Extraction and characterization of l-carnitine in avocado (Persea americana) through instrumental and computational techniques

Abstract

The purpose of this study was the extraction and characterization of l-carnitinefrom avocado (Persea americana) with the use of computational and instrumen-tal techniques. l carnitine was quantified by uv/vis spectroscopy from two avo-cado varieties (fuerte and booth 8). it was found that the booth 8 varietycontains 84 μg of l-carnitine/gram of fresh fruit, while fuerte has 82 μg/g. thekinetics of the acetylation reaction was determined with the use of infraredspectroscopy. therefore, the reaction is second global order with a rate constantof 4.45x10-4l/mol·s a 298±2K. the thermodynamic analysis of the reaction,the determination of the reaction mechanism and the analysis of the reactivityand selectivity of the reactant molecules through computational techniqueswith the b3lYP method and the 6-311g (d,p) basis set were executed. the re-action enthalpy in the gas phase was –8.2 kcal/mol and –4.1 kcal/mol in theaqueous phase. it was established that the acetylation reaction is produced bya nucleophilic attack of the hydrochloride l-carnitine to the acetyl chloride,going through a tetrahedral transition state which ends with the elimination ofchloride acid. also, it was determined that the l-carnitine is a nucleophilic mo-lecule with the oxygen as the active site; the acetyl chloride, on the other handis an electrophile with the carbonyl carbon as the active site.