CHEM44.1 2LDate Submitted: March 12, 2012
Synthesis of Cinnamaldehyde
Cinnamaldehyde, cinnamic aldehyde or 3-phenyl-2-propenal is the major constituent of cinnamon oil, extracted from several species of Cinnamomum (C. verum, C. burmanii, C. cassia), under the family Lauraceae, a group of evergreen trees. Cinnamon bark (particularly C. verum) yields 0.4-0.8% oil, which contains 60-80% cinnamaldehyde, 4-5% sesquiterpenoids (α-humulene, β-caryophyllene, limonene and others), eugenol, cinnamyl acetate, eugenol acetate, cinnamyl alcohol, methyl eugenol, benzaldehyde, benzyl benzoate, cuminaldehyde, monoterpenes (linalool, pinene, phellandrene and cymene), safrole and others (List and Horhammer; Masada; Ravindran qtd. from Khan and Abourashed, 2011). Isolation of cinnamaldehyde from cinnamon oil of Cinnamomum sp. bark, called “quills”, “quillings”, “featherings” and “chips” depending on quality, was first done in 1834 by Dumas and Peligot (Attokaran, 2011).
It has been proven that cinnamaldehyde from cinnamon oil has a very high potential in the pharmaceutical industry, aside from its well known role in the food preparation, specifically as spice, odorant and colorant. Several researches have proven the antimicrobial activity of cinnamaldehyde against Salmonella typhimurium and Bacillus subtilis (Council of Europe, 2008). Also, cinnamaldehyde has been proven to inhibit microbial growth of opportunistic human pathogenic fungi, such as Aspergillus niger, Candida albicans and Rhizopus oligosporus, and various bacteria (Escherichia coli, Enterobacter cloacae, Micrococcus luteus, Staphylococcus aureus, Streptococcus faecalis, and others) (Khan and Abourashed, 2011). Several studies have also unraveled the hypoglycemic (insulin-like) and hypolipidemic properties of cinnamaldehyde since it can cause: elevated glucose oxidation and uptake, causing decrease in blood plasma glucose levels; decreased glycosylated hemoglobin, serum total cholesterol and triglyceride levels; increased plasma insulin, hepatic glycogen and high-density lipoprotein; and restored modified plasma enzyme concentrations to almost normal level (Babu, Prabuseenivasan and Ignacimuthu, 2006).
Though effective approaches in the isolation of cinnamaldehyde from cinnamon oil from quills, low amounts of pure cinnamaldehyde can only be obtained from effective separation processes. Due to this demarcation in the discovery and investigation of other potential medicinal and non-medicinal values of cinnamaldehyde, chemists have also developed synthetic procedures to obtain high amounts of pure cinnamaldehyde, one of which is the mixed aldol condensation of benzaldehyde and acetaldehyde.
Mixed aldol condensation is a reaction of different aldehydes or ketones leading to the formation of aldols (β-hydroxyaldehydes) or ketols (β-hydroxyketones), accompanied by the removal of water to result finally to enals (α, β-unsaturated aldehydes) or enones (α, β-unsaturated ketones). Aldol additions are due to the reaction of enolate ions of carbonyl compounds (from the reaction of acidic α-hydrogens of aldehydes and ketones with bases) with the electrophilic centers of other carbonyl compounds. Synthesized aldols and ketols can dehydrate spontaneously or can be dehydrated, especially when heated, to form enals and enone, the final product(s) of aldol condensations (Moore and Langley, 2010).
Possible side reactions were the Canizzarro reaction of benzaldehyde and the self-condensation of acetaldehyde. Minimization of the possibilities of the stated reactions was done by following a special scheme of procedure.
Characterization tests that were done in to confirm the identity of the products are boiling point determination, reactions with nitric acid and with sodium bisulfite and derivatization with 2,4-dinitrophenylhydrazine. In the experiment conducted, the...