Different multidimensional chromatographic approaches applied to the study of wine malolactic fermentation

Different multidimensional chromatographic techniques were used to study wine aroma pattern changes during malolactic fermentation (MLF). Ethyl lactate enantiomeric ratios were determined using on-line multidimensional gas chromatography. The values found agree with a spontaneous MLF. Off-line multidimensional HPLC/GC was used to deconvolute and enrich the sample and ease enantioselective chromatography. Chiral compound enantiomeric ratio changes during MLF were monitored. Evaluation of enantiomeric ratio changes during MLF has never been studied. (R,R), (S,S) and meso-butane-2,3-diol and pentane-2,4-diol (reported in wines for the first time) were submitted to untrained sensory panel tests. All stereoisomers revealed different sensory notes; pentane-2,4-diol showed an aromatic impact.     

Oxidation of butane-1,3-, butane-1,4-, 2-methyl pentane-2,4- and 3-methyl pentane-2,4-diols by cerium(IV) in aqueous acidic medium catalyzed by rhodium(III)

The oxidation kinetics of butane-1,3-diol, butane-1,4-diol, 2-methyl pentane-2,4-diol and 3-methyl pentane-2,4-diol with cerium(IV) catalyzed by rhodium(III) in aqueous sulfuric acid showed a peculiar nature with respect to the variation in oxidant concentration, such that the reaction follows first-order kinetics in [Ce(IV)] at low [Ce(IV)] and then reaches a maximum with increasing [Ce(IV)], beyond which further increase in the oxidant concentration retards the rate. The rate shows direct proportionality with respect to [diol] at low concentrations, becoming independent of [diol] at higher concentrations. The rate is first order in catalyst. Retarding effects are observed when [H⁺] and [Ce(III)] are increased, while [Cl⁻] and hence ionic strength have a positive effect on the rate. Spectroscopic studies confirmed that the primary hydroxyl groups in butane-1,3-diol and butane-1,4-diol resulted in the formation of 3-hydroxy butanal and 4-hydroxy butanal, respectively. In the case of oxidation of the secondary hydroxyl groups in 2-methyl pentane-2,4-diol and 3-methyl pentane-2,4-diol, the products of oxidation were 4-hydroxy-4-methyl pentan-2-one and 4-hydroxy-3-methyl pentan-2-one, respectively.     

Effect of structure on the thermal degradation and flame retardancy of hexolic anhydride based polyesters

Based on the anhydrides like hexolic (5,6,7,8,10,10-hexachloro -3a,4,4a,5,8,8a,9,9a-octahydro-5,8-methanonaphtho-[2,3-c]-furan-1,3-dione), maleic and phthalic and diols like 1,4-butanediol, cis-2-butene-1,4-diol and 2,3-dichloro-2-butene-1,4-diol, a family of polyesters has been synthesized using azeotropic condensation technique. The structural characterizations of the polyesters have been carried out using infra-red, 1^H - and ¹³C- nuclear magnetic resonance spectroscopic methods. The thermal properties of the polyesters have been studied using thermogravimetric technique. The off-line pyrolysis of these materials was done. The qualitative and semi-quantitative analyses of the volatiles as well as the heavy mass fractions of the degradation products were carried out using a gas chromatograph coupled to a mass selective detector (GC-MSD). Thermogravimetric data indicate that the thermal stability and the char residue of the polyester resins decrease in the order 1,4-butanediol based>cis-2-butene-1,4-diol based>2,3-dichloro-2-butene-1,4-diol based polyesters. The GC-MSD data indicate that the amount of flame cooling agents (hexa-, isomeric penta-, tetra- and isomeric tri-chlorocyclopentadienes) produced during the pyrolysis of the polyesters increases in the order 2,3-dichloro-2-butene-1,4-diol based<cis-2-butene-1,4-diol based<1,4-butanediol based polyesters. The trends observed in these two parameters which are contributing factors to the flame retardancy of the polyester materials were suitably explained on the basis of the effect of the structural changes in the diol part of the polyesters on the primary degradation mechanism, the β-chain scission process.     

Brillouin scattering and optical Kerr effect study of dimethacrylates: temperature effects

In this paper we report a temperature study of Brillouin scattering and optical Kerr effect in the ethane-1,2-diol dimethacrylate, pentane-1,5-diol dimethacrylate and hexane-1,6-diol dimethacrylate belonging to the series of dimethacrylate homologues. Using these methods we have studied the temperature behaviour of the hypersonic velocity, adiabatic compressibility and optical Kerr constant in the temperature range from 283 to 323 K.

The obtained results are compared to those obtained earlier from Brillouin scattering and optical Kerr effect experiments for butane-1,4-diol dimethacrylate and 2,2′-thiodiethyl dimethacrylate (a sulfur-containing monomer). The results are also discussed in terms of changes in the intermolecular interactions and arrangement in the liquid compounds under study.     

Synthesis of corn rootworm pheromones from commercial diols

A mixture of stereoisomers of the corn rootworm pheromones was synthesised via the Grignard coupling of protected bromohydrins with alkylcuprate as a key step. The synthesis of 8-methyldec-2-yl propanoate (I), the northern corn rootworm Diabrotica longicornis Say pheromone, was achieved from pentane-1,5-diol in four steps with an overall yield of 35.1 % and 10-methyltridecan-2-one (II), the southern corn rootworm Diabrotica undecimpunctata howardi Barber pheromone, was synthesised from octane-1,8-diol as commercially available starting material in five steps with an overall yield of 28.7 %.     

1,1,4,4-tetranitrobutane-2,3-diol and its derivatives. 2. Chlorination and bromination of 1,1,4,4-tetranitrobutane-2,3-diol. crystal structure of halogen derivatives of 1,1,4,4-tetranitrobutane-2,3-diol

The bromination of 1,1,4,4-tetranitrobutane-2,3-diol in 60% acetic acid gave 1,4-dibromo-1,1,4,4-tetranitrobutane-2,3-diol in satisfactory yield. The chlorination of 1,1,4,4-tetranitrobutane-2,3-diol under analogous conditions gave 1,4-dichloro-1,1,4,4-tetranitrobutane-2,3-diol as a crystal hydrate. Drying of this latter product in vacuum over phosphorus pentoxide gave 1,4-dichloro-1,1, 4,4-tetranitrobutane-2,3-diol in quantitative yield. The structures of these products were determined by x-ray diffraction structural analysis. The crystal chemical analysis and quantum chemical calculations established an increase in secondary oxygen-halogen interactions in the halodinitromethyl fragment with increasing atomic number of the halogen atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2372–2380, October, 1991.     

Stereoselective ring-opening reactions with AcBr and AcCl. A new method for preparation of some haloconduritols

The actions of AcX (X=Br, Cl) on 7-oxa-bicyclo[2.2.1]hept-5-ene-2,3-diol diacetates and a transoid-epoxide prepared from the acetonide of cyclohexa-3,5-diene-cis-1,2-diol were studied. H₂SO₄-catalyzed cleavage of exo-cis-7-oxa-bicyclo[2.2.1]hept-5-ene-2,3-diol diacetate with AcCl gave (1α,2α,3α,6β)-6-chloro-4-cyclohexene-1,2,3-triol triacetate, from which the corresponding chloroconduritol was obtained by trans-esterification (MeOH/HCl). A similar reaction of the exo-diacetate with AcBr in the presence of H₂SO₄ resulted in bromine addition. The formation of bromine from the reaction of AcBr and H₂SO₄ was observed by independent experiments. H₂SO₄-catalyzed reaction of endo-cis-7-oxa-bicyclo[2.2.1]hept-5-ene-2,3-diol diacetate with AcX (X=Br, Cl) gave (1α,2α,3β,6β)-6-halo-4-cyclohexene-1,2,3-triol triacetates. The reaction of the transoid-epoxide with AcX (X=Br, Cl) with no catalyst gave also (1α,2α,3β,6β)-6-halo-4-cyclohexene-1,2,3-triol triacetates.     

Development of new methods for the synthesis of 2,3-bis(nitroxymethyl)-2,3-dinitrobutane-1,4-diol dinitrate and its intermediates

Known methods for the synthesis of 2,3-bis(nitroxymethyl)-2,3-dinitrobutane-1,4-diol dinitrate and its intermediates were investigated. New procedures were developed for the preparation of these compounds. 2,3-Bis(nitroxymethyl)-2,3-dinitrobutane-1,4-diol dinitrate was studied by X-ray diffraction.

     

Electrosynthesis of glutaric acid and regularities of electrocatalytic oxidation of cycloalkanones at a NiOOH anode in aqueous NaOH

Methods of preparation of glutaric acid by oxidation of cyclopentanone or pentane-1,5-diol in an undivided cell at a NiOOH electrode in aqueous alkali are developed. Yields of the products were 51% or 90%, respectively. The mechanism of electrooxidation of cycloalkanones at a NiOOH electrode is discussed on the basis of literature data and the regularities of the oxidative transformations of cyclohexanone investigated earlier and those of cyclopentanone.     

Expanding the medicinal chemistry toolbox: stereospecific generation of methyl group-containing propylene linkers

Use of alkyl substituted propylene linkers as a strategy for fine-tuning the biological activity of medicinal agents requires ready access to these substrates. Herein, a general strategy is described for stereospecifically generating 18 chiral mono- and di-methylpropylene linkers. All twelve vicinal 1,2-propylene targets were generated from methyl-3-hydroxybutanoate and all 1,3-disubstituted targets from pentane-2,4-diol.     

Sample preparation for the chromatographic determination of ecdysteroids using solid-phase extraction methods

The ecdysteroids are hormones widely distributed in insects and crustaceans, where they are involved in the regulation of moulting. Methods of sample preparation based on solid-phase extraction of the ecdysteroids from biological samples for subsequent chromatographic analysis are reviewed. Most methods use an initial partition of the sample (or extract) between water or aqueous methanol with a non-polar solvent to remove lipids. The aqueous portion is applied to a cartridge containing C₁₈-bonded silica gel. Removal of polar impurities is then effected, followed by recovery of the ecdysteroids from the cartridge and chromatographic analysis. Results are given for the use of phenylboronic acid (PBA) bonded to silica gel as a means of obtaining a much more specific method of extraction. The PBA phase was shown to have a high affinity for ecdysteroids containing a 20,22-cis-diol but not for compounds possessing only a 2,3-cis-diol.     

From Cycloolefins to Linear C2-Symmetrical 1,4-Diamino-2,3-diol Building Blocks—Peptide Mimetics,Biocatalysis, and Pinacol Coupling of α-Amino Aldehydes

Technical olefins and azodicarbonic ester are the starting materials for C₂-symmetrical C₁₆ and C₁₂ 1,4-diamino-2,3-diol building blocks (see structure), which are of interest for a variable access to potentially bioactive compounds (peptide mimetics, enzyme inhibitors). MOM = methoxymethyl.     

Catalytic synthesis of dihydrofurans (review)

Various methods for the preparation of 2,3-dihydrofuran, 2,5-dihydrofuran, 2-methylenetetrahydrofuran, and their alkyl and aryl derivatives are examined. The most promising method for the preparation of 2,3-dihydrofuran is the conversion of 1,4-butanediol on cobalt catalysts. 2,5-Dihydrofuran is obtained by dehydration of 2-butene-1,4-diol on Al₂O₃, cobalt-containing and other catalysts, while 2-methylenetetrahydrofuran is obtained by dehydrohalogenation of tetrahydrofurfuryl halides. The various methods for the isomerization of 2,5-dihydrofuran to 2,3-dihydrofuran are discussed. Examples of the application of dihydrofurans in organic synthesis are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1311, October, 1982.     

Coordination compounds of copper(II) with substituted 3-{[(2-hydroxyphenyl)methylidene]amino}propane-1,2-diols

3-{[(2-Hydroxyphenyl)methylidene]amino}propane-1,2-diol, its 5-chloro-,5-bromo-, 5-nitro-, 3-methoxy derivatives, and 3-{[(2-hydroxynaphthyl-1)methylidene]amino}propane-1,2-diol react with hydrates of copper(II) chloride, bromide and nitrate in ethanol to form coordination compounds Cu(L)X·nH₂O. Template condensation reaction between 3-aminopropane-1,2-diol and 2,3-, 2,4- or 2,5-dihydroxybenzaldehyde in the presence of copper(II) nitrate trihydrate results in similar compounds Cu(L)NO₃·nH₂O. Structure of some of the condensation products was identified by X-ray analysis. Thermolysis of the substances obtained occurs through the dehydration step (70–90°C) and complete thermal decomposition (290–560°C).     

Aza-Baylis-Hillman reactions of N-tosylated aldimines with activated allenes and alkynes in the presence of various Lewis base promoters

[reaction: see text] The attempted aza-Baylis-Hillman reactions of N-tosylated aldimines with ethyl 2,3-butadienoate, ethyl penta-2,3-dienoate, penta-3,4-dien-2-one, methyl propiolate, and but-3-yn-2-one have been systematically investigated in the presence of various nitrogen or phosphine Lewis base promoters. We found that a series of nitrogen-containing heterocyclic compounds, as "abnormal" aza-Baylis-Hillman reaction products, can be formed in the presence of an appropriate Lewis base promoter. The Lewis base and solvent effects in these reactions have been discussed along with the corresponding plausible mechanism.     

Key influence of the nature of the substituent in the propynal molecule on the outcome of its reaction with vicinal di(<Emphasis Type="Italic">N</Emphasis>-hydroxyamine)

The reaction of propynals X-C≡C-CHO, where X = Alk or Ar, with 2,3-di(N-hydroxyamino)-2,3-dimethylbutane gives exclusively 1-X-2-(1-hydroxy-4,4,5,5-tetramethylimidazolidin-2-ylidene)ethanones. In the case of X = Me₃Si, the reaction affords 2-(2-trimethylsilylethynyl)-4,4,5,5-tetramethylimidazolidine-1,3-diol. The reaction of propynal containing X = Et₃Ge yields both types of the products. The resulting imidazolidine-1,3-diol can be quantitatively isomerized to imidazolidin-2-ylideneethanone, oxidized to 2-[2-(triethylgermyl)ethynyl]-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, or transformed into ethynyl-substituted nitronyl nitroxide. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 588–594, March, 2008.     

Ab initio conformational studies on diols and binary diol-water systems using DFT methods. Intramolecular hydrogen bonding and 1:1 complex formation with water

Studies on the conformational equilibrium for the following diols, ethane-1,2-diol (12EG, CAS 107-21-1), 2R-D-(-)-propane-1,2-diol (12PG, CAS 4254-14-2), (2S,3S)-L-(+)-butane-2,3-diol (L23BD, CAS 19132-06-0), and (2S,3R)-meso-butane-2,3-diol (m23BD, CAS 5341-95-7), are described using Gaussian ab initio calculations involving density functional theory (DFT) methods. We also report in this article results on the stability and conformation for the 1:1 water-diol complex formed by ethane-1,2-diol, propane-1,2-diol, and L- and meso-butane-2,3-diol. The relative stability of the intramolecular (internal) hydrogen bond in a range of diols (n = 2 to 6), based on ab initio geometry optimization and determination of the -O...H- distance, dOH, and -O-H...O- angle, theta, increases through the sequence 1,2 approximately equals 2,3 < 1,3 < 1,4 approximately equals 1,5 approximately equals 1,6, as judged from the bond linearity and -O...H- separation. Quantum mechanical and topological analysis of possible intramolecular hydrogen bonding in this complete series of diols provides convincing evidence for this in diols in which the hydroxyl groups are separated by three or more carbon atoms, that is, in (n, n+m) diols for m > or = 2, but not for ethane-1,2-diol or other vicinal diols, which do not satisfy Popelier's topological and electron density criteria based on the AIM theory of Bader. Based on these criteria it is unlikely that vicinal diols are in fact capable of forming an intramolecular hydrogen bond, in spite of geometric and spectroscopic data in the literature suggesting otherwise.     

Cleavage of the carbon-carbon bond in α-glycols under the action of bismuth(v) derivatives

Di(tert-butylperoxy)triphenylbismuth and the triphenylbismuth-tert-butyl hydroperoxide system react with 2,3-dimethylbutane-2,3-diol, benzopinacol, butane-2,3-diol, and ethane-1,2-diol with the cleavage of the C−C bond of α-glycol to form carbonyl compounds. Both heterolytic (through formation of cyclic triphenylbismuth glycolate) and homolytic cleavage occur. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1212–1214, June, 1997.     

1,1,2,2-tetraaminoethane derivatives: III. Condensation of 2-(Dinitromethylene)imidazolidine-4,5-diol with nitrogen-containing nucleophiles

Condensation of 1,1-diamino-2,2-dinitroethylene with glyoxal and formaldehyde in water solutions at pH 7–8 gave rise to 2-(dinitromethylene)imidazolidine-4,5-diol and 1,1-diamino-N,N′-bis(hydroxymethyl)-2,2-dinitroethylene respectively. Condensation products of 2-(dinitromethylene)imidazolidine-4,5-diol with acetonitrile, benzonitrile, urethane, 3,4-diaminofurazan were isolated. The reaction of 4,5-diacetamido-2-(dinitromethylene) imidazolidine sulfate with water in acetonitrile led to the formation of 2-(dinitromethylene)-5-methyl-1,2,3,3a,4,6a-hexahydroimidazo[4,5-d]imidazole. The dehydration of 2-(dinitromethylene)imidazolidine-4,5-diol in a system H₂SO₄-AcOH provided 2-(dinitromethylene)-2,3-dihydro-1H-imidazol-4-ol. 1,1-Diamino-N,N′-bis(hydroxymethyl)-2,2-dinitroethylene in sulfuric acid was converted into 4-(dinitromethylene)-1,3,5-oxadiazinane.     

Solvation of small hydrophobic molecules in formamide: A calorimetric study

The solubility and enthalpy of solution of benzene, cyclohexane, hexane, and heptane in formanide have been determined from titration microcalorimetric experiments at 25°C. The solution enthalpies are significantly more endothermic than in water but still the solubility is much higher. The entropy changes in formamide are small and positive and do not vary significantly with size. The enthalpies of solution of some 1-alkanols, 1-chloro- and 1,5-dichloropentane and pentane-1,5-diol were measured as functions of concentration. The solution enthalpies for 1-alkanols from methanol to decanol increase linearly with chain length. The enthalpic interaction coefficients h_xx are small and negative in formamide while they are large and positive in water. The partial molar heat capacities C _p,2 ^o for 1-propanol, 1-pentanol, benzene and cyclohexane in formamide were determined at 25°C from drop heat capacity measurements. Values of C _p,2 ^o are only slightly larger than the molar heat capacities of the liquid solutes.