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This work proves for the first time the bioelectrochemical production of butyrate from CO2 as a sole carbon source. The highest concentration of butyrate achieved was 20.2 mMC, with a maximum butyrate production rate of 1.82 mMC d-1. The electrochemical characterisation demonstrated that the CO2 reduction to butyrate was hydrogen driven. Production of ethanol and butanol was also observed opening up the potential for biofuel production.

A facile fluorescent method was developed to quantitatively monitor the hydrolysis kinetics of nonfluorescent esters by using a fluorecent endo-functionalized molecular tube and its recognition ability towards small polar molecules in water. It is possible to determine the apparent rate constants and study the structure-activity relationship.

Just add water! The title reaction is catalyzed by an acridine-based pincer complex (1, see scheme). This one-step transformation uses water as the only reagent in the absence of additional bases, oxidants, or reductants. Cyclization of 1,4-diaminobutane and 1,6-diaminohexane catalyzed by 1 leads to the formation of pyrrolidine and azepane, respectively. Copyright

The gas-phase acidity of a series of phosphines and their corresponding phosphine·borane derivatives was measured by FT-ICR techniques. BH 3 attachment leads to a substantial increase of the intrinsic acidity of the system (from 80 to 110 kJ mol-1). This acidity-enhancing effect of BH3 is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. This indicates that the enhancement of the acidity of protic acids by Lewis acids usually observed in solution also occurs in the gas phase. High- level DFT calculations reveal that this acidity enhancement is essentially due to stronger stabilization of the anion with respect to the neutral species on BH3 association, due to a stronger electron donor ability of P in the anion and better dispersion of the negative charge in the system when the BH3 group is present. Our study also shows that deprotonation of ClCH2PH2 and ClCH 2PH2·BH3 is followed by chloride departure. For the latter compound deprotonation at the BH3 group is found to be more favorable than PH2 deprotonation, and the subsequent loss of Cl- is kinetically favored with respect to loss of Cl - in a typical SN2 process. Hence, ClCH2PH 2·BH3 is the only phosphine·borane adduct included in this study which behaves as a boron acid rather than as a phosphorus acid.

(Metrix Presented) Design, synthesis, and esterase and ion channel activity of a novel barrel-stave supramolecule with hydrophobic exterior and histidine-rich interior are reported. Voltage-dependent binding of pyrenyl-8-oxy-1,3,6-trisulfonates by histidi

The rates of exchange of the 2,4,6-trimethylphenolate ion between dimeric lithium 2,4,6-trimethylphenolate-d9 and a series of 2,4,6-trimethylphenyl esters [2,4,6-(CH3)3C6H2COOCH2R; R = CHs

The kinetics of cleavage of m- and p-nitrophenyl alakanoates by 'hydroxypropyl-β-cyclodextrin' (Hp-β-CD) in basic aqueous solution vary significantly with the chain length of the esters (C2 to C10).For both series of esters with short chains (C2 to C6) simple saturation kinetics are observed, indicative of 1:1 (ester:CD) binding and reaction of one molecule of ester with one molecule of Hp-β-CD.For longer chains, there is also a cleavage process involving two molecules of Hp-β-CD.This type of behaviour was not found previously for the same esters reacting with α-CD and with β-CD but it has been observed for some carboxynitrophenyl alkanoates.With the longest esters there is also evidence of productive 1:2 (ester:CD) binding.For the 1:1 binding, there is a linear dependence of the strength on acyl chain length and the close similarity of the dissociation constants for the two series of esters implicate inclusion of the alkyl chains of the esters acyl groups.Transition-state binding is more complex: for the meta-nitro isomers aryl-group inclusion appears dominant whereas for the para isomers there seems to be a switch from aryl-group inclusion to acyl-group inclusion, occurring at a chain length of C6-C7.

The enthalpies of hydrolysis of the monocyclic lactones from γ-butyrolactone to tridecanolactone were determined calorimetrically, and the acyclic ethyl having the number of atoms were studied in the fashion. The enthalpies of reduction of the lactones to the corresponding α,ω-alkanediols with lithium triethylborohydride also were determined. The enthalpies of formation of the lactones and the ethyl esters were derived from these data. They were converted to values for the gas phase by measuring the enthalpies of vaporization of ethyl esters and of lactones. In the of γ-butyrolactone and δ-valerolactone, the enthalpies of formation were in good accord with the previously reported values determined via combustion calorimetry. The strain energies of the lactones were obtained via isodesmic reactions. Valerolactone had a strain energy of 11 kcal/mol, and the largest strain energy was found with octanolactone (13 kcal/mol). The conformations of γ-butyrolactone and δ-valerolactone were studied via MP2/6-31G* geometry optimizations, and the conformations of the other lactones were studied with use of the molecular mechanics program MM3. The energies of the lactones estimated via molecular mechanics were compared with the experimental results.

The kinetics of ester cleavage of 4-carboxy-2-nitrophenyl alkanoates (C2, C4, C6, C7, C8) in aqueous base containing α- or β-cyclodextrin (α- or β-CD) indicate that for the three longer esters there are processes involving two CD molecules which are quite distinct: with α-CD a 2:1 binding leads to inhibition; with β-CD a second-order process provides catalysis.

γ-Cyclodextrin-catalyzed hydrolysis of p-nitrophenyl esters bearing a long alkyl chain proceeded with larger rate acceleration than those with a short alkyl chain.Such rate acceleration behavior was not observed with β-cyclodextrin.The results suggest that the esters with a long alkyl chain take a folded structure (Type A) in the γ-cyclodextrin cavity.

Infrared spectroscopy has been employed to study the chemisorption of a number of unsymmetrical ketones, RCOMe, onto tin(IV) oxide.In every case, the final product was the surface carboxylate, RCO2-(ads).The data suggested a mechanism involving initial coordination of the ketone to a surface tin site, followed by nucleophilic attack of a neighbouring hydroxyl group at the carbonyl carbon atom.

Kinetics of ruthenium(III) chloride catalysed oxidation of acetone, ethylmethyl ketone, isobutylmethyl ketone, pentan-2-one, cyclopentanone and cyclohexanone by sodium metaperiodate in aqueous alkaline medium at constant ionic strength is reported.The order with respect to (IO4)(1-) is found to be zero.The order with respect to (substrate) is unity for acetone, ethylmethyl ketone, isobutylmethyl ketone and cyclopentanone, whereas, pentan-2-one and cyclohexanone exhibit fractional dependence on substrate, in the entire range of substrate concentration studied.Strikingly, the order with respect to is fractional in case of the ketones where substrate dependence is unity and unity where the substrate dependence is fractional.The reaction rate increases linearly following a nearly unit dependence on (OH)(1-) at lower concentration of alkali and levels off after a particular (OH)(1-).The activation parameters have been evaluated.A suitable mechanism has been postulated and rate laws have been deduced.