DETERMINATION THE KINETICS OF ACETYL-SALICYLIC ACID

Aspirin, znan tudi kot acetilsalicilna kislina (CH3COOC6H4COOH), je salicilna droga, ki se pogosto uporablja kot učinkovito sredstvo za lajšanje manjših bolečin, antipiretik za zmanjšanje vročine in protivnetno zdravilo. Namen diplomskega dela je bila sinteza aspirina in določitev reda reakcije. Potek reakcije smo zasledovali z opazovanjem spreminjanja specifične prevodnosti šibkega elektrolita, ocetne kisline (CH3COOH), v odvisnosti od časa. Kinetiko reakcije proizvodnje ocetne kisline kot stranskega proizvoda pri sintezi aspirina iz salicilne kisline (HOC6H4COOH) in anhidrida ocetne kisline ((CH3CO)2O) smo preverili v šaržnem mešalnem reaktorju pri različnih temperaturah: HOC6H4COOH + (CH3CO)2O ↔ CH3COOC6H4COOH + CH3COOH S poviševanjem temperature v reaktorju smo pospešili potek reakcije. Koncentracija reaktantov se med potekom kemijske reakcije zmanjšuje, medtem ko presnova narašča. Na podlagi pridobljenih meritev in izračunov smo določili kinetične parametre in značilnosti sinteze aspirina (red reakcije, konstanto proizvodnosti, aktivacijsko energijo). Ugotovili smo, da reakcija sinteze aspirina poteka po kinetiki 2. reda. Iz dobljenih rezultatov lahko povzamemo, da je kontinuirna metoda z opazovanjem specifične prevodnosti zelo koristna za neprekinjeno merjenje koncentracije. Kemijska kinetika sinteze aspirina je še dokaj neraziskana tema, zato bodo vsekakor potrebne še dodatne raziskave, kar pušča odprta vrata za nadaljnje študije.Aspirin, also known as acetylsalicylic acid (CH3COOC6H4COOH), is a salicylate drug, often used as an effective remedy to relieve minor pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. The purpose of this study was the aspirin synthesis and to determine the order of the reaction. The course of the reaction was studied by measuring weak electrolyte conductivity, acetic acid (CH3COOH), as a function of time. The reaction kinetics when producing acetic acid as a by-product by aspirin synthesis from salicylic acid (HOC6H4COOH) and acetic anhydride ((CH3CO)2O) was checked in a stirred batch reactor under different temperatures: HOC6H4COOH + (CH3CO)2O ↔ CH3COOC6H4COOH + CH3COOH We accelerate the course of reaction with increasing temperature in the reactor. The concentration of the reactants during the course of chemical reaction decreases, while assimilation increases. The kinetic parameters and features of aspirin synthesis (rate order, reaction rate constant, activation energy) were determined on the basis of measurements and calculations. We state that aspirin synthesis reaction follows the kinetics of the second order. The results showed that the continuous method, by observing the specific conductance, was very useful for uninterrupted concentration measurement. The chemical kinetics of aspirin synthesis is relatively unexplored topic, therefore, an extra researches are certainly needed, and this leaves an open door for further studies