Aspects of the photodimerization mechanism of 2,4-dichlorocinnamic acid studied by kinetic photocrystallography.
Photoinduced structural variations in single crystals of 2,4-dichloro-trans-cinnamic acid (C9H6Cl2O2, DiClCA) have been investigated using X-ray diffraction (photocrystallography) and optical spectroscopic methods. During UV irradiation, which initiates the irreversible dimerization reaction, a loss of the long-range order of the reactant single crystal was found, i.e., that the dimerization is a heterogeneous one. This unexpected result emphasizes the still-existing problem of predicting changes or of remaining periodicity during chemical reactions in the solid state. On the basis of the experimental results, we propose a qualitative kinetic reaction scheme for DiClCA heterogeneous dimerization reaction.
Davaasambuu
J
J
Max-Planck-Institut für biophysikalische Chemie, Abteilung Spektroskopie und Photochemische Kinetik, Am Fassberg 11, 37077 Göttingen, Germany.
Busse
G
G
Techert
S
S
D002934:Cinnamates / Q000737:chemistry*; D003460:Crystallization; D019281:Dimerization; D007700:Kinetics; D010777:Photochemistry; D013057:Spectrum Analysis; D014961:X-Ray Diffraction
D002934:Cinnamates; C520767:2,4-dichlorocinnamic acid