The absorption value of the reference solution is zero. The water–ethyl acetate solvent oxidized by ozone for 60 min
has a low absorption value. However, the mixture of anethole and water–ethyl acetate solution oxidized by ozone for 60 min
has a high absorption value. It can be surmised that, in water–ethyl acetate solvent, ozone reacts with water to produce a small
quantity of H O . In contrast, in anethole and water–ethyl acetate solution, ozone firstly reacts with anethole to generate
2
2
carbonyl oxide 1, and then carbonyl oxide 1 reacts with water to produce gem-hydroperoxy alcohol 2, which decomposes with
liberation of the anisaldehyde and a larger quantity of H O .
2
2
The optimal conditions for synthesis of anisaldehyde were as follows: water–ethyl acetate solvent with water content
3
–1
10%; ratio m(anethole)–m(solvent) = 1:3; O /O flow 0.06 m ·h ; reaction time 100 min; and reaction taken at room
3
2
temperature. The yield reaches about 81.7%. Gas chromatography detected a decrease in anethole and an increase in anisaldehyde.
In conclusion, in a mixture of anethole and water–ethyl acetate solvent, anisaldehyde is directly synthesized by
ozonolysis in a one-pot reaction at a relatively high yield. The process reported here is convenient and economical.
EXPERIMENTAL
GC spectrum was recorded on a Shimadzu 2010 gas chromatograph with FID (flame ionization detector). The
injection temperature was 250ꢁC and the column temperature increased gradually from 50ꢁC to 260ꢁC at a growth rate of
1
10ꢁC per minute. The air, hydrogen, and nitrogen flow was 400 mL, 47 mL, and 30 mL per minute, respectively. H NMR
spectra were recorded on a Bruker DRX-400 NMR spectrometer in CDCl with TMS as internal standard, and chemical shifts
3
are recorded as ꢂ values in parts per million (ppm). IR spectrum was measured with an Analect RFX-65 spectrometer, and
–1
wave numbers are given in cm . MS was carried out on a Shimadzu QP-2010 mass spectrometer at an ion source temperature
of 200ꢁC. UV spectrum was recorded on a Shimadzu UV-2550 ultraviolet spectrophotometer. The wavelength was between
350 and 600 nm. All solvents and reagents were purchased from commercial sources and used as received without further
purification.
General Experimental Procedure. Anethole substrate 20 g (0.135 mol) was placed in a bubble column with a water-
jacketed condenser and dissolved in water–ethyl acetate (10% in mass fraction) solvent. The solution was maintained at room
3
–1
temperature, and a stream of O /O (0.06 m ·h , approximately 6% in mass fraction) was bubbled into the reaction solution
3
2
through a bubbling pipe. A sample was taken out every scheduled time by an injector from the reactor and recorded on a gas
chromatograph. When the sampling was competed, the ozonizer voltage was set to zero. Nitrogen was passed through the
solution until the blue color disappeared. The crude reaction mixture was diluted with 50 mL ethyl acetate and 10 mL distilled
water. The separated aqueous layer was extracted twice with 10 mL of ethyl acetate. The organic layers were combined and
dried with anhydrous sodium sulfate. The solvent was removed under reduced pressure to give a colorless liquid. The desired
1
product, anisaldehyde, was obtained in a yield of 81.7% (16.4 g) with 99.5% purity. H NMR (400 MHz, CDCl , ꢂ): 3.87 (3H,
3
–1
s, OCH ), 6.98 (2H, s, Ar-H), 7.82 (2H, s, Ar-H), 9.87 (1H, s, CHO). IR (neat, ꢃ , cm ): 3076 (Ar-H), 2968 (CH ), 2842
3
max
3
and 2742 (O=C-H), 1685 (C=O), 1600 and 1512 (Ph), 1462 (CH ), 1261 (Ar-O), 1028 (CH -O), 835 (Ph). MS (EI, 70 eV, m/z,
3
3
+
I , %): 136 (M , 75), 135 (100), 119 (2), 107 (19), 92 (21), 77 (38), 65 (12), 64 (11), 63 (11), 51 (11), 50 (9), 39 (13), 27 (2).
rel
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