Extraction of boric acid with aliphatic 1,3-diols and other chelating agents

Some 40 compounds have been investigated with reference to their boric acid extraction properties. Preliminary tests showed that aliphatic 1,3-diols with at least 6 carbon atoms possess superior extraction qualities compared to diketones, hydroxyketones, hydroxyamines and other species investigated. The 1,3-diols were then further studied with attention to size and steric configuration. The extraction equilibria involved were thoroughly investigated for 2,2-diphenylpropanediol-1,3 (DPPD). The constants derived showed that this diol, in spite of its large hydrophobic groups, has a smaller reaction constant than the previously investigated 2,2-diethylpropanediol-1,3 (DEPD) and 2-ethylhexanediol-l,3 (EHD). It was found that the extraction capacity has a maximum for 1,3-diols with 8-9 carbon atoms. The largest boron distribution was obtained with 2,2,4-trimethylpentanediol-1,3 (TMPD), which seems to form a very stable ester with boric acid in chloroform at room temperature. The ester formation is supported by n.m.r. and i.r. spectra. The effect of geminal substituents in the 2-position is discussed.     

A theoretical exploration of the 1,3-dipolar cycloadditions onto the sidewalls of (n,n) armchair single-wall carbon nanotubes

The viability of 1,3-dipolar cycloadditions of a series of 1,3-dipolar molecules (azomethine ylide, ozone, nitrone, nitrile imine, nitrile ylide, nitrile oxide, diazomethane, and methyl azide) onto the sidewalls of carbon nanotubes has been assessed theoretically by means of a two-layered ONIOM approach. The theoretical calculations predict the following: (i) other than the 18-valence-electron azomethine ylide and ozone, the 16-valence-electron nitrile ylide and nitrile imine are the best candidates for experimentalists to try; (ii) upon 1,3-dipolar cycloaddition, a 1,3-diople molecule is di-sigma-bonded to a pair of carbon atoms on the sidewall of SWNT, forming a five-membered ring surface species; (iii) the as-formed 1,3-dipole-SWNT bonding is much weaker than that in the products of the molecular 1,3-DC reactions and can be plausibly broken by heating at elevated temperatures; (iv) the sidewalls of the armchair (n,n) SWNTs (n = 5-10) are subject to the 1,3-DCs of ozone and azomethine ylides; (v) both the 1,3-DC reactivity and retro-1,3-DC reactivity are moderately dependent on the diameters of SWNTs, implying the feasibility of making use of the heterogeneous 1,3-DC chemistry to purify and separate SWNTs diameter-specifically.     

Measurement of acrolein and 1,3-butadiene in a single puff of cigarette smoke using lead-salt tunable diode laser infrared spectroscopy

Acrolein and 1,3-butadiene in cigarette smoke generally are measured using two separate analytical methods, a carbonyl derivative HPLC method for acrolein and a volatile organic compound (VOC) GC/MS method for 1,3-butadiene. However, a single analytical method having improved sensitivity and real-time per puff measurement will offer more specific information for evaluating experimental carbon filtered cigarettes designed to reduce the smoke deliveries of these constituents. This paper describes an infrared technique using two lead-salt tunable diode lasers (TDLs) operating with liquid nitrogen cooling with emissions at 958.8 cm(-1) and 891.0 cm(-1) respectively for the simultaneous measurement of acrolein and 1,3-butadiene, respectively, in each puff of mainstream cigarette smoke in real time. The dual TDL system uses a 3.1l volume, 100 m astigmatic multiple pass absorption gas cell. Quantitation is based on a spectral fit that uses previously determined infrared molecular line parameters generated in our laboratory, including line positions, line strengths and nitrogen-broadened half-widths for these species. Since acrolein and ethylene absorption lines overlap and 1,3-butadiene, ethylene and propylene absorption lines overlap, the per puff deliveries of ethylene and propylene were determined since their overlapping absorption lines must be taken into account by the spectral fit. The acrolein and 1,3-butadiene total cigarette deliveries for the 1R5F Kentucky Reference cigarette were in agreement with the HPLC and GC/MS methods, respectively. The limit of detection (LOD) for 1,3-butadiene and acrolein was 4 ng/puff and 24 ng/puff, respectively, which is more than adequate to determine at which puff they break through the carbon filter. The retention and breakthrough behavior for the two primary smoke constituents depend on the cigarette design and characteristics of the carbon filter being evaluated.     

Thermal chemistry of bicyclo[4.2.0]oct-2-enes

At 300 degrees C, bicyclo[4.2.0]oct-2-ene (1) isomerizes to bicyclo[2.2.2]oct-2-ene (2) via a formal [1,3] sigmatropic carbon migration. Deuterium labels at C7 and C8 were employed to probe for two-centered stereomutation resulting from C1-C6 cleavage and for one-centered stereomutation resulting from C1-C8 cleavage, respectively. In addition, deuterium labeling allowed for the elucidation of the stereochemical preference of the [1,3] migration of 1 to 2. The two possible [1,3] carbon shift outcomes reflect a slight preference for migration with inversion rather than retention of stereochemistry; the si/sr product ratio is approximately 1.4. One-centered stereomutation is the dominant process in the thermal manifold of 1, with lesser amounts of fragmentation and [1,3] carbon migration processes being observed. All of these observations are consistent with a long-lived, conformationally promiscuous diradical intermediate.     

Reaction of the 1,3-phenylenediacetatodicopper(I) pyridine complex with dioxygen,hydrogen peroxide and carbon monoxide

Summary The reactions of 1,3-phenylenediacetatodicopper(I) pyridine, prepared from 1,3-phenylenediacetatocopper(II) by metallic copper, were studied. On oxygenation, a copper-dioxygen complex was formed, whereas carbon monoxide yielded an unstable carbonyl complex. The complexes were characterised by spectroscopic measurements.     

Can 1,3-dimethylcyclobutadiene and carbon dioxide co-exist inside a supramolecular cavity?

The calculated free energy barrier at 175 K between 1,3-dimethylcyclobutadiene and carbon dioxide inside a calixarene host (ωB97XD/6-311G(d,p)+polarizable continuum solvent model) has the low value of ~8-10.5 kcal mol(-1). This value casts doubt on the recently claimed isolation and X-ray structure determination at 175 K of 1,3-dimethylcyclobutadiene and carbon dioxide as separate species inside such a cavity.     

Cationic grafting from carbon black. VII. Grafting of polyacetals by cationic ring-opening polymerization of trioxane and 1,3-dioxolane initiated by CO+ClO4− groups on carbon black

The cationic ring-opening polymerization of trioxane and 1,3-dioxolane was found to be initiated by CO⁺CIO₄^? groups on a carbon black surface, which were introduced by the reaction of COCI groups with AgCIO₄. The activation energy of the ring-opening polymerization of trioxane was estimated to be 15.5 kcal/mol. In the polymerization system, poly(oxymethylene) and poly(1,3-dioxolane) formed were effectively grafted onto carbon black depending upon the propagation of these polymers from the carbon black surface; for instance, the grafting ratio of poly(oxymethylene) onto carbon black increased with an increase in conversion and went up to about 180%. Although the grafted chain of poly(oxymethylene) was subject to stepwise thermal depolymerization from the chain ends, the thermal stability of poly(oxymethylene)-grafted carbon black was improved by acetylation of hemiformal end groups. The molecular weight of ungrafted poly(oxymethylene) formed in the polymerization was determined to be 1.8–2.0 × 10⁴. Furthermore, the copolymerization of trioxane with 1,3-dioxolane, styrene, and other comonomers initiated by CO⁺CIO₄^? groups and the thermal stability of these acetal copolymer-grafted carbon black were investigated.     

Tetracyanoethylene pi-complex chemistry. Indirect spectrophotometric determination of Diels-Alder-active 1,3-dienes

An indirect spectrophotometric method, based on the rapid Diels-Alder reaction between cisoid 1,3-dienes and tetracyanoethylene (TCNE) and the destruction of an aromatic-TCNE pi-complex, was developed to determine eleven 1,3-dienes in the 0.05-1.00 x 10(-3)M range. These dienes were: cyclopentadiene; 1,3-cyclohexadiene; trans-1,3-pentadiene; 2,4-dimethyl-1,3-pentadiene; trans-2-methyl-1,3-pentadiene; 2-methyl-1,3-butadiene; 9-methylanthracene; 9,10-dimethylanthracene; 1,6-diphenyl-1,3,5-hexatriene; 2,3-dimethyl-1,3-butadiene; and 1,4-diphenyl-1,3-butadiene. Three 1,3-dienes were determined in the 0.05-1 x 10(-4)M range: cyclopentadiene, trans-2-methyl-1,3-pentadiene, and anthracene. The limit of detection for cyclopentadiene in carbon tetrachloride solutions is 0.11 microg/ml. Fourteen 1,3-dienes were found to form stable pi-complexes and could not be determined by the proposed method. For these 1,3-dienes, the spectra of some of the complexes are reported; in addition, relative equilibrium constants for the pi-complexes of 2,5-dimethyl-2,4-hexadiene, cis-1,3-pentadiene, 4-methyl-1,3-pentadiene, and 1,3-cyclo-octadiene were estimated. An explanation of the transient colour in the 1,3-diene-TCNE Diels-Alder reaction is suggested.     

A convenient synthesis of new heterocycles from benzimidazoles and carbon suboxide

The reaction of carbon suboxide with 2-substituted benzimidazoles was investigated. By this reaction 1,3-diazino- (pyrimido-), 1,3-oxazino- and 1,3-thiazinobenzimidazole-1,3-diones are obtained.     

Stability of reactive low boiling hydrocarbons on carbon based adsorbents typically used for adsorptive enrichment and thermal desorption

In the context of evaluating air sampling methods, laboratory experiments were performed to investigate the stability of eleven selected low boiling hydrocarbons (e.g. 1,3-butadiene, isoprene) adsorbed on four different carbon based adsorbents. The carbon molecular sieves Carboxen 569, Carboxen 1003, Carbosieve SIII and the graphitized carbon black Carbotrap X were tested. The influence of storage duration on the recovery of the analytes was examined by loading the adsorbent tubes with the test compounds via a sample loop under inert gas. Furthermore, the influence of sampling the hydrocarbons continuously from air on the recovery of the analytes was investigated using a simple experimental set-up providing a flow of synthetic air spiked with the hydrocarbons. Analysis of the loaded adsorbent tubes was performed by thermal desorption and capillary gas chromatography. Losses up to 80% of 1,3-butadiene and isoprene were observed for the carbon molecular sieves, occurring even immediately after the sampling step. In contrast, no significant losses of these reactive constituents were detected for Carbotrap X over a storage time of seven days. The laboratory investigations were confirmed in a field experiment.     

Reactivity and core-ionization energies in conjugated dienes. Carbon 1s photoelectron spectroscopy of 1,3-pentadiene

The high-resolution carbon 1s photoelectron spectrum of trans-1,3-pentadiene has been resolved into contributions from the five inequivalent carbon atoms, and carbon 1s ionization energies have been assigned to each of these atoms. Spectra have also been measured for propene and 1,3-butadiene at better resolution than has previously been available. The ionization energies for the sp2 carbons are found to correlate well with activation energies for electrophilic addition and with proton affinities. Comparing the results for 1,3-pentadiene with those for ethene, propene, and 1,3-butadiene as well as with results of theoretical calculations makes it is possible to assess the effect of the terminal methyl group in 1,3-pentadiene. As in propene, the methyl group contributes electrons to the beta carbon through the pi system. In addition, there is a significant (though smaller) contribution from the methyl group to the terminal (delta) CH2 carbon, also through the pi system. Most of the effect of the methyl group is present in the ground-state molecule. There are only relatively small contributions from the methyl group to the ionization energies from redistribution of charge in the pi system in response to the removal of a core electron. In addition to these specific effects, there is an overall decrease in average ionization energy as the size of the molecule increases as well as effects that are specific to the conjugated systems in 1,3-butadiene and 1,3-pentadiene. The results provide insight into the reactivity and regioselectivity of conjugated dienes.     

多微孔活性炭的制备及对二甲苯的吸附研究

研究了以木质活性炭颗粒为原料, 通过KOH再活化的方法制备多微孔活性炭的方法。考察了活性炭和KOH的最佳质量比例, 并通过低温氮吸附、SEM、XRD等手段表征了样品的比表面、孔结构、孔分布、颗粒形貌和晶体结构;通过对含间二甲苯50 mg·L^-1的气流的吸附实验表征了所制备活性炭的二甲苯去除能力, 实验结果表明, 经过KOH再活化显著调高了样品的间二甲苯吸附容量, 这很可能和样品中发达的微孔结构有关。     

Preparation and application of odorless 1,3-propanedithiol reagents

2-Dodecyl-1,3-propanedithiol (2a) was prepared without a malodorous procedure as an odorless reagent that was usable in place of 1,3-propanedithiol (1) in organic reactions, e.g., in the reduction of azides and protection of carbonyl groups. The 1,3-dithioacetals obtained in the latter reaction were effectively reduced to methylene with Raney nickel and reconverted to the original carbonyl compounds by hydrolysis with N-bromosuccinimide in aqueous 2-butanone. In addition, the anion of 1,3-dithiane prepared from 2a and formaldehyde could be utilized as a synthetic equivalent of an anionic carbonyl carbon.     

多微孔活性炭的制备及对二甲苯的吸附研究

研究了以木质活性炭颗粒为原料,通过KOH再活化的方法制备多微孔活性炭的方法。考察了活性炭和KOH的最佳质量比例,并通过低温氮吸附、SEM、XRD等手段表征了样品的比表面、孔结构、孔分布、颗粒形貌和晶体结构;通过对含间二甲苯50mg.L-1的气流的吸附实验表征了所制备活性炭的二甲苯去除能力,实验结果表明,经过KOH再活化显著调高了样品的间二甲苯吸附容量,这很可能和样品中发达的微孔结构有关。     

Catalytic Reaction of Ethyl 2-Diazo-3-oxobutanoate with Alcohols

The effect of the structure of alcohols on their reaction with ethyl 2-diazo-3-oxobutanoate catalyzed by copper(II) trifluoromethanesulfonate has been studied. The corresponding ethyl 2-alkoxy-3-oxobutanoates were obtained in quantitative yield from primary alcohols. Introduction of a 1,3-dioxolane or 1,3-dioxane fragment into the alcohol molecule changes the reaction direction toward the formation of polyoxa macrocycles that are products of formal insertion of the diazo ester into the carbon–oxygen bond.     

One-pot synthesis of xanthene derivatives catalyzed by Fe(III) tetranitrophthalocyanine immobilized on activated carbon

Xanthene derivatives were synthesized by a multicomponent one-pot reaction of aromatic aldehydes, β-naphthol, and 5,5-dimethylcyclohexane-1,3-dione or 1,3-cyclohexanedione upon efficient and eco-friendly catalysis of Fe(III) tetranitrophthalocyanine immobilized on activated carbon in ethanol. The method tolerated a variety of functional groups and the process was carried out under mild conditions to give high yield of products (85–91%) in 30 min. The catalyst can be recycled without any loss in catalytic activity.     

Stability of reactive low boiling hydrocarbons on carbon based adsorbents typically used for adsorptive enrichment and thermal desorption

In the context of evaluating air sampling methods, laboratory experiments were performed to investigate the stability of eleven selected low boiling hydrocarbons (e.g. 1,3-butadiene, isoprene) adsorbed on four different carbon based adsorbents. The carbon molecular sieves Carboxen 569, Carboxen 1003, Carbosieve SIII and the graphitized carbon black Carbotrap X were tested. The influence of storage duration on the recovery of the analytes was examined by loading the adsorbent tubes with the test compounds via a sample loop under inert gas. Furthermore, the influence of sampling the hydrocarbons continuously from air on the recovery of the analytes was investigated using a simple experimental set-up providing a flow of synthetic air spiked with the hydrocarbons. Analysis of the loaded adsorbent tubes was performed by thermal desorption and capillary gas chromatography. Losses up to 80% of 1,3-butadiene and isoprene were observed for the carbon molecular sieves, occurring even immediately after the sampling step. In contrast, no significant losses of these reactive constituents were detected for Carbotrap X over a storage time of seven days. The laboratory investigations were confirmed in a field experiment. Received: 28 June 1999 / Revised: 18 August 1999 / Accepted: 23 August 1999     

Thermodynamic parameters of adsorption of adamantane and its derivatives on graphitized thermal carbon black

The adsorption equilibrium constants for adamantane, 1-fluoro-, 1-chloro-, 1,3-difluoro-, 1,3-dichloro-, 1,3-dibromo-, and 1-hydroxyadamantane, and methyl 1-adamantyl ketone were determined by gas chromatography. The results were compared with molecular statistical calculations based on the known atomic-atomic potentials of the interaction of atoms of the sorbate molecule with the C atom of graphitized thermal carbon black (GTCB). The experimental adsorption heats exceed the calculated values by 3-10 kJ mol^-1. The reasons for this divergence are discussed. The changes in the adsorption entropy show that the molecules of the studied compounds form a layer of the ideal dimeric gas on the GTCB surface upon adsorption.     

Transformations of 1,3-di-p-tolyl-5-p-toluidinomethyl-1,3,5-diazaphosphorinane initiated by electrochemical oxidation at a glassy carbon electrode

Electrochemical oxidation of 1,3-di-p-tolyl-5-p-toluidinomethyl-1,3,5-diazaphosphorinane at a glassy carbon anode yields 5,5′-spirobis(1,3-di-p-tolyl-1,3,5-diazaphosphoniarinane) perchlorate and 1,3-di-p-tolyl-5-p-toluidinomethyl-1,3-diaza-2-carbenia-5-phosphorinane perchlorate. The latter reacts on a Pt^II template to give a complex of a new diphosphine ligand.     

Kinetic Modeling of Fermentative Production of 1, 3-Propanediol by Klebsiella pneumoniae HR526 with Consideration of Multiple Product Inhibitions

During the fermentative production of 1, 3-propanediol (1,3-PD), the multiple product inhibitions cannot be negligible to accurately describe the kinetics of fermentation process. A kinetic model for fermentative production of 1,3-PD by Klebsiella pneumoniae HR526 with glycerol as carbon source under aerobic condition was proposed. The inhibitions of multiple products including 1,3-PD, 2, 3-butanediol (2,3-BD), acetate, and succinate were considered in the model. It was found that 1,3-PD, 2,3-BD, and acetate showed strong inhibitions to cell growth depending on their concentrations. The kinetic model was relatively accurate to predict the experimental data of batch, fed-batch, and continuous fermentations. The model thus can serve as a tool for further controlling and optimizing the fermentation process.