
3ꢀAcetoxyꢀ2ꢀbromoꢀ1,1,1ꢀtrifluoropropane (2) and 2ꢀacetꢀ
oxyꢀ3ꢀbromoꢀ1,1,1ꢀtrifluoropropane (2´). NꢀBromosuccinimide
(72 g, 0.4 mol), glacial acetic acid (300 mL), and conc. H2SO4
(2 mL) were placed in a 500ꢀmL flask equipped with an inlet for
a gas, a thermometer, and a reflux condenser. While stirring, the
reaction mixture was heated to 65—70 °C (Nꢀbromosuccinimide
dissolved completely at this temperature), and CF3—CH=CH2
was passed at such a rate that it was absorbed virtually comꢀ
pletely. After 10—12 h, the reaction mixture was cooled (which
results in the formation of a white precipitate of succinimide)
and poured into 2 L of water to dissolve this precipitate. An oily
yellow liquid was separated; NaCl was added to the aqueous
layer, and the product was extracted with ether. The combined
organic layer was washed with aqueous soda and water and dried
with MgSO4. Distillation gave a mixture of bromoacetates 2
and 2´ (94 : 6) (59.7 g, 62.8%), b.p. 45—46 °C/10 Torr (cf.
Ref. 8: b.p. 149 °C).
Compound 2. 19F NMR (CDCl3), δ: 7.05 (d, CF3, 3J =
CF3CH=CH2 + AcOH + NBS
1
6.1 Hz). H NMR (CDCl3), δ: 2.0 (s, 3 H, CH3); 4.3—4.5 (m,
3 H, CH2—CH). Compound 2´. 19F NMR (CDCl3), δ: 7.5 (d,
CF3, 3J = 6.5 Hz).
CF3CHBrCH2OAc
1
2
(Trifluoromethyl)oxirane (1). Sodium hydroxide (170 g) and
water (130 mL) were placed in a threeꢀnecked flask equipped
with a mechanical stirrer, a dropping funnel, and a Liebig conꢀ
denser and heated in an oil bath to 120—130 °C. A mixture of
bromoacetates 2 and 2´ (81.3 g, 0.346 mol) was added so rapidly
The reaction of trifluoropropene with Nꢀbromoꢀ
succinimide does not occur without heating. Bromoꢀ
acetate 2 isolated by distillation is admixed with
isomeric 2ꢀacetoxyꢀ3ꢀbromoꢀ1,1,1ꢀtrifluoropropane
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 508—509, March, 2002.
1066ꢀ5285/02/5103ꢀ550 $27.00 © 2002 Plenum Publishing Corporation

Synthesis of (trifluoromethyl)oxirane
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 3, March, 2002
551
that a mixture of oxirane 1 and water was promptly distilled off
(vapor temperature 35—50 °C). The organic layer was sepaꢀ
rated, dried with K2CO3, and distilled over a small amount of
potassium carbonate. The yield of oxirane 1 was 17.3 g (41%),
b.p. 39—41 °C (cf. Ref. 9: b.p. 40 °C). 19F NMR (CDCl3), δ: 2.0
(d, J = 5 Hz). 1H NMR (CDCl3), δ: 3.0 (m, 2 H, CH2); 3.4
(m, 1 H, CH).
4. JP 07ꢀ165750; Chem. Abstr., 1995, 123, 198777.
5. C. van der BusscheꢀHunnefeld, C. Cescato, and D. Seebach,
Chem. Ber., 1992, 125, 2795.
6. E. T. McBee and T. M. Burton, J. Am. Chem. Soc., 1952,
74, 3022.
7. P. V. Ramachandran, B. Gong, and H. C. Brown, J. Org.
Chem., 1995, 60, 41.
8. I. L. Knunyants, E. Ya. Pervova, and V. V. Tyuleneva, Izv.
Akad. Nauk SSSR, Otd. Khim. Nauk, 1956, 843 (in Russian).
9. V. A. Ponomarenko, A. M. Khomutov, and N. A.
Zadorozhnyi, Izv. Akad. Nauk SSSR, Ser. Khim., 1968, 1847
[Bull. Acad. Sci. USSR, Div. Chem. Sci., 1968, 17 (Engl.
Transl.)].
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 00ꢀ03ꢀ
32846).
References
10. R. H. Groth, J. Org. Chem., 1960, 25, 102.
1. US Pat. 6.010.806; Chem. Abstr., 1997, 126, 117962.
2. JP 08ꢀ325258; Chem. Abstr., 1997, 126, 104071.
3. JP 07ꢀ291959; Chem. Abstr., 1996, 124, 176074.
Received November 1, 2001;
in revised form December 24, 2001