38
T. Komata et al. / Journal of Fluorine Chemistry 129 (2008) 35–39
74%, 21%, and 5% yields, respectively. After insoluble solid
was filtered off, the filtrate was distilled to give a colorless
liquid (381.5 g). By this distillation, potassium hydroxide was
completely removed. After the addition of methanesulfonic
acid (33.0 g, 0.34 mol), the distillate was heated at 70 8C for
4 h. It was shown by GC analysis that the reaction mixture
contains 3,3,3-trifluoropropanal dimethyl acetal (4) and 3,3,3-
trifluoro-1-methoxypropene (3) in 96% and 1% yields,
respectively. After the reaction mixture was washed with
water (300 g), the organic layer was separated and dried over
[CF2CH2]+ (75), 63 [CF2CH]+ (10), 51 [CHF2]+ (3), 47 [COF]+
(3), 45 [CFCH2]+ (100), 42 [CH2CO]+ (19), 29 [CHO]+ (11), 28
[CO]+ (3). Anal. Calcd. for C3H3F3O2: C, 28.14; H, 2.36.
Found: C, 28.13; H, 1.91.
4.4. Independent synthesis of methyl 3,3,3-
trifluoropropionate (7)
Thionyl chloride (8.4 g, 0.071 mol) and a few drops of DMF
were placed in a 50 ml round-bottomed flask fitted with a
stirrer, a thermometer, a reflux condenser, and a dropping
funnel. After 3,3,3-trifluoropropanoic acid (7; 10.0 g,
0.078 mol) was dropwise added at 40 8C, the mixture was
stirred at 60–70 8C for 3 h. Then, methanol (2.3 g, 0.072 mol)
was added at room temperature and the mixture was stirred at
50 8C for 1 h. The reaction mixture was purified by distillation
(96–97 8C) to give methyl 3,3,3-trifluoropropionate (7; 7.5 g,
74% yield) as a colorless liquid; 1H NMR (CDCl3): d 3.19 (2H,
q, J = 10.6 Hz), 3.77 (3H, s); 19F NMR (CDCl3): d À64.16 (3F,
t, J = 10.6 Hz); EI-MS m/z (rel. int.): 142 [M]+ (9), 122 [M–
HF]+ (16), 111 [M–CH3O]+ (100), 91 [CF2CHCO]+ (25), 83
[CF3CH2]+ (26), 69 [CF3]+ (13), 64 [CF2CH2]+ (15), 63
[CF2CH]+ (5), 59 [C2H3O2]+ (47), 42 [CH2CO]+ (4), 31
[CH3O]+ (116), 29 [CHO]+ (12). Anal. Calcd. for C4H5F3O2: C,
33.81; H, 3.55. Found: C, 33.80; H, 3.14.
˚
MS 4 A (20 g). The obtained reaction mixture was purified by
distillation (89–90 8C) to give 3,3,3-trifluoropropanal dimethyl
acetal (7; 128 g; 47% yield) as a colorless liquid; H NMR
1
(CDCl3): d 2.51 (2H, dq, J = 10.6 and 5.6 Hz), 3.33 (6H, s), 4.70
(1H, d, J = 5.6 Hz); 19F NMR (CDCl3): d À63.34 (3F, d,
J = 10.6 Hz); EI-MS m/z (rel. int.): 158 [M]+ (0.05), 127 [M–
CH3O]+ (47), 83 [CF3CH2]+ (3), 75 [M–CF3CH2]+ (51), 69
[CF3]+ (5), 64 [CF2CH2]+ (5), 63 [CF2CH]+ (100), 59
[C2H3O2]+ (3), 47 [CH3O2]+ (15), 45 [CFCH2]+ (5), 43
[C2H3O]+ (4), 31 [CH3O]+ (17), 29 [CHO]+ (26), 28 [CO]+ (3).
Anal. Calcd. for C5H9F3O2: C, 37.98; H, 5.74. Found: C, 38.12;
H, 5.78.
4.2. General procedure for the hydrolytic oxidation of
3,3,3-trifluoropropanal dimethyl acetal (4)
The oxidizing reagent, which was prepared by mixing 35%
hydrochrolic acid, metal compound, and30%hydrogenperoxide
at À15 to À10 8C, were added to 3,3,3-trifluoropropanal
dimethyl acetal (4) at 60 8C or 80 8C and the reaction mixture
was stirred at the same temperature for 1 h. An aliquot of the
reaction mixture was taken out and analyzed by GC. The
isolation of 1 and its characterization are given in the following
section. The authentic sample of 6 was purchased from SynQuest
Labs., Inc. (Florida, U.S.A.) The structure of 7 was confirmed by
the independent syntheses that were described below.
Acknowledgement
We thank Dr. Yutaka Katsuhara (Central Gass Co., Ltd.) for
helpful discussions.
References
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methyl 3,3,3-trifluoropropionate (7) in 95% and 3% yields,
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1
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propanoic acid (1; 5.0 g, 62% yield) as a colorless liquid: H
NMR (CDCl3): d 3.43 (2H, q, J = 10.8 Hz), 11.07 (1H, bs); 19
F
NMR (CDCl3): d À63.47 (3F, t, J = 10.8Hz); EI-MS m/z (rel.
int.): 128 [M]+ (11), 111 [M–OH]+ (38), 91 [CF2CHCO]+ (15),
89 [M–HF2]+ (20), 83 [CF3CH2]+ (20), 69 [CF3]+ (25), 64
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