Molecular and crystalline structure of pyrocatechol and hydroquinone dimethacrylates and their reactivity in melts

X-ray diffraction analysis of pyrocatechol and hydroquinone dimethacrylates (T _m = 18 and 86–88°C, respectively) shows that the oligomer molecules within crystals are packed in stacks where the methacrylate fragments of neighboring molecules are parallel to each other. The minimum distances between the centers of double bonds of adjacent methacrylate fragments in crystals of pyrocatechol and hydroquinone dimethacrylates are 4.621(3) and 4.269(4) Å. The curves showing the reduced rate of photopolymerization of oligomer melts versus conversion (9,10-phenanthrenequinone used as the initiator) display a maximum at conversions of 1.5–3.0%. The limiting conversion in photopolymerization of molten pyrocatechol dimethacrylate at 25 and 40°C is 20%; for hydroquinone dimethacrylate at 95°C, it is approximately 10%. As the temperature rises from 25 to 40°C, the maximum reduced rate of photopolymerization of pyrocatechol dimethacrylate increases by a factor of 1.4.     

Crystal packing and reactivity of di(meth)acrylates of some derivatives of hydroquinone and pyrocatechol in melts

The X-ray diffraction study of 2,2′-(1,2-phenylene-bis(oxy)diethanol and 2,2′-(1,4-phenylenebis(oxy)diethanol dimethacrylates and 2,2′-(1,4-phenylenebis(oxy)diethanol diacrylate (T _m = 40–42, 68–70, and 62–64°C, respectively) indicates that oligomer molecules are packed in crystals as stacks in which methacrylate fragments of adjacent molecules are parallel to each other. The minimum distances between the centers of C=C double bonds of adjacent methacrylate fragments in crystals of di(meth)acrylates are 4.373, 4.215, and 3.996 respectively. The conversion dependences of the reduced rates of photopolymerization of melted oligomers (9,10-phenanthrenequinone as a photoinitiator) pass through maxima at conversions of 40, 11, and 2%, while the ultimate conversions are 85, 33, and 73%, respectively. The addition of ionic liquids based on phosphonium and imidazolium cations to dimethacrylates of 2,2′-(1,2-phenylenebis(oxy)diethanol and triethylene glycol increases the maximum reduced rate of photopolymerization.     

Conformational analysis of benzenediols: pyrocatechol,resorcinol and hydroquinone

Molecular orbital calculations are carried out for pyrocatechol, resorcinol and hydroquinone. The structural parameters, stable conformations, potential barrier heights, dipole moments and charges for these molecules are discussed. Only one stable isomer for pyrocatechol, three for resorcinol and two for hydroquinone are established.     

Synthesis,molecular, and crystalline structure of 3-benzoyl-1,2-di(ethylsulfonyl)indolizine

Reaction of pyridiniumbenzoyl methylide with (E)-1,2-di(ethylsulfonyl)-1,2-dichloroethene (which has four nucleophilic groups) occurs via a 1,3-dipolar stereo- and regio directed cycloaddition to give 3-benzoyl-1,2-di(ethylsulfonyl)indolizine the structure of which was established using x-ray crystallography. The rotation of the phenyl substituted by 72.6° relative to the indolizine ring plane and the geometry of the ethylsulfonyl groups can be explained by steric hindrance due to shortened intramolecular non-valence contacts.Deceased.A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, Moscow 117813. N. D. Zelinski Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 950–954, July, 1996. Original article submitted May 5, 1996.     

Thermal properties and crystalline structure of poly(10-undecene-1-ol)

Atactic and isotactic-rich poly(10-undecene-1-ol)s were synthesized by metallocene-catalyzed polymerization. The thermal properties and the crystalline structure of the poly(10-undecene-1-ol)s were characterized using Dynamic Scanning Calorimetry (DSC), Temperature-Modulated DSC (MDSC), Fourier Transform Infrared Spectroscopy (FTIR), and Wide-Angle X-ray Scattering (WAXS). It was found that the polymers crystallize primarily at their side chains, which is indicated by similar arrangement of both isotactic-rich and atactic polymers. The polymers form smectic layer structures independent on their tacticity, however, for the isotactic-rich polymers, higher crystallinities were observed than for the atactic polymers in terms of higher melting enthalpies.     

Synthesis of substituted 1,2-di(alkylsulfonyl)indolizines. Molecular and crystal structure of 3-(4-fluorobenzoyl)-6-methyl-1,2-di(propylsulfonyl)indolizine

The reactions of substituted pyridinium salts with E-1,2-di(alkylsulfonyl)-1,2-dichloroethenes proceed regiospecifically. Heating of these reagents in chloroform in the presence of a threefold excess of Et₃N affords substituted 1,2-di(alkylsulfonyl)indolizines in high yields. The structures of the reaction products were confirmed by physicochemical methods, including X-ray diffraction. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1205–1209, May, 2005.     

Double-exponential decay in intramolecular excimer formation: 1,3-di(2-pyrenyl)propane

The fluorescence response functions of 1,3-di(2-pyrenyl)propane in methylcyclohexane can be fitted with two exponentials having the same decay parameters for the excimer and the monomer. This is in contrast to what had been observed before with 1,3-di(1-pyrenyl)propane where three exponentials are required. It is concluded that the different conformers of the propane chain act as a single kinetically uniform group in forming excimers. This signifies that the kinetic scheme applicable to intermolecular excimer formation (the so-called Birks scheme) can also be utilized in the intramolecular case, the more complex kinetics being exceptional.     

Molecular structure and vibrational spectra of 1,3-bis(4-pyridyl)propane by quantum chemical calculations

The experimental and theoretical study on the structures and vibrations of 1,3-bis(4-pyridyl)propane are presented. The FT-IR and Raman spectra of molecule have been measured. The optimized geometric bond lengths have been obtained by DFT show the best agreements with experimental values. The harmonic vibrational frequencies were calculated and scaled values have been compared with experimental FT-IR and FT-Raman spectra. Majority of the computed wavenumbers were found to be in good agreement with experimental observations. A complete assignment of the fundamentals was proposed based on the total energy distribution (TED) calculation.     

Di- and triphenylphosphonites of 2,2-di-(p-hydroxyphenyl)propane

Starting from 2,2-di-(p-hydroxyphenyl)propane and phenylphosphonic acid tetraethylamide we have prepared the first oligoarylenephosphonites with spatially separated phosphorus functionalities. We have studied the principal chemical properties of these compounds. We have shown the capacity of oligoarylenediphosphonites to coordinate with transition metals through one or all phosphorus atoms with formation of mono- and oligo complexes. We have found that monocomplexes can undergo degenerated metallotropic rearrangements.V. I. Lenin Moscow Pedagogical State University, 119883 Moscow, Russia. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 12, pp. 2777–2784, December, 1992.     

Molecular and crystalline structure of 4-phenylthiosemicarbazidodiacetic acid monohydrate

Institute of Chemistry, Moldavian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 2, pp. 177–180, March–April, 1992.     

Reactivity and solvatochromism of 2,2′-bi(4H-5,6-dihydrothiazine)-tetracarbonylmolybdenum(O)

Summary The dependence of the charge-transfer frequency for [Mo(CO)₄(btz)], btz = 2,2-bi(4H-5,6-dihydrothiazine), on solvent is described, and the solvatochromic behaviour of this compound compared with that of other [Mo(CO)₄(LL)] species, with LL = 2,2-bipyrimidine or 2,2-bipyridine, and of iron(II) analogues [Fe(btz)₂(CN)₂] and [Fe(bipy)₂(CN)₂]. Kinetics of solvolysis (k, H, S) are reported for [Mo(CO)₄(btz)] in methanol, acetonitrile, and dimethyl sulphoxide. These kinetic results are analysed into initial state and transition state contributions. A parallel analysis of the solvatochromic results for [Mo(CO)₄(btz)] into ground state and excited state solvation contributions is compared with similar analyses for the solvatochromic organic compoundsp-nitroanisole and dimethylindoaniline.     

The structure of 2,2'-difluorobiphenyl in solid crystalline and liquid crystalline phases

The structure of 2,2-difluorobiphenyl in the solid, crystalline phase has been determined by X-ray diffraction. In this phase the molecules are all in a single conformation having the two fluorine nuclei in a syn -arrangment, with the two ring normals at 58 to one another. The structure of the same molecule, but dissolved in a liquid crystalline solvent has been investigated by NMR spectroscopy. In the liquid crystalline phase there is rotation about the inter-ring bond through an angle phi , with a probability distribution P(phi) which has an absolute maximum at the syn-form with phi about 51 . There is also a second maximum in P(phi) at about 130 , corresponding to the anti-form. The syn- and anti-forms are present in the approximate ratio 0.58:0.42.