Oxetane Research Articles

Conformational Characteristics and Unperturbed Chain Dimensions of the Oxygen-Containing Polymers [−OCH2CR2CH2−]n with R = H, CH3, and CH2CH3

MM3 molecular mechanics calculations reveal that poly(3,3‘-diethyloxetane) (PDEO) differs sharply from poly(3,3‘-dimethyloxetane) (PDMO) and poly(trimethylene oxide) (POM3) in terms of conformational preferences, notwithstanding the similarity of these three polymers as successive members of the homologous series [OCH2CR2CH2]n where R = CH2CH3, CH3, and H, respectively. Within the four-bond repeat unit OCH2CR2CH2, POM3 and PDMO both prefer ttgg while PDEO prefers tttt. These conformational differences are reflected in the predicted values of the characteristic ratio CR = 〈r2〉0/nl2 for the unperturbed chain dimensions (after allowance for the oxygen gauche effect) obtained from rotational-isomeric-state (RIS) calculations: 3.9 for POM3, 4.7 for PDMO, and 23 for PDEO. These CR values for POM3 and PDMO are consistent with experiment (3.9 and 4.3, respectively) and with previous theoretical treatments. The larger R substituent of PDEO compared with PDMO and POM3 imposes steric demands that offset the otherwise strong preference of the C−C backbone bonds for gauche states. This reversal in preference from gauche to trans causes the abrupt increase in CR since now the almost exclusively all-trans backbone of PDEO lacks the distinctive conformational randomness of POM3 and PDMO. In terms of Eσ = Et − Eg for the focal C−C bond in these polymers, comparison of the MM2, MM3, and Discover (plus a variant Discover‘) force fields reveals a wide disparity of values for Eσ and more so for the constituent energy components Estretch, Ebend, Etorsion, EvdW, and Eelectrostatics. The preference of the focal C−C bond in PDEO for trans over gauche involves a surprising degree of interplay among these energy components; hence the conformational analysis of PDEO would represent a stringent test of any existing or prospective force field.

CH Stretching Overtone Spectra of Trimethylene Oxide and Trimethylene Sulfide

The room temperature vapor phase CH stretching overtone spectra of trimethylene oxide and trimethylene sulfide are recorded in the ΔvCH = 2−7 regions. The spectra are interpreted with the local mod...

Ethereal Solvation of Lithium Hexamethyldisilazide: Unexpected Relationships of Solvation Number, Solvation Energy, and Aggregation State

Li, 15N, and I3C NMR spectroscopic studies of 6Li-15N labeled lithium hexamethyldisilazide ((6Li,'5N)- LiHMDS) are reported. Mono-, di-, and mixed-solvated dimers are characterized in the limit of slow solvent exchange for a variety of ethereal ligands including the following: tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHl3 2,2-dimethyltetrahydrofuran (2,2-Me2THF), diethyl ether (EtzO), tert-butyl methyl ether (r-BuOMe), n-butyl methyl ether (n-BuOMe), tetrahydropyran (THP), methyl isopropyl ether (i-PrOMe), and trimethylene oxide (oxetane). The ligand exchange is too fast to observe bound and free diisopropyl ether (i-PrZO), tert-amyl methyl ether (Me2(Et)COMe), and 2,2,5,5-tetramethyltetrahydrofuran (2,2,5,5-Me4THF). Exclusively dissociative ligand substitu- tions occur at low ligand concentrations for all ligands except oxetane. Relative free energies and enthalpies of LiHMDS dimer solvation determined for eight ethereal ligands show an approximate inverse correlation of binding energy and ligand steric demand. Mixed solvation is found to be non-cooperative showing there exists little communication between the two lithium sites on the dimer. The different ethereal solvents display a widely varying propensity to cause formation of LiHMDS monomer. The often-cited correlation of reduced aggregation state with increasing strength of the lithium-solvent interaction receives no support whatsoever. The measured free energies of aggregation display a considerable solvent dependence that is traced to solvent-independent enthalpies of aggregation and solvent-dependent entropies of aggregation. LiHMDS monomer solvation numbers derive from solvent- concentration-dependent monomer:dimer proportions. Moderately hindered ethereal solvents afford LiHMDS monomers in trisolvated forms ((MesSi)zNLiS3) whereas THF and oxetane appear to afford considerable concentrations of five-coordinate tetrasolvates ((Me3Si)zNLiS4), The complex relationship between solvation energy and observable aggregation state is discussed in light of solvent-amide and solvent-solvent interactions on both the monomer and the dimer, the combined contributions of solvation enthalpy and entropy, and the complicating intervention of variable solvation numbers.

A New Synthesis of Fluorinated Oxetanes

A New Synthesis of Fluorinated Oxetanes

Aminolysis of oxetanes: Quite efficient catalysis by lanthanide(III) trifluoromethansulfonates

Ln(III)trifluoromethansulfonates in CH 2Cl 2 efficiently catalyze the aminolysis of trimethylene oxide, 2-octyl-, and 2-phenyloxetane, at r.t., to give the corresponding γ-amino alcohols in very good yields.

Mild LiBF 4-promoted aminolysis of oxetanes

LiBF 4 in acetonitrile efficiently catalyzes the aminolysis of trimethylene oxide and 2-octyl oxetane under mild conditions (r.t. or 80°C) to give the corresponding γ-amino alcohols in very good yields.

Molecular motion and phase transitions of clathrate hydrates**

Abstract Heat capacities and complex dielectric permittivities of three clathrate hydrates of type II, encaging tetrahydrofuran (THF), acetone (Ac), and trimethylene oxide (TMO), were measured at low temperatures. The heat capacity measurement was done in the temperature range 13–300 K by using an adiabatic calorimeter with a built-in cryorefrigerator. The permittivities were measured in the temperature range 20–260 K and in the frequency range 20 Hz-1 MHz. For pure samples, with a glass transition due to freezing out of water, reorientational motion of the host lattice was observed calorimetrically at 85 K for THF and at 90 K for Ac hydrates, respectively. Spontaneous temperature drift rates of the calorimetric cell were measured under adiabatic conditions to derive the characteristic time for enthalpy relaxation. The enthalpy relaxation times thus derived were well correlated in an Arrhenius plot with the dielectric relaxation times derived from the dielectric relaxation of orientation polarization. The situation is the same as hexagonal ice which has a similar four co-ordinated hydrogen-bonded network.

Dielectric study of KOH-doped acetone and trimethylene oxide clathrate hydrates

Dielectric permittivities of KOH( x = 1.8 × 10 −4)-doped acetone and trimethylene oxide (TMO) structure II clathrate hydrates were measured in the 15–250 K temperature range and the 20–10 6Hz frequency range. In the acetone hydrate, the dielectric dispersion associated with water reorientation in the high temperature phase suddenly disappeared at the transition temperature (47 K) and no more dielectric dispersion was observed below that temperature. This indicates that both acetone and water molecules are ordered in the low temperature phase. On the other hand, the dielectric dispersion due to the guest reorientation in TMO hydrate was still observed below the transition at 35 K, showing that the TMO molecules are still orientationally disordered in the low temperature phase. From the analyses of the dielectric relaxation times, the activation enthalpy for the TMO reorientation in the KOH-doped hydrate was larger than that in the pure one, indicating that the TMO molecules in the low temperature phase are bound more tightly than those in the high temperature phase. The distribution of the relaxation times of the TMO reorientation was not affected significantly by the KOH-doping, both being very broad and exhibiting negative temperature dependence. For the water reorientation, the relaxation time and the associated activation enthalpy did not depend appreciably on the guest molecules while the distribution of the relaxation times was guest-dependent; the TMO hydrate had larger distribution than the acetone hydrate. It was also found that the distribution of the relaxation times observed over a wide range of temperatures extending above 200 K became broad progressively as the temperature was lowered.

Synthesis of narrow molecular weight distribution α,ω-hydroxy telechelic polyoxetane by the activated monomer mechanism

The cationic activated monomer mechanism has been used to prepare polyoxetane (poly(trimethylene oxide)) with low dispersities, hydroxy functional end groups and without significant oligomer contamination. Tetrafluoroboric acid and 1,4-butandiol were used as the catalyst system. The polymer has been characterized by n.m.r. and s.e.c.

Bimolecular reactions of ˙CH2CH2OCH: A comparison with the chemical properties of CH3CH2OCH and ionized trimethylene oxide

AbstractThe chemical properties of the distonic radical cation ˙CH2CH2OCH are compared with those of its conventional isomer, ionized trimethylene oxide, and its even‐electron analog, the ethoxymethyl cation (CH3CH2OCH). The rate constants and branching rations have been determined for the gas‐phase reactions of the three ions with several neutral reagents in a dual‐cell Fourier‐transform ion cyclotron resonance device. The reactivity of each ion is found to be quite distinct. Fast electron transfer dominates most of the bimolecular reactions of ionized trimethyleene oxide. The ethoxymethyl cation reacts slowly or not at all with the reagents studied, and the only reaction observed is ethyl cation transfer. The distonic ion ˙CH2CH2OCH undergoes vedry fast reactions with all the neutral reagents, and, in sharp contrast to the other two ions, shows remarkably versatile reactivity. This ion rapidly transfers ionized ethylene to most of the neutral molecules studied. Facile electron transfer occurs with some of the neutral reagents while others abstract a pproton from the ion. Abstraction of a radical by the distonic ion‐a reaction reported earlier for dimethyl disulfide—is not observed for any other reagent.

Heat capacity and transition phenomena of structure I and II trimethylene oxide clathrate hydrates

Heat capacities of structure I and II trimethylene oxide (TMO) clathrate hydrates doped with small amount of potassium hydroxide (x=1.8×10−4 to water) were measured by an adiabatic calorimeter in the temperature range 11–300 K. In the str. I hydrate (TMO·7.67H2O), a glass transition and a higher order phase transition were observed at 60 K and 107.9 K, respectively. The glass transition was considered to be due to the freezing of the reorientation of the host water molecules, which occurred around 85 K in the pure sample and was lowered owing to the acceleration effect of KOH. The relaxation time of the water reorientation and its distribution were estimated and compared with those of other clathrate hydrates. The phase transition was due to the orientational ordering of the guest TMO molecules accommodated in the cages formed by water molecules. The transition was of the higher order and the transition entropy was 1.88 J·K−1(TMO-mol)−1, which indicated that at least 75% of orientational disorder was remaining in the low temperature phase. In the str. II hydrates (TMO·17H2O), only one first-order phase transition appeared at 34.5 K. This transition was considered to be related to the orientational ordering of the water molecules as in the case of the KOH-doped acetone and tetrahydrofuran (THF) hydrates. The transition entropy was 2.36 JK−1(H2O-mol)−1, which is similar to those observed in the acetone and THF hydrates. The relations of the transition temperature and entropy to the guest properties (size and dipole moment) were discussed.

Reaction of Quadricyclane with Electron Deficient p-Benzoquinones

Quadricyclane reacted thermally in a [π2+σ2+σ2] manner with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and chloranil to give cyclobutanes and a spiro oxetane, respectively

Comparative sulfur dioxide infrared spectra: type I and II clathrate hydrate films, large gas-phase clusters, and anhydrous crystalline films

The mechanism by which SO{sub 2} is incorporated into microparticles of ice in the vapor phase is receiving special interest because of the unexpectedly high efficiency with which SO{sub 2} is scavenged by ice crystals. A possible explanation of this efficiency might be found in the tendency for small polar molecules, such as the small ring ethers, to form clathrate hydrates at low temperatures and low partial pressures. This possibility has been examined by spectroscopic studies at {approximately} 120 K of large gas-phase clusters formed from anhydrous SO{sub 2} and H{sub 2}O-SO{sub 2} mixtures with a ratio appropriate for clathrate hydrate formation. On the basis of a comparison with new thin-film infrared data for the simple type I SO{sub 2} hydrate, the mixed SO{sub 2}-ethylene oxide type I hydrate and the type II double hydrate with tetrahydrofuran, it is apparent that SO{sub 2} is not enclathrated under the conditions that are known to cause formation of clathrate hydrate crystalline clusters of ethylene oxide, trimethylene oxide, and tetrahydrofuran.

Trisubstituted oxetanes from 2,7-dioxa-bicyclo-[3,2,0]-hept-3-enes

Photoadducts of aldehydes with furan were transformed to substituted monocyclic oxetanes, using a modification of the Fraser-Reid-Mootoo glycosidation procedure 10.

Infrared spectra of large clusters containing small ether molecules: Liquid, crystalline, and clathrate-hydrate cluster spectra

Large clusters of different structural phases containing the small-ring ether molecules tetrahydrofuran, trimethylene oxide, and ethylene oxide have been prepared and studied spectroscopically using a simple cluster cell based on a small infrared gas cell. Pure ether clusters are formed efficiently upon loading of the precooled cell (80–130 K) to pressures of a few hundred Torr with a gaseous mixture of an ether diluted with N2. For the right choice of temperature the pure ether clusters, which tend to be exceptionally large, initially assume a supercooled liquid structure but convert to the stable crystal structure over the observation time of a few minutes. Approximate nucleation temperatures, for this phase transition, range from 125 K for tetrahydrofuran to 100 K for ethylene oxide. The crystalline-cluster absorption bands, for the ether vibrational modes having large oscillator strengths, are distorted by dominance of the longitudinal mode absorption as expected for ultrathin particles. When water is included as a third component of the gaseous mixture, with a concentration chosen to give cluster compositions appropriate to the respective clathrate hydrate structures, the clusters assume the crystalline clathrate hydrate structures for temperatures close to the optimum values for thin-film clathrate hydrate formation by vapor cocondensation methods.

Oligomerization of oxetane and synthesis of polyterephthalates derived from 1,3‐propanediol and 3,3′‐oxydipropanol

AbstractThe oligomerization of oxetane (trimethylene oxide) initiated by sulfuric acid in methylene chloride in the presence of 1,3‐propanediol (trimethylene glycol) leads to the formation of α‐hydro‐ω‐hydroxyoligo(oxytrimethylene)s. The effect of adding different amounts of trimethylene glycol was studied, and the dimer, 3,3′‐oxydipropanol, could be isolated. Polymers from dimethyl terephthalate and 3,3′‐oxydipropanol and copolymers from 1,3‐propanediol, 3,3′‐oxydipropanol and dimethyl terephthalate were synthesized. The influence of the chemical structure on their thermal transitions was analyzed.

ChemInform Abstract: FT‐IR Spectra of 90 K Films of Simple, Mixed, and Double Clathrate Hydrates of Trimethylene Oxide, Methyl Chloride, Carbon Dioxide, Tetrahydrofuran, and Ethylene Oxide Containing Decoupled D2O.

ChemInform Abstract: FT‐IR Spectra of 90 K Films of Simple, Mixed, and Double Clathrate Hydrates of Trimethylene Oxide, Methyl Chloride, Carbon Dioxide, Tetrahydrofuran, and Ethylene Oxide Containing Decoupled D2O.

FT-IR spectra of 90 K films of simple, mixed, and double clathrate hydrates of trimethylene oxide, methyl chloride, carbon dioxide, tetrahydrofuran, and ethylene oxide containing decoupled water-d2

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFT-IR spectra of 90 K films of simple, mixed, and double clathrate hydrates of trimethylene oxide, methyl chloride, carbon dioxide, tetrahydrofuran, and ethylene oxide containing decoupled water-d2Fouad Fleyfel and J. Paul DevlinCite this: J. Phys. Chem. 1988, 92, 3, 631–635Publication Date (Print):February 1, 1988Publication History Published online1 May 2002Published inissue 1 February 1988https://doi.org/10.1021/j100314a013RIGHTS & PERMISSIONSArticle Views396Altmetric-Citations65LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (686 KB) Get e-Alerts

Steteoselective Synthesis of Unsaturated Oxetanes

Steteoselective Synthesis of Unsaturated Oxetanes

Chain dimensions of poly(3,3′-dimethyl oxetane)

Poly(3,3′-dimethyl oxetane) was synthesized by cationic polymerization of 3,3′-dimethyl oxetane using triethyloxonium hexafluoroantimoniate as initiator. Six fractions were isolated by fractional precipitation with cyclohexane-ethanol. Characterization by viscometric and osmometric studies of solutions of fractions in cyclohexane at 25°C provided values of the intrinsic viscosity, number-average molecular weight and second virial coefficient. From these data, the characteristic ratio was estimated to be slightly higher than for the unsubstituted poly(trimethylene oxide) indicating that the spatial extension is scarcely affected by the dimethyl substitution on the main chain.