SEMESTER EXAM

Question

1. Explain the triterpenoid biosynthetic pathway, identify important factors that determine the quantities               produced many triterpenoids!
2. Describe the structure determination of flavonoids, specificity and intensity of absorption signal by using IR and NMR spectra. Give the example of at least two different structures!
3. In the isolation of alkaloids, in the early stages of acid or base required conditions. Explain the basis of the use of reagents, and give examples of at least three kinds of alkaloids!
4. Explain the relationship between biosynthesis, methods of isolation and structural determination of compounds of natural ingredients. Give an example!

Answer

1. Biosynthesis of Triterpenoid

In general, the biosynthesis of terpenoids three basic reactions, namely:

• The establishment of active isoprene derived from acetic acid via mevalonic acid.
• Merging head and tail isoprene units to form mono-, seskui-, di-, Sester-, and poly-terpenoids.
• Merger tail and the tail of the unit C-15 or C-20 produces triterpenoids and steroids.

Activated acetic acid coenzyme A did produce acid asetoasetat Claisen condensation. The resulting compound is then reacted with acetyl coenzyme A did aldol condensation produces branched carbon chains as found in mevalonic acid. The reactions that followed was phosphorylated, elimination of phosphoric acid and subsequent decarboxylation produces IPP to DMAPP by the enzyme berisomerisasi isomerase. IPP as active isoprene units joined head to-tail with DMAPP and this merger is the first step of the polymerization of isoprene to produce terpenoids. This merger occurs because electrons attack the double bond carbon atoms of IPP to DMAPP a shortage of electrons followed by removal of pyrophosphate ions.

Knowledge triterpenoid biosynthetic pathways (terpenoid) allows for modification of metabolites that can be produced in greater numbers and in a shorter period of time, knowing the structure of the resulting metabolites, and then to do the synthesis to produce its derivatives. Modifications can be done in several ways, namely:

• Blocking the path to optimize the other lane. For example, inhibition of acetate-mevalonic pathway in the formation of isoprene to increase the production of isoprene on track trioses-pyruvate.
• The addition of enzymes, precursors, intermediates, or substrate (enzyme activation). The addition of these substances in the biosynthesis of measures appropriate to increase the production of metabolites. For example, the addition squalen on cell suspension cultures of neem as a precursor to the formation of azadirachtin azadirachtin done when production increases. So that needs to be made the growth curve (Zakiyah, Zulfa, et al, 2003).
• Modification of environmental growth conditions. Certain conditions can trigger cells to produce a metabolite. Based on the hypothesis that believed all along that plant secondary metabolites formed in a depressed condition, as a function of secondary metabolites is as a form of a plant response to environmental conditions to sustain life.

2. NMR SPECTRUM

NMR is used to determine the structure of natural and synthetic components are new, the purity of the components, and the direction of chemical reactions in solution as well as the relationship of components that can undergo chemical reactions. NMR spectroscopy is a tool developed in structural biology. NMR in biology melekuler performed on the sample in the form of a solution to prior purification or extraction. Can be determined by NMR molecular structure and the changes that occur when receiving interference from outside (stimulus, disease or the addition of other substances).

nmr spectrum of flavone

nmr spectrum of quercetin

Identification by 1H NMR spectra showed the presence of five aromatic protons, hydroxyl proton, five aliphatic protons and 3 methyl protons. Based on these data showed a compound of flavonoids (quercetin), which binds to a sugar group is rhamnosil. Based on data from HMBC, rhamnosil bound to C-3 of quercetin. These compounds are known as quercetrin (quercetin-3-O-rhamnosida).

IR SPECTRUM

IR spectroscopic used to determine the functional groups. This may be due to the infrared spectra of organic compounds are typically organic, meaning its compounds will have different spectra. The use of infrared spectra in organic chemistry using the local wavenumber range 666-4000 cm-1. When the compound is passed through the infrared organic compounds, some frequencies are absorbed and others will continue. Infrared spectroscopic used to determine the structural information of organic compounds.

IR spectrum of Rimpang temu ireng

Based on the figure can be seen in the strong bands at 1714.6 cm-1 are specific to carbonyl groups. Uptake sharp 1261.4 and 1217.0 cm-1 arises from the conjugated CO group vibrations. Ribbon at 1091.6 and 1029.9 cm-1 is the absorption of the methoxy group. Ribbon at 3020.3 cm-1 comes from the = CH str supported by bands between 1600 cm-1 and 1500 cm-1 indicates the presence of an aromatic nucleus. Small bands namely weak 1652.9 cm-1 coming from the vinyl. The ribbon on the area under the 3000 cm-1 and reinforced by bands around 1450 cm-1 indicates the presence of alkyl methylene. Based on the above analysis of the IR spectrum, it can be concluded that the compounds contained aromatic group, C = O, CO, vinyl,-CH2-and methoxy.

IR spectrum of Quercetin

IR spectra of quercetrin shows the functional groups OH (3294 cm-1), CC aliphatic (2931 cm-1), C = O (1728 cm-1), C = C aromatic (1504 and 1604 cm-1) and COC ether (1064 cm-1). 13C NMR spectra showed 14 carbon aromatic, one carbonyl, and six aliphatic carbon.

3. Effectively insulating compound of natural ingredients then the selection of organic solvent to be used should be appropriate to the nature of the compound to be isolated, which will be easier to polar solvents dissolve polar compounds and otherwise non-polar compounds more soluble in non-polar solvents (Harborne, 1987).

Alkaloids are usually isolated from the plant by using the method of extraction. Solvents are used when extracting the compound mixture is acidified water molecules. This solvent will be able to dissolve the alkaloid salts, this method has been used to extract ergotamine from ergot fungus ..

Moreover, it can also alkalinize alkaloid-containing plant material by adding sodium carbonate. Bases are formed can then be extracted with an organic solvent such as chloroform or ether, it has been used to mengektraksi alkaloid compounds found in plant seeds of mahogany (Swietenia mahogany Jacq).

For alkaloids that are not heat resistant, insulation can be done using techniques alkalinize the solution concentration by first. By using this technique it will evaporate and hereinafter alkaloids can be purified. Usually used for the purification of the compound nicotine. As for the solution of the alkaloid in water that is acidic, then the solution must basified beforehand. Further alkaloids can be extracted using an organic solvent.

4. Biosynthesis, isolation and structural determination of the method of natural materials closely related compounds. By knowing the process of biosynthesis of a compound of natural materials, it will be known process / chemical reactions that occur in obtaining the desired compound. Then, to obtain the pure compound isolation process is carried out to obtain the compound of natural ingredients required / chill. In isolation, the structure can be determined. Thus, from the results of the determination of the structure can be compared with the structure of chemical compounds produced in the process of biosynthesis to match the structure.

Once known molecular structure is usually followed by a modification of the structure to obtain compounds with the desired activity and stability. Besides, with advances in biotechnology, can also be done to improve the quality of plants or organisms through tissue culture or the creation of a transgenic plant would also produce various kinds of new secondary metabolites of diverse and possibly with a different molecular structure to that found from plants initially. Thus the research opportunities in the field of natural products is also not limited. So the secondary metabolite compounds can be used for the benefit of human life.

Example is in the 1700s, chemists examine the myths that circulate in the community about the benefits of tea to stay young. Once the research is done by experts who know the biosynthesis of tea contains a variety of compounds. Then the experts to obtain the isolated compounds contained in tea. After the isolation, the experts identified strukutr compound, determining the structure of these experts know that tea contains flavonoids that are useful as antioxidants to prevent free radicals that enter the body. One is to prevent cancer and many more benefits.

CHOLESTEROL

I. Structure

fig. 1 cholesterol structure

Cholesterol is a fat-sterol-containing metabolites (English: waxy steroid) which is found in cell membranes and circulated in the blood plasma. Is a kind of lipid molecules that are fat or like it. Cholesterol is a special type of lipid called steroids. Steroids are lipids that have special chemical structure. This structure consists of four rings of carbon atoms.

Steroids include steroid hormones such as cortisol, estrogen, and testosterone. In fact, all steroid hormones are made from chemical changes in the basic structure of cholesterol. At about making a molecule of molecular conversion easier, scientists call it synthetic.

Hypercholesterolemia means that the levels of cholesterol in the blood is too high.

Cholesterol can be made ​​synthetically. Cholesterol synthetic currently implemented in widescreen technology (billboards) as an alternative to the LCD.

II. Properties of cholesterol

Properties
Molecular formula	C27H46O
Molar mass	386.65 g/mol
Appearance	white crystalline powder[2]
Density	1.052 g/cm3
Melting point	148–150 °C[2]
Boiling point	360 °C (decomposes)
Solubility inwater	0.095 mg/L (30 °C)
Solubility	soluble in acetone, benzene,chloroform, ethanol, ether, hexane,isopropyl myristate, methanol
Hazards
Flash point	209.3 ±12.4°C [1

III. Biosynthesis of Cholesterol

Slightly less than half of the cholesterol in the body derives from biosynthesis de novo. Biosynthesis in the liver accounts for approximately 10%, and in the intestines approximately 15%, of the amount produced each day. Cholesterol synthesis occurs in the cytoplasm and microsomes (ER) from the two-carbon acetate group of acetyl-CoA.

The acetyl-CoA utilized for cholesterol biosynthesis is derived from an oxidation reaction (e.g., fatty acids or pyruvate) in the mitochondria and is transported to the cytoplasm by the same process as that described for fatty acid synthesis (see the Figure below). Acetyl-CoA can also be synthesized from cytosolic acetate derived from cytoplasmicoxidation of ethanol which is initiated by cytoplasmic alcohol dehydrogenase (ADH3). All the reduction reactions of cholesterol biosynthesis use NADPH as a cofactor. The isoprenoid intermediates of cholesterol biosynthesis can be diverted to other synthesis reactions, such as those for dolichol (used in the synthesis of N-linked glycoproteins, coenzyme Q (of the oxidative phosphorylation pathway) or the side chain of heme-a. Additionally, these intermediates are used in the lipid modification of some proteins.

Pathway for the movement of acetyl-CoA units from within the mitochondrion to the cytoplasm for use in lipid and cholesterol biosynthesis. Note that the cytoplasmic malic enzyme catalyzed reaction generates NADPH which can be used for reductive biosynthetic reactions such as those of fatty acid and cholesterol synthesis.

The process of cholesterol synthesis has five major steps:

1. Acetyl-CoAs are converted to 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA)

2. HMG-CoA is converted to mevalonate

3. Mevalonate is converted to the isoprene based molecule, isopentenyl pyrophosphate (IPP), with the concomitant loss of CO₂

4. IPP is converted to squalene

5. Squalene is converted to cholesterol.

athway of cholesterol biosynthesis. Synthesis begins with the transport of acetyl-CoA from the mitochondrion to the cytosol. The rate limiting step occurs at the 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reducatase, HMGR catalyzed step. The phosphorylation reactions are required to solubilize the isoprenoid intermediates in the pathway. Intermediates in the pathway are used for the synthesis of prenylated proteins, dolichol, coenzyme Q and the side chain of heme a. The abbreviation "PP" (e.g. isopentenyl-PP) stands for pyrophosphate. Place mouse over intermediate names to see structure.

Acetyl-CoA units are converted to mevalonate by a series of reactions that begins with the formation of HMG-CoA. Unlike the HMG-CoA formed during ketone body synthesis in the mitochondria, this form is synthesized in the cytoplasm. However, the pathway and the necessary enzymes are similar to those in the mitochondria. Two moles of acetyl-CoA are condensed in a reversal of the thiolase reaction, forming acetoacetyl-CoA. The cytoplasmic thiolase enzyme involved in cholesterol biosynthesis is acetoacetyl-CoA thiolase encoded by the ACAT2 gene. Although the bulk of acetoacetyl-CoA is derived via this process, it is possible for some acetoacetate, generated duringketogenesis, to diffuse out of the mitochondria and be converted to acetoacetyl-CoA in the cytosol via the action of acetoacetyl-CoA synthetase (AACS). Acetoacetyl-CoA and a third mole of acetyl-CoA are converted to HMG-CoA by the action of HMG-CoA synthase.

HMG-CoA is converted to mevalonate by HMG-CoA reductase, HMGR (this enzyme is bound in the endoplasmic reticulum, ER). HMGR absolutely requires NADPH as a cofactor and two moles of NADPH are consumed during the conversion of HMG-CoA to mevalonate. The reaction catalyzed by HMGR is the rate limiting step of cholesterol biosynthesis, and this enzyme is subject to complex regulatory controls as discussed below.

Mevalonate is then activated by two successive phosphorylations (catalyzed by mevalonate kinase, and phosphomevalonate kinase), yielding 5-pyrophosphomevalonate. In humans, mevalonate kinase resides in the cytosol indicating that not all the reactions of cholesterol synthesis are catalyzed by membrane-associated enzymes as originally described. After phosphorylation, an ATP-dependent decarboxylation yields isopentenyl pyrophosphate, IPP, an activated isoprenoid molecule. Isopentenyl pyrophosphate is in equilibrium with its isomer, dimethylallyl pyrophosphate, DMPP. One molecule of IPP condenses with one molecule of DMPP to generate geranyl pyrophosphate, GPP. GPP further condenses with another IPP molecule to yield farnesyl pyrophosphate, FPP. Finally, the NADPH-requiring enzyme, squalene synthase catalyzes the head-to-tail condensation of two molecules of FPP, yielding squalene. Like HMGR, squalene synthase is tightly associated with the ER. Squalene undergoes a two step cyclization to yield lanosterol. The first reaction is catalyzed by squalene monooxygenase. This enzyme uses NADPH as a cofactor to introduce molecular oxygen as an epoxide at the 2,3 position of squalene. Through a series of 19 additional reactions, lanosterol is converted to cholesterol.

The terminal reaction in cholesterol biosynthesis is catalyzed by the enzyme 7-dehydrocholesterol reductase encoded by the DHCR7 gene. Functional DHCR7 protein is a 55.5 kDa NADPH-requiring integral membrane protein localized to the microsomal membrane. Deficiency in DHCR7 (due to gene mutations) results in the disorder calledSmith-Lemli-Opitz syndrome, SLOS. SLOS is characterized by increased levels of 7-dehydrocholesterol and reduced levels (15% to 27% of normal) of cholesterol resulting in multiple developmental malformations and behavioral problems.

we can also see of cholesterol biosynthesis with this page :
http://www.cholesterol-and-health.com/Synthesis-Of-Cholesterol.html

IV. Identification Structure

The 13C NMR spectrum below is for an unknown compound with 38 carbons. Several carbons in the spectrum are overlapping with each other, thus, making the interpretation difficult.

To facilitate the process of elucidating the unknown, the 13C NMR spectrum for the unknown (drawn in black) is compared to the 13C NMR spectrum for a pure sample of cholesterol (drawn in red). The signals that line up are part of the same cholesterol scaffold; in all ~25 signals match up. The remaining 13 signals belong to the unknown part that requires further work.

The structures for the unknown and cholesterol are shown below

Mid-Term Exam Answers Chemistry of Natural Products

1. Extraction with supercritical fluid

fig. 1 supercritical fluid

To improve the productivity and increase the quality of the extraction of the active compounds of natural ingredients is the diversification of the isolation of natural products. During this period, the local industry is still based on conventional separation technologies such as steam distillation or extraction with organic solvents. If we start with separation using supercritical fluid technology. Besides staying as digadang separation technology greener, supercritical fluid also offers a performance that is often superior to conventional technologies. In fact, this technology has been used for the removal of caffeine in coffee.

fig. 2 Fluid phase diagrams and territories supercritis

In a nutshell the fluid is a supercritical fluid in a state above the critical temperature and pressure so as not to show any phase separation. Supercritical fluid can diffuse in a solid-like behavior of gases or other substances may dissolve as liquid behavior. So far that is commonly used in the extraction is a mixture of natural material supercritical fluid CO2 (carbon dioxide). Moreover, CO2 methanol, or a combination dimetilether with additive methanol, dimetilether, or the water can also be applied to the separation of the active compound.

use of supercritical CO2 is more advantageous in the extraction process especially to reach the supercritical state has enough pressure 73.9 bar and temperature of 31.1 ° C, which is said relatively soft (compared to methanol which require conditions of 239.5 ° C and 81 bar). CO2 in supercritical conditions, a variety of target compounds will be no change or chemical damage. The course of the process can be fairly simple and can be applied directly on the solid material, such as shredded leaves. After solubilization and extraction process repeatedly, fluid mixture and the active ingredient may be separated with a lower pressure. CO2 supercritical fluid has properties of non-polar and easier to melt the fat while the most active compounds that have economic value is polar. The problem is easily solved in the process of extraction liquid with a little 'longer as a regulator of polarity, such as water or methanol. Many studies have shown that the extraction with supercritical fluid selectivity is higher using conventional means. It is mainly influenced by the physico-chemical properties of the fluid and mass transfer occurring. Meanwhile, if the separation were performed using solvents water, as the system of steam distillation, almost all of the polar active compounds will be transported.

2. Natural ingredient compounds can be synthesized in the laboratory by:

• Cold extraction

          a. Maceration method The maceration is a penyarian easily done by immersing the powder in the  liquid botanical penyari for a few days at room temperature and protected from light. Maceration method used to sum up bulbs that contains chemical Komonen penyari soluble liquid, containing benzoin, tiraks and candles.

The advantage of this method is simple equipment. Moderate losses include the time required to extract the sample long enough, penyari fluids are being used more, can not be used for materials that have a hard texture as benzoin, tiraks and candles.

Maceration method can be modified as follows:

 Change maceration circular

 Change digestion maceration

 Change Maceration circular Multi

 Change remaserasi

 Changes stirrer machine

 Soxhletasi Methods

          b. Soxhletasi is penyarian vegetable sustainable, heated so as to evaporate the liquid penyari, penyari liquid molecules of condensed vapor in the water for cooling back and summarize raw klongsong and then again in round-bottomed flask after passing through the siphon tube. 

The advantage of this method is:

- Can be used to sample the texture is soft and not resistant to direct heating.

- Used or less solvent

- or heating can be arranged

The disadvantage of this method:

- Since the solvent is recycled, extract collected in a container near the heated continually so as to cause a decomposition reaction by heat.

The total number of compounds or extracts will exceed their solubility in specific solvents that can solve in the container and need more volume of solvent to dissolve it.

- When done on a large scale, may not be suitable for use with solvent boiling point is too high, such as methanol or water, since all the tools are under komdensor must be at this temperature for the effective movement of solvent vapors .

This method is limited to the extraction of the pure solvent or mixture of azeotropic and can not be used for the extraction with a mixture of solvents, such as hexane: diklormetan = 1: 1, acidified or basified solvent, since the steam will have a different composition in the liquid solvent into the container.

            c. Percolation Method : Percolation is a way to transmit penyarian penyari through raw powder that has dibasahi.Keuntungan this method does not require the additional step of solid samples (marc) was separated from the extract. The disadvantage is that the contact between the solid sample is irregular or limited with respect to the reflux, and the solvent to cool during the process so that it does not dissolve the components percolation efficient.

• Heat extraction

           a. Method of reflux

The advantage of this method is used to extract samples that have a rough texture and keep the direct heating 

The disadvantage is the need of the total volume of the solvent and a manipulation of the operator.

           b. Method of steam distillation

Steam distillation is a popular method for the extraction of oils evaporate (essential) from plant samples

A method of steam distillation is intended to summarize containing crude oil evaporates or contain chemical components that have a high boiling point at normal atmospheric pressure.

3. Selection of Proper Solvent

The choice of solvent is perhaps the most critical step in the process of recrystallization since the correct solvent must be selected to form a product of high purity and in good recovery or yield. Consequently a solvent should satisfy certain criteria for use in recrystallization. The desired compound should be reasonably soluble in the hot solvent, about 5 g/100 mL (5 mg/100 μL)

being satisfactory and insoluble or nearly insoluble in the cold solvent. Note that the reference temperature for determination of the solubility in "cold" solvent is often taken to be room temperature. This combination of solute and solvent will allow dissolution to occur in an amount of solvent that is

not unduly large and will also permit recovery of the purified product in high yield. A solvent having thistype of solubility properties as a function of

temperature would be said to have a favorable temperature coefficient for the desired solute.

Conversely, the impurities should either be insoluble in the solvent at all temperatures or must remain at least moderately soluble in the cold solvent. In other words, if the impurities are soluble, the temperature coefficient for them must be unfavorable; otherwise the desired product and the impurities would both crystallize simultaneously from solution. The boiling point of the solvent should be low enough so that it can readily be removed from the crystals. The boiling point of the solvent should generally be lower than the melting point of the solid is being purified. The solvent should not react chemically with the substance being purified. The chemical literature is a valuable source of information about solvents suitable for recrystallizing known compounds. If the compound has not been prepared before, it is necessary to resort to trial-and-error techniques to find an appropriate solvent for recrystallization. The process of selection can be aided by consideration of some generalizations about solubility characteristics for classes of solutes. Polar compounds are normally soluble in polar solvents and insoluble in non-polar solvents, for example, whereas non-polar compounds are more soluble in non-polar solvents. Such characteristics are summarized by the adage, "like dissolves like." Of course, although a highly polar compound is unlikely to be soluble in a hot, non-polar solvent, it may be very soluble in a cold, very polar solvent. In this case, a solvent of intermediate polarity may be the choice for a satisfactory recrystallization. Occasionally a mixture of solvents is required for satisfactory recrystallization of a solute. The mixture is usually comprised of only two solvents; one of these dissolves the solute even when cold and the other one does not.

4. To determine the structure of a compound of natural ingredients can be determined :

• Liquid chromatography coupled to UV-detection (LC–UV)
• Liquid chromatography coupled to electrospray ionisation quadrupole ion trap mass spectrometry (LC–ESI–MS/MS)
• Near infrared reflectance spectroscopy (NIRS)

Analysis of HNMR of Caffeine

 H’NMR Spectrum for Caffeine

Empirical Formula: C8H10N4O2
Molecular Weight: 194.1906
Nominal Mass: 194 Da
Average Mass: 194.1906 Da
Monoisotopic Mass: 194.080376 Da

The HNMR spectrum for caffeine is clearly in D2O. There is a strong singlet at 4.8. Therefore, no protons on hydroxyl or carboxyl groups will be visible in the HNMNR spectrum.

The single hydrogen on the cyclopentene structure will be a singlet at approximately 7.9ppm. The proton is bound to a carbon that is double bound to nitrogen. Normally, vinyl protons fall in the 5-6 range. However, since the carbon is double bound to nitrogen, it may account for the higher ppm in this particular peak. There is no proton that this specific hydrogen can couple with. After counting two to three bond lengths away, there is no other proton. Using the N+1 rule, this would be a singlet. This specific hydrogen will show a singlet at 7.9ppm.

The methyl group that is bound to the nitrogen in the cyclopentene structure will show a singlet at approximately 3.9ppm. The range for a proton bound to a carbon that is bound to a halogen or oxygen is 3-4. However, this particular methyl group is bound to nitrogen that is adjacent to a vinyl group on each side. This particular methyl group has a higher ppm number than the two other methyl groups. Vinyl groups fall in the 5-6 range and this would raise the ppm number of this particular methyl group. Again, counting two to three bond lengths away, there is no proton to couple with. Using the N+1 rule, this would be a singlet. Therefore, this would be a singlet at 3.9ppm.

The final methyl group bound to the nitrogen is adjacent one carbonyl group and one vinyl group. This peak is a singlet at 3.4ppm. The range for a proton bound to a carbon that is bound to a halogen or oxygen is 3-4. The range for a vinyl group is 5-6. This peak is slightly higher than the methyl that is adjacent to two carbonyl groups because this specific methyl group is adjacent to one vinyl group. Counting two to three bond lengths away, there is no other proton for coupling. Therefore, using the N+1 rule, this would be a singlet.

GERANIOL

1. Structure of Geraniol 

fig. 1 structur of geraniol

geraniol (C10H18O) has two ethylenically bond, and citronellol (C10H20O) has a hydroxyl group. Geraniol colorless (pale yellow) soluble in alcohol and ether.

Geraniol
IUPAC name[hide] 3,7-Dimethylocta-2,6-dien-1-ol
Identifiers
CAS number	106-24-1
ChemSpider	13849989
UNII	L837108USY
EC number	203-377-1
ChEBI	CHEBI:17447
ChEMBL	CHEMBL25719
Jmol-3D images	Image 1
SMILES [show]
InChI [show]
Properties
Molecular formula	C10H18O
Molar mass	154.25 g mol−1
Density	0.889 g/cm3
Melting point	-15 °C, 258 K, 5 °F ([2])
Boiling point	230 °C, 503 K, 446 °F ([2])
Solubility in water	686 mg/L (20 °C)[2]
(verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

http://en.wikipedia.org/wiki/File:Geraniol_structure.png

2.  Biosynthesis of Geraniol

fig. 2 biosynthesis of geraniol

http://www-personal.une.edu.au/~sglover/CHEM303%20Chapter%201%20HTML/sld042.htm

3. Isomerization of Geraniol

fig. 3 isomerization of geraniol

4. Spectrum of Geraniol

fig. 4 spectrum of geraniol

http://www.sciencedirect.com/science/article/pii/S004060311200411X

5. Isolation of Geraniol from Citronella

Citronella oil was isolated from Citronella leaves by steam distillation. The distillate of Citronella oil was extracted with ether to separate it from water. To increase the geraniol content, Citronella oil was hydrolysed with NaOH in ethanol for 1 hour to convert geranil acetate to geraniol. Identification of geraniol was conducted by Gas Chromatography-Mass Spectroscopy (GC-MS) method.

Ten kilograms of Citronella leaves produced 42,5 mL (0,373%) of yellow-pale Citronella oil with refractive index of 1,4755. The data of GC chromatogram of Citronella oil showed that the geraniol content was about 65,34%. The enrichment of geraniol with NaOH in ethanol caused hydrolysis reaction of geranil acetate to geraniol, and therefore raised the geraniol content up to 81,96%.

fig. 5 isolation Citronella