Kinetics of solid state photodimerization of 1,4-dimethyl-2-pyridinone in its molecular compound.
The [4 + 4] photodimerization of 1,4-dimethyl-2-pyridinone (A) in its molecular compound with 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol (I) was investigated by irradiation of a single crystal of the compound. The conversion to the product in a single-crystal to single-crystal transformation enabled the determination of its crystal structure after each exposure cycle of 10-20 min with a pulsed 355 nm laser light. The unit cell changes as a function of the conversion were monitored and showed monotonic changes. The kinetics of the reaction was studied at two different temperatures (230 and 280 K) and revealed a sigmoidal behavior that could be explained by the JMAK model for crystal growth with a mechanism that is intermediate between random distribution of products in the crystal and the existence of growing nuclei. The Arrhenius plot provided calculated activation energy of 32.5 kJ/mol.
Cao
Deng-Ke
DK
Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel.
Sreevidya
Thekku Veedu
TV
Botoshansky
Mark
M
Golden
Gilad
G
Benedict
Jason Brown
JB
Kaftory
Menahem
M
D018360:Crystallography, X-Ray; D019281:Dimerization; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D010777:Photochemistry; D011728:Pyridones / Q000138:chemical synthesis* / Q000737:chemistry
C552284:1,4-dimethyl-2-pyridinone; D011728:Pyridones; C017679:2-hydroxypyridine