Sorbitol can be produced not only chemically but also biotechnologically

Sorbitol, a polyol found in many fruits, is attracting increasing industrial interest as a sweetener, humectant, texturizer, and softener. It is principally produced by chemical means. The bacterium Zymomonas mobilis is able to produce sorbitol together with gluconic acid from fructose and glucose, respectively. This is possible in a one-step reaction via the enzyme glucose-fructose oxidoreductase, so far only known from Z. mobilis. The possibilities for the production of sorbitol by Z. mobilis are discussed also under the aspect of an industrial process and compared with the current chemical as well as other microbiologic processes. The production process by Z. mobilis shows economic possibilities for certain countries, such as Brazil, considering only the products sorbitol and ethanol as an important byproduct. For the other byproduct, gluconic acid, further studies for its partial substitution must be conducted.     

1H and 13C NMR assignments of new methoxylated furanoflavonoids from Lonchocarpus araripensis

Two new polymethoxylated flavonoids, 2',5',6'-trimethoxy-[2',3' : 3',4']furano dihydrochalcone and 2,4',4,5-tetramethoxy-[2',3' : 6,7]-furanodihydroaurone, were isolated from the root barks of Lonchocarpus araripensis, along with the known compounds 3,4,5,6-tetramethoxy-[2',3' : 7,8]-furanoflavan, 3,6-dimethoxy-1',1'-dimethylcromene-[2',3' : 7,8]-flavone, 3',4'-methylenodioxy-5,6-dimethoxy-[2',3' : 7,8]-furanoflavone, 3,5,6-trimethoxy-[2',3' : 7,8]-furanoflavanone, 3,5,6-trimethoxy-[2',3' : 7,8]-furanoflavone, and 6alpha-hydroxy-medicarpin. The complete (1)H and (13)C NMR assignments of the new furan flavonoids were performed using 1D and 2D pulse sequences, including COSY, HSQC, and HMBC experiments, and comparison with spectral data for analog compounds from the literature, particularly for the new furanodihydroaurone because of several inconsistencies on the carbonyl chemical shifts from the literature.     

Synthesis of new chiral aliphatic amino diselenides and their application as catalysts for the enantioselective addition of diethylzinc to aldehydes

[reaction: see text] A set of chiral aliphatic amino diselenides have been synthesized from readily available starting materials in a straightforward synthetic route via the ring-opening reaction of the parent aziridines. These ligands have been tested as catalysts for the enantioselective addition of diethylzinc to aldehydes. The influence of the alkyl group substituents on the stereoselectivity has been studied, and in the best case, an enantiomeric excess up to 99% could be obtained by using only 0.5 mol % of the chiral diselenide 3a.     

1-substituted beta-carbolines by a Pictet-Spengler cyclization with thioortho esters and carbon-carbon bond formation via N-sulfonyl iminium ions generated from N,S-sulfonyl acetals

The reaction of N-tosyltryptamines with thioortho esters, leading to 1-thiosubstituted tetrahydro-beta-carbolines under modified Pictet-Spengler conditions, is described. The 1-heterosubstituted beta-carbolines furnished 1-substituted beta-carbolines upon reaction with Grignard reagents and silyl derivatives under Lewis acid promotion. [reaction: see text]     

Simple formulae for heavy ion subcoulomb transfer probabilities. Application to one and two-proton transfers in bismuth

A simple analytical formula is given to express the transition probability in a quasi-elastic transfer reaction. This formula is derived from the DWBA amplitude, using assumptions based on the fact that the main contribution to the DWBA integral comes from a narrow domain of distances of approach. Recoil effects are taken into account. This method is applied to calculate the excitation functions for one and two-proton transfer reactions induced in²⁰⁹Bi by heavy ions, below and near the barrier. The curves obtained are compared to the excitation functions measured for the production of residual²¹⁰Po and²¹¹At. The corresponding transfer reactions involve excitation energiesE ^* of the residue lying in the range 0–8 MeV. This excitation energy is taken as a free parameter in the calculation, and the valuesE _opt ^* which lead to the best agreement between the calculated and experimental curves are consistent with the classical values for the optimum reactionQ-values. Nuclear Reactions. Simplified transition probability for quasi-elastic transfer. Calculatedσ(E) ²⁰⁹Bi(X, Y)²¹⁰Po,²¹¹At,X=¹⁴N,¹⁶O,¹⁹F,⁴⁰Ar,⁴⁰Ca,⁵⁶Fe,⁶³Cu near threshold. Compared experimental data. Deduced optimum excitation energy.     

Birefringent hydrogels based on PAAm and lyotropic liquid crystal: Optical, morphological and hydrophilic characterization

In this work, hydrogels of polyacrylamide (or PAAm) with confined lyotropic liquid crystal (potassium laurate-decanol-water, KL-DeOH-H₂O) (or LLC) were synthesized. The hydrogels were characterized by polarized optical microscopy (POM), refractometry, optical transmission, scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS). Besides these techniques, the hydrophilicity of hydrogels was characterized by the degree of swelling. Based on POM, it was observed that the texture of the birefringent hydrogels obtained depends on their cross-linking density, and that it is formed soon after hydrogel synthesis. Refractometry results indicated an behavior antagonist to that obtained for the system constituted by thermotropic liquid crystal inserted into the PAAm lattice in relation to the dependence of Δn on the AAm concentration and the optical transmittance. SEM micrographs show that birefringent hydrogels present rougher surface when compared to the surface of PAAm hydrogels. For the same AAm concentrations, it was observed that the hydrogels with confined LLC present larger swelling values (Q) when compared to those of PAAm hydrogels. The loss of water by birefringent hydrogels is twofold slower than that of PAAm hydrogels. Hydrogels formed by PAAm and lyotropic liquid crystal synthesized in this work can be potentially used in optical devices.     

1H and 13C NMR assignments for two new cordiaquinones from roots of Cordia leucocephala

From the roots of Cordia leucocephala (Boraginaceae), two new meroterpenoid naphthoquinones, 6‐[10‐(12,12‐dimethyl‐13α‐hydroxy‐16‐methenyl‐cyclohexyl)ethyl]‐1,4‐naphthalenedione (cordiaquinone L) and 5‐methyl‐6‐[10‐(12,12‐dimethyl‐13β‐hydroxy‐16‐methenyl‐cyclohexyl)methyl‐1,4‐naphthalenedione (cordiaquinone M) were isolated. Their structures were elucidated after detailed 1D and 2D NMR (COSY, HSQC, HMBC and NOESY) data analyses and comparison with literature data for analogous compounds. Copyright © 2008 John Wiley & Sons, Ltd.     

Total assignment of 1H and 13C NMR spectra of the alkaloid 3,3-diisopentenyl-N-methyl-2,4-quinoldione and novel reaction derivatives

One- and two-dimensional NMR experiments were used for the unambiguous assignment of the 1H and 13C NMR chemical shifts of 3,3-diisopentenyl-N-methyl-2,4-quinoldione and five novel reaction derivatives.     

Conjugate phenylselenolactonization coupled with allylic selenoxide rearrangement for functionalizing dienylacetic acids

Use of the title reactions for the regioselective, and stereoselective functionalization of a range of dienylacetic acids, available from simple organoiron chemistry, is presented.