**2. Material and methods**

Lemon grass leaves were harvested in the month of July, allowed to dry at room temperature for 2 days and cut into pieces of 2 inches in length then distilled in an appropriate stainless steel equipment having a capacity of 15 L along with a condenser having inlet and outlet for water, a tank is heated with a gas burner to continue and complete distillation. **Figure 2** shows a stainless steel tank for distillation.

The azeotropic mixture of essential oil is collected in a separating funnel and the essential oil of lemon grass (5.7 g) was obtained, dried over anhydrous sodium sulfate, and kept in an air tight stoppered bottle. The percentage yield of oil was determined by infrared spectroscopy (IR) and gas chromatography (GC), and obtained data lemon grass oil were plotted on graphs.

## **2.1. Hydrodistillation of essential oil of lemon grass in Dean-Stark apparatus**

Citral (lemon grass oil) was hydrodistilled by using Dean-Stark apparatus, which consists of a round bottomed flask with the capacity of 2 L. Three-fourth of the flask was filled with 500 g of crushed dried leaves of lemon grass along with water and hydrodistilled. The oil was separated and dried over anhydrous sodium sulfate. It yields 0.38% oil. **Figure 3** shows Dean-Stark apparatus.

#### **2.2. Analytical equipment used**

**Infrared spectrophotometer**: Model Thermo Nicolet FT-IR 200 (USA) was used for recording absorption in the infrared region.

**Figure 2.** Stainless steel equipment for hydrodistillation of lemon grass.

**Scheme 7.** Synthesis of citral acetal.

130 Grasses - Benefits, Diversities and Functional Roles

vacuum and product fraction at 121–125°C is citral propylene glycol having fruity odor. GC

Lemon Grass (*Cymbopogon citratus*) http://dx.doi.org/10.5772/intechopen.69518 133

To a citral solution (8 g) was added ethylene glycol (11 g) and benzene (10 ml) with few crystals of para-toluene sulfonic acid in a 250 ml round bottomed flask and stirred by heading. Water was expelled as azeotrop blend with benzene. The remaining item was extracted with hexane and cleaned with sodium bicarbonate arrangement, washed with water and hexane layer was passed over magnesium carbonate. The hexane concentrate was refined off. The left in the cup was refined under vacuum, utilized and gathered three parts at various divisions.

A very small amount of the compounds lemon grass essential oil, distilled citral, citral propylene glycol acetal and citral ethylene glycol acetal), was placed separately between two high purity plates of sodium chloride with the help of hypodermic syringe. IR spectra were then taken for these liquids. Before sampling the plates were washed with anhydrous ether then

A very small amount of compounds (citral and citral acetals) was injected in to a column of PEG-coated on celite support. Nitrogen was used as the carrier gas the flame ionization detector was fitted with it, the temperature was kept at 80–210°C. The peaks obtained were then

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

Citral acetals by using citral was synthesized and tested by GC and IR spectroscopy, results

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

the compounds are smeared between two plates and spectra were recorded.

spectrometry (GC-MS) and IR spectroscopy and obtained the results.

and IR of the fractions were recorded.

These fractions gave fruity odor. GC and IR are recorded.

*2.3.4. IR absorption spectroscopy of compounds*

*2.3.3. Citral ethylene glycol acetal*

*2.3.5. GC of compounds*

**3. Results**

identified and results were noted.

are obtained and graphs are plotted.

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

1445 show the C=C stretching, (see **Table 1** and **Figure 4**).

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

**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, injector 240°C.

#### **2.3. Citral acetals**

#### *2.3.1. Distillation of citral*

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 and graphs were plotted.

#### *2.3.2. Preparation of citral propylene glycol acetal*

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 is dried over MgSO4 then benzene distilled off and the residual product was redistilled under vacuum and product fraction at 121–125°C is citral propylene glycol having fruity odor. GC and IR of the fractions were recorded.

#### *2.3.3. Citral ethylene glycol acetal*

To a citral solution (8 g) was added ethylene glycol (11 g) and benzene (10 ml) with few crystals of para-toluene sulfonic acid in a 250 ml round bottomed flask and stirred by heading. Water was expelled as azeotrop blend with benzene. The remaining item was extracted with hexane and cleaned with sodium bicarbonate arrangement, washed with water and hexane layer was passed over magnesium carbonate. The hexane concentrate was refined off. The left in the cup was refined under vacuum, utilized and gathered three parts at various divisions. These fractions gave fruity odor. GC and IR are recorded.

#### *2.3.4. IR absorption spectroscopy of compounds*

A very small amount of the compounds lemon grass essential oil, distilled citral, citral propylene glycol acetal and citral ethylene glycol acetal), was placed separately between two high purity plates of sodium chloride with the help of hypodermic syringe. IR spectra were then taken for these liquids. Before sampling the plates were washed with anhydrous ether then the compounds are smeared between two plates and spectra were recorded.

#### *2.3.5. GC of compounds*

A very small amount of compounds (citral and citral acetals) was injected in to a column of PEG-coated on celite support. Nitrogen was used as the carrier gas the flame ionization detector was fitted with it, the temperature was kept at 80–210°C. The peaks obtained were then identified and results were noted.
