Caffeine and benzoic acid in soft drinks

Abstract

Many laboratory manuals include lengthy schemes for extraction of caffeine from tea.1 A time-saving experiment using No-I)oz tablets as the source has recently been described in this Journal.2 However, soft drinks derived from the kola bean, and some that are not, also contain caffeine that can be isolated and purified in as little as 1 hr.In some of the soft drinks that we studied, simple extraction with chlorinated solvents yielded caffeine that was contaminated by relatively large amounts of benzoic acid. Showing a strong pl\ dependence (caffeine does not: Ka < 10-14; Kb < 10-14), benzoic acid can easily be held in the aqueous phase, but it. may be extracted and isolated as a second product. In such beverages as Coca-Cola, Pepsi Cola, Royal Crown Cola, Dr. Pepper, Mountain Dew, Orchard Park Cola (a local brand), and the low-sugar and sugar-free versions of several of these, we found that a 12-oz.can contained 25-50 mg of caffeine. Half a can is therefore sufficient for students either to see the crude product, to

A extração de cafeína em bebidas estimulantes: uma nova abordagem para um experimento clássico em química orgânica

“…Caso a aplicação do método 1 em uma amostra de mate solúvel não fosse possível, uma melhor opção seria a utilização da erva mate ao invés das folhas de chá mate. A aplicação do método 1 permite que o estudante obtenha uma quantidade de amostra suficiente (sólido branco amarelado), para realizar uma purificação, tendo a oportunidade de aprender técnicas básicas e muito usadas em química orgânica como a recristalização 15 , sublimação 16 e a cromatografia em coluna 17 podendo, em seguida, determinar o ponto de fusão da amostra pura (238 °C) 7 . Uma quantidade maior de amostra também permite ao estudante a preparação de um derivado da cafeína 18 folhas de chá mate para a extração de cafeína, neste contexto, no melhor do nosso conhecimento, o pó de guaraná não tem sido empregado, sendo que a quantidade de cafeína bruta extraída é uma quantidade apropriada para experimentos subseqüentes ao da sua extração, conforme exemplificamos acima.…”

Classroom demonstrations of polymer principles: IV. Mechanical properties

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A Caffeinated Boost on UV Spectrophotometry: A Lab for High School Chemistry or an Introductory University Chemistry Course

“…This experiment serves as an application of spectrophotometry and its use in the analysis of caffeine in a practical investigation. Numerous procedures highlighting the extraction of caffeine from coffee, tea, soft drinks, and over-the-counter supplements have been published in this Journal , − but few use coffee beans and are appropriate for the high school classroom curriculum. Several other upper-division organic chemistry and analytical chemistry experiments have been published in this Journal that also feature caffeine as the key analyte. − …”