Cinnamyl acetate (3-phenylprop-2-enyl acetate) is a chemical compound of the cinnamyl ester family, in which the variable R group is substituted by a methyl group. As a result of the non-aromatic carbon-carbon double bond, cinnamyl acetate can exist in a Z and an E configuration:
Cinnamyl acetate naturally occurs in fresh bark of cinnamon (Cinnamomum zeylanicum Blume and other Cinnamomum species), with concentrations of 2,800–51,000 ppm.
Cinnamyl acetate is used as a flavour ester in for example bread and animal feed and has a sweet floral-fruity fragrance. Moreover, it is used in several cosmetics, some toiletries but also in non-cosmetic products, for example detergents.
Legislation and control
Cinnamyl acetate, used in fragrances and as flavour ingredient, has been discussed by several institutions. In 1965, the compound was annotated as 'Generally Recognized as Safe as a flavor ingredient’ by the Flavor and Extract Manufacturers" Association (FEMA). The association determined the average maximum use levels in several products that were considered to be safe:
The European Parliament registered cinnamyl acetate as both a flavouring substance and a cosmetic compound in 1996. The Joint (FAO/WHO) Expert Committee on Food Additives (JECFA) described in 2000 that “the substance does not present a safety concern at current levels of intake when used as a flavouring agent”. In 2009, the EFSA Panel on Food Contact Materials, Enzyme, Flavourings and Processing Aids (CEF) concluded that cinnamyl acetate does not give rise to safety concerns when used as flavour ingredient in food. Cinnamyl acetate is also permitted by the U.S. Food & Drug administration for use as flavouring agent in food if the minimum quantity needed for its effect is used.
Production and intake
Estimates of the average annual production and daily intake of cinnamyl acetate as flavouring agent are reported by the WHO. According to this report, the annual volume of production in Europe is 1498 kg, and in the USA 2255 kg. The daily intake per person in Europe is estimated to be 210 μg, and in the USA 300 μg. Per kg body weight the daily intake is estimated for Europeans to be 4 μg/kg and for Americans to be 5 μg/kg.
Synthesis
Since cinnamyl acetate is naturally occurring in plants, it can be extracted and purified to obtain the compound. However, this has a low yield and therefore the production costs are high. The use of chemical methods can offer more efficient strategies to produce cinnamyl acetate.
There are multiple ways to synthesize cinnamyl acetate 2. One way is the synthesis from cinnamyl alcohol 1 and vinyl acetate. This reaction is catalyzed by the enzyme triacylglycerol ester hydrolase, which is a lipase that is very specific towards the ester bond. The byproduct of this reaction is acetaldehyde. The reaction equation for this reaction is:
Since acetaldehyde has an unfavourable deactivating effect on the lipase used in the synthesis, ethyl acetate can be used as reactant instead of vinyl acetate. In this transesterification reaction cinnamyl alcohol 1 reacts with ethyl acetate to form cinnamyl acetate 2 and ethanol. This synthesis requires the lipase Novozym 435, and is performed in a solvent-free system. The reaction is as follows:
Cinnamyl acetate 2 can also be synthesized via a non-enzymatic reaction. An example of such a reaction is one with the use of cinnamyl bromide 3 and sodium acetate as reactants. Since these compounds are immiscible substrates, solid-liquid phase transfer catalysis (PTC) can be used, using quaternary ammonium bromide as a phase transfer catalyst. This is shown in the following reaction:
Besides these three examples, there are many more ways to synthesize cinnamyl acetate.
The addition reaction of dinitrogen trioxide to cinnamyl acetate produces an intermediate in the synthesis of chloramphenicol.
Metabolism
Cinnamyl acetate belongs to the group of cinnamyl derivatives. In general, these cinnamyl derivatives are absorbed from the gut very quickly, after which they are metabolized and excreted as polar metabolites in the urine or feces within 24 hours.