Study catalytic oxidation of
-pinene using hydrogen peroxide-ironIII chloride
SWUP
BC.92
2.4 Procedure for study oxidation reactions
A pure of -pinene 4.85 mL; 30.0 mmol in a 100-mL of round bottom flask was added ironIII chloride 8.11 g; 30.0 mmol. This mixture was setting up on the reflux
apparatus, and further added dropwise of with hydrogen peroxide 30 30.67 mL; 300 mmol. This was undertaken during 10 min, and it was further stirring at 80
o
C 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 was
washed with water 2 x 10 mL, and was extracted with ethyl acetate 3 x 10 mL. Combined the ethyl acetate layers was dried under magnesium sulfate anhydrate and decanted for
further concentrated using rotary evaporator. The product was further analyzed and haracterized by using GCMS and FTIR.
3. Results and discussion
Isolation of -pinene from turputine oils was undertaken under vacuum condition. It
was recorded the pressure scale at 0 mmHg, and first fraction boiled at 30
o
C, and -pinene
was detected in this fraction as major component. It was a clear oils, fresh turpentine oil aroma, density 0.8400 mLg 28
o
C, index refractive 1.4635 26.3
o
C. It was also found that characteristic both GCMS Figure 2 and FTIR Figure 3 spectra data very similar to that
reported by Masruri et al. 2007 and Amini et al. 2014. Mass spectra detected mz 136 for molecule ion of
-pinene. Further fragmentation pattern provided mass fragments mz 121, 105, 93 base peak, 77, 67, 53, and 41, respectively. This pattern as indication for
defragmented of alkyl group from molecular ion of -pinene. Meanwhile from the
chromatogram, it was found the -pinene had 91.01 purity chromatogram did not
reported, see Masruri et al., 2007. In addition, the infrared spectra gave important bands for functional group in
-pinene such as alkene =C-H
stretching
, C=C
stretching
, C=C
bending
vibration and alkyl group C-H
stretching
and C-H
bending
vibration. By this result, the research applied -pinene
isolated from turpentine as starting material for study oxidation reaction using hydrogen peroxide catalyzed by ironIII chloride.
Oxidation of -pinene using hydrogen peroxide, as previously reported by
Maksimchuk et al. 2005, provided verbenol, verbenone, and camphonelic aldehyde Figure 1. Reaction was undertaken at 50
o
C for 5 h reaction. In the investigation, oxidation of -
pinene used mol equivalence of hydrogen peroxide 1.0, and applied reaction in reflux condition. IronIII chloride was mixed first before addition of oxidant. In general, reaction
completed after 16 h stirring Figure 4. Product determination using gas chromatography-mass spectrometry provided a
chromatogram as shown on Figure 5. In general, it was found minimum 17 compounds detected, and the remains
-pinene was still detected at retention time t
R
6.588 min. Tabulation of determined compound was summarized in Table 1. The product of oxidation
reaction can be classified into two groups, which provided isomerization product and the other provided the oxidation product. Isomerization product provided similar molecular
weight MW 136, such as camphene, -ocimene, limonene, -thujene, -terpinolene, and
isomyocorene. Meanwhile the oxidation product group in general has molecular weight above 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 bornyl
acetate 196.
M. Pradhita, Masruri, M.F. Rahman
SWUP
BC.93
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.
Study catalytic oxidation of
-pinene using hydrogen peroxide-ironIII chloride
SWUP
BC.94
Table 1. Tabulation of the oxidation reaction product of -pinene. Peak
number t
R
min Area
Predicted compound
Suggested structure MW
SI
1 6.588
56.64 -Pinene
136 96
2 7.176
1.59 Camphene
136 89
3 10.210
11.54 -Ocimene
136 93
4 10.465
4.61 iso-Cineole
154 89
5 10.950
2.40 -Phellandrene
136 90
6 11.172
3.75 Limonene
136 92
7 11.288
1.78 1,8-Cineole
154 87
8 12.461
1.07 -Thujene
136 89
9 13.524
5.71 -Terpinolene
136 94
10 14.317
1.61 d-Fenchyl
alcohol 154
90 11
14.641 1.45
Isomyocorene 136
83 12
14.908 0.47
1-Terpineol 154
78 13
15.719 3.21
2- Chlorocamphane
172 87
14 16.354
2.04 -Terpineol
154 93
15 17.031
0.53 -Fenchyl
acetate 196
80 16
17.128 1.07
Camphene 136
85 17
18.355 0.52
Bornyl acetate 196
78 Note:
Determination based on the similarity index SI value with library.
Characterization using infrared spectrophotometer provided spectra, showed in Figure 6. In general, it was discovered three important functional groups supported the determined
compounds 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 be also an ester. The correlated compound was determined such as
-fenchyl acetate and bornyl 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 group includes camphene,
-ocimene, -phelandrene, limonene, -thujene, -terpinolene, and
M. Pradhita, Masruri, M.F. Rahman
SWUP
BC.95
isomyocorene. Besides that, infrared spectra also recorded the the presence of alkyl group existed in every molecules. Bands recorded in between 2958 and 2869 cm
-1
characteristic for stretching vibration symmetry and asymmetry of C-H alkyl. And also, their bending vibration
in 1460 and 1382 cm
-1
was clearly come up.
Figure 6. Infrared spectra of oxidation product of -pinene.
4. Conclusion and remarks
