1,2-Diphenylcyclobutene

Dodson, R. M.; Zielske, Alfred G.

doi:10.1021/jo01277a007

Cited by 49 publications

(18 citation statements)

References 1 publication

(1 reference statement)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hydrogenation of this material gave cis-10 which was isomerized to trans-10 by potassium tbutoxide in dimethyl sulfoxide. The syntheses of cis-and trans-10 by this route have since been reported (21). The properties of these compounds prepared in the present study agree with those reported except for the n.m.r.…”

Section: Products Fromsupporting

confidence: 90%

Mechanism of initiation in the thermal polymerization of styrene. Thermal decomposition of cis-3,6-diphenyl-3,4,5,6-tetrahydropyridazine

Kopecky¹,

Evani²

1969

Can. J. Chem.

View full text Add to dashboard Cite

Thermal decomposition of cis-3,6-diphenyl-3,4,5,6-tetrahydropyridzn 1, (k = 5.6 x s-I at 79.5") results in the formation of about 60% styrene, 27% cis-and 13 % trans-l,2-diphenylcyclobutane.The relative product yields vary little over the temperature range 64-133". This indicates that 1 decomposes exclusively to the l,4-diphenyl-l,4-butadiyl diradical, 2, and nitrogen. The diradical, 2, cannot be trapped by styrene and 1 is not an initiator of styrene polymerization. Therefore, 2 is not the radical intermediate responsible for the thermal initiation of styrene polymerization.Canadian Journal of Chemislry, 47, 4041 (1969) The thermal decomposition of 3,6-diphenyl-3,4,5,6-tetrahydropyridazine, 1, was studied a number of years ago (1). A possible initial decomposition product, the 1,4-diphenyl-l,4-butadiyl diradical, 2, has a structure identical to the classical Flory diradical whose formation by "tail to tail" dimerization of styrelle, eq. [I 1, had been held to be responsible for the initiation of the 2 thermal polynlerization of this monomer (2). The only nitrogen-free decomposition product from 1 which was identified was styrene, as the dibromide, in 7% yield. There was no evidence to indicate whether the diradical, 2, was actually formed as an intermediate in the decon~position of 1 or whether there occurred a concerted decomposition reaction to give styrene and nitrogen directly. It was found that 1 was a poor initiator of styrene polymerization. Previous reports also indicated that diradicals generated by thermal decomposition of cyclic peroxides (3,4), by photolysis of a cyclic disulfide (5), and by thermal decomposition of a cyclic azo compound (6) are poor polymerization initiators. These experimental results had been anticipated by kinetic considerations (7, 8).For these and other (9) reasons it had come to be considered unlikely that the thermal polymerization of styrene is initiated by formation of 2. However, the report (9-1 1) that 1,2-diphenylcyclobutane, among other dimers, could be isolated from the thermal polymerization of styrene in dilute solution or in the Dresence of inhibitors maintained the question of the formation of 2 from dimerization of styrene.In the present study the decomposition of 1 has been reinvestigated in order to determine the mode and products of the reaction, and to measure more accurately the efficiency of l as an initiator of styrene polymerization Results Preparation and Stereoclzemistry of 1Attempted preparation of 1 according to the published procedure (1) resulted in the isolation in low yield of material which did evolve gas upon melting but which always melted over a broad temperature range. This material was shown by ultraviolet (u.v.) and nuclear magnetic resonance (n.m.r.) spectroscopy to consist of 1 contaminated with appreciable amounts of the corresponding hydrazone, 3,6-diphenyl-2,3,4,5-tetrahydropyridazine, 9. In this procedure saponification of cis-l,2-dicarbethoxy-3,6-diphenylhexahydropyridazine, 4, with potassium hydroxide in methanol is followed bv d...

show abstract

Section: Products Fromsupporting

confidence: 90%

Mechanism of initiation in the thermal polymerization of styrene. Thermal decomposition of cis-3,6-diphenyl-3,4,5,6-tetrahydropyridazine

Kopecky¹,

Evani²

1969

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…The photophysical data indicate that the p-p* excitation energy in 1-R (l abs = 283-288 nm) is very similar to that of cis-stilbene (277 nm [41] ) and DPCB (297 nm [44] ) (all values for room-temperature EtOH solution). In order to gain further understanding into the nature of the chromophore and electronic structure in 1-R, we carried out a set of theoretical calculations of the gas-phase excitation energies (using TD-DFT, see Quantum chemical calculations, Experimental Section).…”

Section: Photophysics In Solutionmentioning

confidence: 80%

“…The lowest energy (vertical singlet) p-p* transition is well separated from the higher energy transitions and occurs at 294.7 nm (cis-stilbene), 312.7 nm (DPCB), 295.2 nm (1-H), 293.5 nm (1-Me), and 295.8 nm (1-Ph), respectively. For comparison, we include the experimental absorption band peak wavelengths in EtOH solution: l abs = 277 nm (cis-stilbene [41] ), 297 nm (DPCB [44] ), 285.9 nm (1-Me), and 287.9 nm (1-Ph), which are consistently at higher energy than the calculated (gas-phase) values by 2170, 1690, 905, and 928 cm À1 , respectively (note that the energy order is nevertheless preserved). The calculated transition energies using B3LYP/def-TZVP were even further red-shifted, by ~1000 cm À1 (see Supporting Information), which is consistent with previously observed trends for the performance of the various functionals.…”

Section: Fl Quantum Eff [%]mentioning

confidence: 99%

See 1 more Smart Citation

Synthesis, Structure, Photoluminescence and Photoreactivity of 2,3‐Diphenyl‐4‐neopentyl‐1‐silacyclobut‐2‐enes

Yan

Thomson

Bäcker

et al. 2009

Chemistry A European J

View full text Add to dashboard Cite

A series of six 2,3-diphenyl-4-neopentyl-1-silacyclobut-2-enes with different 1,1-substituents has been prepared and characterized by single-crystal X-ray crystallography. These compounds possess a cis-stilbene-like chromophore involving also the four-membered ring, and exhibit a photophysical behavior similar to that of previously reported 1,2-diphenyl-cycloalkenes. This chromophore system is confirmed by a theoretical investigation of the electronic structure and excitation spectra. The absorption and photoluminescence of selected derivatives were studied in solution, as solid powder samples, and in doped-polymer thin films. In well-dissolved solution, the silacyclobutenes show only very weak fluorescence emission (quantum yield approximately 0.1%), due to competition with photochemical and non-radiative photophysical relaxation. When the solubility is degraded in a poor (aqueous) solvent, the formation of nanoscale aggregates leads to a significant enhancement factor in the emission intensity, due to the suppression of the photoreactivity in the more rigid molecular environment, although the quantum yield still remains below a few percent. In the solid-state, however, photoreactivity is completely suppressed leading to fluorescence quantum efficiencies of 8-23% depending on the 1,1-substituents, which demonstrates these compounds' potential as chromophores for condensed-phase luminescence applications. Two dominant competing photochemical reactions have been identified in solution (for excitation in the lowest-energy absorption band, >260 nm), which are analogous to related (sila-)cyclobutenes and stilbenoids. The first involves ring-opening due to cleavage of the 1,4-Si-C bond to form metastable silabutadienes, which was confirmed by isolating the stereospecifically formed allylsilane which results from a secondary reaction with trapping agents such as methanol or water. The second photochemical reaction involves ring closure of the 2,3-diphenyl substructure to form a dihydrophenanthrene analogue, which was confirmed by isolating the phenanthrene derivative that results following subsequent hydrogen abstraction in the presence of oxygen. Measurements of the silacyclobutenes in doped-polymer thin films reveal a spectroscopic behavior ranging from that in solution to the nano-aggregate case as the silacyclobutene dopant concentration is increased.

show abstract

“…This was prepared from the more readily available meso-isomer by hydroxide heating the latter and recrystallising at 190 "C with the anhydrous residue from potassium ethyl iii acetate-cyclohexane. In one preparation large crystals product was similarly prepared via the bismethanesulphonate derivative (9) and was found to be rather more air-sensitive than similar ligands. Its homologue…”

Section: Ypph2mentioning

confidence: 99%

The mechanism of asymmetric hydrogenation. Chiral bis(diphenylphosphino)-α-phenylalkane complexes in catalytic and structural studies

Brown¹,

Murrer²

1982

J. Chem. Soc., Perkin Trans. 2

View full text Add to dashboard Cite

1,2-Diphenylcyclobutene

Cited by 49 publications

References 1 publication

Mechanism of initiation in the thermal polymerization of styrene. Thermal decomposition of cis-3,6-diphenyl-3,4,5,6-tetrahydropyridazine

Mechanism of initiation in the thermal polymerization of styrene. Thermal decomposition of cis-3,6-diphenyl-3,4,5,6-tetrahydropyridazine

Synthesis, Structure, Photoluminescence and Photoreactivity of 2,3‐Diphenyl‐4‐neopentyl‐1‐silacyclobut‐2‐enes

The mechanism of asymmetric hydrogenation. Chiral bis(diphenylphosphino)-α-phenylalkane complexes in catalytic and structural studies

Contact Info

Product

Resources

About