Esterification of borate with NAD+ and NADH as studied by electrospray ionization mass spectrometry and 11B NMR spectroscopy

This paper describes for the first time the direct measurement of boric acid (B(OH)(3)) and borate (B(OH)(4) (-)) adduction to NAD(+) and NADH by electrospray ionization mass spectrometry (ESI-MS) and (11)B NMR spectroscopy. The analysis demonstrates that borate binds to both cis-2,3-ribose diols on NAD(+) forming borate monoesters (1 : 1 addition), borate diesters (1 : 2 addition) and diborate esters (2 : 1 addition), whereas, only borate monoesters were formed with NADH. MS in the negative ion mode showed borate was bound to a cis-2,3-ribose diol and not to the hydroxyl groups on the phosphate backbone of NAD(+), and MS/MS showed that the 1 : 1 addition monoester contained borate bound to the adenosine ribose. Boron shifts of borate monoesters and diesters with NAD(+) were observed at 7.80 and 12.56 ppm at pH 7.0 to 9.0. The esterifications of borate with NAD(+) and NADH were pH dependent with maximum formation occurring under alkaline conditions with significant formation occurring at pH 7.0. Using ESI-MS, the limit of detection was 50 micro M for NAD(+) and boric acid (1 : 1) to detect NAD(+)-borate monoester at pH 7.0. These results suggest esterification of borate with nicotinamide nucleotides could be of biological significance.     

Kinetics and mechanism of the oxidation of ethylene glycol, 2,3-butanediol and pinacol by hexachloroiridate(IV)

Summary The kinetics of oxidation of ethylene glycol, 2,3-butanediol and pinacol have been studied spectrophotometrically under different experimental conditions. The reactions seem to occur through the formation of an intermediate complex between each diol and iridium(IV). The complexes decompose through intermediate free radicals to form formaldehyde, acetaldehyde and acetone, respectively. Thermodynamic parameters have been calculated.     

Ruthenium complex catalyzed n-heterocyclization. Indoles from aminoarenes and glycols.

N-Methylaniline reacted with ethylene glycol in the presence of a homogeneous ruthenium catalyst (1 mol % based on ethylene glycol) to give 1-Methylindole in 51% yield. Similarly, aniline reacted with 2,3-butanediol affording 2,3-dimethylindole in 58% yield. The yields of indoles were affected by the molar ratio of aminoarene to glycol.     

Some aspects of tailoring flame retardancy in HET-acid-based flame retardants

HET acid was condensed with either ethylene glycol or 1,4-butanediol to yield the respective oligoesters. These oligoesters were characterized by molecular weight, measured by vapor-pressure osmometry. The degradation mechanism of oligoesters of HET acid with either ethylene glycol or 1,4-butanediol was elucidated. The thermal properties of these polyesters were studied using differential thermal analysis and thermal volatilization analysis. The mechanism of degradation was proposed on the basis of pyrolysis–gas chromatography studies, the degradation products being subsequently identified by mass spectrometry. It turned out that in the course of decomposition, hexachlorocyclopentadiene was formed, which is believed to be the active substance for flame retardance in these systems. The aspect of tailoring flame retardancy by changing the chemical environment, i.e., by using different diols, is discussed.     

Effect of Solvent Diols and Ligands on the Properties of Sol-Gel Alumina-Silicas

Amorphous alumina-silicas were prepared from a tetra-alkoxysilane and anhydrous aluminum trichloride or an aluminum alkoxide by a sol-gel process using 2-methyl-2,4-pentanediol, pinacol, 1,2-propanediol, 2,3-butanediol or ethylene glycol as the solvent or complexing agent, and the effect of diols and alkoxy groups on the physical and chemical properties of the alumina-silicas was examined. When the diol or the alkoxy group was bulky, the alumina-silicas had relatively larger micropores, a larger pore volume and higher surface areas. In the conversion of methanol catalyzed by the alumina-silicas, the bulkier diols and alkoxides gave catalysts that produced dimethyl ether in higher yield and hydrocarbons in lower yield. Thus, when ethylene glycol was used as the diol, the best catalyst for the production of hydrocarbons, especially the production of olefins such as ethylene, propylene and butene, was obtained. Furthermore, in comparison with alumina-silica prepared by a traditional kneading process, it was found that the sol-gel alumina-silica could efficiently convert methanol to dimethyl ether and hydrocarbons, but the material prepared by kneading had a very low conversion of methanol to other compounds.     

Synthesis and Characterization of Polyurethanes Based on Oligo(ϵ-caprolactone) Prepared by Free-Metal Method

The oligoester diols were synthesized via ring-opening polymerization of ?-caprolactone in the presence of creatinine and diethylene glycol or 1,4-butanediol as initiator systems. Thus, obtained oligomers were successfully used in the synthesis of segmented polyurethanes. The oligoester diols (poly(?-caprolactone) and dihydroxy(polyethylene adipate)) were reacted with 4,4′-methylenebis(phenyl isocyanate) in the presence of 1,4-butanediol as the chain extender to obtain polyurethanes. The physical and mechanical properties of polyurethanes were determined. The structures of the oligoesters and polyurethanes were elucidated by means of NMR, IR and MALDI-TOF MS studies.     

Mobility of molecules of liquid diols in the temperature range of 303–318 K

The self-diffusion coefficients of diols (ethylene glycol (EG), 1,2- and 1,3-propanediols (PD), and 1,4-butanediol (BD)) are measured using the spin echo approach on protons in the temperature range of 303–318 K. The activation energies of self-diffusion are calculated and compared to the activation energies for viscous flow and dipole relaxation in these systems. A conclusion is reached as to the correlation of rotational and translational movements in liquid diols, due to the presence of a spatial network of hydrogen bonds in these solvents.     

Synthesis and Crystal Structure of 2,3-Bis(dinitrofluoromethyl)-1,4-dioxane

For the first time the dinitromethyl group was modified to dinitrofluoromethyl group in the series of aliphatic polynitro compounds in the case of the reaction of 1,1,4,4-tetranitro-2,3-butanediol diacetate with ammonium fluoroxysulfate in the presence of sodium bicarbonate and ethylene glycol. Previously unknown 2,3-bis(dinitrofluoromethyl)-1,4-dioxane was synthesized. Its structure was determined by X-ray diffraction analysis.     

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.     

Negative ions of ethylene sulfite

The formation of negative ions in molecular beams of ethylene sulfite (ES, alternately called glycol sulfite or ethylene glycol, C(2)H(4)SO(3)) molecules has been studied using both Rydberg electron transfer (RET) and free electron attachment methods. RET experiments with jet-cooled ES show an unexpected broad profile of anion formation as a function of the effective quantum number (n(*)) of the excited rubidium atoms, with peaks at n(max)(*) approximately 13.5 and 16.8. The peak at n(max)(*) approximately 16.8 corresponds to an expected dipole-bound anion with an electron binding energy of 8.5 meV. It is speculated that the peak at n(max)(*) approximately 13.5 derives from the formation of a distorted C(2)H(4)SO(3)(-) ion. We suggest that quasifree electron attachment promotes the breaking of one ring bond giving a long-lived acyclic anion and term this process incomplete dissociative electron attachment. Theoretical calculations of plausible ionic structures are presented and discussed. Electron beam studies of ES reveal the presence of multiple dissociative attachment channels, with the dominant fragment, SO(2)(-), peaking at 1.3 eV and much weaker signals due to SO(3)(-), SO(-), and (ES-H)(-) peaking at 1.5, 1.7, and 0.9 eV, respectively. All of these products appear to originate from a broad temporary negative ion resonance centered at approximately 1.4 eV.     

Chiral direction and interconnection of helical three-connected networks in metal-organic frameworks

The control of the interpenetration and chirality of a family of metal-organic frameworks is discussed. These systems contain two- (A) and four-fold (B) interpenetration of helical three-connected networks generated by binding the 1,3,5-benzenetricarboxylate (btc) ligand to a metal center. These frameworks have the general formula Ni(3)(btc)(2)X(m)Y(n).solvent (where X = pyridine or 4-picoline, Y = ethylene glycol, 1,2-propanediol, 1,4-butanediol, meso-2,3-butanediol, 1,2,6-hexanetriol, glycerol). The structural and chemical effects of modifying the alcohol and aromatic amine ligands bound to the metal center include controlling the thermal stability and the degree of interpenetration. Covalent linking of the four interpenetrating networks in the A family and the switching of diol binding from mono- to bidentate are demonstrated. Recognition of chiral diols by the hand of the network helices is investigated by binding an alcohol ligand with two chiral centers of opposite sense to the same helix. This reveals the subtle nature of the helix-ligand interaction.     

On the perturbation of the intramolecular H-bond in diols by supercritical CO2: a theoretical and spectroscopic study

The role played by supercritical carbon dioxide used as a dispersant medium in the synthesis of polyurethane particles has been investigated. High-temperature-high-pressure in situ infrared spectroscopic measurements combined with ab initio calculations were performed to investigate the hydroxyl stretching vibrations of ethylene glycol (EG) and 1,4-butanediol (BD), two monomers commonly used in the field of step growth polymerization. Specific interactions between the diols and CO2 have been put in evidence. While the structural characteristics of EG and BD are very similar--both diols have a gauche conformation due to an internal H-bond between the two hydroxyl functions--they behave differently in the presence of dense CO2. In the case of EG, this internal H-bond is broken, allowing the diol and CO2 to form a complex through the conjunction of a Lewis acid-Lewis base (LA-LB) interaction and a new H-bond. When BD complexes to CO2, this internal H-bond remains and is even reinforced indirectly by the LA-LB interaction occurring between the two moieties. In both cases, such a complex formation induces a polarization of the hydroxyl groups and consequently an increase of their nucleophilicity.     

Synthesis,characterization, and thermal properties of new flavor compounds

Synthesis, characterization, and thermal properties of new, flavor, long chain esters were presented. The new compounds were obtained in the catalytic esterification process of a stoichiometric ratio of trans-3,7-dimethyl-2,6-octadien-1-ol, succinic anhydride, and aliphatic chain diol. As diols ethylene glycol, 1,4-buthylene glycol, 1,5-pentylene glycol, and 1,6-hexylene glycol were applied. The spectroscopic analyses completely confirmed that the applied synthesis conditions allowed obtaining the new compounds with high yield and purity. Their thermal properties were studied in inert and oxidative atmospheres. The esters were less thermally stable in inert (IDT 186–195 °C) than in oxidative (IDT 210–228 °C) atmosphere. Two, non-completely divided decomposition steps were visible during their pyrolysis. In contrast, the new, long chain compounds decompose in three major steps in air. The analyses of the volatile products emitted during their pyrolysis indicated on the asymmetrical disrupt of their bonds. The formation of acyclic and alicyclic monoterpene hydrocarbons, succinic anhydride, diols, alcohols, alkenes, and water was observed. It indicated mainly on the β-elimination reactions during their pyrolysis. Also, β-elimination reactions of esters are mainly expected in air. Initially, it resulted in the formation of acyclic and alicyclic monoterpene hydrocarbons, hydroxyl compounds (diols, alcohols), and its β-elimination products: aldehydes, alkenes, and water. However, the presence of oxygen in the medium causes the partial decarboxylation and oxygenation of aldehydes and thus the formation of alkenes and carbon dioxide. In addition, the beginning of evaporation of succinic anhydride was detected at T _max1. At T _max2 the evaporation of succinic anhydride, their partial decarboxylation to CO₂, the small amounts of diols, alcohols, and aldehyde fragments were indicated. Finally, succinic anhydride, water, and carbon dioxide were only observed during decomposition of studied esters in air.     

Regioselective enzymatic acylation of vicinal diols of steroids

Monoacylated derivatives of a complete set of 2,3- and 3,4-vicinal diols of steroids were prepared by regioselective lipase-catalysed transesterification reactions. The enzymes displayed different selectivities towards the vicinal diols depending on the configuration of the hydroxyl groups.     

一种新型的烯烃邻羟基乙酰氧基化反应

烯烃有多种氧化方式,依试剂和反应条件的不同,可被转化为各种相应的产物。最近,Truesdale等报道,在铋酸钠和乙酸的存在下,烯烃可以直接被氧化为相应的邻羟基乙酸酯,但产率较低(10～40％),反应时间亦较长(3～24h)。Morimoto等以乙酸钴对芳基烯烃进行氧化,     

Ligand size distribution of phenanthroline-functionalized polyethylene glycol-iron(II) complexes determined by electrospray ionization mass spectrometry and computer simulation

The complex formation in solution, and the gas-phase dissociation of a phenanthrolineterminated poly(ethylene glycol) with Fe²⁺ ions were investigated. The size distribution of poly(ethylene glycol)-α-monomethyl-ω-5-[1,10]phenanthroline (mPEG_phen) was determined by electrospray ionization mass spectrometry (ESI-MS). Based on the measured ligand size distribution of mPEG_phen by ESI-MS, the 1:3 complex formation (Fe²⁺/mPEG_Phen) was computer-simulated as a pure random assembly process. The simulated distribution fits excellently to that of the complex Fe(mPEG_phen)₃²⁺ determined from the ESI-MS intensities. In addition, the collision-induced dissociation (CID) of the Fe(mPEG_phen)₃²⁺ complex was also studied by tandem mass spectrometry (ESI-MS/MS) and by computer simulation, as well. The ESI-MS/MS intensity distribution of the Fe(mPEG_phen)₂²⁺ formed from Fe(mPEG_phen)₃²⁺ by the loss of an mPEG_phen ligand under CID conditions fits quite well to the calculated one.     

气相色谱法检测工业用乙二醇纯度及杂质

以Rtx-624色谱柱（30 m×0.32 mm×1.8 μm）为分析柱进行分析，采用校正面积归一化法，建立了检测工业用乙二醇纯度及其中有机杂质的气相色谱分析法。该法可检测传统乙烯法制得的乙二醇中固有杂质二乙二醇、三乙二醇和1，3-二氧杂烷-2-甲醇，同时也适用于检测草酸酯加氢法制得的乙二醇中的新杂质（1，2-丁二醇、1，4-丁二醇、1，2-己二醇、碳酸乙烯酯等）。结果表明，该法具有良好的重复性和较高的检测灵敏度，检出限最低可达0.0002%（质量分数），回收率在91.2%~105.4%之间。该法在乙二醇生产控制、产品检测、市场贸易等过程中具有良好的应用前景。     

Interfacial syntheses of polyphosphonate and polyphosphate esters. I. Effects of alkaline medium

The effects on polymer yield and viscosity in the interfacial condensation of hydroquinone with phenylphosphonic dichloride as a function of the pH of the aqueous medium are reported. Reactions competing with polymer formation are discussed. The beneficial advantages in the use of soluble buffers or bases of limited water solubility to control pH are contrasted with results of conventionally used sodium hydroxide. The results of investigations of other comer pairs for which reaction conditions have not been optimized are also reported; desoxyribose and the diols: thymidine, resorcinol, 2,5-dichlorohydroquinone, 1,3-dihydroxyacetone, 1,4-butanediol, tartaric acid, ethylene glycol, and 2,2-dimethyl-1,3-propanediol are tabulated.     

Protein-resistant self-assembled monolayers on gold with latent aldehyde functions

In the present study, oligo(ethylene glycol) (OEG)-linked alkanethiols were synthesized which carry a vicinal diol on one end of the OEG chain. After self-assembled monolayer (SAM) formation on gold, the vicinal diols were converted into aldehyde functions by exposure to aqueous NaIO4, as previously used for SAMs with OEG chains buried in the center of the SAM [Jang et al. Nano Lett. 2003, 3, 691-694]. Mixed SAMs with latent aldehydes on 5% of the OEG termini showed high protein resistance, which greatly slowed the kinetics of protein coupling on the time scale of minutes. Small bioligands (such as biocytin hydrazide) or small heterobifunctional crosslinkers (maleimidopropionyl hydrazide, pyridyldithiopropionyl hydrazide) with hydrazide functions were efficiently bound to the aldehyde functions on the SAM, providing for specific capture of streptavidin or for fast covalent binding of proteins with free thiols or maleimide functions, respectively. In conclusion, OEG-terminated SAMs with latent aldehydes serve as protein-resistant sensor surfaces which are easily functionalized with small ligands or with heterobifunctional crosslinkers to which the bait molecule is attached in a subsequent step.     

Kinetics and mechanism of the oxidation of some diols by benzyltrimethylammoniumtribromide

The kinetics of oxidation of five vicinal and four non-vicinal diols, and two of their monoethers by benzyltrimethylammonium tribromide (BTMAB) have been studied in 3:7 (v/v) acetic acid-water mixture. The vicinal diols yield the carbonyl compounds arising out of the glycol bond fission while the other diols give the hydroxycarbonyl compounds. The reaction is first-order with respect to BTMAB. Michaelis-Menten type kinetics is observed with respect to diol. Addition of benzyltrimethylammonium chloride does not affect the rate. Tribromide ion is postulated to be the reactive oxidizing species. Oxidation of [1,1,2,2-²H₄] ethanediol shows the absence of a kinetic isotope effect. The reaction exhibits substantial solvent isotope effect. A mechanism involving a glycol-bond fission has been proposed for the oxidation of the vicinal diols. The other diols are oxidized by a hydride ion transfer to the oxidant, as are the monohydric alcohols.