- Kinetics and Mechanism of the Br2-HCN Reaction
-
The reaction between bromine and cyanide in aqueous acid solution (HClO4) has been studied at 25 deg C using a conventional spectrophotometric method.Under conditions of an excess of CN(1-), H(1+), and Br(1-) ions the experimental kinetic law has the form -d/dt = (a + b + c)/(1 + d, where a = 7.5 +/- 1 s-1, b = 45 +/- 10 M-1 s-1, c = 48 +/- 4 M-1 s-1, and d = 12 +/- 4 M-1.The results are consistent with a mechanism involving steps Br2 + CN(1-) -> BrCN + Br(1-) with rate constant k1 = (6.7 +/- 0.9) x 109 M-1 s-1, Br3(1-) + CN(1-) -> BrCN + 2Br(1-) with k2 = (2.4 +/- 0.6) x 109 M-1 s-1, and Br2 + HCN -> BrCN + Br(1-) + H(1+) with k3 = 48 +/- 4 M-1 s-1.A nonlinear regression method was successfully used in analysis of the experimental data.
- Valent, Ivan,Adamcikova, Lubica
-
-
Read Online
- -
-
It has been observed that in E. Schulek's method for the iodometric determination of bromide via BrCN, ClCN is formed depending on the temperature and the pH. The yellow colour of the latter, and also its ability to oxidize iodide, disappear after a short while. Reaction-kinetic experiments have shown that the formation of yellow cyanogen chloride and its reaction with iodide ion is to be considered as a monomolecular collision reaction. Yellow cyanogen chloride represents the hitherto not observable electromeric form of CICN in which the chlorine has a certain amount of positive charge (Cl+O-CN).
- Schulek,Pungor
-
-
Read Online
- Designing chiral amido-oxazolines as new chelating ligands devoted to direct Cu-catalyzed oxidation of allylic C–H bonds in cyclic olefins
-
A new type of amido-oxazoline ligands was conveniently synthesized from inexpensive and commercially available materials in high yields and enantiomeric excesses. The corresponding chiral copper complexes with this class of ligands [C2 symmetric S,S-bis(amido-oxazoline-Cu(II) complex] were synthesized accordingly. The ORTEP diagram of ligand 6a and complex 6a-copper were compared and characterization of the complex confirmed the involvement of both dentate parts of the ligands, the oxygen and nitrogen atoms, in complexation with copper. The utilization of this amido-oxazoline ligands in the copper-catalyzed enantioselective esterification of allylic C–H bonds of cyclic olefins with tert-butyl-4-nitrobenzoperoxoate resulted in the highest activities, yields (up to 95%) and enantioselectivities (up to 96%) in the presence of HZSM-5 zeolite. These new findings highlight the protocol as one of the most attractive and useful methods for the oxidation of the asymmetric allylic C–H bond of cycloalkenes compared to other methodologies reported in the literature.
- Samadi, Saadi,Jadidi, Khosrow,Samadi, Mojgan,Ashouri, Akram,Notash, Behrouz
-
supporting information
p. 862 - 867
(2019/01/08)
-
- Integration of Bromine and Cyanogen Bromide Generators for the Continuous-Flow Synthesis of Cyclic Guanidines
-
A continuous-flow process for the in situ on-demand generation of cyanogen bromide (BrCN) from bromine and potassium cyanide that makes use of membrane-separation technology is described. In order to circumvent the handling, storage, and transportation of elemental bromine, a continuous bromine generator using bromate–bromide synproportionation can optionally be attached upstream. Monitoring and quantification of BrCN generation was enabled through the implementation of in-line FTIR technology. With the Br2 and BrCN generators connected in series, 0.2 mmol BrCN per minute was produced, which corresponds to a 0.8 m solution of BrCN in dichloromethane. The modular Br2/BrCN generator was employed for the synthesis of a diverse set of biologically relevant five- and six-membered cyclic amidines and guanidines. The set-up can either be operated in a fully integrated continuous format or, where reactive crystallization is beneficial, in semi-batch mode.
- Glotz, Gabriel,Lebl, René,Dallinger, Doris,Kappe, C. Oliver
-
supporting information
p. 13786 - 13789
(2017/10/09)
-
- Process for Preparing High Purity Dicyclopentadiene-phenol Type Cyanate Compounds
-
The present invention refers to brominated cyanide (Cyanogen bromide) and phenol en- claw pen hit D between D (Dicyclopentadiene-phenol) compound formed by manufacturing method relates to cyanate ester compounds, said compounds are isopropyl alcohol (IPA), water, methyl ethyl ketone (MEK) by a cleaning process for the oxide layer produced cyanate ester compound purity recent printed circuit board (PCB) and copper-clad laminate (CCL) from a microelectronic substrate such as required of high-thermal resistance, low dielectric, a low hygroscopicity in exhibits excellent performance.
- -
-
Paragraph 0029-0031
(2016/12/26)
-
- METHOD FOR PRODUCING CYANOGEN-HALIDE, CYANATE ESTER COMPOUND AND METHOD FOR PRODUCING THE SAME, AND RESIN COMPOSITION
-
A method for efficiently producing a cyanogen halide with suppressed side effects, and a method for producing a high-purity cyanate ester compound at a high yield includes contacting a halogen molecule with an aqueous solution containing hydrogen cyanide and/or a metal cyanide, so that the hydrogen cyanide and/or the metal cyanide is allowed to react with the halogen molecule in the reaction solution to obtain the cyanogen halide, wherein more than 1 mole of the hydrogen cyanide or the metal cyanide is used based on 1 mole of the halogen molecule, and when an amount of substance of an unreacted hydrogen cyanide or an unreacted metal cyanide is defined as mole (A) and an amount of substance of the generated cyanogen halide is defined as mole (B), the reaction is terminated in a state in which (A):(A)+(B) is between 0.00009:1 and 0.2:1.
- -
-
Paragraph 0277
(2015/12/09)
-
- HALOGEN-ALKYL-1,3 OXAZINES AS BACE1 AND/OR BACE2 INHIBITORS
-
The present invention provides compounds of formula (I) having BACE1 and/or BACE2 inhibitory activity, their manufacture, pharmaceutical compositions containing them and their use as therapeutically active substances. The active compounds of the present invention are useful in the therapeutic and/or prophylactic treatment of e.g. Alzheimer's disease and type 2 diabetes.
- -
-
Page/Page column
(2014/04/03)
-
- Non-Nucleoside reverse transcriptase inhibitors
-
Compounds of formula I, wherein R1, R2, R3, X and Ar, are as defined herein or pharmaceutically acceptable salts thereof, inhibit HIV-1 reverse transcriptase and afford a method for prevention and treatment of HIV-1 infections and the treatment of AIDS and/or ARC. The present invention also relates to compositions containing compounds of formula I useful for the prevention and treatment of HIV-1 infections and the treatment of AIDS and/or ARC.
- -
-
Page/Page column 16
(2009/01/23)
-
- NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITORS
-
Compounds of formula (I), wherein R1, X1, X2 and A, are as defined herein or pharmaceutically acceptable salts thereof, inhibit HIV-1 reverse transcriptase and afford a method for prevention and treatment of HIV-1 infections and the treatment of AIDS and/or ARC. The present invention also relates to compositions containing compounds of formula (I) useful for the prevention and treatment of HIV-1 infections and the treatment of AIDS and/or ARC.
- -
-
Page/Page column 36
(2009/01/20)
-
- Cathepsin cysteine protease inhibitors
-
This invention relates to a novel class of compounds which are cysteine protease inhibitors, including but not limited to, inhibitors of Cathepsins K and L. These compounds are useful for treating diseases in which inhibition of bone resorption is indicated, such as osteoporosis.
- -
-
-
- Reaction of AgOCN with NO, NO2, CINO2, CINO, and BrNO: Evidence of the Formation of OCN-NO2 and OCN-NO
-
Reactions of silver cyanate with binary nitrogen oxides, NO and NO2, and ternary nitrogen oxohalides, C1NO2, C1NO, and BrNO, were studied by means of gas phase IR spectroscopy. The experimental data for the neat reactions of AgOCN with NO2 and AgOCN with C1NO2 are compatible with the formation of an intermediate, short-lived OCN-NO2 molecule, which undergoes cleavage-rearrangement to give N2O and CO2. In contrast, NO does not react with AgOCN. The reaction of XNO (X = Cl, Br) and AgOCN is much more complex, leading to a mixture of NO, NO2, N2O, CO2, NCNCO, and X(CO)NCO. A reaction mechanism that involves the formation of neutral nitrosyl isocyanate, OCN-NO, has been proposed as the initial step. The two neutral intermediates, OCN-NO2 and OCN-NO, were computed by ab initio methods at the correlated MP2 level of theory and are discussed in terms of intramolecular stabilization by donor-acceptor interaction (negative hyperconjugation).
- Klapo?tke, Thomas M.,Schulz, Axel
-
p. 7897 - 7904
(2008/10/09)
-
- Non-metal redox kinetics: Hypobromite and hypoiodite reactions with cyanide and the hydrolysis of cyanogen halides
-
Pulsed-accelerated-flow spectroscopy is used to measure second-order rate constants (where the initial half-lives are 3-9 μs) for the reactions of cyanide ion with OBr- and with OI- (25.0°C, μ = 1.00 M). The proposed mechanism includes parallel paths with halogen-cation transfer to CN- by solvent-assisted reaction with OX- (X = Br, I) and by direct reaction with HOX: OX- + CN- + H2O → kox XCN + 2OH- OX- + H2O ? HOX + OH- HOX + CN- → kHOX XCN + OH- The relative reactivities of the hypohalites with CN- (kox) are as follows: OI- (6 × 107 M-1 s-1) ≈ OBr- (5.7 × 107 M-1 s-1) ? OCl- (310 M-1 s-1). The rate constants for the hypohalous acid reactions with CN- (kHOX) are as follows: HOBr (4.2 × 109 M-1 s-1) > HOCl(1.22 × 109 M-1 s-1). The base hydrolysis of ICN is studied spectrophotometrically by the appearance of I- at 225 nm (ε = 12 070 M-1 cm-1). Saturation kinetics are observed with increased OH- concentration. This is attributed to rapid equilibration to give HOICN- (KOH = 3.2 M-1), which inhibits the OH- attack at the carbon atom in ICN to form OCN- (k4 = 1.34 × 10-2M-1s-1). The base hydrolysis of BrCN is studied by following the disappearance of the 105 amu peak with membrane introduction mass spectrometry. Rate constants for the reactions of BrCN with OH- (kOH = 0.53 ± 0.01 M-1 s-1) and with CO32- are determined (kCO3 = (7.5 ± 0.3) × 10-3 M-1 s-1). The relative reactivities of cyanogen halides for the base hydrolysis are as follows: ClCN ? BrCN ? ICN.
- Gerritsen, Cynthia M.,Gazda, Michael,Margerum, Dale W.
-
p. 5739 - 5748
(2008/10/08)
-
- Kinetics and Mechanism of the BrO3(1-)-SCN(1-)-H(1+) Reaction
-
The reaction of BrO3(1-) with SCN(1-) in dilute HClO4 is investigated in both batch and flow reactor modes.The stoichiometry of the reaction is BrO3(1-) + SCN(1-) + H2O -> HSO4(1-) + HCN + Br(1-) when SCN(1-) is in excess and 7BrO3(1-) + 5SCN(1-) + 2H(1+) -> 5BrCN + Br2 + 5SO4(2-) + H2O when BrO3(1-) is in excess.There is a two-stage induction period in the batch mode when BrO3(1-) is in excess before the occurrence of a third stage in which Br2 finally accumulates.The end of the first stage corresponds to the consumption of SCN(1-), and the end of the second corresponds to the consumption of CN(1-).Both of these species react rapidly with Br2.Bromine accumulates during the third stage as a result of the reaction of Br(1-) with BrO3(1-).A large range of feed-stream concentrations and flow rates was investigated in CSTR mode.No periodic or quasiperiodic oscillations were found that could not be eliminated by substituting gravity feeding for a peristaltic pump.However, the system is very sensitive to environmental perturbation and thus very noisy at low flow rates.The reaction is simulated on the basis of a mechanism proposed here.The agreement between experiments and simulations is very good.Simulations at low flow rates show a very rapid change with flow rate of steady-state along a line connecting the three stages mentioned above with BrO3(1-) in excess.This is likely the source of the experimental sensitivity to perturbation.
- Zhang, Yi-Xue,Field, Richard J.
-
p. 1224 - 1228
(2007/10/02)
-
- Mechanism of Oxidation of Thiocyanate Ion by Bromamine-T and Hypobromite Ion in Alkaline Medium. A Kinetic Study
-
Kinetics and mechanism of oxidation of thiocyanate ion by bromamine-T (BAT) and hypobromite ion have been investigated in alkaline medium.The rate followed first order kinetics in with both BAT and OBr-, but fractional and inverse fractional orders in -> with BAT and OBr-, respectively.The rate was independent of -> with BAT and small fractional order in -> with OBr-.Increase in ionic strength of the medium increased the rate with BAT and had no effect in hypobromite oxidations.Decrease in dielectric constant of the medium by changing the solvent composition with methanol increased the rate with BAT and had no significant effect with OBr- oxidation.Activation parameters have been computed from the Arrhenius plots.Mechanisms consistent with the observed kinetics have been proposed and the related rate laws deduced.The formation equilibrium constant and the rate constant for the rate-controlling step have been computed from the double reciprocal plots.Comparison of kinetic results in acid and alkaline media reveal that BAT is more powerful oxidant in alkaline medium than in the former.
- Gowda, B. Thimme,Bhat, J. Ishwara
-
p. 159 - 163
(2007/10/02)
-
- Novel heterocyclic derivatives bearing an amino radical, processes for their production and the pharmaceutical compositions containing them
-
This invention relates to novel heterocyclic derivatives bearing an amino group and to processes for making said compounds. More particularly this invention provides novel heterocyclic compounds the hetero ring of which has two hetero atoms, the same or different, substituted with a free or substituted amino group. These compounds are useful as active ingredients of drugs.
- -
-
-
