Heterogeneous zeolite-based catalyst for esterification of α-pinene to α-terpinyl acetate

Article abstract of DOI:10.13005/ojc/350150

The purpose of this study is to determine the most effective type of heterogeneous catalyst such as natural zeolite (ZA), Zr-natural zeolite (Zr/ZA) and zeolite Y (H/ZY) in esterification of α-pinene. α-terpinyl acetate was successfully synthesized from α-pinene and acetic anhydride by their heterogeneous catalysts. The esterification reaction was carried out with reaction time, temperature and zeolite catalysts. The most effective catalysts used in the synthesis of α-terpinyl acetate is catalyst H/ZY with the yield is 52.83% at 40oC for the time 4 h with a selectivity of 61.38%. The results showed that the effective separation of catalyst could contribute to developing a new strategy for the synthesis of α-terpinyl acetate.

Full text of DOI:10.13005/ojc/350150

ISSN: 0970-020 X
CODEN: OJCHEG
2019, Vol. 35, No.(1):
Pg. 399-403
ORIENTAL JOURNAL OF CHEMISTRY
An International Open Access, Peer Reviewed Research Journal
www.orientjchem.org
Heterogeneous Zeolite-Based Catalyst for Esterification of
α-Pinene to α-Terpinyl Acetate
NANIk WIJAYATI1,2, ELLA kUSUMASTUTI1, DANTE ALIgHIRI1,2*,
BAITI ROHMAWATI1 and RETNO ARIADI LUSIANA3
1Essential Oil Study Center, Faculty of Mathematics and Natural Sciences, Universitas Negeri Semarang,
Indonesia.
2Chemistry Department, Faculty of Mathematics and Natural Sciences, Universitas Negeri Semarang,
Indonesia.
3Chemistry Department, Faculty of Mathematics and Natural Sciences, Universitas Diponegoro,
Indonesia.
*Corresponding author E-mail: dante_alighiri@mail.unnes.ac.id
http://dx.doi.org/10.13005/ojc/350150
(Received: November 01, 2018; Accepted: January 23, 2019)
ABSTRACT
The purpose of this study is to determine the most effective type of heterogeneous catalyst
such as natural zeolite (ZA), Zr-natural zeolite (Zr/ZA) and zeolite Y (H/ZY) in esterification of
α-pinene. α-terpinyl acetate was successfully synthesized from α-pinene and acetic anhydride
by their heterogeneous catalysts. The esterification reaction was carried out with reaction time,
temperature and zeolite catalysts. The most effective catalysts used in the synthesis of α-terpinyl
acetate is catalyst H/ZY with the yield is 52.83% at 40oC for the time 4 h with a selectivity of 61.38%.
The results showed that the effective separation of catalyst could contribute to developing a new
strategy for the synthesis of α-terpinyl acetate.
keywords: Zeolite, α-pinene, Terpinyl Acetate, Esterification.
INTRODUCTION
treated with liquid mineral acid and the resulting
α-terpineol is then esterified with acetic anhydride
Terpinyl acetate is important to fine
chemical and has been used in the fields of flavor,
fragrance, food, medicine, cosmetics, organic
synthesis and pharmaceutical industries1-4.Terpinyl
acetate synthesis can be done by an esterification
reaction α-pinene with acid catalyst5-7. Usually, it
is prepared industrially in two stages: α-pinene is
and a catalyst8-11
.
Esterification reaction of α-pinene has
been carried out using homogeneous as well as
heterogeneous catalysts. Heterogeneous catalysts
have been considered as an alternative catalyst12.
They are metal oxides, zeolites, and active metals13.
This is an
Open Access article licensed under a Creative Commons license: Attribution 4.0 International (CC- BY).
Published by Oriental Scientific Publishing Company © 2018

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The mechanism of the esterification catalyzed by
heterogeneous catalysts is still debated14-16. We
have also proposed a similar intermediate in the
esterification reaction using natural zeolite.
acidity by gravimetric method and tested with Front
Transmittance InfraRed (FTIR Perkin Elmer Version
10.4.00).
α-terpinyl acetate synthesis was carried
out in a batch reactor with a magnetic stirrer. First,
the 1 g of α-pinene, 10 ml acetic anhydride, 10
ml dichloromethane, and 5 ml of distilled water
were introduced in the reactor, followed by the 0.5 g
of catalysts. The reaction mixture was continuously
stirred during the reaction using a magnetic stirrer
at a temperature of 40°C. To optimize α-terpinyl
acetate formation, experiments were conducted
to study factors such as reaction time and type of
catalyst.The reaction mixture is then separated from
the catalyst with a centrifuge for 10 min and speed
of 350 rpm. The reaction products were analyzed
by Gas chromatography–mass spectrometry
(GC-MS).
Several studies on the terpinyl acetate
synthesis by α-pinene esterification reaction has
been conducted by several previous researchers who
have already converted α-pinene to terpinyl acetate
with catalyst zeolite H-beta and it turns out the results
is a concentration of terpinyl acetate by 29%8. li
et al., (2013) have done a terpinyl acetate synthesis
with catalyst from ionic solutions with results of
terpinyl acetate concentration by 30.8%6, Terpinyl
acetate is synthesized with lipase catalyst17-19. The
terpinyl acetate synthesis with this catalyst results
terpinyl acetate as much as 40.3%5.
In this study, esterification of α-pinene to
α-terpinyl acetate by using a heterogeneous catalyst
such as natural zeolite (H/ZA), Zr-natural zeolite
(Zr/ZA) and zeoliteY (H/ZY) were done to determine
the most effective type of catalyst.
RESULT AND DISCUSSION
Preparation of Zr/ZA catalysts made by
impregnating Zr metal. Zr metals are impregnated
in ionic form, Zr4+ cation that exchange with the
cation H+ in H/ZA. Activation of zeolite Y is done
by calcination at a temperature 550oC for 4 hours.
Activation is aimed to enable the acid sites on the
zeolite, remove organic substances, and eliminate
gas products are still entrapped in the zeolite.
EXPERIMENTAL
The materials used in this study is
turpentine oil from central Java, natural zeolite
from Malang, and zeolite Y from Sigma Aldrich.
Other chemicals such as sodium sulfate anhydrous
(Na2SO4), zirconum (IV) chloride (ZrCl4), and acetic
anhydride were purchased from Merck. All solid
materials were directly used after drying without
further purification.
Characterization of catalyst crystallinity is
performed by using XRD.Diffractogram of the catalyst
H/ZA, Zr/ZA, and H/ZY is presented in Figure 1.
Naturalzeoliteissoakedwith1%hydrofluoric
acid (HF) solution for 30 min then washed with
aquademin, dried in an oven at 120oC for 3 hours.
Natural zeolite is then soaked with hydrochloric
acid (HCl) for 30 min at 50°C while stirring with
a magnetic stirrer. The zeolite is washed with
aquademin until the chloride ion (Cl–) disappears and
then soaked with 1 N ammonium chloride (NH4Cl)
solution. Natural zeolite is impregnated with 10%
(w/w) of zirconium (Zr) metal. Zr/ZA and Y Zeolite
catalysts were calcined at 500oC for 4 hours.
Fig.1. Diffractogram of catalysts (a)H/ZY, (b)H/ZA and
(c) Zr-natural zeolite
Characterization of the catalysts includes
crystallinity analysis is observed by X-Ray Diffraction
(XRD Shimadzu 6000), surface morphology by
Scanning Electron Microscopy (SEM Phenom),
Based on XRD analysis of H/ZY, H/ZA,
and Zr/ZA, their angle position of diffraction (2q)

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and their distance between the field will describe
the types of crystals. The sharp intensity on area
2q=9.77°, 21.45°, 25.63°, 27.49°indicatesthemordenite
characteristic20.The peak at 2q = 9.84°, 21.34°, 25.87°,
27.21° in natural zeolite sample from Malang indicated
mordenite group in dominant phase.
Analysis of the morphology of the catalyst
surface was performed using SEM instrument
to observe microscopically catalyst H/ZA, Zr/
ZA, and H/ZY (Fig. 3).The images specify that
the zeolite surface is coated by Zr4+. In catalyst
H/ZA has irregular morphology, such as the hollow
porous rocks. Based on the results of XRD, natural
zeolite Malang has the characteristics of mordenite
crystals shaped like needles, but the results are not
visible needle shape, while the Zr-zeolite catalyst
morphology seems natural form mordenite crystals
resemble needles. Based on the results of SEM
magnification 10000x known that catalyst H/ZY
have a uniform morphology in the form of granules
resembling an irregular cube. Based on the results
of SEM magnification 10000x known that the form
of the catalyst H/ZY is in the form of granules
resembling an irregular cube.
The total acid sites based on data in
Table 1. The samples H/ZY has the highest total
acidity. In Zr/ZA catalyst has a higher acidity than
H/ZA. This is due to the developing of zirconium
metal in the catalyst.Zirconium has d orbitals that are
not fully filled so can effectively accepts an electron
pair from a base adsorbate.Donation amount of acid
site of a zirconium metal is lewis acid sites21. The
H/ZY catalyst has a higher acidity value than the
H/ZA and Zr/ZA catalysts so that the H/ZY catalyst
is more effective in the esterification reaction.
Table 1:The total acidity of Zeolite H/ZY, H/ZA,
and Zr/ZA
Material
Total acidity (mmol/g)
H/ZA
Zr/ZA
H/ZY
0.81
5.70
8.87
Fig. 3. The morphology of the catalysts (a) H/ZA,
(b), Zr/ZA (c) H/ZY
Acidity for each adsorbent and catalyst
depends on the nature of the adsorbent and the
catalyst surface, which can be a lewis acid or
Bronsted acid. To be able to distinguish the type
of Bronsted acid sites (1640 cm-1) and lewis acid
sites (1400 cm-1) in the zeolite, it can be seen from
Fig. 2. The presence of the lewis acid can appear
at the top of the range of 1450 cm-1, whereas the
Bronsted acid appears at the top of the range 1550
to 1640 cm-1. A weak peak at 788 cm-1 appears in
The greatest concentration of product
α-terpinyl acetate in esterification reaction performed
from the reaction by using a catalyst H/ZY.The H/ZY
catalyst has the highest acidity values than ZA and Zr/
ZA catalyst so that the catalyst H/ZY more effectively
carry out the esterification reaction. In catalyst Zr/ZA
has an acidity value higher than the ZA catalyst, but
on the outcome of the esterification reaction α-pinene
level of α-terpinyl acetate products that produced is
lower, it could be due to the Zr metal is too large so
thattheclosedporezeolite and finally inhibitthe action
of catalysts in α-terpinyl acetate formation.
the spectrum of the modified zeolite10,22
.
Table 2: Concentration and selectivity of
α-terpinyl acetate
Catalysts
Conversion (%)
Selectivity (%)
H/ZY
H/ZA
Zr/ZA
52.83
28.77
23.53
61.38
30.41
24.64
Theα-pineneesterificationwithtemperature
variations of 30, 40 and 60°C with a reaction time of
3 h and the ratio of pinene acetic anhydride
compound (1:15) yielded α-terpenyl acetate with
0.18, 21.40, and 14.72% with the conversion of 4.99,
74.13and52.44.Theeffectofreactiontemperatureon
Fig. 2. FT-IR spectra acidity of catalyst (a) H/ZY,
(b) H/ZA and (c) Zr/ZA

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α-pinene esterification is shown in Table 2.When the
temperature was low, the yield of α-terpinyl acetate
was low.As the temperature was increased, the yield
of α-terpinyl acetate increased accordingly.When the
temperature was high, the yield of α-terpinyl acetate
tended to decrease. The results showed the yield of
α-terpinyl acetate first increased and then decreased
with increasing temperature.
As shown in Fig. 5, once the carbonium
ion is produced by protonation of α-pinene, there
exists a competition between ring enlarging (II,
III, IV) and ring-opening reactions (VI). In the
ring-opening reaction, the esterification product
is α-terpinyl acetate. The esterification reaction of
α-pinene as in situ in a reaction that occurs through
hydration reactions prior to the addition of distilled
water to form α-terpineol then α-terpineol with
acetate anhydride to form α-terpinyl acetate (XI) and
by-products such as bornyl acetate (V) and fenchyl
acetate (VIII). A similar behavior was observed by
liu et al.,(2013)6, and lu et al., (2008)9.
Figure 4 shows the effect of various
heterogeneous catalysts on the reaction, including all
minorproducts.The reaction time was 4 h α-terpinyl
acetate reached its highest value of 52.83%.
Fig. 5.The esterification reaction α-pinene with acetic anhydride.
(I) α-pinene (II, III,VI, IX) ion carbonium(IV) borneol (V) bornyl
acetate (VII) fencyl alcohol (VIII) fencyl acetate (X) α-terpineol
(XI) α-terpinyl acetate.
Fig. 4. The concentration of reagent and product over
catalysts versus time
CONCLUSION
is 52.83% at 4 h with a selectivity of 61.38%.
Synthesis of α-terpinyl acetate can
be done by an esterification reaction α-pinene
as in situ with the heterogeneous zeolite-based
catalysts. The most effective catalysts used in
the synthesis of α-terpinyl acetate is catalyst
H/ZY with the largest concentration product yield
ACkNOWLEDgMENT
The authors would like to thank
Ditjen Penguatan Riset dan Pengembangan,
Kemenristekdikti, Republic Indonesia for the support.
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