Microwave-assisted preparation of naphthenic acid esters

• Published in: Journal of the Serbian Chemical Society 2006-01, Vol.71 (12), p.1263-1268
• Main Authors: Cirin-Novta, Vera, Kuhajda, Ksenija, Kevresan, Slavko, Kandrac, Julijan, Grbovic, Ljubica, Vujic, Djura
• Format: Article
• Language: English
• Subjects: ethyl; methyl; microwave dielectric heating; n-butyl- and tert-butyl esters; naphtenic acids
• ISSN: 0352-5139; 1820-7421
• DOI: 10.2298/JSC0612263C

The synthesis of esters of natural petroleum acids of the naphthenic type assisted with microwave irradiation under the conditions of acid catalysis was carried out with various alcohols: methanol, ethanol, n-butanol and tert-butyl alcohol. Microwave dielectric heating of the reaction mixture in an unmodified microwave oven with activation of the naphthenic acids with sulfuric and p-toluenesulfonic acid afforded the esters of the naphthenic acids. Depending on the catalyst and the steric and nucleophilic properties of the alcohols, the yield of naphthenic esters ranged from 31.25% to 88.90%. As a consequence of microwave dielectric heating, the esterification time was reduced from 6-10 h to 5 min. . Sinteza estara prirodnih naftnih kiselina naftenskog tipa uz pomoc mikrotalasnog zracenja u uslovima kisele katalize izvedena je sa razlicitim alkoholima: metanolom, etanolom, n-butanolom i tert-butil-alkoholom. Mikrotalasnim dielektricnim zagrevanjem reakcione smese u nemodifikovanoj mikrotalasnoj pecnici i uz aktivaciju naftnih kiselina sumpornom i p-toluensulfonskom kiselinom sintetizovani su estri naftnih kiselina. U zavisnosti od katalizatora, zatim sternih i nukleofilnih osobina alkohola, prinos naftnih estara je varirao od 31,25%do 88,90 %. Reakciono vreme esterifikacije smanjeno je sa 6-10 sati na 5 minuta pri iskljucivo mikrotalasnom dielektricnom zagrevanju. .