L-sorbose acetonation catalyzed by heteropolyacids

Full text of DOI:10.1023/A:1011977624957

Pharmaceutical Chemistry Journal
Vol. 35, No. 5, 2001
L-SORBOSE ACETONATION CATALYZED BY HETEROPOLYACIDS
M. A. Nadtochii,1 L. E. Burova,1 I. B. Vasil’eva,1 and T. A. Melent’eva1
Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 35, No. 5, pp. 47 – 48, May, 2001.
Original article submitted June 27, 2000.
One stage in the commercial synthesis of ascorbic acid is
the acetonation of L-sorbose with the formation of
diacetonesorbose (DAS). This process proceeds in the pres-
ence of acid catalysts such as zinc chloride, phosphoric anhy-
dride, hydrogen chloride, etc. At present, commercial pro-
cesses are frequently catalyzed by oleum [1]. The main dis-
advantage of this method is that neutralization of acetone
solutions of di- and monosorbose is accompanied by a large
amount of sodium sulfate (1.45 kg per kg DAS), which is a
waste product.
In recent years, the role of acid catalysts in various syn-
theses is frequently played by heteropolyacids (HPAs) [2].
For example, it was demonstrated that HPAs may serve as
catalysts in the process of methylation of 2-keto-L-gulonic
acid [3]. However, no data were reported on the use of HPAs
in the acetonation reactions.
the initial components: acetone, 100 ml; sorbose, 10 g; HPA,
5 g. The acid catalysate composition was analyzed by gas
chromatography for the content of sorbose and DAS. The re-
sults of these analyses are summarized in Table 1. These data
indicate that HPAs can be used as catalyst in the process of
L-sorbose acetonation.
In order to ensure a more complete conversion of sorbose
into DAS, it is necessary to remove water (both formed dur-
ing the reaction and introduced with the initial components)
from the reaction zone. We employed for this purpose NaA
zeolite (known to be a good absorber of water) placed into
the Soxhlet apparatus. The process was carried out at the
boiling point of the reaction mixture (56 – 57°C). The opti-
mum variant is offered by the following charge: acetone,
150 ml; sorbose, 10 g; HPA (H3PW12O40), 0.15 – 0.2 g
[HPA/sorbose ratio, 0.02 : 1; acetone/sorbose ratio, 15 : 1
(liter/kg)] (Table 2).
We also checked for the possibility of using other HPAs
in the acetonation process. Comparative data obtained for
tungstophosphoric, tungstoboric, and tungstogermanic acids
(Table 3) showed that all these acids can be used as catalyst
for L-sorbose acetonation. With a view to repeated use of the
HPA catalyst, we have stiudied the possibility of isolating
HPAs after termination of the acetonation
We have studied the acetonation of L-sorbose in the pres-
ence of HPA catalysts, including tungstophosphoric,
molybdophosphoric, and tungstosilicic acids. The process
was carried out for 5.5 h at 45°C with the following charge of
1
State Research Institute of Vitamins, State Unitary Enterprise, Moscow,
Russia.
process. The most expedient method of re-
covery was provided by HPA neutralization
TABLE 1. Effect of Various Heteropolyacids (HPAs) on L-Sorbose Acetonation
followed by isolating DAS and separating a
tungsten-containing concentrate. The latter
can be used for the utilization of tungsten.
The neutralization was performed with the
aid of a sodium hydroxide solution after
distillation of acetone and mesityl oxide.
DAS was extracted with chloroform, the re-
maining aqueous – organic mixture was
evaporated, and the residue was calcined at
650 – 700°C to obtain a mixture of so-
dium,, silicon, and tunsten oxides that can
be used for the utilization of tungsten or the
synthesis of HPA.
Concentration
in reaction mixture, %
Residual
sorbose,
g
Yield, %*
HPA
DAS
3.24
1.2-MAS 2.3-MAS
DAS
1.2-MAS 2.3-MAS
Tungstophosphoric
7.7
4.9
0.87
1.07
17.52
5.50
6.76
Tungstophosphoric
(anhydrous)
5.90
1.32
1.78
31.60
8.36
11.27
Tungstophosphoric
(recrystallized
from acetone)
5.1
5.0
5.3
5.66
5.35
6.38
1.30
–
1.85
0.50
1.90
30.62
28.89
30.86
8.31
–
11.83
3.19
Molybdophosphoric
Tungstosilicic
1.37
7.86
10.86
*
1,2-MAS and 2,3-MAS denote 1,2-monoacetonesorbose and 2,3-monoacetonesorbose,
respectively.
282
0091-150X/01/3505-0282$25.00 © 2001 Plenum Publishing Corporation

L-Sorbose Acetonation Catalyzed by Heteropolyacids
283
TABLE 2. Effect of Reagent Ratio on the Yield of Diacetonesor-
TABLE 3. Dependence of DAS Yield on the Nature of the Hetero-
bose (DAS)
polyacid (HPA)
Charge
Charge
Acetona-
tion time,
h
DAS
yield,
%
Acetonation
DAS
yield,
%
HPA
HPA
(H3PW12O40),
g
time,
h
acetone, ml sorbose, g HPA, g
acetone,
ml
sorbose,
g
H3PW12O40
H3PW12O40
H5BW12O40
H5BW12O40
H4GeW12O40
H4GeW12O40
H4GeW12O40
150
150
150
150
200
150
150
10
10
10
10
10
10
10
0.2
4.0
4.0
4.5
4.0
4.0
4.5
4.0
81.5
79.0
77.6
77.1
80.4
78.7
79.2
0.15
0.20
0.15
0.20
0.15
0.20
1.0
0.5
200
150
150
110
150
150
150
150
10
10
10
10
10
10
10
10
2.75
2.50
3.00
4.00
4.50
5.00
4.0
79.32
78.35
78.53
33.28
69.74
68.15
77.68
77.66
0.2
0.1
0.1
0.1
0.15
0.15
4.0
11.15 – 11.65 g DAS (yield, 78 – 81.5%). After DAS extrac-
tion, the aqueous-organic layer was evaporated, the residue
was calcined at 650 – 700°C, and the powdered residue was
used for utilizing tungsten or HPA synthesis. Not less than
95% of the initial tungsten was recovered.
EXPERIMENTAL PART
Into three-neck flask equipped with a Soxhlet apparatus
was placed 0.15 – 0.20 g HPA (H3PW12)40), 150 ml anhy-
drous acetone, and 10 g sorbose. The Soxhlet apparatus was
charged with 30 – 40 g of calcined NaA zeolite. The mixture
was boiled for 3 – 4 h, cooled to – 5 … – 10°C, and allowed
to stand at this temperqture for 0.5 h. Then 0.1 – 0.15 ml of a
8 % NaOH solution was added and mesityl oxide was dis-
tilled off. Finally, DAS was extracted with chloroform
(3 ´ 30 m) and the solvent was distilled off to yield
REFERENCES
1. A. M. Nadtochii, L. E. Burova, I. B. Vasil’eva, and T. A. Me-
lent’eva, Khim.-Farm. Zh., 35(4), 52 – 53 (2001).
1. I. V. Kozhevnikov and K. I. Matveev, Usp. Khim., 51(11), 1875
(1982).
2. T. A. Melent’eva, E. M. Knyazeva, and A. M. Taber, Khim.-
Farm. Zh., 26(9 – 10), 112 (1992).