Synthesis of d-decalactone

Article abstract of DOI:10.14233/ajchem.2013.14048

The application and shortcomings of typical synthetic method of title d-decalactone was introduced in brief. A synthesis of 2-pentylidene cyclopentanone starting from cyclopentanone and n-valeraldehyde through aldol condensation, followed by dehydration, was studied and the yield reached 86.3 %. Then 2-pentenyl cyclopentanone was prepared in a yield of 91.5 % from 2-pentylidene cyclopentanone with a hydrogenation methodology under atmospheric pressure and use Pt/C as catalytic. Through Baeyer-Villiger oxidation, d-decalactone was synthesized in a yield of 61.2 %. Experiments by orthogonal experiment method to optimize the reaction conditions to determine the response of a reasonable process parameters and the analysis of the factors affecting the reactions. The structures and compositions of these compounds were accomplished by IR and GC-MS.

Full text of DOI:10.14233/ajchem.2013.14048

Asian Journal of Chemistry; Vol. 25, No. 8 (2013), 4520-4522
http://dx.doi.org/10.14233/ajchem.2013.14048
Synthesis of δ-Decalactone
*
JIA BU, GUANGXUE LI , MINGZHU ZHAO, JIAMING LI, FENG JIANG, HUALU ZHAN and YANG CHU
Institute of Chemical Engineering, Anhui University of Science and Technology, Huainan 232001, P.R. China
*Corresponding author: E-mail: gxli@aust.edu.cn
(Received: 10 May 2012;
Accepted: 15 February 2013)
AJC-13002
The application and shortcomings of typical synthetic method of title δ-decalactone was introduced in brief. A synthesis of 2-pentylidene
cyclopentanone starting from cyclopentanone and n-valeraldehyde through aldol condensation, followed by dehydration, was studied and
the yield reached 86.3 %. Then 2-pentenyl cyclopentanone was prepared in a yield of 91.5 % from 2-pentylidene cyclopentanone with a
hydrogenation methodology under atmospheric pressure and use Pt/C as catalytic. Through Baeyer-Villiger oxidation, δ-decalactone was
synthesized in a yield of 61.2 %. Experiments by orthogonal experiment method to optimize the reaction conditions to determine the
response of a reasonable process parameters and the analysis of the factors affecting the reactions. The structures and compositions of
these compounds were accomplished by IR and GC-MS.
Key Words: δ-Decalactone, Cyclopentanone, n-Valeraldehyde, Synthesis.
conditions, the slightest mistake can cause the product purity
INTRODUCTION
is not high7. In addition, on the Baryer-Villiger oxidation, tradi-
tional oxidants as potassium peroxydisulfate or peracetic acid,
but because they are not safe, by-products are more δ-hydroxy
acid, the yield is not high. The use of H2O2 as an oxidant and
its by-product is water, do not pollute the environment and
safe, inexpensive, clean product, so it obtains more and more
attention. But the activity of H2O2 relatively peracetic acid is
weak, generally add catalyst to provide reaction activity when
used. Therefore, to develop some appropriate and efficient
catalyst is particularly important8.
δ-Decalactone is a colourless or light yellow liquid with
a strong aroma of sweet cream and nuts, strong fragrant flowers
at the end. It is the main component of natural fragrant cream,
mainly used for modulating food flavor, specifically for soft
drinks, ice cream, candy, milk, dairy products, biscuits, condi-
ments and bakery products1. The product is also an important
high-grade feed additive, feed flavor can improve and improve
livestock and poultry rapid growth. As a natural cream
containing a large number of animal fat, too much inhalation
can lead to cardiovascular disease. So δ-decalactone plays an
important role to protect people's health when we add cream
spices to vegetable oil as margarine which used in food indus-
try2. Therefore, to discuss δ-decalactone's chemical synthesis
methods and synthesis techniques have the great meaning.
About the synthesis of δ-decalactone, together in two
ways: first, through all kinds of means synthetic δ-hydroxy
acid and then esterification resulted δ-lactone3,4. The source
of the raw materials is difficult, can't series production or some
reaction route is too long, the total yield is low, it is difficult to
realize the industrialization production5. Second, first synthesic
2-pentylidene cyclopentanone this intermediate and then by
Baryer-Villiger oxidation get δ-lactone6. The main disadvantage
of this method is that 2-pentylidene cyclopentanone during
the Baryer-Villiger oxidation of ring expansion reaction may
take place reverse insertion reaction and the by-product is the
δ-decalactone isomer, it is difficult to remove and harsh reaction
EXPERIMENTAL
Germany Brook, the VECTOR33 Fourier transform
infrared spectrometer, Japanese Shimadzu company QP-50SOA
GC-MS, Reagents used were analytical grade.
Synthesis of 2-pentylidene cyclopentanone:Add 25 mL
the mass fraction of 1 % NaOH solution and 0.7 g polyethylene
glycol-600 to neck flask, heating up to 30 ºC, dropping 19.8 g
cyclopentanone within 0.5 h. Colour of solution gradually from
colourless into orange. And stirring at 30 ºC slowly dropping
n-valeraldehyde 11 g, ca. 1.5 h dropwise, the solution colour
changed from orange to brown and after dropping to maintain
the temperature 30 ºC, stirred 2 h. Cooling, add 36 % acetic
acid adjusted pH for 6 to 7. In the separatory funnel stratification,
the upper for organic layer, the lower the inorganic layer.
Toluene extraction of inorganic layer, layered, the upper
toluene layer, the lower layer for waste water. Combined

Vol. 25, No. 8 (2013)
Synthesis of δ-Decalactone 4521
organic layer and toluene layer, add the flask with a water
separator, add 0.2 g oxalic acid, heat and stir until no more
moisture out, cooling, washing with saturated salt water and
5 % NaHCO3, atmospheric distillation out toluene, residues
in the 98-100 ºC/400 Pa distillation a yellow solution of 2-
pentylidene cyclopentanone. By GC-MS analysis, the yield
ca. 86.3 %.
chemical reaction9. Fixed cyclopentanone 19.8 g, n-valeraldehyde
11 g and a certain amount of phase transfer catalyst, 25 mL of
1 wt % NaOH solution, changing the system temperature to
study the temperature on the reaction.
Temperature on the reaction: Fig. 1 showed cyclopen-
tanone and n-valeraldehyde being can react at 0 ºC. As the
reaction temperature increases, the yield of product 2-pentylidene
cyclopentanone also increased, to 30 ºC maximum. Tempe-
rature continues to rise, the yield changed little, but because
of high temperature will speed up cyclopentanone and n-
valeraldehyde are cross-condensation product of increased
purity of the product will be correspondingly reduced10. There-
fore, 30 ºC is reasonable parameters.
Synthesis of 2-pentenyl cyclopentanone: Add 5 g 2-
pentylidene cyclopeantanone, 0.2 g catalyst of Pt/C and 40 mL
ethanol to the atmosphere of the reactor which in N2. Sealing
device and using N2 to wash, ensure the device does not contain
other gases. Then normal pressure ventilation with H2, control
temperature 50 ºC, ca. 20 h the reaction is completed. A few
times before hydrogenation faster, when no hydrogen, filter
the catalyst in reaction, the catalyst washed with ethanol and
set aside. Rotating evaporation of anhydrous ethanol, vacuum
distillation, collect 82-83 ºC/Pa fractions, light yellow solution
of 2-pentenyl cyclopentanone. By GC-MS analysis, the yield
is ca. 91.5 %.
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60
40
20
Synthesis of δ-decalactone: Add 10 g 2-pentenyl cyclo-
pentanone, 30 mL methanol, 2 mL concentrated sulfuric acid
to the falsk which was equipped with condenser, thermometer,
magnetic stirrer, stirring and heating to 50 ºC or so, dropping
32 g H2O2 (ca. 2.5 h), after dropping maintain the reaction
temperature 50 ºC stirring 1.5 h, the solution slowly from light
yellow to colorless and appear cloudy. Layer, upper for organic
layer, lower for inorganic. Inorganic layer extracted several
times by adding 10 mL toluene, layered, the upper toluene
layer, the lower for waste water the combined organic layers
toluene layer with 5 % NaHCO3 solution, washed to pH 7-8,
then washed several times with brine 10 mL, layered, the upper
organic layer, the lower layer of waste brine. Organic layer
vacuum distillation, collecting 118-120 ºC distillate, δ-
decalactone. By GC-MS analysis, the yield was 61.2 %. The
infrared spectral data of the products are given below:
0
10
20
Temperature (ºC)
Fig. 1. Temperature on the reaction
30
40
50
Raw material input ratio on the reaction: At 30 ºC, 25
mL of 1 wt % NaOH solution, 19.8 g cyclopentanone, a certain
amount of phase transfer catalyst, changing the n-valeraldehyde
input, study material input ratio on the reaction. The results
shown in Fig. 2.
Infrared spectral data of 2-pentylidene cyclopentanone
Wave number (cm-1)
2869 and 2868
2958
Characteristic absorption
-CH3, -CH2
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80
60
40
20
-H on the double bone
C=O
1722
1649
C=C
Infrared spectraal data of 2-pentenyl cyclopentanone
Wave number (cm-1)
2927 and 2861
1703
Characteristic absorption
-CH3, -CH2
C=O
Infrared spectral data of δ-decalactone
Wave number (cm-1)
2931 and 2868
1711
Characteristic absorption
-CH3, -CH2
C=O
1244
C-O
1:1
1.2:1
1.5:1
1.8:1
2:1
2.2:1
Raw material input ratio
Fig. 2. Raw material input ratio on the reaction
RESULTS AND DISCUSSION
2-Pentylidene cyclopentanone synthesis condition
As the aldehyde condensation reaction between aldehydes
and ketones is greater than the activity of the condensation
reaction between the activity in order to avoid excessive side
Temperature on the reaction: Temperature is an important
factor that influences the direction and speed of response of

4522 Bu et al.
Asian J. Chem.
effects occur , must be excessive ketones11. From the figure,
n(cyclopentanone):n(n-valeraldehyde) = 1.8, the yield of
product was maximum, continue to increase the amount of
cyclopentanone, the reaction yield basically stabilized.
Orthogonal experiment: Reaction at 30 ºC, the alkali
concentration, phase transfer catalyst and the amount of acid
catalyst for the L9(34) orthogonal experiment to optimize the
reaction conditions from 1 % alkali concentration, phase
transfer catalyst is a polyethylene glycol-600, the amount of
0.7 g, acid catalyst is 0.2 g.
Orthogonal experiment:At 50 ºC, the amount of hydrogen
peroxide and the amount of solvent, the amount of acid
promoter for the L9(34) orthogonal experiment to optimize
the reaction conditions from the amount of hydrogen peroxide
as n(hydrogen peroxide):n(2-pentenyl cyclopentanone) = 4:1,
the reaction solvent is methanol, the amount of 30 mL, acid
accelerator dosage 2 mL.
Conclusion
This work presents a new method for synthesizing title
compounds by reaction of n-valeraldehyde and cyclopentanone
via condensation, dehydration, reduction and oxidation. In the
cyclopentanone and n-valeraldehyde condensation reaction,
the reaction at 30 ºC, condensation optimized by orthogonal
experiment reaction conditions, namely alkali concentration
of 1 % and the phase transfer catalyst is polyethylene glycol-
600, its dosage is 0.7 g, caid catalyst is 0.2 g. Under these
conditions, synthesis of 2-pentylidene cyclopentanone yield
of ca. 86.3 %. Baeyer-Villiger oxidation reaction using
hydrogen peroxide rearrangement as oxidant and through the
orthogonal experiment, select the appropriate reaction
conditions:reaction temperature is 50 ºC, hydrogen peroxide
dosage of n(hydrogen peroxide):n(2-pentenyl cyclopentanone)
= 4:1,solvent is methanol and the amount of 30 mL, acid
accelerator dosage 2 m. In these conditions, synthesic result
in high ester, production rate of 61.2 %.
Synthesis conditions of δ-decalactone
Temperature on the reaction: Oxidation is an exothermic
reaction, control the appropriate reaction temperature, in order
to maintain a reasonable speed and avoid hydrogen peroxide
oxidation behaviour of thermal instability, showing the
importance of reaction12. So must choose a suitable reaction
temperature.
Add 2-pentenyl cyclopentanone 10 g, 30 mL methanol,
concentrated sulfuric acid 2 mL, 32 g hydrogen peroxide,
change the reaction temperature, effects of different tempe-
rature on the reaction.
From the Fig. 3 we can see, the reaction at 50 ºC, the
yield is better. Although the reaction temperature is conducive
to positive, but will also accelerate the decomposition of
hydrogen peroxide. Therefore, the temperature controlled at
50 ºC is most reasonable.
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Temperature (ºC)
Fig. 3. Temperature on the reaction
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