High-productivity continuous biofilm reactor for butanol production

Corn steep liquor (CSL), a byproduct of the corn wet-milling process, was used in an immobilized cell continuous biofilm reactor to replace the expensive P2 medium ingredients. The use of CSL resulted in the production of 6.29 g/L of total acetone-butanol-ethanol (ABE) as compared with 6.86 g/L in a control experiment. These studies were performed at a dilution rate of 0.32 h⁻¹. The productivities in the control and CSL experiment were 2.19 and 2.01 g/(L·h), respectively. Although the use of CSL resulted in a 10% decrease in productivity, it is viewed that its application would be economical compared to P2 medium. Hence, CSL may be used to replace the P2 medium. It was also demonstrated that inclusion of butyrate into the feed was beneficial to the butanol fermentation. A control experiment produced 4.77 g/L of total ABE, and the experiment with supplemented sodium butyrate produced 5.70 g/L of total ABE. The butanol concentration increased from 3.14 to 4.04 g/L. Inclusion of acetate in the feed medium of the immobilized cell biofilm reactor was not found to be beneficial for the ABE fermentation, as reported for the batch ABE fermentation. Names are necessary to report factually on available data. However, the USDA neither guarantees nor warrants the standard of the product, and the use of the names by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Säurekatalysierte Umlagerungen von 1,5-Dimethyl-6-methyliden-tricyclo[3.2.1.02,7]oct-3-en-8endo-olen

Acid Catalysed Rearrangement of 1,5-Dimethyl-6-methyliden-tricyclo[3.2.1.0^2,7]oct-3-en-8endo-ols The tricyclic alcohols 2,3,4 and 6 (Scheme 1) are synthesized by the reaction of the tricyclic ketone 1 with sodiumborohydrid or metalloorganic reagents. Their configuration at C(8) is determined by NMR. in the presence of Eu(fod)₃. The exo-attack of 1 by the nucleophil forming the endo-alcohol is favored, the π-electrons of C(3) = C(4) hindering the endo-attack. On treatment with sulfuric acid in dioxane/water at 25° the tertiary alcohols yield aryl-substituted ketones. 3 gives in 78.5% yield a mixture of the 3-(dimethylphenyl)-2-butanones 12 and 13 , in addition to 16.5% of (2,3,4-trimethylphenyl)-2-propanon ( 14 ) (Scheme 2). The alcohols 4 and 6 yield mixtures of the 2-(dimethylphenyl)-3-pentanones 19 and 20 (72%), and 2-(dimethylphenyl)-propiophenones 21 and 22 (68%), respectively (Scheme 2). In the case of the secondary alcohol 2 mainly products derived from hydration at the C(6), C(9) double bond are formed, namely the mixture of diols 23 and 24 (21%), and the mixture of the isomeric 2-(dimethylphenyl)propanals 25, 26 and 27 (3%) (Scheme 3). - The structures of 12–14, 19/20, 21/22, 23/24 and 25/26/27 were established by spectroscopic data. In the case of 12 and 13 the degradation of their mixture to the known 1-(dimethylphenyl)ethanols 17/18 confirmed the assignment. - The most probable mechanism for the rearrangement of 3 is shown in Schemes 4 and 5. The reaction proceeds from 3 through a, b and g to 12 and 13; 14 is formed via e, f and i . In the case of 4 and 6 only the reaction analogue to 3 → a → b → g ?12/13 takes place. The isomeric aldehyds 25–27 formed from 2 could have the structures s, t , and v . The former two could be generated in a similar way as 12/13 from 3 , the latter one as shown in Scheme 8.     

Über die Carotinoide Flavoxanthin und Chrysanthemaxanthin: 1H-NMR.-, 13C-NMR.- und Massen-Spektren und absolute Konfiguration. (Kritische Überprüfung veröffentlichter chemischer und physikalischer Daten)

On the Carotenoids Flavoxanthin and Chrysanthemaxanthin: ¹H-NMR., ¹³C-NMR. and Mass Spectra, Absolute Configuration, Survey of Published Data Very pure flavoxanthin ( 1 ) and chrysanthemaxanthin ( 2 ) have been reisolated from flower heads of Taraxacum officinale. Both compounds were characterized by chromatographic, chemical and chiroptical data and extensive NMR. measurements. Examination of many published data on 1 and 2 led to the conclusion that flavoxanthin has often been mistaken for chrysanthemaxanthin and vice versa. Chemical degradation of 1 and 2 to (?)-loliolide ( 5 ) coupled with NMR. evidence (ASIS, spin-decoupling, NOE) allowed the assignment of the absolute configurations of 1 and 2 . Thus (+)-flavoxanthin is (3S,5R,8R, 3′R,6′R)-5, 8-epoxy-5, 8-dihydro-β, ε-carotene-3, 3′-diol and (+)-chrysanthemaxanthin its C(8)-epimer.     

Vapor pressure of R227ea + ethanol at 343.13 K by molecular simulation

A new molecular model for 1,1,1,2,3,3,3-heptafluoropropane (R227ea) was developed on the basis of quantum chemical calculations and optimized using experimental vapor pressure and bubble density data. In combination with an existing model for ethanol, a molecular model for the binary mixture R227ea + ethanol was defined, using the Lorentz–Berthelot combining rule. It was validated at 283.17 K, where, considering the statistical uncertainties, it agrees to the experimental vapor pressure. The vapor–liquid equilibrium, comprising both bubble line and dew line data, was predicted at 343.13 K by molecular simulation. The Peng–Robinson equation of state fails for this system.     

Field desorption mass spectrometry of 1-methylpyridinium salts

Quaternary pyridinium salts were investigated by field desorption, field ionization and electron impact mass spectrometry. Thermal decomposition of the salts under field desorption conditions was found to give very abundant volatile products, identified as the dihydro analogues and the ‘methides’ of the cations. The formation of the volatile compounds, especially those with molecular weights corresponding to those of the (cation ?1), (cation +1) and (cation +13) was studied in detail by deuterium and ¹³C labelling experiments.     

Reaktionen von 2- und 3-phenylsubstituierten Alkylakyliden-iminium-Ionen in der Gasphase. 5. Mitteilung über stossinduzierte Fragmentierungen von felddesorbierten Kationen

Reactions of 2- and 3-Phenyl Substituted Alkylalkylidene Iminium Ions in the Gas Phase The collision-induced fragmentations of 2- and 3-phenyl substituted alkylalkylidene iminium ions are reported. Besides the homolytic cleavage of the azaallyl bond a nucleophilic attack of the unsubstituted phenyl group at the iminium function is observed in the gas phase, yielding carbonium ions such as cyclopropanspirobenzenium ( 3 ), indanylium ( 10 ) and indenylium ions ( 11 ).     

High pressure-promoted cycloadditions of ketene acetals and α,β-unsaturated aldehydes and ketones

Cycloadditions of ketene acetals with α,β-unsaturated carbonyl compounds are strongly promoted by high pressure. The influence of the solvent and the substitution pattern on the product distribution at 12 kBar has been investigated. In the polar solvent, acetonitrile, α,β-unsaturated aldehydes not having large β-substituents, yield mainly cyclobutane aldehydes, which are minor products at normal pressure. The products can be transformed under basic conditions without ring opening.     

Konstitution und absolute Konfiguration der Rhoeadin-Alkaloide (+)-Alpinigenin und (+)-cis-Alpinigenin

The constitution and absolute configuration of the rhoeadine alkaloids (+)-alpinigenine and (+)-cis-alpinigenine. The fundamental structure of the hemi-acetal phenylbenzazepine alkaloid (+)-alpinigenine ( 1 ), isolated from Papaver bracteatum LINDL ., was derived essentially from ¹H-NMR.- and mass-spectra of 1 and its derivatives 7, 10 and 14 (cf. Scheme 2). The positioning of the four methoxy groups in the two aromatic rings could be deduced from the ¹H-NMR.-spectra of the N-oxides 14 and 15 in which, as a result of favourable sterical and conformational behaviour, an interaction exists between the N-oxide oxygen atom and one of the two ortho protons in ring C. The B/D-trans-fused 1 undergoes isomerization in 1N HCl to cis-alpinigenine ( 16 ). A stereochemical correlation between bases in the trans-and cis-series was enabled via an Emde degradation of the corresponding methylacetal-methyliodides 21 resp. 19 leading to the enantiomeric isochroman derivatives 22 resp. 23 which are achiral at C (2) (Scheme 4). The configuration at C (14) in the hemi-acetals (eg. 1 and 16 ) and the methyl ethers (eg. 7 and 8 ) is discussed in detail (cf. Scheme 7). (+)-Alpinigenine ( 1 ) has the (1S, 2R, 14R) configuration and (+)-cis-alpinigenine ( 16 ), in chloroform or acetone solution, the (1R, 2R, 14R) configuration.     

Employing the structural diversity of nature: development of modular dipeptide-analogue ligands for ruthenium-catalyzed enantioselective transfer hydrogenation of ketones

A library of novel dipeptide-analogue ligands based on the combination of tert-butoxycarbonyl(N-Boc)-protected alpha-amino acids and chiral vicinal amino alcohols were prepared. These highly modular ligands were combined with [[RuCl(2)(p-cymene)](2)] and the resulting metal complexes were screened as catalysts for the enantioselective reduction of acetophenone under transfer hydrogenation conditions using 2-propanol as the hydrogen donor. Excellent enantioselectivity of 1-phenylethanol (up to 98 % ee) was achieved with several of the novel catalysts. Although most of the ligands contained two stereocenters, it was demonstrated that the absolute configuration of the product alcohol was determined by the configuration of the amino acid part of the ligand. Employing ligands based on L-amino acids generated S-configured products, and catalysts based on D-amino acids favored the formation of the R-configured alcohol. The combination N-Boc-L-alanine and (R)-phenylglycinol (Boc-L-Ab) or its enantiomer (N-Boc-D-alanine and (S)-phenylglycinol, Boc-D-Aa) proved to be the best ligands for the reduction process. Transfer hydrogenation of a number of aryl alkyl ketones were evaluated and excellent enantioselectivity, up to 96 % ee, was obtained.     

Determination of polycyclic aromatic sulfur heterocycles (PASH) in diesel fuel by high performance liquid chromatography and photodiode-array detection

An oxidation method (sulfone method) for the determination of polycyclic aromatic sulfur heterocycles (PASH) in diesel fuel is presented. The aromatic fraction of a diesel fuel, isolated by solid phase extraction, is oxidized under controlled conditions with hydrogen peroxide. The oxidation products, mainly methylated dibenzosulfone, are determined and quantified directly, without further clean-up, by HPLC with photodiode-array detection.