666-16-0Relevant academic research and scientific papers
Conformational stability, r0 structural parameters, and vibrational assignments of mono-substituted cyclobutanes: Fluorocyclobutane
Ganguly, Arindam,Klaassen, Joshua J.,Guirgis, Gamil A.,Gounev, Todor K.,Durig, James R.
, p. 831 - 840 (2011)
Variable temperature (-55 to -100 °C) studies of the infrared spectra (3500-400 cm-1) of fluorocyclobutane, c-C4H7F, dissolved in liquid xenon have been carried out as well as the infrared spectra of the gas. By utilizing eight pairs of conformers at 10 different temperatures, the enthalpy difference between the more stable equatorial conformer and the axial form has been determined to be 496 ± 40 cm-1 (5.93 ± 0.48 kJ/mol). The percentage of the axial conformer present at ambient temperature is estimated to be 8 ± 1%. The ab initio MP2(full) average predicted energy difference from a variety of basis sets is 732 ± 47 cm-1 (9.04 ± 0.44 kJ/mol) and the average value of 602 ± 20 cm-1 from density functional theory predictions by the B3LYP method are significantly larger than the experimentally determined enthalpy value. By utilizing previously reported microwave rotational constants for the equatorial and axial conformers combined with ab initio MP2(full)/6-311+G(d,p) predicted structural values, adjusted r0 parameters have been obtained. The determined heavy atom structural parameters for the equatorial [axial] conformer are: distances () C-F = 1.383(3) [1.407(3)], Cα-Cβ = 1.543(3) [1.546(3)], C β-Cγ = 1.554(3) [1.554(3)] and angles (°) ∠CαCβCγ = 85.0(5) [89.2(5)], ∠CβCαCβ = 89.3(5) [89.2(5)], ∠F-(CβCαC β) = 117.4(5) [109.2(5)] and a puckering angle of 37.4(5) [20.7(5)]. The conformational stabilities, harmonic force fields, infrared intensities, Raman activities, depolarization ratios and vibrational frequencies have been obtained for both conformers from MP2(full)/6-31G(d) ab initio calculations and compared to experimental values where available. The results are discussed and compared to the corresponding properties of some other monosubstituted cyclobutanes with halogen and pseudo-halogen substituents.
Microwave spectrum of the axial conformer and potential energy function of the ring puckering motion in fluorocyclobutane
Caminati, Walther,Favero, Laura B.,Maris, Assimo,Favero, Paolo G.
, p. 25 - 32 (1996)
The microwave spectrum of fluorocyclobutane has been investigated in the 26-40 GHz frequency range. The spectrum of the axial conformer has been assigned for the first time, while measurements of the equatorial species, and of several of its puckering vibrational satellites, have been extended. The energy of the axial conformer is 620(30) cm-1 higher than that of the equatorial one. Previously reported potential energy functions of the ring puckering have been corrected, interpreting the available vibrational spacings, the shifts of the rotational constants upon puckering excitation and the centrifugal distortion constants with a flexible model.
On the reactivity of naphthalene and biphenyl dianions: Tying up loose ends concerning an SN2-ET dichotomy in alkylation reactions
Blasco, Inmaculada,Pérez, Henoc,Guijarro, Albert
, p. 388 - 395 (2015/06/02)
Naphthalene and biphenyl dianions are interesting compounds that can be obtained by double reduction of the corresponding arenes in solution with certain alkali metals. These dianions are highly reactive and rather elusive species with very high laying and highly delocalized electrons. They share many aspects of the reactivity of the alkali metal they originated from and consequently behave primarily as strong electron transfer (ET) reagents. We report here kinetic evidence for a different type of reactivity in their alkylation reactions with alkyl fluorides. By using cyclopropylmethyl fluoride (c-C3H5CH2F) as a very fast radical probe, we were able to settle that this alkylation does not involve the classical electron transfer reaction followed by radical coupling between diffusing radicals, but supports the alternative SN2 concerted mechanism, discerning thus this mechanistic SN2-ET dichotomy.
Rearrangement and double fluorination in the deiodinative fluorination of neopentyl iodide with xenon difluoride
Patrick, Timothy B.,Zhang, Likang,Li, Quinhua
, p. 11 - 15 (2007/10/03)
Alkyl iodides give products from the neopentyl rearrangement on reaction with xenon difluoride. Neopentyl iodide performs a double rearrangement and yields a gem-difluoro product, 2,2-difluoro-3-methylbutane. Studies of the mechanism show that an alkene intermediate is involved in the double rearrangement process. Alkenes can be substituted as substrates in reaction with xenon difluoride-iodine to give gem-difluoro products. 13C Labeling verifies the skeletal rearrangement process.
A new synthesis of 3-fluoro- and 3-chlorocyclobutenes from dihalocyclobutanes. The five isomers of chlorofluorocyclobutane
Craig, Norman C.,Borick, Steven S.,Fisher, Michael A.,Tucker, Thomas R.,Xiao, Yong-Zhuang
, p. 215 - 224 (2007/10/02)
3-Fluorocyclobutene (1) and 3-chlorocyclobutene (2) have been obtained by simpler syntheses and in higher yield than previously reported.One of the synthetic steps involves a three-phase-transfer-catalysis technique that could be of wider utility.New examples are cited of applying AgF2, an underutilized reagent, as a fluorinating agent near room temperature.Compounds 1 and 2 have been characterized by mass, NMR and vibrational spectroscopies.The NMR spectra have been fully analyzed.Useful group frequencies in the vibrational spectra of halocyclobutenes have been identified.The five monochloromonofluorocyclobutane precursors of fluorocyclobutenes have also been separated and characterized.From NMR coupling constans, conformer mixtures have been identified for three of the isomers.
