F:Flammable;74-96-4Relevant articles and documents
Verbascoside, synthetic derivatives and other glycosides from Argentinian native plant species as potential antitumoral agents
Garro, Hugo A.,Bruna-Haupt, Ezequiel,Cianchino, Valeria,Malizia, Florencia,Favier, Silvina,Menacho-Márquez, Mauricio,Cifuente, Diego,Fernández, Claudio O.,Pungitore, Carlos R.
, p. 4703 - 4708 (2021)
A phytochemical study was performed on three native plant species from the central-western zone of Argentina: Buddleja cordobensis Grisebach, Baccharis salicina Torr. & A. Gray and Nepeta cataria L. We could obtain verbascoside (1) from B. cordobensis. From N. cataria, we could obtain 1, 5, 9-epi-deoxyloganic acid (2) L. Finally, we could isolate 2-β-(L-rhamnopyranosyl)-3-angeloyloxy-15-acetyloxy-7,13(14)-E-dien-ent-labdane (3) and 2-β-(L-rhamnopyranosyl)-3-α-angeloyloxy-15-hydroxy-7,13(14)-E-dien-ent-labdane (4) from B. salicina. Moreover, three derivatives from 1, and one semi-synthetic derivative from 2, were prepared. PCR reaction was used to analyse the activity against DNA polymerase and cell culture to determine cytotoxicity and antitumoral activity. Verbascoside (1) was strongly active in the nanomolar scale (IC50 = 356 nM) against DNA polymerization. Moreover, verbascoside was also strongly active in the nanomolar scale against human melanoma cell line (IC50 = 256 nM) and human colorectal cell line (IC50 = 320 nM). Furthermore, derivatives 6 and 7 were cytotoxic against both cancer cell lines.
Reactivity of mono-halogen carbene radical anions (CHX-; X = F, Cl and Br) and the corresponding carbanions (CH2X-; X = Cl and Br) in the gas phase
Born, Monique,Ingemann, Steen,Nibbering, Nico M. M.
, p. 2537 - 2547 (1996)
The gas-phase reactions of mono-halogen substituted carbene radical anions, CHX- (X = F, Cl and Br) and the corresponding carbanions, CH2X- (X = Cl and Br) with halomethanes and organic esters have been examined with the use of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The chlorine and bromine containing (radical) anions react by SN2 substitution with the parent chloro- and bromo-methanes, whereas an SN2 and/or a BAC2 reaction occurs with the methyl ester of trifluoroacetic acid and dimethyl carbonate. The main features of the results are: (i) the SN2 substitution of a given carbene radical anion with CH3C1 or CH3Br is less efficient than this reaction of the corresponding carbanion, (ii) the radical anions react less efficiently with dimethyl carbonate than the carbanions, (iii) the SN2 substitution is less important for the radical anions than for the carbanions in the reactions with the two carbonyl compounds, (iv) for both types of ions, the BAC2 pathway becomes relatively more important as the halogen atom is changed from chlorine to bromine. These findings are discussed in terms of the thermodynamics of the overall processes in combination with considerations of the potential energy surfaces which can describe these gas-phase processes.
Synthesis of ethyl 4,5-bis(diethoxyphosphorylmethyl)-3-furoate
Pevzner
, p. 62 - 67 (2016)
Preparative procedure for 4,5-bis(diethoxyphosphorylmethyl)-3-furoate from 4-chloromethyl-3-furoate is developed. It includes substitution of chlorine with iodine, phosphorylation by means of the Arbuzov reaction, chloromethylation of 4-(diethoxyphosphorylmethyl)-3-furoate in the position 5 of the furan ring, substitution of chlorine with iodine in the obtained chloromethyl derivative, and repeated phosphorylation with triethyl phosphite. It was found that ethyl 4-(diethoxyphosphorylmethyl)-5(chloromethyl)-3-furoate reacts with sodium diethyl phosphite by two pathways. Besides usual nucleophilic substitution leading to phosphonate, transfer of the reaction center in the position 2 of the furan ring takes place. The ambident diethylphosphite anion in this case reacts at the oxygen to give tertiary phosphite. The latter is oxidized with the air oxygen to form ethyl 2-(diethoxyphosphoryloxy)-4-(diethoxyphosphorylmethyl)-5-methyl-3-furoate. Unlike that analogous iodomethyl phosphonate is phosphorylated selectively under the conditions of the Arbuzov reaction.
The Ethyl Halides: Stable Neutral and Radical Cation Isomers where X = F, Cl, Br, I
Blanchette, Marcia C.,Holmes, John L.,Lossing, F. P.
, p. 701 - 709 (1987)
The following isomers of the ethyl halide molecular ions have all been shown to be stable species in the gas phase: +.; +.; (ΔH0f = 1012 kJ mol-1); +. (ΔH0f = 971 kJ mol-1); +.; +. (ΔH0f = 1058 kJ mol-1); +. (ΔH0f = 995 kJ mol-1) and +..Neutralization-reionization mass spectrometry, employing Xe as the electron transfer target gas and O2 as the target gas for reionization, indicated that the ylides CH3ClCH2 and CH3BrCH2 could not be generated by such means.However, the species CH3CHClH, CH2CH2ClH and CH2CH2BrH ( and posibly CH3CHBr ) were unambiguously identified.
Effects of Preferential Solvation and of Solvent-Solvent Interaction on the Rates of Nucleophilic Substitution involving Anions in Binary Mixed Solvents. Theoretical Approach
Kondo, Yasuhiko,Kusabayashi, Shigekazu
, p. 109 - 118 (1982)
Theoretical procedures for investigating rate constants and activation parameters measured in binary mixed solvents have been presented on the basis of the concept of ideal associated mixtures.In methanol+acetonitrile mixtures the behaviour of the rate constant and of activation parameters for the ethyl iodide plus bromide ion reaction were interpreted as resulting from the specific interaction of bromide ion with methanol.In methanol+NN-dimethylacetamide mixtures association complex formation between methanol and NN-dimethylacetamide makes a significant contribution to the activation parameters, and this factor must be taken into account in interpreting the observed rate behaviour.
Nucleophilic Substitution in Binary Mixed Solvents. Kinetics and Transfer Enthalpies of Anions in the Mixed Solvents Methanol+Propylene Carbonate and Methanol+N-methyl-2-pyrrolidone
Yasuhiko, Kondo,Kazumi, Yuki,Takeshi, Yoshida,Niichiro, Tokura
, p. 812 - 824 (1980)
Rate constants and activation enthalpies for the reaction of ethyl iodide with bromide ion have been determined in two solvent mixtures, i.e., methanol+propylene carbonate and methanol+N-methyl-2-pyrrolidone mixtures.Heats of solution have also been determined for ethyl iodide, tetra-n-butylammonium-bromide, -perchlorate and -tetra-n-butylborate in the two solvent mixtures.Judging from these transfer enthalpies, perchlorate ion seems to be a pertinent model compound for the activated complex of the reaction.Single ion transfer enthalpies have been evaluated on the basis of the (n-Bu)4NB(n-Bu)4 assumption in the two solvent mixtures.Transfer enthalpy against composition profiles for perchlorate ion are similar in the two solvent mixtures, whereas for bromide ion the corresponding profiles are quite different in the two solvent mixtures, i.e., a sharp minimum was observed for the profile in MeOH+PC mixtures.From these observations and from other evidence, it is concluded that bromide ion solvation involves both electrostatic interactions and specific interactions between solute and solvents.Model calculation performed on the basis of the above views reproduce the bromide ion profile in MeOH+PC mixtures well.
Process for desulpherization and hydrogen recovery
-
, (2021/11/13)
A process for removing hydrogen sulfide from a sour gas stream is presented. The method oxidizes hydrogen sulfide to sulfuric acid by reducing aqueous bromine to hydrobromic acid in solution. The aqueous bromine solution does not react with hydrocarbon components common to natural gas including methane and ethane. This allows the process to both sweeten sour gas and convert its hydrogen sulfide content to sulfuric acid in a single step. In the present process, sulfuric acid is concentrated to eliminate its bromine content prior to being removed from the system, while the remaining hydrobromic acid solution is electrolyzed to regenerate aqueous bromine and produce hydrogen. Hydrobromic acid electrolysis requires less than half the energy required by water electrolysis and is an inherently flexible load that can shed or absorb excess power to balance supply and demand.
Synthesis and mass spectra of rearrangement bio-signature metabolites of anaerobic alkane degradation via fumarate addition
Chen, Jing,Zhou, Lei,Liu, Yi-Fan,Hou, Zhao-Wei,Li, Wei,Mbadinga, Serge Maurice,Zhou, Jing,Yang, Tao,Liu, Jin-Feng,Yang, Shi-Zhong,Wu, Xiao-Lin,Gu, Ji-Dong,Mu, Bo-Zhong
, (2020/05/01)
Metabolite profiling in anaerobic alkane biodegradation plays an important role in revealing activation mechanisms. Apart from alkylsuccinates, which are considered to be the usual biomarkers via fumarate addition, the downstream metabolites of C-skeleton rearrangement can also be regarded as biomarkers. However, it is difficult to detect intermediate metabolites in both environmental samples and enrichment cultures, resulting in lacking direct evidence to prove the occurrence of fumarate addition pathway. In this work, a synthetic method of rearrangement metabolites was established. Four compounds, namely, propylmalonic acid, 2-(2-methylbutyl)malonic acid, 2-(2-methylpentyl)malonic acid and 2-(2-methyloctyl)malonic acid, were synthesized and determined by four derivatization approaches. Besides, their mass spectra were obtained. Four characteristic ions were observed at m/z 133 + 14n, 160 + 28n, 173 + 28n and [M - (45 + 14n)]+ (n = 0 and 2 for ethyl and n-butyl esters, respectively). For methyl esterification, mass spectral features were m/z 132, 145 and [M - 31]+, while for silylation, fragments were m/z 73, 147, 217, 248, 261 and [M - 15]+. These data provide basis on identification of potential rearrangement metabolites in anaerobic alkane biodegradation via fumarate addition.
Halogen-Dependent Surface Confinement Governs Selective Alkane Functionalization to Olefins
Zichittella, Guido,Scharfe, Matthias,Puértolas, Bego?a,Paunovi?, Vladimir,Hemberger, Patrick,Bodi, Andras,Szentmiklósi, László,López, Núria,Pérez-Ramírez, Javier
supporting information, p. 5877 - 5881 (2019/02/20)
The product distribution in direct alkane functionalization by oxyhalogenation strongly depends on the halogen of choice. We demonstrate that the superior selectivity to olefins over an iron phosphate catalyst in oxychlorination is the consequence of a surface-confined reaction. By contrast, in oxybromination alkane activation follows a gas-phase radical-chain mechanism and yields a mixture of alkyl bromide, cracking, and combustion products. Surface-coverage analysis of the catalyst and identification of gas-phase radicals in operando mode are correlated to the catalytic performance by a multi-technique approach, which combines kinetic studies with advanced characterization techniques such as prompt-gamma activation analysis and photoelectron photoion coincidence spectroscopy. Rationalization of gas-phase and surface contributions by density functional theory reveals that the molecular level effects of chlorine are pivotal in determining the stark selectivity differences. These results provide strategies for unraveling detailed mechanisms within complex reaction networks.
An Activated TiC–SiC Composite for Natural Gas Upgrading via Catalytic Oxyhalogenation
Zichittella, Guido,Puértolas, Bego?a,Siol, Sebastian,Paunovi?, Vladimir,Mitchell, Sharon,Pérez-Ramírez, Javier
, p. 1282 - 1290 (2018/02/09)
Alkane oxyhalogenation has emerged as an attractive catalytic route for selective natural gas functionalization to important commodity chemicals, such as methyl halides or olefins. However, few systems have been shown to be active and selective in these reactions. Here, we identify a novel and highly efficient TiC–SiC composite for methane and ethane oxyhalogenation. Detailed characterization elucidates the kinetics and mechanism of the selective activation under reaction conditions to yield TiO2–TiC–SiC. This catalyst outperforms bulk TiO2, one of the best reported catalysts, reaching up to 85 % selectivity and up to 3 times higher titanium-specific space-time-yield of methyl halides or ethylene. This is attributed to the fact that the active TiO2 phase generated in situ is embedded in the thermally conductive SiC matrix, facilitating heat dissipation thus improving selectivity control.
