- Kinetic Studies of Cascade Reactions in High-Throughput Systems
-
The application of robotic systems to the study of complex reaction kinetics is considered, using the cascade reaction A → B → C as a working example. Practical problems in calculating the rate constants k 1 and k2 for the reactions A → B and B → C from concentration measurements of CA, CB, or CC are discussed in the light of the symmetry and invertability of the rate equations. A D-optimal analysis is used to determine the points in time and the species that will give the best (i.e., most accurate) results. When exact data are used, the most robust solution results from measuring the pair of concentrations (CA, CC). The system's information function is computed using numeric methods. This function is then used to estimate the amount of information obtainable from a given cascade reaction at any given time. The theoretical findings are compared with experimental results from a set of two-stage cascade experiments monitored using UV-visible spectroscopy. Finally, the pros and cons of using a single reaction sample to estimate both k1 and k2 are discussed.
- Iron, David,Boelens, Hans F. M.,Westerhuis, Johan A.,Rothenberg, Gadi
-
-
Read Online
- Preparation method of aliphatic mercaptan
-
The invention provides a novel method for preparing (CH3CH2) 2NCH2CH2SH, wherein alkali is added when (CH3CH2) 2NH is recovered, so that the content of impurities in the recovered (CH3CH2) 2NH is reduced, and particularly, the impurities which can influence the synthesis of (CH3CH2) 2NCH2CH2SH in the recovered (CH3CH2) 2NH are removed, so that the recovered (CH3CH2) 2NH can be reused in the production of (CH3CH2) 2NCH2CH2SH.
- -
-
Paragraph 0053-0054; 0083-0084; 0097-0098
(2021/08/28)
-
- Preparation method of aliphatic mercaptan
-
The invention provides a novel method for preparing (CH3CH2) 2NCH2CH2SH, i.e., the reaction is carried out at a lower temperature, and the reaction is controllable by adopting a manner of dropwise adding materials, so that the safe production is realized.
- -
-
Paragraph 0030-0031; 0035-0036; 0039-0040; 0042-0043; ...
(2021/08/28)
-
- Preparation process of ethane episulfide
-
The invention relates to a preparation process for synthesizing ethane episulfide from thiocyanate and ethylene carbonate, the preparation process comprises the following steps of: dissolving dried thiocyanate in a medium-polarity ketone solvent which is not easy to ionize, pressing ethylene carbonate into the ketone solution of thiocyanate through nitrogen, heating to react to generate a gas-phase product, condensing the gas-phase product to obtain ethane episulfide, filtering reaction liquid, recycling the liquid, and drying the solid so as to obtain the high-purity cyanate. The reaction belongs to homogeneous reaction, reactants are in full contact, and the process has the advantages of mild and controllable reaction, high reaction efficiency, low energy consumption, few side reactions, simple post-treatment and the like.
- -
-
Paragraph 0021-0023
(2021/12/07)
-
- Taurine synthesis method (by machine translation)
-
The invention provides a taurine synthesis method, and solves the problems of by-product accumulation, high temperature and high pressure in ammonia decomposition reaction, strong strong acid and strong base in acidification and the like in an addition reaction in a traditional taurine synthesis process. The method comprises the following steps: 1) carrying out cyclization reaction of sulfur solution and ethylene contact to obtain a solution of sulfur dissolved in carbon disulfide; 2) carrying out an addition reaction with ammonia or liquid ammonia contact to obtain an amino thiol; 3) carrying out an oxidation reaction in the presence of a catalyst to obtain the crude taurine. (by machine translation)
- -
-
Paragraph 0036-0037; 0041-0042; 0045-0046; 0049-0050
(2020/07/15)
-
- A process for preparing cyclic ethane
-
The invention discloses a preparation process of ethylene sulfide. The preparation process comprises the following steps: heating potassium thiocyanate at a vacuum condition for dehydrating; continuously charging nitrogen to protect the reaction until a reaction system is at a micro-pressure; subsequently adding ethylene carbonate to perform a synthetic reaction; condensing to obtain liquid ethylene sulfide. The reaction system is also provided with an ethylene sulfide tail gas adsorbing device and an air drying device so as to prevent polymerization reaction of ethylene sulfide, so that the preparation process of ethylene sulfide is little in side reaction, high in reaction yield and small in environmental pollution.
- -
-
Paragraph 0031; 0032; 0035; 0036
(2016/12/01)
-
- Atom economical synthesis of di- and trithiocarbonates by the lithium: Tert -butoxide catalyzed addition of carbon disulfide to epoxides and thiiranes
-
Alkali metal alkoxides were studied as catalysts for the addition of CS2 to epoxides. A screening of several commercially available alkoxides revealed lithium tert-butoxide as an active and selective catalyst for this reaction. The influence of different reaction parameters as well as the substrate scope under optimized reaction conditions has been studied. Terminal and highly substituted epoxides as well as thiiranes were converted. In total 28 products were prepared and isolated in yields up to 95%. Notably, the reactions were performed under mild conditions without additional solvents. The regio- and stereoselectivity of the reaction has been studied e.g. by converting (R)-styrene and (R)-propylene oxide. Moreover, the test reaction was monitored by 13C NMR and a plausible mechanism for the conversion of terminal and internal epoxides is given. This proposal is in agreement with the observed regio- and stereoselectivity of the reaction.
- Diebler,Spannenberg,Werner
-
supporting information
p. 7480 - 7489
(2016/08/16)
-
- Polyfunctional thiirane compounds
-
Describes novel polyfunctional thiiranes. Also described are polymerizable compositions comprising such novel polyfunctional thiiranes, and polymerizates, e.g., optical lenses, prepared therefrom. The described polymerizates may have a refractive index of at least 1.6, and an Abbe number of at least 27.
- -
-
-
- Thermal degradation processes in polysulfide copolymers investigated by direct pyrolysis mass spectrometry and flash pyrolysis - Gas chromatography/mass spectrometry
-
This is the first report on the analysis of random block polysulfide copolymers containing different amounts of repeating units in the copolymer backbone, which has been studied by direct pyrolysis mass spectrometry (DPMS) and by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The homopolymers such as poly(ethylene sulfide) (PES), poly(styrene sulfide) (PSS), and two random copolymers, viz., poly(ethylene sulfidex-co-styrene sulfidey) [copolymer I (x = y = 0.5) and copolymer II (x = 0.74, y = 0.26)] were investigated by both DPMS and Py-GC/MS (except copolymer II) techniques. In the case of copolymer I, the thermal degradation products of SE1, SE2, S2, and S2E (S = styrene sulfide, E = ethylene sulfide) were detected in DPMS, whereas the formation of SE1 and SE2 were observed by Py-GC/MS technique. However, for copolymer II, SE3 was also found along with SE1, SE2, S2, and S2E in DPMS. The formation of additional product (SE3) observed in copolymer II could be due to an increase in the block length formed during copolymerization. Further, a comparative study on thermal degradation of PES, poly(ethylene disulfide) (PEDS), and poly(ethylene tetrasulfide) (PETS) were investigated by Py-GC/MS. The pyrolysis products detected by both DPMS and Py-GC/MS indicates that the thermal decomposition of these polymers yield cyclic sulfides through an intramolecular exchange or by backbiting processes. The linear products with thiol and vinyl groups were also observed by Py-GC/MS along with the cyclic products via carbon hydrogen transfer reaction.
- Sundarrajan,Surianarayanan,Srinivasan,Kishore
-
p. 3331 - 3337
(2007/10/03)
-
- Gas Phase Thermolysis of Pyrazolines. 5. Electronic Structure and Gas Phase Thermolysis of Tetrazole Derivatives Studied by Photoelectron Spectroscopy
-
The photoelectron spectra of substituted tetrazoles 1-3, 1,4-dihydro-5H-tetrazol-5-ones 4-9, and 1,4-dihydro-5H-tetrazole-5-thiones 10-15 have been recorded. Based on PM3 and some ab initio calculations, the ionization potentials have been assigned to molecular orbitals. Gas-phase thermolyses of 1-15 have been studied by real-time gas analysis controlled by photoelectron spectroscopy. Compounds 1 and 2 lose formaldehyde and thioformaldehyde, respectively, leaving unsubstituted tetrazole (16), which decomposes mainly through extrusion of a nitrogen molecule and formation of cyanamide. Thiirane is split off from 3, and the remaining molecule decomposes into smaller products. Compounds 4-9 are cleaved by [3+2] cycloreversion to isocyanates and azides. Some of the unsymmetrically substituted compounds exhibit a marked selectivity in this reaction. For thiones 10-15 [3+2] cycloreversion is the main way of decomposition affording isothiocyanates and azides. In addition, the sulfur atom can split off and dimerize or abstract hydrogen atoms to form hydrogen sulfide. Some products like thiirene, formaldehyde, thioformaldehyde and acetaldehyde are generated solely from substituent. Photoelectron spectroscopy proved to be an excellent method for such thermolysis studies.
- Awadallah, Adel,Kowski, Klaus,Rademacher, Paul
-
p. 113 - 122
(2007/10/03)
-
- Preparation and reactions of 2-chloroethyl 1-thio-β-D-glycopyranosides derived from D-galactose, D-glucose, and 2-acetamido-2-deoxy-D-glucose
-
Chloroethyl 1-thio-β-D-glycopyranosides of the D-galacto and D-gluco configurations 5a-5c were prepared by alkylation of the corresponding 1-thio-β-D-hexopyranoses 3a-3c with 1-bromo-2-chloroethane followed by deacetylation. The starting 1-thio-β-D-hexopyranoses were obtained from the acetylated glycopyranosyl halides via isothiouronium salts. It was demonstrated that the chloroethyl thioglycosides 5a-5c undergo hydrolysis in aqueous solutions to give the 2-hydroxyethyl thioglycosides 6a-6c and reducing hexoses and that this hydrolysis proceeds via episulfonium salts. The hydrolysis was monitored by 1H and 13C NMR spectroscopy. In 1% aqueous solutions of sodium carbonate containing phenol or aniline, the thioglycosides 5a-5c provide, in addition to the above hydrolysis products, also the phenoxyethyl and phenylaminoethyl thioglycosides 9a, 10a and 9b, 10b, respectively.
- Cerny, Miloslav,Trnka, Tomas,Budesinsky, Milos
-
p. 1489 - 1500
(2007/10/03)
-
- Cationic complexes of technetium-99M
-
Tridentate mono-anionic ligands have the structure where each of X and Y is independently P, As or N, Z is phenol, thiophenol or thiol, and A and Q are hydrocarbon linking groups. The ligands from cationic complexes with Technetium-99m, e.g. [TcIII K2 ]+ where K is the ligand, having useful imaging properties.
- -
-
-
- The macrocyclization reaction of terminal dibromoalkanes with sulfide on alumina. The use of a solid support as an alternative to the high dilution technique
-
The reaction of a series of terminal dibromoalkanes with S-2 on Al2O3 has been examined. The use of a solid support for the macrocyclization represents a viable alternate procedure to the more traditional high dilution technique in solution. The cyclization also occur with thioacetamide on unactivated alumina.
- Tan,Pagni,Kabalka,Hillmeyer,Woosley
-
p. 7709 - 7712
(2007/10/02)
-
- HCl Elimination from Ethanesulfenyl Chloride and Chlorodimethyl Sulfide
-
Thioacetaldehyde (5) is prepared by matrix photolysis of ethanesulfenyl chloride (3) or thiirane (4) and by flash pyrolysis of allyl ethyl sulfide (6).Matrix irradiation of 3 or 5 with 222-nm light results in a dehydrogenation, and a mixture of thiirene (7), ethynethiol (8), and thioketone (9) is formed.Flash pyrolysis of chlorodimethyl sulfide ((1) yields ethenethiol (11) together with thiirane (4), whereas ethanesulfenyl chloride (2) gives ethene under the same conditions.The identification of thioacetaldehyde (5) is based on the comparison between the experimental and calculated IR spectra. Key Words: Matrix isolation / Elimination of HCl, photochemically / Flash pyrolysis / Calculations, ab initio / Photochemistr
- Maier, Guenther,Floegel, Ulrich,Reisenauer, Hans Peter,Hess, B. Andes,Schaad, Lawrence J.
-
p. 2609 - 2612
(2007/10/02)
-
- Selective Conversion of 2-Mercaptoalkanols to Thiirans with Orthocarbonates
-
Tetraalkyl orthocarbonates 1 were demonstrated to serve as potent cyclodehydrating agents for 2-mercaptoalkanols 2 to give the corresponding thiirans in good yields in acid-catalyzed reactions in aprotic solvents.Effect of catalysts, solvents, and alkyl substituents of 1 were examined.Activity of the acid catalysts depended on their acidity (pKa), and the strong Lewis acid BF3*OEt2 also had high catalytic activity.Effects of solvents and alkyl substituents of 1 were little observed.
- Takata, Toshizaku,Endo, Takeshi
-
p. 1818 - 1820
(2007/10/02)
-
- ESR Studies of the Thietane and Thiirane Radical Cations in Freon Matrices. Evidence for Ethylene Molecule Extrusion from the ? Thiirane Dimer Radical Cation .+>
-
ESR spectroscopy has been used to study the structures and reactions of the radical cations produced from the three- and four-membered sulfur-containing ring compounds, thiirane and thietane, the radical cations being generated by γ irradiation of dilute solutions of the parent compounds in Freon matrices at 77 K.With use of CFCl3 as the matrix, the monomer radical cations have been identified and characterized as having (2)B1 ring-closed structures with the unpaired electron localized on the sulfur atom.The hyperfine coupling to the four equivalent β-hydrogens in the thietane cation (31.1 G) is normal, but the corresponding value for the thiirane cation (16.1 G) is lower by almost a factor of 2, suggesting that hyperconjugation to methylene groups is much reduced in three-membered rings.In the more mobile CFCl2CF2Cl and CF3CCl3 matrices, dimer radical cations of thiirane and thietane are produced by the combination of a monomer radical cation with a neutral molecule at low temperatures (2?*1 S-S bond.Both of the dimer cations are unstable above 105 K in the CFCl2CF2Cl matrix, the thietane dimer radical cation decomposing to give the 2-thietanyl radical as a result of hydrogen atom or proton transfer, whereas the thiirane dimer radical cation undergoes a novel reaction involving the extrusion of an ethylene molecule.Evidence for ethylene formation in the latter reaction comes indirectly from the ESR observation of secondary radicals with the structure RCH2CH2 on annealing γ-irradiated solutions of thiirane in CFCl2CF2Cl.Similar radicals are also generated in γ-irradiated thiirane solutions in CF3CCl3 at 145-150 K, the ESR spectrum being indistinguishable from that of identically treated ethylene solutions.The ethylene extrusion is depicted as a concerted reaction in which the driving force is supplied by the transfer of the unpaired electron from the ?* (S-S) orbital of the dimer cation to a vacant p orbital on the terminal sulfur atom of the remaining C2H4S2+ moiety.
- Qin, Xue-Zhi,Meng, Qing-cheng,Williams, Francon
-
p. 6778 - 6788
(2007/10/02)
-
- THE CHEMISTRY OF α,ω-MERCAPTOALCOHOLS IN THE PRESENCE OF DIETHOXYTRIPHENYLPHOSPHORANE. TEMEPERATURE DEPENDENCE OF CYCLODEHYDRATIONS AND S-ETHYLATIONS
-
Diethoxytriphenylphosphorane (DTPP) is easily prepared by oxidative addition of triphenylphosphine with diethyl peroxide.DTPP converts a variety of mercaptoalcohols to cyclic sulfides as well as hydroxythioethers.The temperature dependence (+25 --> -25 deg C) of the product distribution has synthetic petential.
- Robinson, Philip L.,Kelly, Jeffery W.,Slayton, A. Evans
-
-
- DIOXYPHOSPHORANES, AN EMERGING CLASS OF VERSATILE REAGENTS FOR ORGANIC SYNTHESIS
-
Several ?-dioxyphosphoranes have been prepared and their structural characterizations using NMR techniques support the trigonal bipyramidal conformer as the most stable for the acyclic phosphoranes.Their utility in smooth conversions of hydroxylated substrates to the corresponding X-heterocycles is documented.
- Kelly, Jeffery W.,Robinson, Philip L.,Evans, Slayton A.
-
p. 147 - 150
(2007/10/02)
-
- EFFICIENT SYNTHESES OF A NEW PENEM ANTIBIOTIC, SODIUM (5R,6S)-2-(2-FLUOROETHYLTHIO)-6-PENEM-3-CARBOXYLATE
-
Two useful routes to sodium (5R,6S)-2-(2-fluoroethylthio)-6-penem-3-carboxylate (1) via trithiocarbonate (3) are reported.An intramolecular Wittig reaction of 6 and an oxalimide cyclization of 9 with phosphite are employed as key steps.
- Kawamoto, Isao,Endo, Rokuro,Suzuki, Kosato,Hata, Tadashi
-
p. 123 - 128
(2007/10/02)
-
- Photochemistry of Low-Temperature Matrices Containing Carbonyl Sulfide: Reactions of Sulfur Atoms with the Phosphorus Trihalides PF3 and PCl3 and the Hydrocarbons CH4, C2H4, and C2H2
-
Exposure of a solid argon matrix containing the molecules OCS and PX3 (X = F or Cl) at ca. 20 K to broad-band ultraviolet radiation leads to the formation of CO and the corresponding thiophosphorus(V) halides SPX3, as witnessed by the infrared spectrum of the matrix.Photolysis of a solid methane matrix containing OCS at 13-20 K on exposure to radiation with wavelengths near 230 nm gives rise to CO, methanethiol, CH3SH, thioformaldehyde, H2C=S, and carbon disulfide, CS2, as the only products to be detected by their infrared spectra.Yet there is no sign of either CH3SH or H2C=S on photolysis of OCS in a CH4-doped argon matrix with the composition Ar:CH4:OCS = 100:20:1.Evidently the photolysis of OCS generates 1D sulfur atoms which add to an adjacent CH4 molecule with the formation of a vibrationally activated intermediate *; this relaxes to give CH3SH or decomposes to give H2C=S.Similar experiments have been carried out with solid argon matrices including OCS and either C2H4 or C2H2.In the presence of C2H4 there is no hint of C-H insertion; instead the C2H4 undergoes sulfur atom addition at the double bond to give thiirane, , as the sole product to be identified by its infrared spectrum.By contrast, C2H2 yields thioketene, H2C=S, ethynethiol, HCCSH, and carbon disulfide, CS2, as the main products, as well as thiirane, , as a minor product.The response of the hydrocarbon molecules in argon matrices can be interpreted in terms of the diffusion and reaction of ground-state 3P sulfur atoms but not of 1D sulfur atoms which are too short-lived to undergo significant migration.It appears that 3P sulfur atoms react with both C2H4 and C2H2 to yield a triplet diradical: that derived from C2H4 favors cyclization, whereas that derived from C2H2 rearranges preferentially to H2C=C=S and this in turn enters into secondary reactions to give HCCSH and CS2.
- Hawkins, Michael,Almond, Matthew,Downs, Anthony J.
-
p. 3326 - 3334
(2007/10/02)
-
- RADICAL CATIONS OF ORGANIC SULPHIDES AND DISULPHIDES FORMED BY RADIOLYSIS: AN ELECTRON SPIN RESONANCE STUDY
-
Exposure of dilute solutions of various organic sulphides in fluorotrichloromethane at 77 K to 60Co γ-rays gave species identified by their e.s.r. spectra as the parent radical cations.The average β-proton coupling (R2CHS.R)+ of ca. 20 G is about half that for the corresponding ether cations, indicating greatly reduced ?-? delocalisation.However, the spread of g-values (ca. 2.032, 2.015, 2.00) is much greater than that for the ether cations.These cations readily react with other disulphide molecules to form (R2S.-SR2)+ dimer cations.The spectrum for tetrahydrothiophene (tetramethylene sulphide) exhibits a large coupling to two axial protons (ca. 42 G) and two equatorial protons (ca. 19 G), the coupling constants again being about half those for tetrahydrofuran cations.However, conformational inversion did not occur below the softening point of the solids (ca. 160 K) in marked contrast with the ether cations.The three-and four-membered ring cations (ethylene and trimethylene sulphide cations) gave very similar spectra with gx = gy, and four equivalent protons having an isotropic coupling of ca. 31 G.Thus their structures are similar to the normal R2S.+ cations, the equivalence of the g-values being interpreted in terms of effective C-S-C bond angles (θ) close to 90 deg.This, in turn, implies that θ > 90 deg for the unconstrained cations.It is noteworthy that the ethylene oxide (oxirane) cation exhibits a smaller coupling to its four protons (16 G).This implies a drastic change in structure for the oxirane cation which is clearly not the case for the sulphur analogue.Disulphides of structure R-S-CH2-S-R form cyclic ?* radicals with weak S-S bonding, in marked contrast with the oxygen analogues (acetal cations) which have ?-structures conferring very high spin-density onto the CH2 protons.Other molecules containing two RSR units form similar cyclic ?* radicals.Persulphides of structure RS-SR readily give the ?-cations (RS.SR)+, characterised by g-values in the region of 2.035, 2.018, 2.002.The smaller range of g values for (PhS.-SPh)+ cations is interpreted in terms of ca. 30percent spin-delocalisation into both the benzene rings.
- Rao, Ramakrishna D. N.,Symons, M. C. R.,Wren B. W.
-
p. 1681 - 1688
(2007/10/02)
-
- Carbene Reactions. Part 16. Thermolyses of Norbornadiene-7-spiro-2'-(1',3'-dithiolane) S-Oxides
-
The gas-phase thermolysis of the norbornadienespirodithiolane S-oxides (5) and (7) led to benzene, ethylene, and carbon disulphide as the major products, possibly involving carbon disulphide oxides as intermediates.Thermolyses of the related sulphones (9) or (14) led to completely different product patterns.
- Hoffmann, Reinhard W.,Barth, Wolfgang,Carlsen, Lars,Egsgaard, Helge
-
p. 1687 - 1692
(2007/10/02)
-
- Synthesis and Thermal Decomposition of 1,3-Dithietane and Its S-Oxides
-
Syntheses of 1,3-dithietane (1), 1,3-dithietane 1-oxide (2), 1,3-dithietane 1,1-dioxide (3), cis-1,3-dithietane 1,3-dioxide (4), trans-1,3-dithietane 1,3-dioxide (5), and 1,3-dithietane 1,1,3-trioxide (6) are reported for the first time.These compounds are converted in high yield to the previously described sulfene dimer 1,3-dithietane 1,1,3,3-tetraoxide (7).The structures of 2 and 7 are found to be respectively puckered (by microwave spectroscopy) and planar (by X-ray crystallography).Spectroscopic and physical data are discussed (photoelectron (PE) and NMR spectros copy, pKa values, oxidation potentials) along with some data on base-catalyzed H/D exchange.The PE spectra are assigned using MO models on different levels, including PNO/CEPA for thioformaldehyde (CH2S).Thermal decomposition is investigated using three independent methods: mass, microwave, and PE spectroscopy.Two types of decomposition channels are observed: retro 2+2 and retro 3+1.Among others, species like thioformaldehyde and sulfine (CH2SO, thioformaldehyde S-oxide) are produced.They are characterized by their microwave structure as well as by their PE ionization patterns and IR spectra.
- Block, E.,Corey, E.R.,Penn, R.E.,Renken, T.L.,Sherwin, P.F.,et al.
-
p. 3119 - 3130
(2007/10/02)
-
- Gas-phase Thermolyses. Part 7. Gas-phase Thermolysis of 1,2,3-Oxadithiolan 2-Oxide and Thiiran 1-Oxide. On the Intermediacy of 1,2-Oxathietan
-
The unimolecular gas-phase thermolyses of 1,2,3-oxadithiolan 2-oxide and thiiran 1-oxide have been studied by the flash vacuum thermolysis-field ionization mass spectrometry (f.v.t.-f.i.m.s.) technique in the temperature range from 1043 to 1404 K.The reactions are rationalized in terms of sulphoxide-sulphenate rearrangement and atomic oxygen, sulphur monoxide, and sulphur dioxide extrusions.Evidence is presented for the common intermediacy of 1,2-oxathietan from the thermolyses of both 1,2,3-oxadithiolan 2-oxide and thiiran 1-oxide.
- Carlsen, Lars,Egsgaard, Helge
-
p. 279 - 282
(2007/10/02)
-
- Formation of C-S Bond by the Elimination of Perfluorocarboxylic Acid
-
Thiirane was readily generated from 2-mercaptoethyl trifluoroacetate or pentafluoropropionate by the intramolecular elimination of the perfluorocarboxylic acid with triethylamine.Alkyl benzyl sulfides were also prepared from benzyl trifluoroacetate or pentafluoropropionate and alkanethiols by the intermolecular elimination of the perfluorocarboxylic acid.
- Kawa, Hajimu,Ishikawa, Nobuo
-
p. 2097 - 2098
(2007/10/02)
-
- Proton Affinities and Photoelectron Spectra of Three-Membered-Ring Heterocycles
-
Proton affinities and photoelectron spectra have been measured for azirane, phosphorane, oxirane, and thiirane and for the corresponding dimethylamine, phosphine, ether, and sulphide.The photoelectron spectra have been fully assigned by the use of ab initio STO-431G calculations and structural correlations within these series of molecules.The lone-pair ionization potentials of the heterocycles are higher than those of their open-chain dimethyl analogues because of charge redistribution effects in the C-X bonds and increased lone-pair's character in azirane and phosphirane.The proton affinities are lower in the heterocycles than in their dimethyl analogues as a result of increases in lone-pair's character and, especially for phosphirane, an increase in the RXR angle strain on protonation.Ab initio calculations on the protonated heterocycles and XHn models are presented to help interpret the proton-affinity data.
- Aue, Donald H.,Webb, Hugh M.,Davidson, William R.,Vidal, Mariano,Bowers, Michael T.,at al.
-
p. 5151 - 5157
(2007/10/02)
-
- Pesticidal compositions containing phosphoric esters and divalent sulphur compounds
-
Pesticidal composition comprising: a pesticidal, phosphoric ester the molecule of which has at least one alkyl group of 1 to 3 carbon atoms, 0.05 to 10% of an agent stabilizing the said ester against decomposition by protonisation, together with adjuvants characterized in that the stabilizing agent comprises at least one sulphur compound containing per molecule at least one divalent sulphur atom of which one valence is bonded to an atom chosen from sulphur, carbon, nitrogen, hydrogen, and metals capable of giving a salt, the other valence being bonded to an atom chosen from hydrogen, the carbon atom already noted, a second carbon atom, the nitrogen atom already noted, a second nitrogen atom, the metal atom already noted in the case of a metal of valence greater than one, a second atom of metal and oxygen when the first valence is not attached to an atom of hydrogen, the proportion of sulphur calculated with reference to the weight of the sulphur compound being between 5 and 99%. Process for stabilizing a phosphoric ester of which the molecule possesses at least one alkyl group containing 1 to 3 carbon atoms characterized in that there is added to the phosphoric ester or to a mixture which contains it, 0.05 to 10% calculated on the weight of the phosphoric acid ester of an agent capable of stabilizing the said phosphoric ester against protonisation and comprising at least one sulphur compound such as that defined thereupon.
- -
-
-