Esterification Between Citric Acid and Callistemon citrinus, Rice-Husk, Garcinia dulcis Catalysed by Citric Acid’s-H+- Monomers and Polymers Formation Mechanism

Esterification between citric acid molecules and molecules of Callistemon citrinus, rice husk and Garcinia dulcis (pulp-peel and pips) were carried out such as the citric acid molecules quantities (moles) were negligible against to these raw materials’ reactive molecules quantities (moles). Results showed generally an important initial, total conversions (after 60 minutes) of citric acids molecules which confirmed the essential role of raw materials’ aromatics molecules characterized by their alkene organic-function titrated with HF-0.00261N (Hydrofluoric acid) as support of citric acid’s protonic acid H+ catalyst (a portion of the carboxylic acids’ citric acid molecules used), support of non-ionic citric acid’s carboxylic acid (a portion of the carboxylic acids’ citric acid molecules used) and support of raw materials molecules reagents. So, the citric acid partial order of esterification of these used raw materials (Callistemon citrinus, rice husk and Garcinia dulcis (pulp-peel and pips)) with citric acid molecules were determined. Also, the brown citric acid equivalent monomers formed during esterification were calculated and their evolution were followed for all raw materials and results allowed to determine the citric acid’s protonic acid activities. In the same time, relationship between raw materials’ external specific surfaces, estimated by calculated and measured densities, and conversion or brown citric acid equivalent formed were established to conduct finally at the catalyst turnover. The variation of alkene organic-function concentration and/or quantities not only in solution but also in all by-products allowed to an ionic mechanism of these esterification with citric acid catalyzed by citric acid’s protonic acid H+ (a portion of the carboxylic acids’ citric acid molecules used) supported on all raw materials’ aromatics molecules and fiber structures in glass-flask where not only carbonic acids molecules but also hydrogens molecules gas were emitted. Finally, seeing that a non-negligible alkene organic-function quantities were titrated on all by-products, their valorization as catalytic support of citric acid molecules polymerization were carried out and a procedure constituted principally with estimation of dichloromethane and hexane insoluble/soluble products, titration with HF-0.00261N of the unsaturated organic-function in hexane soluble products and titration with NaOH-0.05N of the black citric acid equivalent quantities evolutions were established and the results confirmed the ionic mechanism of esterification with citric acid molecules during which not only carbonic gas and hydrogen gas were emitted but also new monomers and each equivalent saturated products (characterized by their globally white color and unsaturated organic-function titrated with HF-0.00261N), new polymers and poly-polymers (characterized by their globally black color and titrated with NaOH-0.05N) different to that obtained with radical mechanism catalyzed by Lewis acid sites were formed.