![]() These and other volatile esters with characteristic odours are used in synthetic flavours, perfumes, and cosmetics. Many are responsible for the fragrance and flavour of flowers and fruits for example, isopentyl acetate is present in bananas, methyl salicylate in wintergreen, and ethyl butyrate in pineapples. Research suggests that heavy metals in pigments react with oils in paint to form soaps when exposed to moisture (e.g., the original wet coating of paint or increased humidity), the soaps can become sticky or dissolve, causing damage to the painting.Ĭarboxylic acid esters of low molecular weight are colourless, volatile liquids with pleasant odours, slightly soluble in water. Oil paintings may also be affected by saponification, particularly those created using pigments containing heavy metals. Wet chemical fire extinguishers, which are used for fires that involve fats and oils, rely on saponification reactions to convert burning fats to soap, which is noncombustible. The hydrolysis of esters in the presence of alkalies such as potassium hydroxide (lye) or sodium-a reaction called saponification-is utilized in the preparation of soaps from fats and oils and is also used for the quantitative estimation of esters. One ester may be converted to another ester by reaction (transesterified) with an alcohol, a carboxylic acid, or a third ester in the presence of a catalyst. Esters may also be obtained by reaction of acid halides or acid anhydrides with alcohols or by reaction of salts of carboxylic acids with alkyl halides. The reverse of the esterification reaction is an example of hydrolysis. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning. ![]() 100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions. ![]()
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