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1.
Ozonolysis of a Series of Methylated Alkenes: Reaction Rate Coefficients and Gas‐Phase Products
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Tristan Braure Véronique Riffault Alexandre Tomas Romeo Iulian Olariu Cecilia Arsene Yuri Bedjanian Patrice Coddeville 《国际化学动力学杂志》2015,47(9):596-605
The gas‐phase ozonolysis of three methylated alkenes, i.e., trans‐2,2‐dimethyl‐3‐hexene (22dM3H), trans‐2,5‐dimethyl‐3‐hexene (25dM3H), and 4‐methyl‐1‐pentene (4M1P), has been investigated in the presence of sufficient hydroxyl radical scavenger in a laminar flow reactor at ambient temperature (296 ± 2 K) and P = 1 atm of dry air (RH ≤ 5%). Ozone levels in the reactor were monitored by an automatic analyzer. Alkene and gas‐phase product concentrations were determined via online sampling either on three‐bed adsorbent cartridges followed by thermodesorption and GC/FID‐MS analysis or on 2,4‐dinitrophenylhydrazine (DNPH) cartridges for subsequent HPLC/UV analysis. Reaction rate coefficients of (3.38 ± 0.12) × 10?17 for 22dM3H and (2.71 ± 0.26) × 10?17 for 25dM3H, both in cm3 molecule?1 s?1 units, have been obtained under pseudo–first‐order conditions. Primary carbonyl products have been identified for the three investigated alkenes, and branching ratios are reported. In the case of 4M1P ozonolysis, the yield of a Criegee intermediate was indirectly determined. Kinetics and product study results are compared to those of literature when available. This work represents the first investigation of reaction products in the ozonolysis of 22dM3H, 25dM3H, and 4M1P in a flow reactor. 相似文献
2.
James Elver Johnson Joanne A. Maia Karen Tan Abdolkarim Ghafouripour Patrice De Meester Shirley S. C. Chu 《Journal of heterocyclic chemistry》1986,23(6):1861-1868
O-Methyl-α-ketophenylacetohydroximoyl chloride ( 1 ) was prepared by the reaction of O-methyl-α-methoxyphenylacetohydroximoyl chloride ( 5 ) with N-bromosuccinimide and concentrated hydrobromic acid. Reaction of 1 with ethylenediamine gave 3-phenyl-5,6-dihydro-2(1H)-pyrazinone-O-methyloxime ( 6 ). 3-Phenyl-5,6-cyclohexano-5,6-dihydro-2(1H)-pyrazininone-O-methyloxime ( 7 ) was prepared by reaction of 1 with trans-1,2-diaminocyclohexane. The X-ray structure of 6 has been determined. The crystals are orthorhombic, space group Pbca with a = 10.264(3), b = 18.262(4), c = 23.530(4)Å, V = 4411(2)Å3, and Z = 16. The structure, which was refined to R = 0.038 using 1652 observed reflections, shows the amidoxime moiety to be the Z configuration. Reaction of benzohydroximoyl chloride with aziridine gave (Z)-aziridinylbenzaldoxime ( 16a ). Ultraviolet irradiation of a benzene solution of 16a gave a mixture of the Z and E isomers 16a and 16b . The E isomer 16b underwent thermal isomerization to 16a at 100°. Reaction of 16a with dimethyl sulfate in sodium hydroxide solution gave (Z)-O-methylaziridinylbenzaldoxime ( 17a ). Photoisomerization of a hexane solution of 17a gave a mixture of the Z and E isomers 17a and 17b which were separated by preparative glc. The isomers 17a and 17b are resistant to thermal Z = E isomerization. The mechanisms of thermal isomerization of benzamidoximes are discussed. 相似文献
3.
After a review of 1-perfluoroalkene RFCFCF2 synthesis, with RFC4F9, C5F11, C6F13, we have studied their fine structures by 19F N.M.R. This study has led us to first generalize the rules set for the chemical shifts and coupling constants of olefinic fluorine atoms of fluoropropene and their derivatives. Then, we have been able to determinate unambiguously the chemical shifts of the difluoromethylene groups of the perfluorinated chains. We have thus shown, by irradiation, that inversions may take place in the chemical shifts of the CF2 groups at the β and γ position of the double bond. 相似文献
4.
Marchand P Griffe L Caminade AM Majoral JP Destarac M Leising F 《Organic letters》2004,6(8):1309-1312
The functionalization of phosphorus-containing dendrimers was easily achieved through thioacylation reactions involving new dendrimers capped with dithioester end groups and various functionalized amines. These reactions were successfully applied to the first generation (12 end groups) and the third generation of the dendrimer (48 end groups) and allowed their functionalization by various primary or secondary amines, alcohols, glycols, and azides. [reaction: see text] 相似文献
5.
A number of α-β acetylenic carbinols RFCCC(OH)RR′, in which the acetylenic proton was substituted by a F-alkyl group, were first prepared, from a classical reaction of (F-alkynyl)- lithium derivatives RFCCLi upon various carbonyl compounds.On another hand, the reaction of propargyl bromide metallic complexes (organoaluminic, or ultrasonic irradiation activated organozinc) upon some polyfluorinated ketones RFCOR led to the formation, in convenient yields, of the propargylic carbinols HCCCH2C(OH)RRF.The synthesis and properties of these series of new (F-alkyl) substituted acetylenic and propargylic alcohols are described and discussed. 相似文献
6.
Rhodopsin is the dim light photosensitive pigment of animals. In this work, we undertook to study the structure of rhodopsin from swine and compare it with bovine and rat rhodopsin. Porcine rhodopsin was analyzed using methodology developed previously for mass spectrometric analysis of integral membrane proteins. Combining efficient protein cleavage and high performance liquid chromatography separation with the sensitivity of mass spectrometry (MS), this technique allows the observation of the full protein map and the posttranslational modifications of the protein in a single experiment. The rhodopsin protein from a single porcine eye was sequenced completely, with the exception of two single-amino acid fragments and one two-amino acid fragment, and the gene sequence reported previously was confirmed. The posttranslational modifications, similar to the ones reported previously for bovine and rat rhodopsin, were also identified. Although porcine rhodopsin has a high degree of homology to bovine and rat rhodopsins and most of their posttranslational modifications are identical, the glycosylation and phosphorylation patterns observed were different. These results show that rhodopsin from a single porcine eye can be characterized completely by MS. This technology opens the possibility of rhodopsin structural and functional studies aided by powerful mass spectrometric analysis, using the fellow eye as an internal control. 相似文献
7.
Fluorescence quenching of a thioxanthone derivative by methyl- and methoxy-substituted benzenes (MeB and MeOB, respectively) is performed in solvents of different polarity. Emissive exciplexes are observed even in polar solvents and provide kinetic and spectroscopic data over a large scale of solvent polarity. These data were subsequently analyzed by use of a new theoretical model that leads to a thermodynamic relationship between exciplex and electron-transfer driving forces Delta G(exc) and Delta G(et), respectively. The remarkable agreement found between this model and both kinetic and spectroscopic data supports its validity. Moreover, the difference observed between MeB and MeOB compounds in quenching efficiency is analyzed by this model and provides the main parameters governing exciplex features, especially the resonance integral between locally excited and charge-transfer states. 相似文献
8.
Sulfenylation of indole using sulfenyl chlorides leads to the initial formation of a 3-indolyl sulfide, while excess reagent introduces a second sulfide at the 2-position of the ring. The mechanism of this second sulfenylation has not, to date, been rigorously elucidated. The development of the first, regioselective synthesis of mixed indole 2,3-bis(sulfides) has allowed the study of the sulfenylation of 3-indolyl sulfides using a different sulfenyl chloride. Our results afford evidence that the reaction proceeds via an intermediate 3,3-disulfenylated indolenine species, with subsequent migration of one of the sulfide groups to the 2-position. 相似文献
9.
Stanton JF Dudek J Theulé P Gupta H McCarthy MC Thaddeus P 《The Journal of chemical physics》2005,122(12):124314
The C 1B1<--X 1A1 band system of the potential interstellar species Si3C has been recorded in a silane/acetylene discharge by resonant two-color two-photon ionization spectroscopy. The origin band is located near 24,925 cm-1 (3.09 eV). Several other features in the spectrum are assigned to progressions in the Si-Si stretching modes as well as to sequence and hot band transitions. The assignment was facilitated by ab initio calculations, which also indicate that this is the strongest electronic transition of Si3C in the visible region of the spectrum. Features in the spectrum are broadened considerably (ca. 10 cm-1), and suggest an excited state lifetime of a few picoseconds. Possible reasons for the short-lived nature of the excited state are discussed. 相似文献
10.
Palumbo Anthony V. Lee S. Y. Boerman Patrice 《Applied biochemistry and biotechnology》1994,45(1):811-822
Applied Biochemistry and Biotechnology - EDTA degradation by anAgrobacterium sp. has been examined by quantifying14C-labeled CO2 produced from iron-[2-14C] EDTA and by measured loss of nonlabeled... 相似文献