Chemical insights from high-resolution X-ray photoelectron spectroscopy and ab initio theory: propyne, trifluoropropyne, and ethynylsulfur pentafluoride.

High-resolution carbon 1s photoelectron spectroscopy of propyne (HC triple bond CCH3) shows a spectrum in which the contributions from the three chemically inequivalent carbons are clearly resolved and marked by distinct vibrational structure. This structure is well accounted for by ab initio theory. For 3,3,3-trifluoropropyne (HC triple bond CCF3) and ethynylsulfur pentafluoride (HC triple bond CSF5), the ethynyl carbons show only a broad structure and have energies that differ only slightly from one another. The core-ionization energies can be qualitatively understood in terms of conventional resonance structures; the vibrational broadening for the fluorinated compounds can be understood in terms of the effects of the electronegative fluorines on the charge distribution. Combining the experimental results with gas-phase acidities and with ab initio calculations provides insights into the effects of initial-state charge distribution and final-state charge redistribution on ionization energies and acidities. In particular, these considerations make it possible to understand the apparent paradox that SF5 and CF3 have much larger electronegativity effects on acidity than they have on carbon 1s ionization energies.     

Carboncarbon bond cleavage during lithium aluminum hydride reduction of a terminal propargyl alcohol

Reduction of dehydronerolidol with lithium aluminum hydride in the presence of sodium methoxide gave, in addition to the expected nerolidol, geranyl acetone. Labeling experiments established that the C-1 methyl of geranyl acetone is derived from one of the carbons of the acetylene.     

Identification, by infra-red spectroscopy, of surface species during propyne hydrogenation

The species retained by a Pd/ZrO₂ catalyst after propyne hydrogenation was investigated by infra-red spectroscopy. The main species identified were a di-sigma adsorbed propene and a sigma/pi adsorbed propyne.     

Synthesis of unsaturated organosilicon compounds from propargyl alcohol

Summary -Trialkylsilylpropargyl and allyl alcohols, and also propargyloxysilanes were synthesized from propargyl alcohol.     

掺杂聚丙炔醇及其酯的湿敏特性

聚醋酸丙炔酯;湿敏性;掺杂聚丙炔醇及其酯的湿敏特性     

掺杂聚丙炔醇的电性能和表征

聚丙炔醇（ＰＯＨＰ）经碘、硫酸、三氯化铁、盐酸掺杂，其电导率可提高六个数量级，硫酸、三氯化铁、盐酸掺杂ＰＯＨＰ都显示良好的稳定性。通过红外光谱、光电子能谱、顺磁共振的研究。对掺杂ＰＯＨＰ的电荷转移过程及可能存在的栽流子进行了研究。     

Fluorine as a pi donor. Carbon 1s photoelectron spectroscopy and proton affinities of fluorobenzenes

The carbon 1s ionization energies for all of the carbon atoms in 10 fluorine-substituted benzene molecules have been measured by high-resolution photoelectron spectroscopy. A total of 30 ionization energies can be accurately described by an additivity model with four parameters that describe the effect of a fluorine that is ipso, ortho, meta, or para to the site of ionization. A similar additivity relationship describes the enthalpies of protonation. The additivity parameters reflect the role of fluorine as an electron-withdrawing group and as a pi-electron donating group. The ionization energies and proton affinities correlate linearly, but there are four different correlations depending on whether there are 0, 1, 2, or 3 fluorines ortho or para to the site of ionization or protonation. That there are four correlation lines can be understood in terms of the ability of the hydrogens at the site of protonation to act as a pi-electron acceptor. A comparison of the ionization energies and proton affinities, together with the results of electronic structure calculations, gives insight into the effects of fluorine as an electron-withdrawing group and as a pi donor, both in the neutral molecule and in response to an added positive charge.     

Reactivity and core-ionization energies in conjugated dienes. Carbon 1s photoelectron spectroscopy of 1,3-pentadiene

The high-resolution carbon 1s photoelectron spectrum of trans-1,3-pentadiene has been resolved into contributions from the five inequivalent carbon atoms, and carbon 1s ionization energies have been assigned to each of these atoms. Spectra have also been measured for propene and 1,3-butadiene at better resolution than has previously been available. The ionization energies for the sp2 carbons are found to correlate well with activation energies for electrophilic addition and with proton affinities. Comparing the results for 1,3-pentadiene with those for ethene, propene, and 1,3-butadiene as well as with results of theoretical calculations makes it is possible to assess the effect of the terminal methyl group in 1,3-pentadiene. As in propene, the methyl group contributes electrons to the beta carbon through the pi system. In addition, there is a significant (though smaller) contribution from the methyl group to the terminal (delta) CH2 carbon, also through the pi system. Most of the effect of the methyl group is present in the ground-state molecule. There are only relatively small contributions from the methyl group to the ionization energies from redistribution of charge in the pi system in response to the removal of a core electron. In addition to these specific effects, there is an overall decrease in average ionization energy as the size of the molecule increases as well as effects that are specific to the conjugated systems in 1,3-butadiene and 1,3-pentadiene. The results provide insight into the reactivity and regioselectivity of conjugated dienes.     

Carbon-13 chemical shifts of some propargyl alcohol derivatives

The natural abundance ¹³C chemical shifts of a range of propargyl alcohol derivatives have been determined and individual resonances assigned. The shielding effects of the triple bond and hydroxyl group on neigbouring carbons have been characterised. The observed for these compounds are compared to those of alkyl or allyl alcohols.     

Gas-phase thermolysis of allyl propargyl amine,allyl cyanomethyl propargyl amine,allyl propargyl 2-thiapropyl amine,and allyl methanesulfonyl propargyl amine

The title amines have been pyrolyzed in a stirred-flow reactor, at temperatures of 360–500°C, pressures of 7–16 torr, and residence times of 0.5–2.9 s, using toluene as carrier gas. The reaction products were allene, propene, and the corresponding imines. The ratio allene:propene varied in the range 6.7–1.6. The amines with CH₂CN and SO₂CH₃ substituents also formed HCN and SO₂. These appear to arise from complex free radical decomposition of the imine product. The first-order rate coefficients for the production of allene plus propene followed the Arrhenius equations: Allyl propargl amine: Allyl cyanomethyl propargyl amine: Allyl propargyl 2-thiapropyl amine: Allyl methanesulfonyl propargyl amine: Nonconcerted mechanisms, involving polar six center cyclic transition states, are suggested for the elimination of allene and propene. © 1994 John Wiley & Sons, Inc.     

Photofragment translational spectroscopy of propargyl radicals at 248 nm

The photodissociation of propargyl radical, C(3)H(3), and its perdeuterated isotopolog was investigated using photofragment translational spectroscopy. Propargyl radicals were produced by 193 nm photolysis of allene entrained in a molecular beam expansion and then photodissociated at 248 nm. Photofragment time-of-flight spectra were measured at a series of laboratory angles using electron impact ionization coupled to a mass spectrometer. Data for ion masses corresponding to C(3)H(2)(+), C(3)H(+), C(3)(+), and the analogous deuterated species show that both H and H(2) loss occur. The translational energy distributions for these processes have average values E(T)=5.7 and 15.3 kcal/mol, respectively, and are consistent with dissociation on the ground state following internal conversion, with no exit barrier for H loss but a tight transition state for H(2) loss. Our translational energy distribution for H atom loss is similar to that in a previous work on propargyl in which the H atom, rather than the heavy fragment, was detected. The branching ratio for H loss/H(2) loss was determined to be 97.62.4+/-1.2, in good agreement with previous calculations.     

Photofragmentation of SiF4 upon Si 2p and F 1s core excitation: cation and anion yield spectroscopy

We have studied the fragmentation dynamics of core-excited SiF4 by means of soft-x-ray photoexcitation and partial positive and negative ion yield measurements around the Si L2,3-shell and F K-shell ionization thresholds. All detectable ionic fragments are reported and we observe significant differences between the various partial ion yields near the Si 2p threshold. The differences are similar to our previous results from CH3Cl showing more extended fragmentation in correspondence to transitions to Rydberg states. At variance with smaller systems, we observe negative ion production in the shape resonance region. This can be related to the possibility in a relatively large system to dissipate positive charge over several channels.     

A novel palladium catalyst for the polymerization of propargyl alcohol

Homogeneous polymerization of propargyl alcohol (OHP) with Pd (C?CCH₂OH)₂(PPh₃)₂ [Pd?C] catalyst in CHCl₃-CH₃OH mixed solvent system has been investigated. [Pd?C] was found to be a novel effective catalyst for the OHP polymerization. Some features, kinetic behavior, and effect of solvent for the OHP polymerization are described and discussed. The overall polymerization activation energy was found to be 75.6kJ/mol and the rate equation can be expressed as R_p = k_p[OHP] [Pd?C]^0.7, where k_p = 3.14 × 10^-4 L^0.7/ mol^0.7 S (60°C). Polypropargyl alcohol (POHP) obtained is a brown powder with a number-average molecular weight (M?_n) of 10³-2 × 10³, and soluble in MeOH, DMF, and DMSO. Conducting properties of the resulting POHP were investigated. © 1994 John Wiley & Sons, Inc.     

Synthesis of pyrrole-dihydrothiazole ensembles from 1-allenyl-1H-pyrrole,isothiocyanates, and propargyl bromide

Russian Journal of Organic Chemistry - N-Alkylidene-1-(propargylsulfanyl)-2-(1H-pyrrol-1-yl)buta-1,3-dien-1-amines at treatment by a superbasic system t-BuONa–THF–DMSO under standard...     

Yotta-photonic excitation spectroscopy of salicylidene-m-bromo-aniline

The observation of triplet-triplet absorption and emission spectra of salicylidene-m-bromo-aniline in solution, is complicated by the possible colored isomer formation during the optical pumping for yotta-photonic excitation at room temperature. The short-lived (singlet-singlet) and long-lived (triplet-triplet) absorption spectra were recorded phographically by microsecond flash and nano-second laser flash photolysis techniques. Salicylidene-m-bromo-aniline complexes were purified by repeated recrystallization until further recrystallization produced no further changes for X-ray diffraction pattern and optical absorption, emission properties. For yotta-photon excitation system, light could be faster than usual, because of heat and to many photonic collisions in the cavity, slowed down by the molecule, and stopped or frozen in a molecular orbital for a short time from nano-second to atto-second. The physical properties of the absorbed photons, in a very high photon flux density (i.e. in a photon field) are different in photonic character, and the emitted photons by the excited states behaves differently in photon field, no splitting occurs for the absorbed or emitted lines like in electrical or magnetic fields.     

Theoretical study on the gas phase reaction of propargyl alcohol with hydroxyl radical

The reaction of propargyl alcohol with hydroxyl radical has been studied extensively at CCSD(T)/aug‐cc‐pVTZ//MP2/cc‐pVTZ level. This is the first time to gain a conclusive insight into the reaction mechanism and kinetics for this important reaction in detail. Two reaction mechanisms were revealed, namely addition/elimination and hydrogen abstraction mechanism. The reaction mechanism confirms that OH addition to C?C triple bond forms the chemically activated adducts, IM1 (·CHCOHCH₂OH) and IM2 (CHOH·CCH₂OH), and the hydrogen abstraction pathways (? CH₂OH bonded to the carbon atom and alcohol hydrogen) may occur via low barriers. Harmonic model of Rice–Ramsperger–Kassel–Marcus theory and variational transition state theory are used to calculate the overall and individual rate constants over a wide range of temperatures and pressures. The calculated rate constants are in good agreement with the experimental data. At atmospheric pressure with Ar as bath gas, IM1 (·CHCOHCH₂OH) and IM2 (CHOH·CCH₂OH) formed by collisional stabilization are dominant in the low temperature range. The production of CHCCHOH + H₂O via hydrogen abstraction becomes dominate at higher temperature. The fraction of IM3 (CH₂COHCH₂·O) is very significant over the moderate temperature range. © 2014 Wiley Periodicals, Inc.