Analytical aspects of cyanobacterial volatile organic compounds for investigation of their production behavior

In order to fully understand the role of volatile organic compounds (VOCs) under natural conditions, an adaptable analytical method was developed as the first step. β-Ionone, β-cyclocitral, 2-methyl-1-butanol and 3-methyl-1-butanol were simultaneously analyzed in addition to geosmin and 2-MIB using GC/MS with SPME. The slight modification of a known method allowed the simultaneous detection and quantification of these VOCs. The SIM of the 3-methyl-1-butanol was always accompanied by a shoulder peak, suggesting the presence of two compounds. In order to separate both compounds, the GC/MS conditions were optimized, and the additional peak was identified as 2-methyl-1-butanol by direct comparison of the authentic compound, indicating that the Microcystis strain always produces a mixture of 2-methyl-1-butanol and 3-methyl-1-butanol. Furthermore, it was found that 2-methyl-1-butanol and 3-methyl-1-butanol were predominant in the dissolved fractions. β-Cyclocitral was easily oxidized to provide the oxidation product, 2,6,6-trimethylcyclohexene-1-carboxylic acid, which causes the blue color formation of cyanobacteria as a consequence of acid stress. The intact acid could be satisfactorily analyzed using the usual GC/MS without derivatization.     

Reactions of 1,3,2-dioxaphospholane derivatives with thiocyanatoalcohols

The reactions of 2-dimethylamino-, 2-methoxy-, 2-chloro-4,5-dimethyl-1,3,2-dioxaphos-pholanes with 4-thiocyanato-2-butanol in all cases yield 2-(1-methyl-3-thiocyanatopropoxy)-4,5-dimethyl-1,3,2-dioxaphospholane. The latter reacts with elemental sulfur to form the corresponding thiophosphate.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2130–2131, December, 1993.     

Thermodynamic Study of Cadmium Chloride in Aqueous Mixtures of 2-Butanol from Potential Difference Measurements

The standard molal potential differences (E_m∘) have been determined for the cell: CdHg_x(two phase) | CdCl₂(m), H₂O(1 − w), 2-butanol (w) | AgCl(s) | Ag(s) in aqueous mixtures of low mass fraction of 2-butanol (w_2-butanol = 0.05, 0.10, and 0.15) by using the literature data for the stability constants of the chlorocadmium complexes and the present potentiometric data for this cell at five temperatures from (293.15 to 313.15) K and at 10 molalities of CdCl₂ from (0.002 to 0.02) mol-kg⁻¹. The resulting values of E∘_m have been used to calculate the standard thermodynamic quantities (Δ_rG^∘, Δ_rH^∘, and Δ_rS^∘) for the cell reaction, the stoichiometric mean molal activity coefficients (γ_±) of CdCl₂, and the standard thermodynamic functions for CdCl₂ transfer (Δ_t G∘, Δ_t H∘, and Δ_t S∘) from water to the examined aqueous mixtures of 2-butanol. The values obtained have been compared with the analogous literature data for aqueous mixtures of 2-butanone; standard thermodynamic quantities for transfer of CdCl₂ and HBr from water to mixtures containing the same mass fraction of 2-butanol have also been compared. For both electrolytes, these quantities show analogous trends with the alcohol content. This transfer process is nonspontaneous and endothermic. Enthalpy and entropy are evidently influenced by structural changes.     

Characterization and catalytic behavior of silica-supported copper catalysts prepared by impregnation and ion-exchange methods

Two kinds of Cu/SiO₂ catalysts were prepared by impregnation (IM) and ion-exchange (IE) methods, and tested in dehydrogenation of 2-butanol to methyl-ethyl-ketone. Some kinds of Cu²⁺ on the IE catalyst could not be reduced during the reaction, and it produced the butene. The copper oxide over the IM catalyst could be reduced during the reaction, and showed stable dehydrogenation activity for 2-butanol.     

Characterization of Cu-ZnO-Cr2O3/SiO2 catalysts and application to dehydrogenation of 2-butanol to 2-butanone

The Cu-ZnO-Cr₂O₃/SiO₂ catalysts were prepared by impregnation method, which exhibited high activity for the dehydrogenation of 2-butanol to 2-butanone. These catalysts were characterized by means of XRD, EPR and BET. The experimental results indicated that (i) the valence states of copper play a key role, (ii) groups of copper atoms were the main active sites in this reaction, and (iii) copper oxide would lead to the condensation product of 5-methyl-3-heptanone.     

2-Alkyl-3-chloro(bromo)tetrahydrofurans

The reaction ofRS(SR)-2,3-dibromo- and 2,3-dichlorotetrahydrofurans with ethylmagnesium bromide in ether was investigated. It was shown that the main reaction products are 2-ethyl-3-bromotetrahydrofuran (27%) and 3-bromo-2-(2-ethyl-3-tetrahydrofuryl)tetrahydrofuran (65%) in the first case and 2-ethyl-3-chlorotetrahydrofuran (33%) and 3-chloro-2-(3-chloro-2-tetrahydrofuryl)tetrahydrofuran (65%) in the second.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. I. M. Gubkin Moscow Institute of Petroleum and Gas, 111917 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1430–1434, June, 1992.     

Chiral Recognition of Propranolol with <Emphasis Type="Bold">β</Emphasis>-Cyclodextrin in the Presence of 1- and 2-Butanol

The purpose of this work is to investigate the chiral recognition characteristics of β-cyclodextrin with two propranolol enantiomers in the presence of organic additives. Steady-state fluorescence measurements of propranolol β-cyclodextrin (β-CD) complexes were performed for solutions containing either 1- or 2-butanol. For each 2-butanol isomer solution, the interactions were assessed by comparing the changes in the fluorescence of (R)-(+)- propranolol versus (S)-(-)-propranolol as a function of CD concentration. A similar comparison study was done for the propranolol enantiomers in the presence of 1-butanol. The intensity changes for propranolol are relatively small upon addition of β-CD in the presence of the butanol alcohol. However, the present work shows that the interaction of (R)-(+)-propranolol with β-CD is influenced by the chirality of 2-butanol in contrast to (S)-(-)-propranolol.This revised version was published online in July 2005 with a corrected issue number.     

Unusual thermal isomerization of 3-bromo-2-ethyltetrahydropyran

3-Bromo-2-ethyltetrahydropyran undergoes isomerization at 230 °C into a 6411 mixture of 7-bromo-4-heptanone and 7-bromo-3-heptanone.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1147–1149, June, 1993.     

以三乙酸甘油酯为底物制备光学活性戊醇的探索

1前言(S)-2-甲基-1-丁醇在手性精细化学品及药物合成中有重要的作用[1]。从20世纪90年代起,国外的(R,S)-2-甲基-1-丁醇拆分方面做了一些有益的尝试。Ayter Sagiroglu等人利用固定化脂肪酶催化三丁酸甘油酯与(R,S)-2-甲基-1-丁醇发生不对称酯交换反应,可制备e.e.为98%的(S)-2-甲基-1-丁醇[2]。同时我们的研究表明,无溶剂体系中,以猪胰脂肪酶或酵母脂肪酶为催化剂,三丁酸甘油酯为底物,拆分(R,S)-2-甲基-1-丁醇,可制备e.e.值大于90%的(S)-2-甲基-1-丁醇[3]。采用三丁酸甘油酯,虽然所得产品e.e.较高,但其价格昂贵(1000元/kg)、反应周期较长…     

Formation of 4-N-Arylamino-1-butanol Derivatives from Aromatic Nitro Compounds via a Novel Palladium-Catalyzed Tetrahydrofuran Ring-Opening Reaction

Abstract

4-N-Arylamino-1-butanol derivatives are produced via a palladium-catalyzed tetrahydrofuran ring-opening reaction. This reaction occurs during the reduction of aromatic nitro groups with polymethylhydrosiloxane (PMHS) and potassium fluoride in the presence of hydrogen peroxide. This represents a novel route for the synthesis of 4-N-arylamino-1-butanols.     

Racemization of chiral amino alcohols III: Effect of Mg or Ca addition on the activity and stability of the Co/γ-Al2O3 catalyst

The racemization of R-(-)-2-amino-1-butanol in a reaction using Co/γ-Al₂O₃ catalysts and catalysts modified by Mg or Ca was investigated in this paper. Complete racemization was achieved with a yield of over 83% at using the Mg modified Co/γ-Al₂O₃ catalyst under optimized reaction conditions of 170°C and 2.5 MPa of H₂. The catalysts were thoroughly characterized by XRD, XPS, TPR, SEM and TEM. The addition of Mg and Ca may be advantageous for dispersing and stabilizing the active species of the Co/γ-Al₂O₃ catalyst, protecting from sintering, significantly improving its catalytic activity and stability.     

Synthesis and applications of mesoporous Cu-Zn-Al2O3 catalyst for dehydrogenation of 2-butanol

A series of mesoporous Cu-Zn-Al₂O₃ materials have been synthesized at ambient temperature and their structure was characterized by XRD, N₂ physical adsorption and TPR techniques. Their catalytic applications for the dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were evaluated in a fixed-bed flow reactor at atmospheric pressure. It is demonstrated from the XRD patterns that both the as-synthesized samples and calcined samples have the typical XRD patterns of meso-structured materials and the results of N₂O chemical adsorption showed that Cu was embedded in the framework of the mesoporous materials and homogeneously dispersed in the mesoporous Cu-Zn-Al₂O₃ materials. The catalytic activity of 2-butanol dehydrogenation was varied in the order of CZA(10)<CZA(CP)<CZA(20)<CZA(30); while the selectivity of MEK was increased in the order of CZA(CP)<CZA(10)<CZA(20)<CZA(30).     

Enthalpies of solution of Nal in aqueous isobutanol,sec-butanol,andtert-butanol mixtures

Enthalpies of solution of Nal in aqueous isobutanol,sec-butanol, andtert-butanol mixtures in the complete miscibility range of the alcohols have been measured. The standard enthalpy of solution vs. composition curves exhibit maximum in the water-rich region and a minimum in the non-aqueous region.     

Electrochemical Reduction of Carbon Dioxide to 1-Butanol on Oxide-Derived Copper

The electroreduction of carbon dioxide using renewable electricity is an appealing strategy for the sustainable synthesis of chemicals and fuels. Extensive research has focused on the production of ethylene, ethanol and n-propanol, but more complex C₄ molecules have been scarcely reported. Herein, we report the first direct electroreduction of CO₂ to 1-butanol in alkaline electrolyte on Cu gas diffusion electrodes (Faradaic efficiency=0.056 %, j_1-Butanol=−0.080 mA cm⁻² at −0.48 V vs. RHE) and elucidate its formation mechanism. Electrolysis of possible molecular intermediates, coupled with density functional theory, led us to propose that CO₂ first electroreduces to acetaldehyde-a key C₂ intermediate to 1-butanol. Acetaldehyde then undergoes a base-catalyzed aldol condensation to give crotonaldehyde via electrochemical promotion by the catalyst surface. Crotonaldehyde is subsequently electroreduced to butanal, and then to 1-butanol. In a broad context, our results point to the relevance of coupling chemical and electrochemical processes for the synthesis of higher molecular weight products from CO₂.     

Adsorption of n-Butanol on Pb–Ga in Aqueous Solutions: Effect of Metal on the Adsorption of Organic Compounds in the Absence of Metal–Water Chemisorption Interaction

The potential dependence of the differential capacitance is measured by an ac bridge at 420 Hz and 32°C at Pb–Ga/H₂O interface in 0.05 M Na₂SO₄ solutions containing n-butanol in different concentrations. Adsorption parameters for n-butanol are determined using a regression analysis and compared with those for Hg, Tl–Ga, and Bi–Ga. As follows from this comparison, though there is no chemisorption interaction between these metals and water, the energy of n-butanol adsorption at these metals depends on the metal nature. The Pb–Ga data fit a common correlation dependence of the electronic capacitance of different electrodes (C _m ^–1)_phys on the energy of the n-butanol molecules adsorption thereon in the absence of a metal–water chemisorption interaction. This finding evidences that the dependence of the energy parameters for the adsorption of organic compounds on the metals' electronic properties, when characterized by (C _m ^–1)_phys, is of general nature.     

PMo or PW heteropoly acids supported on MCM-41 silica nanoparticles: Characterisation and FT-IR study of the adsorption of 2-butanol

Mesoporous silica, prepared in basic conditions, has been loaded (20% weight) with 12-molybdophosphoric (PMo) or 12-tungstophosphoric (PW) acid and calcined at different temperatures ranging between 250 and 550 °C. The samples have been characterised by N₂ adsorption-desorption at −196 °C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), UV-visible diffuse reflectance, Raman spectroscopy and temperature programmed reduction (TPR). The acidity and catalytic activity have been, respectively, examined by monitoring the adsorption of pyridine and 2-butanol by FT-IR spectroscopy. The results indicate that PW and PMo acids are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles. While PMo retains its Keggin structure up to 550 °C, PW decomposes at this temperature into crystalline WO₃ and phosphorous oxides. In both cases, the morphology, hexagonal symmetry and long-range order observed for the support are preserved with calcination up to 450 °C. The Brönsted-type acid sites found in all samples, whose surface concentration decreases as the calcination temperature increases, are responsible for the selective formation of cis-butene detected upon adsorption of 2-butanol. The sample containing PW calcined at 450 °C also shows selectivity to methyl ethyl ketone.     

Racemization of chiral amino alcohols: Catalyst selection and characterization

Summary The transformation of R-(-)-2-amino-1-butanol to the racemic mixtures was selected as a model for the racemization of chiral amino alcohols. A 40% Co/γ-Al2O3 catalyst was found to be active enough for the complete racemization in over 80% yield and characterized by XRD, XPS, TPR and BET, etc.     

Limiting Partial Molar Volumes of Electrolytes in 2-Methyl-2-Butanol <Emphasis Type="Bold">+</Emphasis> Water Mixtures at 298.15 K

Partial molar volumes at infinite dilution, V⁰₂, of alkali–metal halides (LiCl, NaCl KCl RbCl CsCl, NaBr, KBr, KI), tetra-n-alkylammonium bromides, R₄NBr (R=Me, Et, n-Pr, n-Bu, n-Pen), NaBPh₄, and Ph₄PCl have been determined in binary solvent mixtures of water with 2-methyl-2-butanol covering the water-rich region and the alcohol-rich region at 298.15 K. V⁰₂ for alkali–metal halides show relatively little dependence on the solvent composition. However, in the case of hydrophobic electrolytes the observed effects are more pronounced. A good linear dependence between V⁰₂(R₄NBr) and the molecular weight of the tetra-n-alkylammonium cation is found. Limiting single-ion volumes have been obtained using the assumption that V⁰(Ph₄P⁺)–V⁰(BPh^–₄)=2.0 cm³-mol^–1. The trends in the single-ion volumes are discussed in both solvent regions.     

1,3-Diphenylpropane-1,3-diamines,VIII. Reactions of lithiated oximes and oxime ethers with C=N-electrophiles

Summary The reaction of lithiated acetophenone oximes and their O-methyl ethers with benzylideneamines affords (1,3-diphenyl-3-hydroxyimino-1-propyl)-amines or their O-methyl derivatives, respectively, which are precursors of 1,3-diphenylpropane-1,3-diamines.Dedicated with warm regards to Prof. Dr. Dr. h.c. mult.H. Oelschläger, Jena (Germany) on the occasion of his 75^th birthday