1. PREPARATION OF PERFUMING AGENT ETHYL BENZOATE FROM SIAM BENZOIN
Chalerm Saiin*, Suthatip Markmee, Patcharaporn Kamman, Sommart Meemak
MedicinalChemistry Research Unit, Department of Pharmaceutical Chemistry and Pharmacognosy, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok 65000, Thailand
INTRODUCTION
MATERIAL AND METHOD
Siam Benzoin: Bought from Traditional Medicine Store,
Phitsanulok, Thailand
Benzoin is the balsamic resin obtained from Styrax tonkinensis (Pierre) Craib ex Hartwich. or other species of the Section Anthostyrax of the genus Styrax, known in commerce as Siam Benzoin, or from Styrax benzoin Dryander or Styrax paralleloneurus Perkins, known in commerce as Sumatra Benzoin (Family Styracaceae).
Siam Benzoin consists principally of coniferyl benzoate, plus smaller amounts of free benzoic acid, the triterpene
siaresinol, and a trace of vanillin.
Sumatra Benzoin contains various resinous esters of benzoic and cinnamic acids, together with free benzoic, cinnamic, siaresinolic (19-hydroxyoleanolic acid) and sumaresinolic (6-hydroxyoleanolic acid) acids and traces of vanillin. The proportion of total cinnamic acid is usually
about twice that of total benzoic acid.
Objective of the study:
To develop the method for preparing perfuming agent ethyl benzoate from Siam Benzoin (Kamyan Thai).
Method:
Step 1: Identification of Siam Benzoin
1. pH
2. Sublimation
3. Reaction with 6% w/v ethanolic FeCl2
4. Reaction with KMnO4 TS
5. Thin-Layer Chromatography
Step 2: Determination of benzoic acid in Siam Benzoin
using acid-base titration technique
1. Retrosynthesis with ethanolic KOH TS
2. Isolation process
3. Acid-base titration:
titrant; M NaOH, indicator; phenol red TS
RESULTS AND CONCLUSION
The method for preparing perfuming agent ethyl benzoate from Siam benzoin (Kamyan Thai) was developed.
The first step, Siam benzoin was identified according to the Thai Pharmacopoeia monograph with some modifications: Siam benzoin exhibited acidic property when tested with Litmus paper; A large number of long rod-shape colorless crystals was obtained after sublimation; A solution of bright green color was shown after a reaction with 6 % w/v ferric chloride in ethanol; Benzaldehyde smell was not generated after a reaction with potassium permanganates TS; A dark spot on thin- layer chromatography plate was shown under ultraviolet light.
The second step, benzoic acid in sample Siam benzoin was determined using acid-base titration method. The result showed % of benzoic acid.
The third step, Siam benzoin (1.00 Kg) was reaction with 6 % ethanolic potassium hydroxide. Then, benzoic acid was extracted with ether, 5 % aqueous sodium hydrogencarbonate and chloroform, respectively. Crystallization in ethanol and water provided % (0.13 Kg) of benzoic acid.
The Forth step, esterification of benzoic acid (40.00 g) with ethanol using concentrated sulfuric acid as a catalyst provided % (13.47 g) ethyl benzoate.
Step 3: Preparation of benzoic acid from Siam Benzoin
Powder of Siam Benzoin (1.00 Kg)
Reaction Mixture
Residue
Benzoic acid (0.13 Kg)
Retrosynthesis with
Ethanolic KOH TS
Isolation
Crystallization
Step 4: Synthesis of ethyl benzoate
REFERENCES
The Drug Committee and the Food and Drug Administration of Thailand. Thai Pharmacopoeia 1987 volume 1 part 1. Bangkok: Department of Medicinal Sciences. Ministry of Public Health; 1987: p47-49.
2. C. Saiin, S. Markmee, P. Kamman, S. Meemak. Preparation of food preservative benzoic acid from Kamyan Thai. Proceeding of the 7th Agro-Industry Conference, CD-ROM, Chiang Mai: Faculty of Engineering and Agro-Industry, Maejo University, June, 2005.
ACKNOWLEDGEMENT
This poster presentation was supported in part by a grant from Faculty of Pharmaceutical Sciences, Naresuan University, Thailand