Aryl hydroxyalkyl carbonates as precursors of phenolic flavoring agents

Abstract

A variety of aryl hydroxyalkyl carbonates (1-7) have been synthesized and thermolyzed in the neat state at 150 and 250 °C. The aryl hydroxyalkyl carbonates 9 and 10 derived from glycerol and 11 derived from ethylene glycol decomposed at room temperature. Alkyl substitution in the diol moiety of the 1-[ [(aryloxy)carbonyl] oxy] -3-propanol derivatives 4 and 5 enhanced the phenolic release as compared to the unsubstituted derivative 3. 2-[[(2-Methoxy-4-formylphenoxy)carbonyl]oxy]-4-pentanol (8) decomposed at room temperature while 2-[[(2-methoxyphenoxy)carbonyl]oxy]-4-pentanol (5) was stable, which was attributed to the effectiveness of the aryl moieties as leaving groups. Increasing the chain length between the hydroxyl group and carbonate moiety from three methylene units (3), to four (6), to five (7) decreased the phenolic release from 67% to 45% to 10%, respectively.Alkyl-and alkoxy-substituted phenols such as 2-methoxyphenol have desirable flavor properties. These compounds have been detected in a wide variety of food products and have been used as flavoring agents (Fenaroli, 1975). However, their use as flavoring agents can be limited by their low odor threshold and high volatility. As a consequence, a limitation on the amount of the flavoring agent that can be utilized as well as losses on storage result.To overcome these limitations, the use of a phenolic flavor precursor could be employed. The requirements of such a flavor precursor would include being nonvolatile, odorless, and stable in the product on storage. Then, when