**3. Results**

**Gas chromatograms**: Gas chromatography studies were carried out on "Shmadzu" Model GC 14A, packed column SE-30, stationary phase PEG (polyethylene glycol), temperature condition 80–210°C, 5°C increment/min sampling recording temperature 80–210°C/10 min.

• GC of citral ethylene glycol acetal was carried out on packed column SE-30, column condition 185°C° for 2 min to 210°C for 5 min, detector flame ionization detector (FID) 270°C,

The purpose of experiment is to synthesize citral acetals, citral was redistilled under vacuum and collected the fraction between 110 and 117°C. Then IR and GC of this citral were recorded

In a round bottomed distillation flask (500 ml), a solution of citral (16 g), propylene glycol (22 g) in toluene (60 ml), and 5–7 crystals of para-toluene sulfonic acid as a catalyst is added. Then fit the flask with Dean-Stark apparatus and heated the flask at 110°C with continuous stirring. An azeotropic mixture of water and toluene was distilled off, sodium bicarbonate used to neutralize the reaction residue, benzene is used for extraction of above residue and it

then benzene distilled off and the residual product was redistilled under

injector 240°C.

**Figure 3.** Dean-Stark apparatus.

132 Grasses - Benefits, Diversities and Functional Roles

*2.3.1. Distillation of citral*

and graphs were plotted.

is dried over MgSO4

*2.3.2. Preparation of citral propylene glycol acetal*

**2.3. Citral acetals**

Essential oil from lemon grass was extracted by hydrodistillation. This oil, also known as citral, is tested for its chemical composition and functional groups by gas chromatography-mass spectrometry (GC-MS) and IR spectroscopy and obtained the results.

Citral acetals by using citral was synthesized and tested by GC and IR spectroscopy, results are obtained and graphs are plotted.

#### **3.1. Interpretation of IR spectra of lemon grass**

The IR spectra of lemon grass oil having strong characteristic peaks at 3476 show the presence of OH and peaks at 2967, 2917, 2856, and 2759 cm−1 show the C–H stretching, a peak at 1686 shows the unsaturated conjugated C=O group present in citral, and peaks at 1650 1613, and 1445 show the C=C stretching, (see **Table 1** and **Figure 4**).


**3.2. Interpretation of GC data of lemon grass oil**

**Sr# Compound name Percentage composition**

 Other isomers 2.2 3.8 1.9 2.9 1.1 1.9 0.9 1.3 0.9 1.3

 0.8 0.8

**Table 2.** GC data for lemon grass oil.

**Figure 5.** GC data for lemon grass oil.

 Citral (cis and trans) 36.5 40 34.6 25.2 10 16.4 Myrcene 7.1 10 11.6 Other isomers 3.7 5.4 7.4 3.7 4.8 5.4 3.4 4.4 4.5 Geraniol 2.6 3.8 3.0

Different fractions of lemon grass oil spectra on GC showed peaks of six major components. It contained 36, 40 and 34% citral A and 25, 20 and28% citral B, and 7, 5 and 8% in three fractions of steam distilled essential oils, respectively. Fractions 1, 2, and 3 also showed peaks of myrcene along with geranial and other isomers. It is reported that essential oil is usually contained citral A (47%), citral B (33%), myrcene (10%), and geraniol (2%) by GC analysis, see **Table 2** and **Figure 5**, obtained by gas chromatography and gas chromatograph of lemon grass.

Total 86.2 89.6 82.9

**F1 F2 F3**

Lemon Grass (*Cymbopogon citratus*) http://dx.doi.org/10.5772/intechopen.69518 **Table 1.** IR absorption spectra of lemon grass oil.

**Figure 4.** IR absorption spectra of lemon grass oil.

#### **3.2. Interpretation of GC data of lemon grass oil**

**Sr.# Peaks Intensity Assignment** 3476 Broad –OH 2967 Sharp & Str –C–H 2917 Sharp & Str C=O 2856 Sharp CH3

1710 Str C=O

1194 Sharp & Str

1043 Str

**Table 1.** IR absorption spectra of lemon grass oil.

Grasses - Benefits, Diversities and Functional Roles

**Figure 4.** IR absorption spectra of lemon grass oil.

1120

 1686 Sharp & Str α,β unsaturation 1650 Sharp –HC=CH– 1613 Sharp –HC=CH– 1445 Sharp C–H 1376 Sharp & Str O–H

1153 Str –HC=CH–

,CH2 ,C–H Different fractions of lemon grass oil spectra on GC showed peaks of six major components. It contained 36, 40 and 34% citral A and 25, 20 and28% citral B, and 7, 5 and 8% in three fractions of steam distilled essential oils, respectively. Fractions 1, 2, and 3 also showed peaks of myrcene along with geranial and other isomers. It is reported that essential oil is usually contained citral A (47%), citral B (33%), myrcene (10%), and geraniol (2%) by GC analysis, see **Table 2** and **Figure 5**, obtained by gas chromatography and gas chromatograph of lemon grass.


**Table 2.** GC data for lemon grass oil.

**Figure 5.** GC data for lemon grass oil.

#### **3.3. Interpretation of IR spectra of citral-propylene glycol acetal**

The IR spectra indicate peaks at 3019, 2925, and 2869, which is associated with the C–H stretching. The medium top peaks at 1667, 1514, 1460, and 1380 show the presence of the C=C stretching due to unimmersion in citral part in this compound. The extending vibrations at 1056, 1106, are because of ether linkage in the given compound (see **Table 3** and **Figure 6**).

#### **3.4. Translation of GC information of citral propylene glycol acetal**

The response blend of citral propylene glycol acetal later extraction with benzene, redistilled under vacuum at 64–88°C. Noteworthy, parts are appeared in **Table 4**. The redistilled compound is thymol rose. As the citral contained cis and trans geometrical isomers, it gave numerous items by response to propylene glycol, because of taking after reason.

The citral propylene glycol acetal anticipated that it would give four more isomers because of development of two hilter kilter focuses at C2 and C4 of 1,3-dioxo-4 methyl-citral acetal (see **Table 4** and **Figure 7**).


**Sr.# Compound name % Age composition**

**Figure 6.** IR absorption spectra of citral propylene glycol acetal.

**Table 4.** GC data of citral propylene glycol acetal.

1 Citral propylene glycol acetal 55.4 31.2 2 Citral (cis/trans) 16.23 18.5 3 6.5 10.3 4 6.1 6.2 5 Other isomers 4.9 5.8 6 4.5 4.2 7 2.9 4.0 8 1.2 3.5 9 0.7 2.4 10 0.4 2.1

**F1**

Total 98.83 95.7

**F2**

Lemon Grass (*Cymbopogon citratus*) http://dx.doi.org/10.5772/intechopen.69518 137

**Table 3.** IR absorption data of citral propylene glycol acetal.

**Figure 6.** IR absorption spectra of citral propylene glycol acetal.

**3.3. Interpretation of IR spectra of citral-propylene glycol acetal**

**3.4. Translation of GC information of citral propylene glycol acetal**

**F1 F2 F3**

1 3019 3019 3019 Sharp & Str v.

5 1744 Wk & sharp

10 1380 1380 13880 Sharp & Str

11 1108 1106 1106 Str

12 1055 1055 1056

**Table 3.** IR absorption data of citral propylene glycol acetal.

2 2925 2925 2925 Sharp & Str C=O 3 2871 2871 2869 Sharp CH3

4 1894 Wk & sharp Isomers

6 1667 Wk & sharp –CH=CH– 7 1608 1608 Med Unsaturation

8 1514 1514 1514 Sharp & med C=C 9 1460 1460 1460 Sharp & Str O–H

**Table 4** and **Figure 7**).

136 Grasses - Benefits, Diversities and Functional Roles

The IR spectra indicate peaks at 3019, 2925, and 2869, which is associated with the C–H stretching. The medium top peaks at 1667, 1514, 1460, and 1380 show the presence of the C=C stretching due to unimmersion in citral part in this compound. The extending vibrations at 1056, 1106, are because of ether linkage in the given compound (see **Table 3** and **Figure 6**).

The response blend of citral propylene glycol acetal later extraction with benzene, redistilled under vacuum at 64–88°C. Noteworthy, parts are appeared in **Table 4**. The redistilled compound is thymol rose. As the citral contained cis and trans geometrical isomers, it gave

The citral propylene glycol acetal anticipated that it would give four more isomers because of development of two hilter kilter focuses at C2 and C4 of 1,3-dioxo-4 methyl-citral acetal (see

close

–CH3 ,CH2 , C–H

> ,CH2 ,C–H

**Sr.# Peaks Intensity Assignment**

numerous items by response to propylene glycol, because of taking after reason.


**Table 4.** GC data of citral propylene glycol acetal.


**Figure 7.** GC data for citral propylene glycol acetal.

#### **3.5. Interpretation of infrared absorption spectra of citral ethylene glycol acetal**

The IR spectra of citral ethylene glycol acetal have trademark top at 2924, which demonstrates the C–H extending. Top at 2867 demonstrates the nearness of CH3 , CH2 , and CH in the given compound. Crest at 1665 shows unimmersion in compound. Top at 1055 demonstrates the nearness of C–O and at 814 shows C=C. Other crest at 1513, 1460, and 1379 demonstrates the nearness of different isomers in the compound (see **Table 5** and **Figure 8**).

**3.6. Elucidation of GC information of citral ethylene glycol acetal**

**Figure 8.** IR absorption spectra of citral ethylene glycol acetal.

1 Citral ethylene glycol acetal 52.7 2 (Cis & trans) 38.5 3 Other isomers 8.3 4 0.3 Total 99.8

**Table 6.** GC data for citral ethylene glycol acetal.

**Sr# Compound name % Age composition**

and **Figure 9**).

Citral ethylene glycol acetal was subjected to GC examination and rate arrangement of major components was resolved by GC, indicating two pinnacles of citral ethylene glycol acetal which are two isomers: cis and trans. This is defended as the beginning citral has two geometrical isomers. Different isomers are additionally present in little sum (see **Table 6**

Lemon Grass (*Cymbopogon citratus*) http://dx.doi.org/10.5772/intechopen.69518 139


**Table 5.** IR absorption data of citral ethylene glycol acetal.

**Figure 8.** IR absorption spectra of citral ethylene glycol acetal.

**3.5. Interpretation of infrared absorption spectra of citral ethylene glycol acetal**

onstrates the C–H extending. Top at 2867 demonstrates the nearness of CH3

**Sr.# Peaks Intensity Assignment**

2 3649 Med C–H 3 2924 Sharp & Str C–H 4 2867 Sharp & Str CH3

 1665 Med C=C 1513 Sharp & Str C=O 1460 Sharp C–H 1379 Med OH

10 814 Med C=C

1 3747 Wk

**Figure 7.** GC data for citral propylene glycol acetal.

138 Grasses - Benefits, Diversities and Functional Roles

9 1055 Med

**Table 5.** IR absorption data of citral ethylene glycol acetal.

**Figure 8**).

The IR spectra of citral ethylene glycol acetal have trademark top at 2924, which dem-

CH in the given compound. Crest at 1665 shows unimmersion in compound. Top at 1055 demonstrates the nearness of C–O and at 814 shows C=C. Other crest at 1513, 1460, and 1379 demonstrates the nearness of different isomers in the compound (see **Table 5** and

, CH2

,CH2 ,CH , and

#### **3.6. Elucidation of GC information of citral ethylene glycol acetal**

Citral ethylene glycol acetal was subjected to GC examination and rate arrangement of major components was resolved by GC, indicating two pinnacles of citral ethylene glycol acetal which are two isomers: cis and trans. This is defended as the beginning citral has two geometrical isomers. Different isomers are additionally present in little sum (see **Table 6** and **Figure 9**).


**Table 6.** GC data for citral ethylene glycol acetal.

[7] LIN, T.S. (1981) Study on the variation of yield and composition of essential oil from *Litsea cubeba*. Bulletin of the Taiwan Forestry Research Institute, No. 355. 14 pp.

Lemon Grass (*Cymbopogon citratus*) http://dx.doi.org/10.5772/intechopen.69518 141

[8] Robbins, S. R. J, Citrohella, Lemon Grass & Eunclyptus Oils. London: Tropical Production

[9] Shahdab Q, Hanif M, Chandhary FM. Antifungal activity by lemon grass essential oils.

[10] Sabcho Dimitrov, Yana Koleva, T. Wayne Schultz, et al. (2004), Enviromental Toxicology and chemistry, Interspecies quantitative structure-activity relationship model for alde-

[11] Gradeft P. as Patent 3840601 (1975). Constamitino V, Apperly DC. Catalysis Letters.

[12] Kamogawa, et al. Chemical Society of Japan. 1981;54(**5**):1577-1578 (Accession Number

[13] Shahzadi P, Alam S, Muhammad A. Book on Synthesis of Citral Acetals. Saarbrücken, Germany: Lap, OmniScriptum GmbH & Co. KG; 2014. p. 64. ISBN-13,9783659636110

Pakistan Journal of Scientific and Industrial Research. 1992;**35:**246-249

Institution (TPI); 1983

1994;23:361 p

**1981**: 497641 CAPLUS).

hydes: Aquatic toxicity, DOI: 10.1897/02-579

**Figure 9.** GC data for citral ethylene glycol acetal.
