TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: In the method: the irradiation takes place with only one type of electromagnetic frequency including microwaves, ultrasound or radio waves or with different types of electromagnetic frequencies, simultaneously or in succession; and the acid catalyst used in the reaction is a free acid catalyst or immobilized on a support. Preferred Components: (I) is tert-butyl methyl ether. The feedstock is: vegetable oils such as coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil, canola oil, safflower oil, sesame oil, soybean oil, sunflower oil, almond oil, beech nut oil, cashew oil, hazelnut oil, Macadamia oil, pine nut oil, pistachio oil, walnut oil, citrus oils, grapefruit seed oil, lemon oil, orange oil, castor oil, hemp oil, mustard oil, radish oil, rice bran oil, Salicornia oil, soybean oil, Jatropha oil, jojoba oil, linseed oil, poppy oil, Stillingia oil, fruit tree oil, artichoke oil, carrot seed oil, mango oil or sea-buckthorn oil; animal fats such as beef tallow, lard, poultry fat or fish oils; or waste oils and fats from various sources, such as oils and fats used in restaurants and the catering industry in general, and present in the waste of the agrifood and seafood industries. The acid catalyst is: strong mineral acids and organic acids; zeolites, molecular sieves, phosphates, zirconates, kaoiinite, montmorillonite, pillared clays, hydrotalcites and acid ion-exchange resins; solid acid or suitably acid-functionalized materials such as perfluorinated oxides and/or polymers; silica and silica doped with aluminum, titanium or zirconium in different morphologies, heteropolyacids, acids adsorbed and/or covalently bonded to metal oxides; organic sulfonic and/or organic carboxylic acids immobilized on amorphous silica and/or mesostructured and microstructured silica; polyoxymetalates stabilized on silica and/or titania; Keggin structures containing niobium ions; niobium oxides; or ionic liquids and/or carbon nanotubes functionalized with organic sulfonic acids and/or organic carboxylic acids. The acid catalyst is alkyl sulfonic acid bound to amorphous silica. Preferred Definitions:    R3, R4, R5 = methyl (preferred), ethyl, propyl, isopropyl, butyl, tert-butyl, ethenyl, propenyl, isopropenyl, butenyl, isobutenyl, hexenyl, ethynyl, propynyl or butynyl; and    R1 = methyl (preferred), ethyl, propyl, isopropyl or butyl.    EXAMPLE - 500 mg of glycerol tripalmitate was dissolved in 1.6 ml of tert-butyl-methyl ether and was placed in a microwave test tube, and 30 mg of catalyst including amorphous silica 10% functionalized with sulfonic groups, was added to the solution. The reaction mixture was irradiated by 20 watt microwaves, under stirring, for a reaction time of up to 3 hours, then HPLC assay was carried out which demonstrated total conversion of glycerol tripalmitate to methyl palmitate and a mixture of mono- and di-tert-butyl glycerol ethers, in 70:30 ratio.