Reaction Of Cinnamaldehyde Research Articles

Use of a post-column reaction and a spectrophotometric detector for the liquid chromatographic determination of water

A sensitive method for the determination of water in the presence of common interferents is presented. An ion-exchange column in the Li + form and acetonitrile-methanol (60:40) as eluent are used to separate water from other sample components. The detection system is based on the effect of water on the equilibrium which results from the reaction of cinnamaldehyde (added to the eluent) and methanol in the eluent to form cinnamaldehyde dimethylacetal plus water. This equilibrium is shifted in the catalytic atmosphere of an H + -form post-column reactor. The extent of the shift and the resulting change in absorbance at 310 nm are proportional to the amount of water present. The method is rapid, sensitive, relatively free from interferences and gives a linear calibration graph over approximately three orders of magnitude difference in water concentration.

Lewis acid-promoted conjugate reduction of α,β-unsaturated carbonyl compounds by 2-phenylbenzothiazoline (2-phenyl-2,3-dihydrobenzothiazole)

Reduction of various α,β-unsaturated ketones (3a–g) and (4a–d) in methanol by the benzothiazoline (1) in the presence of aluminium chloride gives, in all cases, the corresponding saturated ketones (5a–g) and (6a–d) without any of the unsaturated or saturated alcohol. Reduction of α,β-unsaturated esters (7a,b) similarly gives the saturated esters (9a,b), while reaction of cinnamaldehyde (8) with compound (1) does not occur at all. Among the Lewis acids examined, aluminium chloride gives the best results. Reduction of 2′-azachalcone (21) with 2-phenyl[2-2H]benzothiazoline reveals that, in the reduction product, the deuterium atom is located at the β-position with respect to the carbonyl group. The result obtained from the reduction of the same substrate with compound (1) in methan[2H]ol shows that no incorporation of a hydrogen atom from the solvent takes place and suggests (indirectly) that the introduced hydrogen atom at the α-position of the product comes from the benzothiazoline (1). The reaction of (Z)-1,2-dibenzoyl-1,2-diphenylethylene (30) with compound (1) in the presence of aluminium chloride stereospecifically yields meso-1,2-dibenzoyl-1,2-diphenylethane (31). This shows that the transfer of two hydrogens from compound (1) to the carbon–carbon double bond of the enone proceeds via cis-addition. Experiments with ethyl phenylpropiolate (28) also support cis-reduction for the present conjugate reduction. These results are interpreted in terms of a mechanism involving synchronous transport of a pair of hydrogens from the benzothiazoline (1); i.e., a cyclic addition of the two hydrogens either in exact or nearly exact concurrence.

Mechanism of cinnamaldehyde sensitization*

The skin sensitization of cinnamaldehyde is probably initiated by the reaction of cinnamaldehyde with epsilon-amino groups on protein side chains. Alpha-Substituted cinnamaldehydes, which are known not to be skin sensitizers, react very slowly or not at all with amines in comparison with cinnamaldehyde.