Computation studies on possible coloring agents for the quantitative determination of vitamin A

Date

2005

Degree

Bachelor of Science in Agricultural Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Norriel S Nipales

Abstract

Semi-empirical computation on the Carr-Price reaction as well as prospective colorimetric agents (bismuth chloride, phosphorous trichloride, stannous chloride, and stannic chloride), in different solvent type and number of solvent molecules was performed in order to determine the molecular properties that affect the ease of interaction of each system, using the software HyperChem 7.0. Geometry optimization was simulated to attain the structure with the lowest bond strain, and single point calculation was used to obtain the values for the HOMO-LUMO gap and total energy and optimization energy Increasing the number of solvent molecules for all types of system decreases the total energy and optimization energy required for the system to attain the most stable structure. Ether was found to be the solvent, which provides the Carr-Price reaction most favorable conditions for the stability of the interaction. Chloroform gave the HOMO- LUMO gap that was expected from the Carr-Price reaction. For the prospective colorimetric agents, it was found that the most probable alternative as the colorimetric agent is stannous chloride, based on the consistency of the HOMO-LUMO gap that was obtained. A system where stannous chloride was solvated by ether was also simulated; and it was compared to the system where chloroform was used as the solvent The most stable systems were Carr-Price reaction in three molecules of chloroform and SnCl2 and vitamin A in two molecules of chloroform. Both these systems were simulated with three water molecules. The effect of water was studied by adding three molecules of water to the systems. It was found that a small shift in wavelength is predicted in the Carr-Price reaction while a shift to lower wavelength is expected with the SnCl2. Experimental results agreed with the calculated results. It was observed that with the presence of water, SnClytvitamin A energy, a blue color was observed.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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