94379-18-7Relevant academic research and scientific papers
Spectroscopic and product studies of the effect of para substituents on the reactivity of triplet bis(2,6-dimethylphenyl)carbenes
Hu, Yingmo,Ishikawa, Yui,Hirai, Katsuyuki,Tomioka, Hideo
, p. 2207 - 2218 (2007/10/03)
A series of diazobis(2,6-dimethylphenyl)methanes (1) bearing eight symmetrical para di-substituents have been prepared and photolyzed to generate the corresponding carbenes (2). Product analysis studies showed that carbenes (2) decay mainly either by dimerization to form tetra(aryl)ethylene (3) or by attack at an o-methyl group to afford 1,2-dihydrobenzocyclobutenes (4) by way of o-quinodimethanes (6) in solution. The zero-field splitting parameters, D and E, were measured in matrices of different viscosities and are analyzed in terms of a sigma-dot (σ.) scale of spin-delocalization substituent constants. Fairly good correlation with σ. was found for the D values of 32 in its minimum energy geometry. Stabilities of 32 were estimated either by measuring the temperature at which the triplet carbene signals disappeared upon thawing the matrix or by analyzing the decay kinetics of 32 in a degassed solution at room temperature. They are examined in terms of the D values in matrix at low temperature and in terms of product distributions in solution at room temperature.
Polymethylated and poly(tert)butylated diphenylcarbenes. Generation, reactions, kinetics, and deuterium isotope effects of sterically congested triplet carbenes
Tomioka, Hideo,Okada, Hidetsumu,Watanabe, Tetsuya,Banno, Kohji,Komatsu, Kazunori,Hirai, Katsuyuki
, p. 1582 - 1593 (2007/10/03)
Dimesitylcarbene (2a) was shown to decay by undergoing dimerization and to have a half-life of 160 ms, some 5 orders of magnitude longer-lived than diphenylcarbene. Didurylcarbene (2b) was twice as long-lived as 2a, while decamethyldiphenylcarbene (2c) de
Singlet and Triplet Dimesitylcarbene
Nazran, A. S.,Griller, D.
, p. 543 - 547 (2007/10/02)
The triplet states of essentially all diarylcarbenes react with substrates such as methanol or their parent diazo compounds both of which are thought to be specific quenchers for the singlet state.To rationalize these results, investigators have proposed that the singlet and triplet states of these carbenes are linked by efficient equilibria.In this kinetic study we have found that the singlet and triplet states of dimesitylcarbene exhibit quite distinct chemistries.The singlet state alone reacts with methanol, 1-propanol, and 1,3-cyclohexadiene, while the triplet carbene dimerizes to give olefin or, for example, reacts with oxygen.No evidence was found for reaction of the triplet carbene via the singlet manifold.Arguments are presented to explain the enhanced free energy difference between the spin states of this carbene and the relative persistence if its triplet.
