Accurate Mass Determination of Amino Alcohols by Turboionspray／Time—of—Flight Mass Spectrometry

ＩｎｔｒｏｄｕｃｔｉｏｎＡｍｉｎｏａｌｃｏｈｏｌｓａｒｅａｎｉｍｐｏｒｔａｎｔｃｌａｓｓｏｆｃｏｍｐｏｕｎｄｓｉｎｓｙｎｔｈｅｔｉｃｏｒｇａｎｉｃｒｅａｃｔｉｏｎｓ .Ｔｈｅｉｒｍｏｌｅｃｕｌｅｓｔｒｕｃｔｕｒｅｓｂｅｃｏｍｅｕｎｓｔｅａｄｙｗｈｅｎａｎａｌｙｚｅｄｂｙｅｌｅｃｔｒｏｎｉｍｐａｃｔ(ＥＩ) .ＴｈｅｆｒａｇｍｅｎｔｓｏｂｔａｉｎｅｄｆｒｏｍＥＩａｒｅｕｓｕａｌｌｙａｓ ｓｉｇｎｅｄｔｏｎｅｕｔｒａｌｌｏｓｓｅｓｓｕｃｈａｓＨ2 Ｏ ,ＣＨ3 ＯＨ (Ｆｉｇ .1) .ＥＩｉｓｎｏｔａｕｓｅｆｕｌｍｅ…     

Benzoylation of Toluene over Al-promoted SO_4~(2-)/M_xO_y(M=Zr,Ti,Fe) Catalysts

ＴｈｅｂｅｎｚｏｙｌａｔｉｏｎｏｆｔｏｌｕｅｎｅｗｉｔｈｂｅｎｚｏｙｌｃｈｌｏｒｉｄｅｉｓａｎｉｍｐｏｒｔａｎｔａｃｉｄｃａｔａｌｙｔｉｃＦｒｉｅｄａｌＣｒａｆｔｓｒｅａｃｔｉｏｎ．Ｌｅｗｉｓａｃｉｄｓ,ｓｕｃｈａｓｄｅｈｙｄｒａｔｅｄＡｌＣｌ３ａｎ...     

Facile and Effective Synthesis of Glucopyranosyl Oligosacchardes with Alternative (1→3)-α- and -β-Linkages in the Presence of C-2 Ester Capable of Neighboring Group Participation

β (1→ 3) Ｌｉｎｋｅｄｇｌｕｃａｎｓｏｃｃｕｒｉｎａｖａｒｉｅｔｙｏｆｂｉｏ ｌｏｇｉｃａｌｌｙｉｍｐｏｒｔａｎｔｎａｔｕｒａｌｐｒｏｄｕｃｔｓ ,ｓｕｃｈａｓａｎｔｉｔｕｍｏｒｓｃｈｉｚｏｐｈｙｌｌａｎ ,ｓｃｅｒｏｇｌｕｃａｎａｎｄｌｅｎｔｉｎａｎ ,1ｗｈｉｌｅα (1→3) ｌｉｎｋｅｄｇｌｕｃａｎｓｅｘｉｓｔｉｎｓｏｍｅｍｅｄｉｃａｌｌｙｉｍｐｏｒｔａｎｔｆｕｎｇｉｓｕｃｈａｓＣｒｙｐｈｏｎｅｃｔｒｉｎｉｐａｒａｓｉｔｉｃａａｎｄＧａｎｏｄｅｒｍａｌｕ ｃｉｄｕｍ .2 Ｆｏｒａｓｔｕｄｙｏｎｔｈｅ…     

A New Type of Deaggregators, the Bolaamphiphilic DeAgrs. Observations of the Dependence of Deaggregating Ability on Aggregator Concentration and Solvent Aggregating Power

ＩｎｔｒｏｄｕｃｔｉｏｎＡｇｇｒｅｇａｔｉｏｎｉｓａｃｏｍｍｏｎｐｈｅｎｏｍｅｎｏｎｆｏｒｍａｎｙｓｉｍ ｐｌｅｏｒｇａｎｉｃｍｏｌｅｃｕｌｅｓａｓｗｅｌｌａｓｃｏｍｐｌｅｘｍｏｌｅｃｕｌｅｓｗｉｔｈｉｍｐｏｒｔａｎｔｂｉｏｌｏｇｉｃａｌａｃｔｉｖｉｔｙ .Ｆｏｒｍａｔｉｏｎｏｆａｇｇｒｅｇａｔｅｓｍａｙｂｅｄｒｉｖｅｎｂｙｄｉｆｆｅｒｅｎｔｎｏｎ ｃｏｖａｌｅｎｔｉｎｔｅｒａｃｔｉｏｎｓ ,ｓｕｃｈａｓｈｙｄｒｏｇｅｎｂｏｎｄｉｎｇ ,1ｅｌｅｃｔｒｏｓｔａｔｉｃｉｎｔｅｒａｃｔｉｏｎ ,2 ｏｒｈｙ ｄｒ…     

Investigation on False Peak Phenomena in On-line Sweeping Technique in MEKC

ＩｎｔｒｏｄｕｃｔｉｏｎＭｉｃｅｌｌａｒｅｌｅｃｔｒｏｋｉｎｅｔｉｃｃｈｒｏｍａｔｏｇｒａｐｈｙ (ＭＥＫＣ)ｗａｓｉｎｖｅｎｔｅｄｔｏｅｘｔｅｎｄｔｈｅｕｔｉｌｉｔｙｏｆｃａｐｉｌｌａｒｙｅｌｅｃｔｒｏｐｈｏｒｅｓｉｓ(ＣＥ)ａｎｄｐｅｒｍｉｔｔｅｄｔｈｅｓｅｐａｒａｔｉｏｎａｎｄａｎａｌｙｓｉｓｏｆｎｅｕｔｒａｌｃｏｍｐｏｕｎｄｓ .ＢｕｔｊｕｓｔｌｉｋｅｏｔｈｅｒｍｏｄｅｓｏｆＣＥ ,ＭＥＫＣａｒｅｈａｍｐｅｒｅｄｂｙｔｈｅｌｏｗｃｏｎｃｅｎｔｒａｔｉｏｎｓｅｎｓｉｔｉｖｉｔｙｏｆｔｈｅｕｌｔｒａ …     

Application of Nafion／Cobalt Hexacyanoferrate Chemically Modified Electrodes for the Determination of Electroinactive Cations by Ion Chromatography

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｉｏｎｃｈｒｏｍａｔｏｇｒａｐｈｙ (ＩＣ)ｈａｓｂｅｅｎｒｅｃｏｇｎｉｚｅｄａｓａｕｓｅｆｕｌｍｅｔｈｏｄｆｏｒｔｈｅｓｅｐａｒａｔｉｏｎｏｆｉｎｏｒｇａｎｉｃａｎｉｏｎｓａｎｄｃａｔｉｏｎｓｓｉｎｃｅｉｔｓｉｎｔｒｏｄｕｃｔｉｏｎｂｙＳｍａｌｌｅｔａｌ .ｉｎ 1975 .1ＡｓｉｇｎｉｆｉｃａｎｔｔｒｅｎｄｉｎｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆＩＣｍｅｔｈｏｄｉｓｓｅａｒｃｈｆｏｒｓｅｎｓｉｔｉｖｅａｎｄｕｎｉｖｅｒｓａｌｄｅｔｅｃｔｉｏｎｍｅｔｈｏｄｓ .Ｔｈｅｍａｉｎｄｅｔ…     

Phase equilibria of supercritical CO_2-ethanol-stearic acid ternary system and hydrogen bonding between ethanol and stearic acid

Ｓｕｐｅｒｃｒｉｔｉｃａｌｆｌｕｉｄｓ(ＳＣＦｓ)ｈａｖｅｍａｎｙｆｅａｔｕｒｅｓｓｕｃｈａｓｈｉｇｈｄｉｆｆｕｓｉｖｉｔｙ,ｌｏｗｖｉｓｃｏｓｉｔｙ,ａｎｄｈｉｇｈｃｏｍｐｒｅｓｓｉｂｉｌｉｔｙ.Ｔｈｅｓｅｍａｋｅｔｈｅｍａｔｔｒａｃｔｉｖｅｓｏｌｖｅｎｔｓｆｏｒｍａｎｙｉｎｄｕｓｔｒｉａｌｐｒｏｃｅｓｓｅｓ.Ｓｕｐｅｒｃｒｉｔｉｃａｌ(ＳＣ)ＣＯ2ｉｓｔｈｅｍｏｓｔｐｏｐｕｌａｒａｍｏｎｇｔｈｅｍ,ｂｅｃａｕｓｅｉｔｉｓｎｏｎｔｏｘｉｃ,ｎｏｎｆｌａｍｍａｂｌｅ,ｅａｓｙｔｏｏｂｔａｉｎ,ａｎｄｈａｓａ…     

Study on the Extraction of L-Phenylalanine with Organo-phosphoric Acid in Two and Three-phase System

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｈｅｅｘｔｒａｃｔｉｏｎｏｆａｍｉｎｏａｃｉｄｓｈａｓｒｅｃｅｎｔｌｙａｔｔｒａｃｔｅｄａｇｒｅａｔｄｅａｌｏｆａｔｔｅｎｔｉｏｎ .Ｔｈｅｙｃｏｕｌｄｂｅｅｘｔｒａｃｔｅｄｉｎｔｏｒｅ ｖｅｒｓｅｍｉｃｅｌｌｅｓｏｒｍｉｃｒｏｅｍｕｌｓｉｏｎｓｗｉｔｈａｓｕｒｆａｃｔａｎｔｓｕｃｈａｓＡＯＴ [ｓｏｄｉｕｍｄｉ (2 ｅｔｈｙｌｈｅｘｙｌ)ｓｕｌｆｏｓｕｃｃｉｎａｔｅ].Ｌｅａ ｄｉｄｉｓｅｔａｌ.ｉｎｖｅｓｔｉｇａｔｅｄｔｈｅｐａｒｔｉｔｉｏｎｏｆａｍｉｎｏａｃｉｄｓｂｅ …     

Phase state of iron system colloidal catalyst in butadiene polymerization

ＴｈｅａｃｔｉｖｉｔｙｏｆＦｅ(ｎａｐｈ)2Ａｌ(ｉＢｕ)3ＣＨ2ＣＨＣＨ2Ｃｌｃａｔａｌｙｓｔｉｓｈｉｇｈｉｎｂｕｔａｄｉｅｎｅｐｏｌｙｍｅｒｉｚａｔｉｏｎｗｉｔｈｈｙｄｒｏｇｅｎａｔｅｄｇａｓｏｌｉｎｅａｓｓｏｌｖｅｎｔ[1].Ｔｈｅｋｉｎｅｔｉｃｓｏｆｔｈｅｃａｔａｌｙｓｔｈａｓｂｅｅｎｓｔｕｄｉｅｄａｓａｈｏｍｏｇｅｎｅｏｕｓｃａｔａｌｙｔｉｃｓｙｓｔｅｍ[2].Ｈｏｗｅｖｅｒ,ｔｈｅｐｒｅｐａｒａｔｉｖｅｍｅｔｈｏｄｓｏｆｔｈｅｃａｔａｌｙｓｔｉｎｃｌｕｄｉｎｇｒａｔｉｏａｎｄａｄｄｉｎｇｏｒｄｅｒｏ…     

Lipases-Catalyzed Alcoholysis for the Preparation of Chiral 1- or 2-Hydroxyalkanephosphonates 

Ｃｈｉｒａｌ 1 ｏｒ 2 ｈｙｄｒｏｘｙａｌｋａｎｅｐｈｏｓｐｈｏｎａｔｅｓｓｈｏｗｉｎｔｒｉｇｕ ｉｎｇｐｒｏｐｅｒｔｉｅｓｉｎｂｉｏｌｏｇｙａｎｄｏｒｇａｎｉｃｃｈｅｍｉｓｔｒｙ .1Ｔｈｅｔｒａｄｉ ｔｉｏｎａｌｓｙｎｔｈｅｔｉｃｒｏｕｔｅｌｅａｄｉｎｇｔｏｓｕｃｈｃｏｍｐｏｕｎｄｓｓｏｍｅｔｉｍｅｓｈａｓｄｒａｗｂａｃｋｓｓｕｃｈａｓｈａｒｓｈｒｅａｃｔｉｏｎｃｏｎｄｉｔｉｏｎｓ ,ｅｘｐｅｎｓｉｖｅｒｅａｇｅｎｔｓａｎｄｌｏｗｃｈｅｍｉｃａｌｙｉｅｌｄｓ .2 Ｔｏｅｘｐｌｏｒｅｎｅｗａｎｄｃｏｎｖ…     

Characters of the Plateau of Methanol Increment in Frontal Analysis in Reversed Phase Liquid Chromatography

With insulin methanol-water,and the ion-pairing agent,hydrochloric acid and trifluroacetic acid(TEA),the character of the first plateau(FP)on the elution curve of frontal analysis in reversed phase liquid chromatography(RPLC)was investigated by on-line UV-spectrometry and identified with nuclear magnetic resonance(NMR) spectrometry and mass spectrometry.The profile of the FP is the same as that of a usual elution curve of methanol in frontal analysis(FA).When the insulin concentration was limited to a certain range,the height of the FP was found to be proportional to the insulin concentration in mobile phase and its length companying to shorten,The FP profile on the intersection of two tangents reflects the components of the microstructure in the depth direction of the bonded stationary phase layer and the desorption dynamics of the displaced components.The displaced methanol was quantitatively determined by NMR and on-line UV spectrometries.TFA with high UV absorbance can not be used as an ionpairing agent for the investigation of the FP in RPLC,but if can be used as a good marker to investigate the complicated transfer process of components in the stationary phase in RPLC.A stoichiometric displacement process between solute and solvent was proved to be valid in both usual and FA in RPLC.From the point of view of dynamics of mass transfer, the solutes can only contact to the surface of stationary phase in usual RPLC,while solute can penetrate into it in FA of RPLC.The solvation of insulin in methanol and water solution as an example indicating the usage of the FP in the FA was also investigated in this paper.     

An Integrated Theory of Adsorption and Partition Mechanism and Eash Contribution to Solute Retention in Reversed Phase Liquid Chromatography

With the combination of the the stoichiometric displacement model for retention (SDM-R) in reversed phase liquid chromatography (RPLC) and the stoichiometric displacement model for adsorption (SDM-A) in physical chemistry,the total number of moles of the re-solvated methanol of stationary phase side.nr,and that of solute side in the mobile phase,q,corresponding the one mole of the desorbing solute,were separately determined and referred as the characterization parameters of the contributions of the adsorption mechanism and partition mechanism to the solute retention,respectively.A chromatographic system of insulin,using mobile phase consisting of the pseudo-homologue of alcohols(methanol,ethanol and 2-propanol)-water and trifluoroacetic acid was employed.The maximum number of the methanol layers on the stationary phase surface was found to be 10.6,only 3 of which being valid in usual RPLC,traditionally referred as a volume process in partition mechanism.However,it still follows the SDM-R.Both of q and nr of insulin were found not to be zero,indicating that the retention mechanism of insulin is a mixed mode of partition mechanism and adsorption mechanism.When methanol is used as the organic modifier,the ratio of q/nr was 1.13,indicating the contribution to insulin retention due to partition mechanism being a bit greater than that due to adsorption mechanism.A linear relationship between q,or nr and the carbon number of the pseudo-homologue in the mobile phase was also found.As a methodology for investigating the retention mechanism retention and behavior of biopolymers.a homologue of organic solvents as the organic modifier in mobile phase has also been explored.     

Isomorphous rare‐earth tris[bis(2,6‐diisopropylphenyl) phosphate] complexes and their catalytic properties in 1,3‐diene polymerization and in the inhibited oxidation of polydimethylsiloxane

Crystals of mononuclear tris[bis(2,6‐diisopropylphenyl) phosphato‐κO]pentakis(methanol‐κO)lanthanide methanol monosolvates of lanthanum, [La(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 1 ), cerium, [Ce(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 2 ), and neodymium, [Nd(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 3 ), have been obtained by reactions between LnCl₃(H₂O)_n (n = 6 or 7) and lithium bis(2,6‐diisopropylphenyl) phosphate in a 1:3 molar ratio in methanol media. Compounds ( 1 )–( 3 ) crystallize in the monoclinic P2₁/c space group and have isomorphous crystal structures. All three bis(2,6‐diisopropylphenyl) phosphate ligands display a κO‐monodentate coordination mode. The coordination number of the metal atom is 8. Each [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₃(CH₃OH)₅] molecular unit exhibits four intramolecular O—H…O hydrogen bonds, forming six‐membered rings. The unit forms two intermolecular O—H…O hydrogen bonds with one noncoordinating methanol molecule. All six hydroxy H atoms are involved in hydrogen bonding within the [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₃(CH₃OH)₅]·CH₃OH unit. This, along with the high steric hindrance induced by the three bulky diaryl phosphate ligands, prevents the formation of a hydrogen‐bond network. Complexes ( 1 )–( 3 ) exhibit disorder of two of the isopropyl groups of the phosphate ligands. The cerium compound ( 2 ) demonstrates an essential catalytic inhibition in the thermal decomposition of polydimethylsiloxane in air at 573 K. Catalytic systems based on the neodymium complex tris[bis(2,6‐diisopropylphenyl) phosphato‐κO]neodymium, ( 3′ ), which was obtained as a dry powder of ( 3 ) upon removal of methanol, display a high catalytic activity in isoprene and butadiene polymerization.     

A Direct Evidence of Stoichiometric Displacement between Insulin and Methanol in Reversed Phase Liquid Chromatography

Ｗith four kinds of mobile phases,methanol-water,ethanol-water,2-propanol and acetonitrile-water(all containing 0.1％rifluroacetic acid),the displacement between solute and solvent in RPLC was proved to be universal in frontal analysls(FA).Based on the measured Z value in usual RPLC to be a constant and the quantitative determination of methanol increment in mobile phase in FA,the stoichiometric displacement(SD)between insulin and methanol was directly proved by the experiment.The SD was also proved to occur only on about the one-fourth of the maximum amount of adsorbed methanol in the bonded phase layer(BPL)without any dynamic problem of mass transfer,while in FA,the SD firstly occurs on the surface of the BPL and then gradually sinks into the deeper sites companied with a dynamic problem.Although the displaces soplvent by the same solute is less in the former case,the SD is independent of how deep of the solute enters the BPL.In addition,the adsorbed amount of solute on and adsorbent not only depends on the numbers of the adsorbed layer on the adsorbent surface,but also on the extent of the complete removal of the displace able solvent in the BPL.The pyhsical fundamental of the SD and the methodoloby for investigation were also discussed.     

Cobalt(II), nickel(II) and copper(II) complexes of iso­quinoline‐3‐carbox­ylate

The crystal structures of the title complexes, namely trans‐bis­(iso­quinoline‐3‐carboxyl­ato‐κ²N,O)­bis­(methanol‐κO)cobalt(II), [Co(C₁₀H₆NO₂)₂(CH₃OH)₂], and the corresponding nickel(II) and copper(II) complexes, [Ni(C₁₀H₆NO₂)₂(CH₃OH)₂] and [Cu(C₁₀H₆NO₂)₂(CH₃OH)₂], are isomorphous and contain metal ions at centres of inversion. The three compounds have the same distorted octahedral coordination geometry, and each metal ion is bonded by two quinoline N atoms, two carboxyl­ate O atoms and two methanol O atoms. Two iso­quinoline‐3‐carboxyl­ate ligands lie in trans positions, forming the equatorial plane, and the two methanol ligands occupy the axial positions. The complex mol­ecules are linked together by O—H⋯O hydrogen bonds between the methanol ligands and neighbouring carboxyl­ate groups.     

Theoretical study on the gas‐phase reaction mechanism between rhodium monoxide and methane for methanol production

The gas‐phase reaction mechanism between methane and rhodium monoxide for the formation of methanol, syngas, formaldehyde, water, and methyl radical have been studied in detail on the doublet and quartet state potential energy surfaces at the CCSD(T)/6‐311+G(2d, 2p), SDD//B3LYP/6‐311+G(2d, 2p), SDD level. Over the 300–1100 K temperature range, the branching ratio for the Rh(⁴F) + CH₃OH channel is 97.5–100%, whereas the branching ratio for the D‐CH₂ORh + H₂ channel is 0.0–2.5%, and the branching ratio for the D‐CH₂ORh + H₂ channel is so small to be ruled out. The minimum energy reaction pathway for the main product methanol formation involving two spin inversions prefers to both start and terminate on the ground quartet state, where the ground doublet intermediate CH₃RhOH is energetically preferred, and its formation rate constant over the 300–1100 K temperature range is fitted by k_CH3RhOH = 7.03 × 10⁶ exp(?69.484/RT) dm³ mol^?1 s^?1. On the other hand, the main products shall be Rh + CH₃OH in the reactions of RhO + CH₄, CH₂ORh + H₂, Rh + CO +2H₂, and RhCH₂ + H₂O, whereas the main products shall be CH₂ORh + H₂ in the reaction of Rh + CH₃OH. Meanwhile, the doublet intermediates H₂RhOCH₂ and CH₃RhOH are predicted to be energetically favored in the reactions of Rh + CH₃OH and CH₂ORh + H₂ and in the reaction of RhCH₂ + H₂O, respectively. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010     

trans‐(Methanol)(methyl­di­phenyl­phosphine)­bis­(pentane‐2,4‐dionato)­cobalt(III) hexa­fluoro­phosphate hydrate

The title compound [Co(C₅H₇O₂)₂(C₁₃H₁₃P)(CH₄O)]PF₆·H₂O, (I), which was converted from trans‐[Co(acac)₂(PMePh₂)(H₂O)]PF₆ (acac is pentane‐2,4‐dionato) by recrystallization from aqueous methanol, has been confirmed as have a coordinated methanol ligand. The molecular structure of the complex cation, trans‐[Co(acac)₂(PMePh₂)(MeOH)]⁺, is similar to that of the above aqua complex found in the ClO₄ salt [Kashiwabara et al. (1995). Bull. Chem. Soc. Jpn, 68 , 883–888]. The Co—O bond length for the coordinated methanol is 2.059 (3) Å. There is an intermolecular hydrogen bond between the OH group of the coordinated methanol and one of the O atoms of the acac ligands in an adjacent complex cation [O5?O3′ = 2.914 (4) Å], giving a centrosymmetric dimeric dicationic complex.     

Overloaded elution band profiles of ionizable compounds in reversed‐phase liquid chromatography: Influence of the competition between the neutral and the ionic species

The parameters that affect the shape of the band profiles of acido‐basic compounds under moderately overloaded conditions (sample size less than 500 nmol for a conventional column) in RPLC are discussed. Only analytes that have a single pK_a are considered. In the buffer mobile phase used for their elution, their dissociation may, under certain conditions, cause a significant pH perturbation during the passage of the band. Two consecutive injections (3.3 and 10 μL) of each one of three sample solutions (0.5, 5, and 50 mM) of ten compounds were injected on five C₁₈‐bonded packing materials, including the 5 μm Xterra‐C₁₈ (121 Å), 5 μm Gemini‐C₁₈ (110 Å), 5 μm Luna‐C₁₈(2) (93 Å), 3.5 μm Extend‐C₁₈ (80 Å), and 2.7 μm Halo‐C₁₈ (90 Å). The mobile phase was an aqueous solution of methanol buffered at a constant _W^WpH of 6, with a phosphate buffer. The total concentration of the phosphate groups was constant at 50 mM. The methanol concentration was adjusted to keep all the retention factors between 1 and 10. The compounds injected were phenol, caffeine, 3‐phenyl 1‐propanol, 2‐phenyl butyric acid, amphetamine, aniline, benzylamine, p‐toluidine, procainamidium chloride, and propranololium chloride. Depending on the relative values of the analyte pK_a and the buffer solution pH, these analytes elute as the neutral, the cationic, or the anionic species. The influence of structural parameters such as the charge, the size, and the hydrophobicity of the analytes on the shape of its overloaded band profile is discussed. Simple but general rules predict these shapes. An original adsorption model is proposed that accounts for the unusual peak shapes observed when the analyte is partially dissociated in the buffer solution during its elution.     

Kinetics of OH reactions with N2H4, CH3NHNH2 and (CH3)2NNH2 in the gas phase

The gas phase reaction kinetics of OH with three di‐amine rocket fuels—N₂H₄, CH₃NHNH₂, and (CH₃)₂NNH₂—was studied in a discharge flow tube apparatus and a pulsed photolysis reactor under pseudo‐first‐order conditions in [OH]. Direct laser‐induced fluorescence monitoring of the [OH] temporal profiles in a known excess of the [diamine] yielded the following absolute second‐order OH rate coefficient expressions; k₁ = (2.17 ± 0.39) × 10^?11 e^(160±30)/T, k₂ = (4.59 ± 0.83) × 10^?11 e^(85±35)/T and k₃ = (3.35 ± 0.60) × 10^?11 e^(175±25)/T cm³ molec^?1 s^?1, respectively, for reactions with N₂H₄, CH₃NHNH₂ and (CH₃)₂NNH₂ in the temperature range 232–637 K. All three reactions did not show any discernable pressure dependence on He or N₂ buffer gas pressure of up to 530 torr. The magnitude of the weak temperature and the lack of pressure effects of the OH + N₂H₄ reaction rate coefficient suggest that a simple direct metathesis of H‐atom may not be important compared to addition of the OH to one of the N‐centers of the diamine skeleton, followed by rapid dissociation of the intermediate into products. Our findings on this reaction are qualitatively consistent with a previous ab initio study [ 3 ]. However, in the alkylated diamines, direct H‐abstraction from the methyl moiety cannot be completely ruled out. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 354–362, 2001     

A high‐performance liquid chromatography assay with a triazole‐bonded column for evaluation of d‐amino acid oxidase activity

Elution profiles of kynurenic acid (KYNA) and 7‐chlorokynurenic acid (Cl‐KYNA) were examined by high‐performance liquid chromatography (HPLC) using a triazole‐bonded stationary phase column (Cosmosil® HILIC) under isocratic elution of a mobile phase consisting of CH₃CN–aqueous 10 mm ammonium formate between pH 3.0 and 6.0. The capacity factors of KYNA and Cl‐KYNA varied with both the CH₃CN content and the pH of the mobile phase. The elution order of KYNA and Cl‐KYNA was reversed between the CH₃CN‐ and H₂O‐rich mobile phases, suggesting that hydrophilic interactions and anion‐exchange interactions caused retention of KYNA and Cl‐KYNA in the CH₃CN‐ and H₂O‐rich mobile phases, respectively. The present HPLC method using a triazole‐bonded column and fluorescence detection (excitation 250 nm, emission 398 nm) was applied to monitor in vitro production of KYNA from d ‐kynurenine (d ‐KYN) by d ‐amino acid oxidase (DAO) using Cl‐KYNA as an internal standard. A single KYNA peak was clearly observed after enzymatic reaction of d ‐KYN with DAO. Production of KYNA from d ‐KYN was suppressed by the addition of commercial DAO inhibitors. The present HPLC method can be used to evaluate DAO activity and DAO inhibitory effects in candidate drugs for the treatment of schizophrenia. Copyright © 2015 John Wiley & Sons, Ltd.