Proceedings of the IConSSE FSM SWCU (2015), pp. BC.90–96ISBN: 978-602-1047-21-7

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Study catalytic oxidation of -pineneusing hydrogen peroxide-iron(III) chloride

Merry Pradhita, Masruri *, Mohammad Farid RahmanaDepartment of Chemistry, Brawijaya University, Jl. Veteran Malang 65145, Indonesia

AbstractIndonesia has abundance source of alpha-pinene, and mainly can be isolated fromturpentine oils. This oils itself, was harvested from pine tree (Pinus merkusii Junh. & deVr). This paper reveals the recent investigation on oxidation of α-pinena using hydrogenperoxide catalyzed by iron(III) chloride. Meanwhile the end objective of this studybasically was derivatization of α-pinene to provide basic and fine chemicals for industryand pharmaceuticals. A green oxidator, hydrogen peroxide, commonly provided epoxidegroup to the alkene double bond of α-pinene. However, it was found a diverse oxidationproduct was observed during reaction catalyzed by iron(III) chloride. Analysis of theoxidation product was performed by using gas chromatography-mass spectrometry andinfrared spectrophotometry.

Keywords α-pinene, carvone, catalytic, oxidation, turpentine oil

1. Introduction

Indonesia as a tropical country has wide area for forestry. And also, its natural productsand natural oils harvested from forestry is an indispensable product including the essentialoils. Pine forestry generally grows species of Pine merkusii Junh. & de Vr, along island ofIndonesia and produces turpentine oils beside its gum rosin. It was reported in 2013, totalproduction was recorded about 11,851 ton (Perum Perhutani, 2014). It was predictedincrease by ten during a decade. However, this production was exported directly as rawturpentine oils.

α-pinene contains in turpentine oils as major component. Recent investigationreported that α-pinene composed turpentine oil harvested from local forestry in average88% from total component (Amini et al., 2014). This high composition leads to purification ofα-pinene of turpentine oil for further application (Masruri et al., 2007). Previous resultdescribed α-pinena has activity to inhibit bacterial growth and also possible for antiseptic(Masruri et al., 2007; Leite et al., 2007), bioactivity as anti-inflammation in neuronal cell(Khotimah et al., 2006). Besides, it was also reported application α-pinene as starting materialin organic synthetic for adhesive, finishing product, ink, and perfumery (Sarwar, 2012).

Transformation of α-pinene into fine chemicals by oxidation reaction was alsoreported by other researcher. It applied various different oxidation agents. For example,hydrogen peroxide (H2O2) using some catalyst such as titanium(VI), iron(III), zirconium(IV),titanium-supported silica, and solid acid (H5PW11TiO40). Some products were reported suchas verbenol (4-9%), verbenone (2-10%), dan campholenic aldehyde (2-9%) (Maksimchuk et

* Corresponding author. Tel.: +62 341 575838 ext 111; E-mail address: masruri@ub.ac.id

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al., 2005). Reaction was generally undertaken in room temperature until 50 oC (Maksimchuket al., 2005). However, low selectivity and yield was always reported (see Figure 1).

Figure 1. Scheme of oxidation reaction of α-pinene.

Oxidation using hydrogen peroxide is interesting process since the by-product resultedis water. It is known as a green oxidator. It has efficiency of oxygen atom to convert organicsubstances by 47% (Noyori et al., 2003). According to Hasan and co-worker, oxidation usinghydrogen peroxide is economically and ecologically advantageous. It was easily to manage,handle, low cost, and only provided water as by product (Hasan et al., 2011). Thus, applyinghydrogen peroxide basically follows the principles of green oxidation. This study will reportoxidation of α-pinene using hydrogen proxide and catalyzed by iron(III) chloride. The resultwas expected can open the way to control selectivity and further application of Indonesianturpentine oils.

2. Materials and methods

2.1 Materials

The materials used for research including turpentine oils (given from PT PerhutaniAnugerah Kimia, Trenggalek, East Java). Procedure and method for -pinene purificationwas undertaken following Masruri et al. (2007). Other materials was some chemicals used asbought from the manufacturer or as mentioned, including hydrogen peroxide 30% (Merck),iron(III) chloride (Merck), ethyl acetate (Smart Lab), n-hexane (Smart Lab), magnesium sulfateanhydrate (Merck), pre-coated silica TLC F60 (Merck), and aquadest.

2.2 Instrumentation and glassware

Some instrumentation for analysis was used such as ultraviolet-visiblespectrophotometer (Shimadzu UV-1601), infrared spectrophotometer (Shimadzu FTIR-8400S), and gas chromatography-mass spectrometry (Shimadzu GCMS-QP2010S),refractometer (Abbe), analytical balance (Ohaus), and magnetic stirrer-heater. Meanwhilesome glassware applied such as a set of vacuum fractional distillation, pycnometer, TLCdevelopment glass, and other minor glassware.

2.3 Procedure for distillation of turpentine oils

Turpentine oil was distillated follow procedure from Masruri et al. (2007). A 100 mL ofdried turpentine oil was placed in a round-flask from a setting of vacuum fractionaldistillation apparatus. Stirring and vacuuming was undertaken until the oil boiled. Thepressure and boiling point were monitored and kept constant until first fraction collected. -Pinene was collected in the first fraction, and further analysis for its density, purity, indexrefractive.

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2.4 Procedure for study oxidation reactions

A pure of α-pinene (4.85 mL; 30.0 mmol) in a 100-mL of round bottom flask wasadded iron(III) chloride (8.11 g; 30.0 mmol). This mixture was setting up on the refluxapparatus, and further added dropwise of with hydrogen peroxide 30% (30.67 mL; 300mmol). This was undertaken during 10 min, and it was further stirring at 80 oC for 2 h.Reaction progress was monitor by spotting the reaction sampling on TLC. Disappearing of -pinene on TLC plate as indication that reaction completed. Then, the reaction mixture waswashed with water (2 x 10 mL), and was extracted with ethyl acetate (3 x 10 mL). Combinedthe ethyl acetate layers was dried under magnesium sulfate anhydrate and decanted forfurther concentrated using rotary evaporator. The product was further analyzed andharacterized by using GCMS and FTIR.

3. Results and discussion

Isolation of -pinene from turputine oils was undertaken under vacuum condition. Itwas recorded the pressure scale at 0 mmHg, and first fraction boiled at 30 oC, and -pinenewas detected in this fraction as major component. It was a clear oils, fresh turpentine oilaroma, density 0.8400 mL/g (28 oC), index refractive 1.4635 (26.3 oC). It was also found thatcharacteristic both GCMS (Figure 2) and FTIR (Figure 3) spectra data very similar to thatreported by Masruri et al. (2007) and Amini et al. (2014). Mass spectra detected m/z 136 formolecule ion of -pinene. Further fragmentation pattern provided mass fragments m/z 121,105, 93 (base peak), 77, 67, 53, and 41, respectively. This pattern as indication fordefragmented of alkyl group from molecular ion of -pinene. Meanwhile from thechromatogram, it was found the -pinene had 91.01% purity (chromatogram did notreported, see Masruri et al., 2007). In addition, the infrared spectra gave important bands forfunctional group in -pinene such as alkene (=C-Hstretching, C=Cstretching, C=Cbending vibration) andalkyl group (C-Hstretching and C-Hbending vibration). By this result, the research applied -pineneisolated from turpentine as starting material for study oxidation reaction using hydrogenperoxide catalyzed by iron(III) chloride.

Oxidation of -pinene using hydrogen peroxide, as previously reported byMaksimchuk et al. (2005), provided verbenol, verbenone, and camphonelic aldehyde (Figure1). Reaction was undertaken at 50 oC for 5 h reaction. In the investigation, oxidation of -pinene used mol equivalence of hydrogen peroxide 1.0, and applied reaction in refluxcondition. Iron(III) chloride was mixed first before addition of oxidant. In general, reactioncompleted after 16 h stirring (Figure 4).

Product determination using gas chromatography-mass spectrometry provided achromatogram as shown on Figure 5. In general, it was found minimum 17 compoundsdetected, and the remains -pinene was still detected at retention time (tR) 6.588 min.Tabulation of determined compound was summarized in Table 1. The product of oxidationreaction can be classified into two groups, which provided isomerization product and theother provided the oxidation product. Isomerization product provided similar molecularweight (MW 136), such as camphene, -ocimene, limonene, -thujene, -terpinolene, andisomyocorene. Meanwhile the oxidation product group in general has molecular weightabove 154, such as iso-cineole (154), (1,8)-cineole (154), d-fenchyl alcohol (154), 1-terpineol(154), 2-chlorochamphene (172), -terpineol (154), -fenchyl acetate (196), and bornylacetate (196).

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Figure 2. Mass spectra of -pinene sample, afforded from GCMS analysis.

Figure 3. Infrared spectra of -pinene sample, afforded from FTIR analysis.

Figure 4. Monitoring reaction progress.

Figure 5. Chromatogram of oxidation reaction product of -pinene.

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Table 1. Tabulation of the oxidation reaction product of -pinene.Peak

number tR (min) Area (%) Predictedcompound Suggested structure* MW

(SI)

1 6.588 56.64 -Pinene136(96)

2 7.176 1.59 Camphene 136(89)

3 10.210 11.54 -Ocimene136(93)

4 10.465 4.61 iso-Cineole O 154(89)

5 10.950 2.40 -Phellandrene136(90)

6 11.172 3.75 Limonene 136(92)

7 11.288 1.78 1,8-CineoleO 154

(87)

8 12.461 1.07 -Thujene136(89)

9 13.524 5.71 -Terpinolene136(94)

10 14.317 1.61 d-Fenchylalcohol OH

154(90)

11 14.641 1.45 Isomyocorene 136(83)

12 14.908 0.47 1-TerpineolHO 154

(78)

13 15.719 3.21 2-Chlorocamphane

Cl 172(87)

14 16.354 2.04 -Terpineol OH154(93)

15 17.031 0.53 -Fenchylacetate

O

O

196(80)

16 17.128 1.07 Camphene 136(85)

17 18.355 0.52 Bornyl acetateO

O 196(78)

Note: *Determination based on the similarity index (SI) value with library.

Characterization using infrared spectrophotometer provided spectra, showed in Figure6. In general, it was discovered three important functional groups supported the determinedcompounds in mass spectra analysis. First, the hydroxyl group was detected in 3444 cm-1.This band correlates to alcoholic compound such as d-fenchyl alcohol, 1-terpineol, and -terpineol. Second, band detected in 1710 cm-1 that specific for carbonyl compound. It can bealso an ester. The correlated compound was determined such as -fenchyl acetate andbornyl acetate. Last, the band specify for isomerization products and detected in 1645 cm-1

for stretching vibration of C=C alkene. Correlated compound for this functional groupincludes camphene, -ocimene, -phelandrene, limonene, -thujene, -terpinolene, and

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isomyocorene. Besides that, infrared spectra also recorded the the presence of alkyl groupexisted in every molecules. Bands recorded in between 2958 and 2869 cm-1 characteristic forstretching vibration symmetry and asymmetry of C-H alkyl. And also, their bending vibrationin 1460 and 1382 cm-1 was clearly come up.

Figure 6. Infrared spectra of oxidation product of -pinene.

4. Conclusion and remarks

In summary, oxidation reaction of -pinene using hydrogen peroxide-catalyzed byiron(III) chloride provided three general compound groups. Firstly is alcoholic compound.Secondly is carbonyl compound. And thirdly is isomerization compound. All thosecompounds were also detected their characteristic functional group on the infrared spectra.However, in term of selectivity, it was found that this method still provides low chemo-selectivity. Future strategy should be undertaken in order to improve both yield andselectivity to the targeted products.

Acknowledgment

This research was financed by research grant “Penelitian Unggulan Perguruan Tinggi(PUPT)” year 2015 to (MSR and M.F.R) of Brawijaya University from Ministry of Research,Technology and Higher Education, Indonesia.

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Leite, A.M., Lima, E.D.O., Souza, E.L.D., Diniz, M.D.F.F.M., Trajano, V.N., & Medeiros, I.A. D (2007).Inhibitory effect of beta-pinene, alpha-pinene and eugenol on the growth of potential infectiousendocarditis causing gram-positive bacteria. Revista Brasileira de Ciências Farmacêuticas, 43 (1),121–126.

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