Synthesis and characterization of glyceryl monoesters (C12 & C16) of coconut fatty acids for use as evaporation suppressants

Date

10-2009

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Milagros M. Peralta

Abstract

ABSTRACT

MORETE, MARK JEFFREY ROPEROS. University of the Philippines Los Balms, October 2009. Synthesis and Characterization of Glycol!! Monoestersl_Cl2 & C16, of Coconut Fatty Acids for Use as Evaporation Suppressants.

ADVISER: Dr. Milagros M. Peralta

The glyceryl monoesters of lauric and palmitic acid were prepared from fractionated coconut fatty acids via a tandem Fischer esterification to the corresponding methyl esters and subsequent base-catalyzed transesterification with glycerol. The intermediate and final products were analyzed using TLC and GC for purity determination and extent of formation. These were also subjected to characterization using IR and NMR spectroscopy. Highest yields of 71.42% and 85.49% were obtained for methyl dodecanoate and methyl hexadecanoate respectively. Yields of 55% and 86.68% on the average were obtained from glyceryl monolaurate (experimental m.p. 38 °C; literature m.p. 40 ± 5 °C) and glyceryl monopalmitate (experimental m.p. 56 °C; literature m.p. 57 ± 5 °C) respectively. The molecular dimension of a suppressant molecule was calculated to determine the minimum rate of its application in a given area. The molecular radius was determined to be 4.46 A considering its ability to form intra-hydrogen bonds. The cytotoxicity activities of glyceryl monoesters were determined using brine shrimp assay. Results showed that glyceryl monoesters to be insignificantly inactive with their high L13,0 (224.0127 μg/mL for glyceryl monolaurate and 2194.5890 μgfmL for glyceryl monopalmitate) compared with the LD50 of 30 pg/mL or less for a toxic compound. Soil residue analysis was used to assess the persistence of glyceryl monoesters in the environment. Result showed a time dependent decreasing trend in concentration probably due to volatilization and degradation. After 7 days, only 14.042% of glyceryl monolaurate and 18.575% of glyceryl monopalmitate were left in the paddies as residue. Preliminary assessment of the ability of glyceryl monoesters to retard water evaporation was done using lab-scale test. Under this condition, glyceryl monopalmitate was able to retard evaporation by 61.416%, followed by glyceryl monolaurate (59.212%) and 2:3 octadecanol-hexadecanol mixture (51.965%) over an average 18-hr time period. ANOVA (analysis of variance) and LSD (least significant method) results showed a significant difference in the ability of glyceryl monoesters to retard evaporation in comparison with the standard 2:3 octadecanol-hexadecanol alcohol mixture. The results confirm that glyceryl monoesters of coconut fatty acids can be used as effective evaporation suppressant for ricefields that are non-toxic, non-persistent and environmentally friendly.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2009 C4 M67

Document Type

Thesis

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